core: turn olivecore into liboakcore.so with a pure C ABI

liboakcore is now a shared library that exposes only a C ABI:
- every value class (Rational, TimeRange, Color, Bezier, AudioParams,
  SampleBuffer) and the free-function groups (StringUtils, fraction
  utils, Timecode) is wrapped in an opaque-handle C API under
  core/include/olive/core/oakcore/ (init/copy/free + self-first
  functions), implemented in core/src/capi/
- consumers keep the original C++ API unchanged through same-name
  wrapper classes that hold the handle and forward across the C
  boundary; original implementations moved to core/src/oliveimpl
  (namespace olive::core::internal) and are hidden from export
- TimeRangeList/TimeRangeListFrameIterator are reimplemented inline
  over the wrapper (iterators/containers don't cross C ABI)
- generic Value container stays internal (unused by consumers) and is
  no longer part of the public umbrella header
- hidden visibility + OAKCORE_BUILD export macro; nm shows zero
  olive::* symbols exported
- install into the platform's standard libdir (GNUInstallDirs);
  Windows DLLs next to the executables, macOS into the app bundle
- TimelineWorkArea::in/out/length now return by value: the wrapped
  TimeRange getters return values, and forwarding them through const
  references dangled (found via RenderWorkerFootageTest crash)
- tests: 9 new pure C ABI test executables (oakcore_*_test) covering
  every public C function; 4 stale legacy core tests removed (they
  targeted a long-renamed API and were never built due to a malformed
  option() that also kept OLIVECORE_BUILD_TESTS off)
- CI/CD: oakcore.dll staged for NSIS, liboakcore.so added to the
  AppImage validation list, build-tree DLL copies on Windows

.github/workflows/cd.yml

@@ -67,10 +67,12 @@ jobs:
           # The FFmpeg bridge DLL is built outside app/ and is not reachable
           # via PATH, so ntldd cannot discover it from the executables alone
           cp build/ffmpeg_bridge/bin/ffmpeg_bridge.dll app/packaging/windows/nsis/oak-editor/
+          # Same for the liboakcore DLL
+          cp build/core/oakcore.dll app/packaging/windows/nsis/oak-editor/
           windeployqt6 app/packaging/windows/nsis/oak-editor/oak-editor.exe
           # Copy all non-Qt MSYS2 DLLs recursively for every binary we ship
           cd app/packaging/windows/nsis/oak-editor
-          for binary in oak-editor.exe oak-render-worker.exe oakgl.dll oakvulkan.dll ffmpeg_bridge.dll; do
+          for binary in oak-editor.exe oak-render-worker.exe oakgl.dll oakvulkan.dll ffmpeg_bridge.dll oakcore.dll; do
             [ -f "$binary" ] || continue
             for l in $(ntldd -R "$binary" | grep -E 'mingw64|ucrt64|clang64' | sed 's/^[ \t]*//' | cut -d' ' -f3); do
               cp -v "$l" .
@@ -369,9 +371,11 @@ jobs:
           ls AppDir/usr/lib/liboakvulkan.so                  || (echo "Missing liboakvulkan.so" && exit 1)
           ls AppDir/usr/lib/libvulkan.so*                    || (echo "Missing libvulkan" && exit 1)
           ls AppDir/usr/lib/libffmpeg_bridge.so              || (echo "Missing libffmpeg_bridge.so" && exit 1)
+          ls AppDir/usr/lib/liboakcore.so                    || (echo "Missing liboakcore.so" && exit 1)
           # Ensure every shipped binary resolves all of its dependencies
           ! ldd AppDir/usr/bin/oak-editor | grep "not found"
           ! ldd AppDir/usr/bin/oak-render-worker | grep "not found"
+          ! ldd AppDir/usr/lib/liboakcore.so | grep "not found"
           ! ldd AppDir/usr/lib/liboakgl.so | grep "not found"
           ! ldd AppDir/usr/lib/liboakvulkan.so | grep "not found"
 

app/CMakeLists.txt

@@ -295,7 +295,8 @@ elseif (APPLE)
             COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:olive-render-worker> $<TARGET_BUNDLE_DIR:olive-editor>/Contents/MacOS/
             COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:oakgl> $<TARGET_BUNDLE_DIR:olive-editor>/Contents/MacOS/
             COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:ffmpeg_bridge> $<TARGET_BUNDLE_DIR:olive-editor>/Contents/MacOS/
-            COMMENT "Copying oak-render-worker, render backends, and ffmpeg_bridge into Oak.app"
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:olivecore> $<TARGET_BUNDLE_DIR:olive-editor>/Contents/MacOS/
+            COMMENT "Copying oak-render-worker, render backends, ffmpeg_bridge and liboakcore into Oak.app"
     )
     if (TARGET oakvulkan)
         add_custom_command(TARGET olive-editor POST_BUILD
@@ -307,6 +308,14 @@ elseif (UNIX)
     install(TARGETS olive-editor RUNTIME DESTINATION bin)
 endif ()
 
+if (WIN32)
+    # Windows has no RPATH: shared libraries must sit next to the executable
+    add_custom_command(TARGET olive-editor POST_BUILD
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:ffmpeg_bridge> $<TARGET_FILE_DIR:olive-editor>
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:olivecore> $<TARGET_FILE_DIR:olive-editor>
+    )
+endif ()
+
 # Set link libraries
 target_link_libraries(olive-editor PRIVATE ${OLIVE_LIBRARIES})
 target_link_libraries(libolive-editor PRIVATE ${OLIVE_LIBRARIES})

app/timeline/timelineworkarea.cpp

@@ -106,17 +106,17 @@ void TimelineWorkArea::save(QXmlStreamWriter *writer) const
 							 QString::fromStdString(this->out().to_string()));
 }
 
-const Rational &TimelineWorkArea::in() const
+Rational TimelineWorkArea::in() const
 {
 	return workarea_range_.in();
 }
 
-const Rational &TimelineWorkArea::out() const
+Rational TimelineWorkArea::out() const
 {
 	return workarea_range_.out();
 }
 
-const Rational &TimelineWorkArea::length() const
+Rational TimelineWorkArea::length() const
 {
 	return workarea_range_.length();
 }

app/timeline/timelineworkarea.h

@@ -40,9 +40,9 @@ public:
 	bool enabled() const;
 	void set_enabled(bool e);
 
-	const Rational &in() const;
-	const Rational &out() const;
-	const Rational &length() const;
+	Rational in() const;
+	Rational out() const;
+	Rational length() const;
 	const TimeRange &range() const;
 	void set_range(const TimeRange &range);
 

core/CMakeLists.txt

@@ -19,7 +19,7 @@ cmake_minimum_required(VERSION 3.13 FATAL_ERROR)
 
 project(libolivecore VERSION 1.0.0 LANGUAGES CXX)
 
-option(OLIVECORE_BUILD_TESTS ON)
+option(OLIVECORE_BUILD_TESTS "Build liboakcore tests" ON)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -36,7 +36,20 @@ if(UNIX AND NOT APPLE AND NOT DEFINED OpenGL_GL_PREFERENCE)
 endif()
 find_package(OpenGL REQUIRED)
 
-add_library(olivecore
+# liboakcore is a shared library. It exports a pure C ABI (see
+# include/olive/core/oakcore/): every public function is declared with
+# OAKCORE_API and all C++ symbols are hidden, so no C++ ABI crosses the
+# library boundary. Consumers use the wrapper headers in include/olive/core.
+add_library(olivecore SHARED
+  src/capi/audioparams.cpp
+  src/capi/bezier.cpp
+  src/capi/color.cpp
+  src/capi/fractionutils.cpp
+  src/capi/rational.cpp
+  src/capi/samplebuffer.cpp
+  src/capi/stringutils.cpp
+  src/capi/timecodefunctions.cpp
+  src/capi/timerange.cpp
   src/render/audioparams.cpp
   src/render/samplebuffer.cpp
   src/util/bezier.cpp
@@ -50,7 +63,23 @@ add_library(olivecore
   src/util/value.cpp
 )
 
+set_target_properties(olivecore PROPERTIES
+  OUTPUT_NAME oakcore
+  POSITION_INDEPENDENT_CODE ON
+  C_VISIBILITY_PRESET hidden
+  CXX_VISIBILITY_PRESET hidden
+  VISIBILITY_INLINES_HIDDEN ON
+)
+
+# OAKCORE_BUILD marks the library side of the export macros (dllexport)
+target_compile_definitions(olivecore PRIVATE OAKCORE_BUILD)
+
+# The library builds against its internal implementation headers
+# (src/oliveimpl); consumers only ever see the public C API and wrapper
+# headers (include/olive/core). oliveimpl must come first so that internal
+# sources never pick up a wrapper header by accident.
 target_include_directories(olivecore PRIVATE
+  "${CMAKE_CURRENT_SOURCE_DIR}/src/oliveimpl"
   "${CMAKE_CURRENT_SOURCE_DIR}/include/olive/core"
   "${CMAKE_SOURCE_DIR}/third_party/openfx/include/"
 )
@@ -70,8 +99,19 @@ else()
   message("   OpenTimelineIO interchange will be disabled.")
 endif()
 
-install(TARGETS olivecore)
-install(DIRECTORY "${CMAKE_CURRENT_SOURCE_DIR}/include/olive" DESTINATION "${CMAKE_INSTALL_PREFIX}/include")
+# liboakcore installs into the platform's standard library directory
+# (/usr/lib, /usr/lib64 or the Debian multiarch path), not a custom one.
+# Windows DLLs go next to the executables in bin.
+include(GNUInstallDirs)
+if (WIN32)
+  install(TARGETS olivecore
+          RUNTIME DESTINATION bin
+          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
+else ()
+  install(TARGETS olivecore
+          LIBRARY DESTINATION ${CMAKE_INSTALL_LIBDIR}
+          ARCHIVE DESTINATION ${CMAKE_INSTALL_LIBDIR})
+endif ()
 
 if (OLIVECORE_BUILD_TESTS)
   enable_testing()
@@ -82,13 +122,20 @@ if (OLIVECORE_BUILD_TESTS)
     )
     target_link_libraries(${name} PRIVATE olivecore)
     target_include_directories(${name} PRIVATE
+      "${CMAKE_CURRENT_SOURCE_DIR}/include"
       "${CMAKE_CURRENT_SOURCE_DIR}/include/olive/core"
     )
     add_test(${name} ${name})
   endfunction()
 
-  make_test(rational-test)
-  make_test(stringutils-test)
-  make_test(timecode-test)
-  make_test(timerange-test)
+  # Pure C ABI tests for the liboakcore public interface
+  make_test(oakcore_audioparams_test)
+  make_test(oakcore_bezier_test)
+  make_test(oakcore_color_test)
+  make_test(oakcore_fractionutils_test)
+  make_test(oakcore_rational_test)
+  make_test(oakcore_samplebuffer_test)
+  make_test(oakcore_stringutils_test)
+  make_test(oakcore_timecodefunctions_test)
+  make_test(oakcore_timerange_test)
 endif()

core/include/olive/core/core.h

@@ -33,6 +33,7 @@
 #include "util/tests.h"
 #include "util/timecodefunctions.h"
 #include "util/timerange.h"
-#include "util/value.h"
+// util/value.h is deliberately not part of the public API: the generic
+// Value container is unused by consumers and stays internal to the library
 
 #endif // OAK_LIBOLIVECORE_H

core/include/olive/core/oakcore/audioparams.h

@@ -0,0 +1,157 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_AUDIOPARAMS_H
+#define OAKCORE_AUDIOPARAMS_H
+
+#include <stdint.h>
+
+#include "export.h"
+#include "rational.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file audioparams.h
+ * @brief C ABI for the audio stream parameter value type
+ *
+ * Opaque handle + free functions. All returned OakAudioParams* and
+ * OakRational* are owned by the caller and must be released with
+ * oakcore_audioparams_free() / oakcore_rational_free() respectively.
+ *
+ * Sample formats cross the boundary as plain ints carrying the
+ * olive::core::SampleFormat::Format enum values (render/sampleformat.h);
+ * channel layouts are plain 64-bit masks (render/channellayout.h).
+ */
+typedef struct OakAudioParams OakAudioParams;
+
+/**
+ * Creates parameters for the given sample rate, channel layout mask and
+ * sample format. The timebase is initialized to 1/sample_rate.
+ */
+OAKCORE_API OakAudioParams *oakcore_audioparams_create(int sample_rate,
+													   uint64_t channel_layout,
+													   int format);
+
+/**
+ * Creates default (invalid) parameters: sample_rate=0, empty channel
+ * layout, invalid format.
+ */
+OAKCORE_API OakAudioParams *oakcore_audioparams_create_invalid(void);
+
+OAKCORE_API OakAudioParams *oakcore_audioparams_copy(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_free(OakAudioParams *self);
+
+OAKCORE_API int oakcore_audioparams_sample_rate(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_sample_rate(OakAudioParams *self,
+													 int sample_rate);
+
+OAKCORE_API uint64_t oakcore_audioparams_channel_layout(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_channel_layout(OakAudioParams *self,
+														uint64_t mask);
+
+OAKCORE_API OakRational *oakcore_audioparams_time_base(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_time_base(OakAudioParams *self,
+												   const OakRational *timebase);
+
+/**
+ * Returns a new owned handle to Rational(1, sample_rate).
+ */
+OAKCORE_API OakRational *oakcore_audioparams_sample_rate_as_time_base(
+	const OakAudioParams *self);
+
+OAKCORE_API int oakcore_audioparams_format(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_format(OakAudioParams *self, int format);
+
+OAKCORE_API int oakcore_audioparams_enabled(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_enabled(OakAudioParams *self, int enabled);
+
+OAKCORE_API int oakcore_audioparams_stream_index(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_stream_index(OakAudioParams *self,
+													  int stream_index);
+
+OAKCORE_API int64_t oakcore_audioparams_duration(const OakAudioParams *self);
+OAKCORE_API void oakcore_audioparams_set_duration(OakAudioParams *self,
+												  int64_t duration);
+
+/**
+ * Time/byte/sample conversions. All of these require valid parameters
+ * (oakcore_audioparams_is_valid()); calling them on invalid parameters is
+ * an error (the library asserts in debug builds).
+ */
+OAKCORE_API int64_t oakcore_audioparams_time_to_bytes(const OakAudioParams *self,
+													  double time);
+OAKCORE_API int64_t oakcore_audioparams_time_to_bytes_rational(
+	const OakAudioParams *self, const OakRational *time);
+OAKCORE_API int64_t oakcore_audioparams_time_to_bytes_per_channel(
+	const OakAudioParams *self, double time);
+OAKCORE_API int64_t oakcore_audioparams_time_to_bytes_per_channel_rational(
+	const OakAudioParams *self, const OakRational *time);
+OAKCORE_API int64_t oakcore_audioparams_time_to_samples(const OakAudioParams *self,
+														double time);
+OAKCORE_API int64_t oakcore_audioparams_time_to_samples_rational(
+	const OakAudioParams *self, const OakRational *time);
+OAKCORE_API int64_t oakcore_audioparams_samples_to_bytes(const OakAudioParams *self,
+														 int64_t samples);
+OAKCORE_API int64_t oakcore_audioparams_samples_to_bytes_per_channel(
+	const OakAudioParams *self, int64_t samples);
+OAKCORE_API OakRational *oakcore_audioparams_samples_to_time(
+	const OakAudioParams *self, int64_t samples);
+OAKCORE_API int64_t oakcore_audioparams_bytes_to_samples(const OakAudioParams *self,
+														 int64_t bytes);
+OAKCORE_API OakRational *oakcore_audioparams_bytes_to_time(
+	const OakAudioParams *self, int64_t bytes);
+OAKCORE_API OakRational *oakcore_audioparams_bytes_per_channel_to_time(
+	const OakAudioParams *self, int64_t bytes);
+
+OAKCORE_API int oakcore_audioparams_channel_count(const OakAudioParams *self);
+OAKCORE_API int oakcore_audioparams_bytes_per_sample_per_channel(
+	const OakAudioParams *self);
+OAKCORE_API int oakcore_audioparams_bits_per_sample(const OakAudioParams *self);
+OAKCORE_API int oakcore_audioparams_is_valid(const OakAudioParams *self);
+
+/**
+ * Equality like operator==: 1 when equal, 0 otherwise. Compares format,
+ * sample rate, timebase and channel layout (not the footage parameters).
+ */
+OAKCORE_API int oakcore_audioparams_equals(const OakAudioParams *self,
+										   const OakAudioParams *other);
+
+/**
+ * Enumerates AudioParams::k_supported_channel_layouts. Out-of-range indices
+ * return 0.
+ */
+OAKCORE_API int oakcore_audioparams_supported_channel_layout_count(void);
+OAKCORE_API uint64_t oakcore_audioparams_supported_channel_layout_at(int index);
+
+/**
+ * Enumerates AudioParams::k_supported_sample_rates. Out-of-range indices
+ * return 0.
+ */
+OAKCORE_API int oakcore_audioparams_supported_sample_rate_count(void);
+OAKCORE_API int oakcore_audioparams_supported_sample_rate_at(int index);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_AUDIOPARAMS_H */

core/include/olive/core/oakcore/bezier.h

@@ -0,0 +1,74 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_BEZIER_H
+#define OAKCORE_BEZIER_H
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file bezier.h
+ * @brief C ABI for the keyframe easing bezier curve value type
+ *
+ * Opaque handle + free functions. All returned OakBezier* are owned by
+ * the caller and must be released with oakcore_bezier_free().
+ */
+typedef struct OakBezier OakBezier;
+
+OAKCORE_API OakBezier *oakcore_bezier_create(void);
+OAKCORE_API OakBezier *oakcore_bezier_create_xy(double x, double y);
+OAKCORE_API OakBezier *oakcore_bezier_create_full(double x, double y,
+												  double cp1_x, double cp1_y,
+												  double cp2_x, double cp2_y);
+OAKCORE_API OakBezier *oakcore_bezier_copy(const OakBezier *self);
+OAKCORE_API void oakcore_bezier_free(OakBezier *self);
+
+OAKCORE_API double oakcore_bezier_x(const OakBezier *self);
+OAKCORE_API double oakcore_bezier_y(const OakBezier *self);
+OAKCORE_API double oakcore_bezier_cp1_x(const OakBezier *self);
+OAKCORE_API double oakcore_bezier_cp1_y(const OakBezier *self);
+OAKCORE_API double oakcore_bezier_cp2_x(const OakBezier *self);
+OAKCORE_API double oakcore_bezier_cp2_y(const OakBezier *self);
+
+OAKCORE_API void oakcore_bezier_set_x(OakBezier *self, double x);
+OAKCORE_API void oakcore_bezier_set_y(OakBezier *self, double y);
+OAKCORE_API void oakcore_bezier_set_cp1_x(OakBezier *self, double cp1_x);
+OAKCORE_API void oakcore_bezier_set_cp1_y(OakBezier *self, double cp1_y);
+OAKCORE_API void oakcore_bezier_set_cp2_x(OakBezier *self, double cp2_x);
+OAKCORE_API void oakcore_bezier_set_cp2_y(OakBezier *self, double cp2_y);
+
+OAKCORE_API double oakcore_bezier_quadratic_xto_t(double x, double a, double b,
+												  double c);
+OAKCORE_API double oakcore_bezier_quadratic_tto_y(double a, double b, double c,
+												  double t);
+OAKCORE_API double oakcore_bezier_cubic_xto_t(double x, double a, double b,
+											  double c, double d);
+OAKCORE_API double oakcore_bezier_cubic_tto_y(double a, double b, double c,
+											  double d, double t);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_BEZIER_H */

core/include/olive/core/oakcore/color.h

@@ -0,0 +1,123 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_COLOR_H
+#define OAKCORE_COLOR_H
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file color.h
+ * @brief C ABI for the high precision RGBA color value type
+ *
+ * Opaque handle + free functions. All returned OakColor* are owned by the
+ * caller and must be released with oakcore_color_free().
+ *
+ * A color is always 4 float channels in red/green/blue/alpha order. Channel
+ * values are unbounded: values outside [0, 1] are valid (HDR).
+ *
+ * Functions taking a `format` argument expect the same values as
+ * PixelFormat::Format (render/pixelformat.h): invalid = -1, u8 = 0, u10 = 1,
+ * u16 = 2, f16 = 3, f32 = 4.
+ */
+typedef struct OakColor OakColor;
+
+OAKCORE_API OakColor *oakcore_color_create(void);
+OAKCORE_API OakColor *oakcore_color_create_rgba(float r, float g, float b,
+												float a);
+OAKCORE_API OakColor *oakcore_color_copy(const OakColor *self);
+OAKCORE_API void oakcore_color_free(OakColor *self);
+
+/**
+ * Creates a color from hue/saturation/value.
+ *
+ * Hue expects a value between 0.0 and 360.0. Saturation and value expect a
+ * value between 0.0 and 1.0.
+ */
+OAKCORE_API OakColor *oakcore_color_from_hsv(float h, float s, float v);
+
+/**
+ * Creates a color from raw pixel data in the given pixel format. At most 4
+ * channels are read; missing channels default to 0.
+ */
+OAKCORE_API OakColor *oakcore_color_from_data(const char *data, int format,
+											  int nb_channels);
+
+OAKCORE_API float oakcore_color_red(const OakColor *self);
+OAKCORE_API float oakcore_color_green(const OakColor *self);
+OAKCORE_API float oakcore_color_blue(const OakColor *self);
+OAKCORE_API float oakcore_color_alpha(const OakColor *self);
+
+OAKCORE_API void oakcore_color_set_red(OakColor *self, float red);
+OAKCORE_API void oakcore_color_set_green(OakColor *self, float green);
+OAKCORE_API void oakcore_color_set_blue(OakColor *self, float blue);
+OAKCORE_API void oakcore_color_set_alpha(OakColor *self, float alpha);
+
+OAKCORE_API void oakcore_color_to_hsv(const OakColor *self, float *hue,
+									  float *sat, float *val);
+OAKCORE_API float oakcore_color_hsv_hue(const OakColor *self);
+OAKCORE_API float oakcore_color_hsv_saturation(const OakColor *self);
+OAKCORE_API float oakcore_color_value(const OakColor *self);
+
+OAKCORE_API void oakcore_color_to_hsl(const OakColor *self, float *hue,
+									  float *sat, float *lightness);
+OAKCORE_API float oakcore_color_hsl_hue(const OakColor *self);
+OAKCORE_API float oakcore_color_hsl_saturation(const OakColor *self);
+OAKCORE_API float oakcore_color_lightness(const OakColor *self);
+
+/**
+ * Borrowed pointer to the 4 float channels (rgba order), valid until
+ * oakcore_color_free().
+ */
+OAKCORE_API float *oakcore_color_data(OakColor *self);
+OAKCORE_API const float *oakcore_color_const_data(const OakColor *self);
+
+/**
+ * Writes the color as raw pixel data in the given pixel format. At most 4
+ * channels are written; out must have room for nb_channels * bytes-per-channel
+ * (u10 always packs to 4 bytes).
+ */
+OAKCORE_API void oakcore_color_to_data(const OakColor *self, char *out,
+									   int format, int nb_channels);
+
+/**
+ * Super rough luminance value mostly used for UI (determining whether to
+ * overlay with black or white text).
+ */
+OAKCORE_API float oakcore_color_get_rough_luminance(const OakColor *self);
+
+OAKCORE_API void oakcore_color_add_assign(OakColor *self,
+										  const OakColor *other);
+OAKCORE_API void oakcore_color_sub_assign(OakColor *self,
+										  const OakColor *other);
+OAKCORE_API void oakcore_color_add_scalar_assign(OakColor *self, float value);
+OAKCORE_API void oakcore_color_sub_scalar_assign(OakColor *self, float value);
+OAKCORE_API void oakcore_color_mul_scalar_assign(OakColor *self, float value);
+OAKCORE_API void oakcore_color_div_scalar_assign(OakColor *self, float value);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_COLOR_H */

core/include/olive/core/oakcore/export.h

@@ -0,0 +1,45 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_EXPORT_H
+#define OAKCORE_EXPORT_H
+
+/**
+ * @file export.h
+ * @brief Symbol visibility macros for liboakcore
+ *
+ * liboakcore exposes a pure C ABI: every public function is declared with
+ * OAKCORE_API and everything else is hidden. No C++ symbols cross the
+ * library boundary.
+ */
+
+#if defined(_WIN32) || defined(__CYGWIN__)
+  #ifdef OAKCORE_BUILD
+    #define OAKCORE_API __declspec(dllexport)
+  #else
+    #define OAKCORE_API __declspec(dllimport)
+  #endif
+#elif defined(__GNUC__) || defined(__clang__)
+  #define OAKCORE_API __attribute__((visibility("default")))
+#else
+  #define OAKCORE_API
+#endif
+
+#endif /* OAKCORE_EXPORT_H */

core/include/olive/core/oakcore/fractionutils.h

@@ -0,0 +1,88 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_FRACTIONUTILS_H
+#define OAKCORE_FRACTIONUTILS_H
+
+#include <stdint.h>
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file fractionutils.h
+ * @brief C ABI for the fraction utility functions
+ *
+ * Pure integer helpers: there is no object and therefore no opaque handle.
+ * In/out values are passed through pointer out-parameters.
+ */
+
+/**
+ * @brief Rounding modes for oakcore_fractionutils_rescale_rnd()
+ *
+ * Mirrors the FFmpeg AVRounding modes: NEAR_INF rounds to the nearest value
+ * with halfway cases rounded away from zero, UP rounds toward positive
+ * infinity.
+ */
+typedef enum OakFractionRounding {
+	OAK_FRACTION_ROUNDING_NEAR_INF = 0,
+	OAK_FRACTION_ROUNDING_UP = 1
+} OakFractionRounding;
+
+/**
+ * @brief Reduces the fraction *num / *den in place so that both fit within max
+ *
+ * Divides out the greatest common divisor and, if the values still do not
+ * fit within max, finds the closest approximation using continued fractions.
+ *
+ * A zero denominator is preserved (with the numerator set to zero).
+ * num and den must not be NULL.
+ */
+OAKCORE_API void oakcore_fractionutils_reduce_fraction(int64_t *num,
+													   int64_t *den,
+													   int64_t max);
+
+/**
+ * @brief Three-way comparison of the fractions an/ad and bn/bd
+ *
+ * Returns -1 if a < b, 0 if a == b, 1 if a > b, and INT_MIN when the
+ * comparison is meaningless (degenerate zero-denominator fractions).
+ */
+OAKCORE_API int oakcore_fractionutils_compare_fractions(int an, int ad,
+														int bn, int bd);
+
+/**
+ * @brief Rescales a by the fraction b/c: returns a * b / c
+ *
+ * The intermediate product is computed with 128-bit arithmetic where
+ * available so that no precision is lost for large timestamps.
+ */
+OAKCORE_API int64_t oakcore_fractionutils_rescale_rnd(int64_t a, int64_t b,
+													  int64_t c,
+													  OakFractionRounding rnd);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_FRACTIONUTILS_H */

core/include/olive/core/oakcore/rational.h

@@ -0,0 +1,87 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_RATIONAL_H
+#define OAKCORE_RATIONAL_H
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file rational.h
+ * @brief C ABI for the rational number value type
+ *
+ * Opaque handle + free functions. All returned OakRational* are owned by
+ * the caller and must be released with oakcore_rational_free().
+ */
+typedef struct OakRational OakRational;
+
+OAKCORE_API OakRational *oakcore_rational_create(int numerator);
+OAKCORE_API OakRational *oakcore_rational_create_nd(int numerator,
+													int denominator);
+OAKCORE_API OakRational *oakcore_rational_create_nan(void);
+OAKCORE_API OakRational *oakcore_rational_copy(const OakRational *self);
+OAKCORE_API void oakcore_rational_free(OakRational *self);
+
+OAKCORE_API int oakcore_rational_numerator(const OakRational *self);
+OAKCORE_API int oakcore_rational_denominator(const OakRational *self);
+OAKCORE_API double oakcore_rational_to_double(const OakRational *self);
+
+/**
+ * Writes "num/den" into buf (NUL-terminated when buf_size > 0).
+ * Returns the number of characters that would have been written excluding
+ * the NUL, so buf == NULL or a too-small buffer can be used to query the
+ * required size.
+ */
+OAKCORE_API int oakcore_rational_to_string(const OakRational *self, char *buf,
+										   int buf_size);
+
+OAKCORE_API OakRational *oakcore_rational_from_double(double value, int *ok);
+OAKCORE_API OakRational *oakcore_rational_from_string(const char *str, int *ok);
+
+OAKCORE_API int oakcore_rational_is_null(const OakRational *self);
+OAKCORE_API int oakcore_rational_is_nan(const OakRational *self);
+
+OAKCORE_API OakRational *oakcore_rational_flipped(const OakRational *self);
+OAKCORE_API void oakcore_rational_flip(OakRational *self);
+
+OAKCORE_API void oakcore_rational_add_assign(OakRational *self,
+											 const OakRational *other);
+OAKCORE_API void oakcore_rational_sub_assign(OakRational *self,
+											 const OakRational *other);
+OAKCORE_API void oakcore_rational_mul_assign(OakRational *self,
+											 const OakRational *other);
+OAKCORE_API void oakcore_rational_div_assign(OakRational *self,
+											 const OakRational *other);
+
+/**
+ * Three-way comparison like compare_fractions: -1, 0 or 1.
+ */
+OAKCORE_API int oakcore_rational_compare(const OakRational *self,
+										 const OakRational *other);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_RATIONAL_H */

core/include/olive/core/oakcore/samplebuffer.h

@@ -0,0 +1,149 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_SAMPLEBUFFER_H
+#define OAKCORE_SAMPLEBUFFER_H
+
+#include <stddef.h>
+
+#include "export.h"
+#include "rational.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file samplebuffer.h
+ * @brief C ABI for the planar audio sample buffer
+ *
+ * Opaque handle + free functions. Every returned OakSampleBuffer or
+ * OakAudioParams handle is owned by the caller and must be released with
+ * oakcore_samplebuffer_free() or oakcore_audioparams_free() respectively.
+ * Samples are always stored planar (one float array per channel).
+ */
+typedef struct OakSampleBuffer OakSampleBuffer;
+typedef struct OakAudioParams OakAudioParams;
+
+OAKCORE_API OakSampleBuffer *oakcore_samplebuffer_create(void);
+OAKCORE_API OakSampleBuffer *oakcore_samplebuffer_create_length(
+	const OakAudioParams *params, const OakRational *length);
+OAKCORE_API OakSampleBuffer *oakcore_samplebuffer_create_samples(
+	const OakAudioParams *params, size_t samples_per_channel);
+OAKCORE_API OakSampleBuffer *oakcore_samplebuffer_copy(
+	const OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_free(OakSampleBuffer *self);
+
+OAKCORE_API OakSampleBuffer *oakcore_samplebuffer_rip_channel(
+	const OakSampleBuffer *self, int channel);
+
+/**
+ * Copies the samples of one channel into out. Returns the total number of
+ * floats in the channel (equal to the sample count), so out == NULL (or a
+ * too-small buffer) can be used to query the required size; at most out_size
+ * floats are written.
+ */
+OAKCORE_API int oakcore_samplebuffer_rip_channel_vector(
+	const OakSampleBuffer *self, int channel, float *out, int out_size);
+
+/**
+ * Returns a copy of the buffer's audio parameters as a new owned handle
+ * (release with oakcore_audioparams_free()).
+ */
+OAKCORE_API OakAudioParams *oakcore_samplebuffer_audio_params(
+	const OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_set_audio_params(
+	OakSampleBuffer *self, const OakAudioParams *params);
+
+OAKCORE_API size_t oakcore_samplebuffer_sample_count(
+	const OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_set_sample_count(OakSampleBuffer *self,
+													   size_t sample_count);
+OAKCORE_API void oakcore_samplebuffer_set_sample_count_length(
+	OakSampleBuffer *self, const OakRational *length);
+
+/**
+ * Borrowed pointer to the samples of one channel; it becomes invalid when the
+ * handle is destroyed or reallocated and must not be freed by the caller.
+ * Returns NULL when the buffer is not allocated or the channel is out of
+ * range.
+ */
+OAKCORE_API float *oakcore_samplebuffer_data(OakSampleBuffer *self,
+											 int channel);
+
+/**
+ * Fills out with one borrowed sample pointer per channel (see
+ * oakcore_samplebuffer_data()). out must have room for
+ * oakcore_samplebuffer_channel_count() entries.
+ */
+OAKCORE_API void oakcore_samplebuffer_to_raw_ptrs(OakSampleBuffer *self,
+												  float **out);
+
+OAKCORE_API int oakcore_samplebuffer_channel_count(const OakSampleBuffer *self);
+OAKCORE_API int oakcore_samplebuffer_is_allocated(const OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_allocate(OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_destroy(OakSampleBuffer *self);
+
+OAKCORE_API void oakcore_samplebuffer_reverse(OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_speed(OakSampleBuffer *self,
+											double speed);
+
+OAKCORE_API void oakcore_samplebuffer_transform_volume(OakSampleBuffer *self,
+													   float f);
+OAKCORE_API void oakcore_samplebuffer_transform_volume_for_channel(
+	OakSampleBuffer *self, int channel, float volume);
+OAKCORE_API void oakcore_samplebuffer_transform_volume_to(
+	float f, const OakSampleBuffer *input, OakSampleBuffer *output);
+OAKCORE_API void oakcore_samplebuffer_transform_volume_for_channel_to(
+	int channel, float volume, const OakSampleBuffer *input,
+	OakSampleBuffer *output);
+OAKCORE_API void oakcore_samplebuffer_transform_volume_for_sample(
+	OakSampleBuffer *self, size_t sample_index, float volume);
+OAKCORE_API void oakcore_samplebuffer_transform_volume_for_sample_on_channel(
+	OakSampleBuffer *self, size_t sample_index, int channel, float volume);
+
+OAKCORE_API void oakcore_samplebuffer_clamp(OakSampleBuffer *self);
+
+OAKCORE_API void oakcore_samplebuffer_silence(OakSampleBuffer *self);
+OAKCORE_API void oakcore_samplebuffer_silence_range(OakSampleBuffer *self,
+													size_t start_sample,
+													size_t end_sample);
+OAKCORE_API void oakcore_samplebuffer_silence_bytes(OakSampleBuffer *self,
+													size_t start_byte,
+													size_t end_byte);
+
+OAKCORE_API void oakcore_samplebuffer_set(OakSampleBuffer *self, int channel,
+										  const float *data,
+										  size_t sample_offset,
+										  size_t sample_length);
+
+/**
+ * Copies channel "from" of other into channel "to" of self; from == -1 uses
+ * the same index as to.
+ */
+OAKCORE_API void oakcore_samplebuffer_fast_set(OakSampleBuffer *self,
+											   const OakSampleBuffer *other,
+											   int to, int from);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_SAMPLEBUFFER_H */

core/include/olive/core/oakcore/stringutils.h

@@ -0,0 +1,94 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_STRINGUTILS_H
+#define OAKCORE_STRINGUTILS_H
+
+#include <stdarg.h>
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file stringutils.h
+ * @brief C ABI for the string utility functions
+ *
+ * StringUtils consists of static functions only, so there are no objects
+ * and no opaque handle. Functions returning string lists hand back a
+ * caller-owned char** that must be released with
+ * oakcore_stringutils_free_string_array().
+ */
+
+/**
+ * Splits s on separator and returns a newly allocated array of newly
+ * allocated NUL-terminated strings; *count receives the element count.
+ * Release the result with oakcore_stringutils_free_string_array().
+ * A NULL or empty s yields one empty string, mirroring the C++
+ * implementation. Returns NULL only on allocation failure.
+ */
+OAKCORE_API char **oakcore_stringutils_split(const char *s, char separator,
+											 int *count);
+
+/**
+ * Splits s wherever the regular expression pattern matches (std::regex
+ * ECMAScript syntax). Same ownership and NULL semantics as
+ * oakcore_stringutils_split().
+ */
+OAKCORE_API char **oakcore_stringutils_split_regex(const char *s,
+												   const char *pattern,
+												   int *count);
+
+/**
+ * Releases an array returned by oakcore_stringutils_split() or
+ * oakcore_stringutils_split_regex(). Safe to call with arr == NULL.
+ */
+OAKCORE_API void oakcore_stringutils_free_string_array(char **arr, int count);
+
+/**
+ * Parses an int from s in the given base (usually 10, or 16 for hex).
+ * Returns the parsed value, or 0 on parser error. ok is an optional output
+ * parameter set to 1 on success and 0 on failure.
+ */
+OAKCORE_API int oakcore_stringutils_to_int(const char *s, int base, int *ok);
+
+/**
+ * Formats a string with vsnprintf semantics: writes into buf
+ * (NUL-terminated when buf_size > 0) and returns the number of characters
+ * that would have been written excluding the NUL, so buf == NULL or a
+ * too-small buffer can be used to query the required size.
+ */
+OAKCORE_API int oakcore_stringutils_format(char *buf, int buf_size,
+										   const char *fmt, ...);
+
+/**
+ * va_list form of oakcore_stringutils_format(), for forwarding from other
+ * variadic functions.
+ */
+OAKCORE_API int oakcore_stringutils_format_v(char *buf, int buf_size,
+											 const char *fmt, va_list args);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_STRINGUTILS_H */

core/include/olive/core/oakcore/timecodefunctions.h

@@ -0,0 +1,145 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_TIMECODEFUNCTIONS_H
+#define OAKCORE_TIMECODEFUNCTIONS_H
+
+#include <stdint.h>
+
+#include "export.h"
+#include "rational.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file timecodefunctions.h
+ * @brief C ABI for the time/timecode/timestamp conversion functions
+ *
+ * Free functions only (the wrapped class is all-static, so there is no
+ * object handle of its own). Times and timebases are passed as borrowed
+ * OakRational handles; every returned OakRational* is owned by the caller
+ * and must be released with oakcore_rational_free().
+ *
+ * Terminology used throughout:
+ *
+ * `time` - time in seconds presented in a Rational form
+ * `timebase` - the base time unit of an audio/video stream in seconds
+ * `timestamp` - an integer representation of a time in timebase units
+ * (in many cases is used like a frame number)
+ * `timecode` - a user-friendly string representation of a time according to OakTimecodeDisplay
+ */
+
+/**
+ * @brief User-friendly timecode display modes
+ *
+ * Values must stay in sync with the wrapped class's Display enum.
+ */
+typedef enum OakTimecodeDisplay {
+	OAK_TIMECODE_DISPLAY_DROP_FRAME = 0,
+	OAK_TIMECODE_DISPLAY_NON_DROP_FRAME = 1,
+	OAK_TIMECODE_DISPLAY_SECONDS = 2,
+	OAK_TIMECODE_DISPLAY_FRAMES = 3,
+	OAK_TIMECODE_DISPLAY_MILLISECONDS = 4
+} OakTimecodeDisplay;
+
+/**
+ * @brief Rounding modes for time/timestamp conversions
+ *
+ * Values must stay in sync with the wrapped class's Rounding enum.
+ */
+typedef enum OakTimecodeRounding {
+	OAK_TIMECODE_ROUNDING_CEIL = 0,
+	OAK_TIMECODE_ROUNDING_FLOOR = 1,
+	OAK_TIMECODE_ROUNDING_ROUND = 2
+} OakTimecodeRounding;
+
+/**
+ * @brief Convert a time (according to a Rational timebase) to a user-friendly string representation
+ *
+ * Writes the timecode into buf (NUL-terminated when buf_size > 0).
+ * Returns the number of characters that would have been written excluding
+ * the NUL, so buf == NULL or a too-small buffer can be used to query the
+ * required size.
+ */
+OAKCORE_API int oakcore_timecode_time_to_timecode(const OakRational *time,
+												  const OakRational *timebase,
+												  OakTimecodeDisplay display,
+												  int show_plus_if_positive,
+												  char *buf, int buf_size);
+
+/**
+ * @brief Convert a user-friendly timecode string to a time in seconds
+ *
+ * Returns a new owned OakRational (free with oakcore_rational_free()).
+ * ok is set to 1 on success and 0 on failure (may be NULL).
+ */
+OAKCORE_API OakRational *oakcore_timecode_timecode_to_time(const char *timecode,
+														   const OakRational *timebase,
+														   OakTimecodeDisplay display,
+														   int *ok);
+
+/**
+ * @brief Convert a millisecond count to an "HH:MM:SS" string
+ *
+ * Same buf/buf_size convention as oakcore_timecode_time_to_timecode().
+ */
+OAKCORE_API int oakcore_timecode_time_to_string(int64_t ms, char *buf,
+												int buf_size);
+
+/**
+ * @brief Snap a time to the nearest timestamp boundary of a timebase
+ *
+ * Returns a new owned OakRational (free with oakcore_rational_free()).
+ */
+OAKCORE_API OakRational *oakcore_timecode_snap_time_to_timebase(const OakRational *time,
+																const OakRational *timebase,
+																OakTimecodeRounding rounding);
+
+OAKCORE_API int64_t oakcore_timecode_time_to_timestamp(const OakRational *time,
+													   const OakRational *timebase,
+													   OakTimecodeRounding rounding);
+OAKCORE_API int64_t oakcore_timecode_time_to_timestamp_d(double time,
+														 const OakRational *timebase,
+														 OakTimecodeRounding rounding);
+
+OAKCORE_API int64_t oakcore_timecode_rescale_timestamp(int64_t ts,
+													   const OakRational *source,
+													   const OakRational *dest);
+OAKCORE_API int64_t oakcore_timecode_rescale_timestamp_ceil(int64_t ts,
+															const OakRational *source,
+															const OakRational *dest);
+
+/**
+ * @brief Convert a timestamp in timebase units back to a time in seconds
+ *
+ * Returns a new owned OakRational (free with oakcore_rational_free()).
+ */
+OAKCORE_API OakRational *oakcore_timecode_timestamp_to_time(int64_t timestamp,
+															const OakRational *timebase);
+
+OAKCORE_API int oakcore_timecode_timebase_is_drop_frame(const OakRational *timebase);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_TIMECODEFUNCTIONS_H */

core/include/olive/core/oakcore/timerange.h

@@ -0,0 +1,110 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAKCORE_TIMERANGE_H
+#define OAKCORE_TIMERANGE_H
+
+#include "export.h"
+#include "rational.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file timerange.h
+ * @brief C ABI for the time range value type
+ *
+ * Opaque handle + free functions. All returned OakTimeRange and OakRational
+ * pointers are owned by the caller and must be released with
+ * oakcore_timerange_free() and oakcore_rational_free() respectively.
+ */
+typedef struct OakTimeRange OakTimeRange;
+
+OAKCORE_API OakTimeRange *oakcore_timerange_create(void);
+OAKCORE_API OakTimeRange *oakcore_timerange_create_io(const OakRational *in,
+													  const OakRational *out);
+OAKCORE_API OakTimeRange *oakcore_timerange_copy(const OakTimeRange *self);
+OAKCORE_API void oakcore_timerange_free(OakTimeRange *self);
+
+OAKCORE_API OakRational *oakcore_timerange_in(const OakTimeRange *self);
+OAKCORE_API OakRational *oakcore_timerange_out(const OakTimeRange *self);
+OAKCORE_API OakRational *oakcore_timerange_length(const OakTimeRange *self);
+
+OAKCORE_API void oakcore_timerange_set_in(OakTimeRange *self,
+										  const OakRational *in);
+OAKCORE_API void oakcore_timerange_set_out(OakTimeRange *self,
+										   const OakRational *out);
+OAKCORE_API void oakcore_timerange_set_range(OakTimeRange *self,
+											 const OakRational *in,
+											 const OakRational *out);
+
+OAKCORE_API int oakcore_timerange_equal(const OakTimeRange *self,
+										const OakTimeRange *other);
+
+OAKCORE_API int oakcore_timerange_overlaps_with(const OakTimeRange *self,
+												const OakTimeRange *other,
+												int in_inclusive,
+												int out_inclusive);
+OAKCORE_API int oakcore_timerange_contains_range(const OakTimeRange *self,
+												 const OakTimeRange *other,
+												 int in_inclusive,
+												 int out_inclusive);
+OAKCORE_API int oakcore_timerange_contains_time(const OakTimeRange *self,
+												const OakRational *time);
+
+OAKCORE_API OakTimeRange *oakcore_timerange_combined(
+	const OakTimeRange *self, const OakTimeRange *other);
+OAKCORE_API OakTimeRange *oakcore_timerange_combine(const OakTimeRange *a,
+													const OakTimeRange *b);
+OAKCORE_API OakTimeRange *oakcore_timerange_intersected(
+	const OakTimeRange *self, const OakTimeRange *other);
+OAKCORE_API OakTimeRange *oakcore_timerange_intersect(const OakTimeRange *a,
+													  const OakTimeRange *b);
+
+OAKCORE_API OakTimeRange *oakcore_timerange_add(const OakTimeRange *self,
+												const OakRational *rhs);
+OAKCORE_API OakTimeRange *oakcore_timerange_sub(const OakTimeRange *self,
+												const OakRational *rhs);
+OAKCORE_API void oakcore_timerange_add_assign(OakTimeRange *self,
+											  const OakRational *rhs);
+OAKCORE_API void oakcore_timerange_sub_assign(OakTimeRange *self,
+											  const OakRational *rhs);
+
+/**
+ * Splits the range into chunks of chunk_size (the first and last chunk are
+ * clamped to the range bounds) and writes a newly allocated owned handle per
+ * chunk into out_ranges. Returns the total number of chunks, so
+ * out_ranges == NULL (or a too-small array) can be used to query the
+ * required size; oakcore_timerange_split_count() is the direct equivalent
+ * of that query.
+ */
+OAKCORE_API int oakcore_timerange_split_count(const OakTimeRange *self,
+											  int chunk_size);
+OAKCORE_API int oakcore_timerange_split(const OakTimeRange *self,
+										int chunk_size,
+										OakTimeRange **out_ranges,
+										int out_size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKCORE_TIMERANGE_H */

core/include/olive/core/render/audioparams.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -21,11 +21,12 @@
 
 #ifndef OAK_LIBOLIVECORE_AUDIOPARAMS_H
 #define OAK_LIBOLIVECORE_AUDIOPARAMS_H
-#include <cstring>
 
-#include <assert.h>
+#include <cstdint>
 #include <vector>
 
+#include "olive/core/oakcore/audioparams.h"
+
 #include "channellayout.h"
 #include "sampleformat.h"
 #include "../util/rational.h"
@@ -36,9 +37,9 @@ namespace olive::core
 /**
  * @brief Audio parameters class managing audio stream configuration
  *
- * Channel layouts are stored as plain 64-bit masks (see channellayout.h).
- * Because the mask is a simple value type, AudioParams has value semantics
- * and can be copied freely.
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakAudioParams handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation.
  */
 class AudioParams {
 public:
@@ -47,12 +48,8 @@ public:
 	 * sample_rate=0, channel_layout empty, format=INVALID
 	 */
 	AudioParams()
-		: sample_rate_(0)
-		, channel_layout_mask_(0)
-		, channel_count_(0)
-		, format_(SampleFormat::invalid)
+		: handle_(oakcore_audioparams_create_invalid())
 	{
-		set_default_footage_parameters();
 	}
 
 	/**
@@ -63,31 +60,61 @@ public:
 	 */
 	AudioParams(const int &sample_rate, uint64_t channel_layout,
 				const SampleFormat &format)
-		: sample_rate_(sample_rate)
-		, channel_layout_mask_(channel_layout)
-		, channel_count_(0)
-		, format_(format)
+		: handle_(oakcore_audioparams_create(sample_rate, channel_layout, format))
 	{
-		set_default_footage_parameters();
-		timebase_ = sample_rate_as_time_base();
-		calculate_channel_count();
 	}
+
+	AudioParams(const AudioParams &rhs)
+		: handle_(oakcore_audioparams_copy(rhs.handle_))
+	{
+	}
+
+	AudioParams(AudioParams &&rhs) noexcept
+		: handle_(rhs.handle_)
+	{
+		rhs.handle_ = nullptr;
+	}
+
+	~AudioParams()
+	{
+		oakcore_audioparams_free(handle_);
+	}
+
+	AudioParams &operator=(const AudioParams &rhs)
+	{
+		if (this != &rhs) {
+			oakcore_audioparams_free(handle_);
+			handle_ = oakcore_audioparams_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	AudioParams &operator=(AudioParams &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakcore_audioparams_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
+
 	int sample_rate() const
 	{
-		return sample_rate_;
+		return oakcore_audioparams_sample_rate(handle_);
 	}
 
 	void set_sample_rate(int sample_rate)
 	{
-		sample_rate_ = sample_rate;
+		oakcore_audioparams_set_sample_rate(handle_, sample_rate);
 	}
 
 	/**
 	 * @brief Channel layout as a 64-bit mask (0 if unspecified)
 	 */
-	const uint64_t &channel_layout() const
+	uint64_t channel_layout() const
 	{
-		return channel_layout_mask_;
+		return oakcore_audioparams_channel_layout(handle_);
 	}
 
 	/**
@@ -96,122 +123,208 @@ public:
 	 */
 	void set_channel_layout(uint64_t mask)
 	{
-		channel_layout_mask_ = mask;
-		calculate_channel_count();
+		oakcore_audioparams_set_channel_layout(handle_, mask);
 	}
+
 	Rational time_base() const
 	{
-		return timebase_;
+		return Rational::from_handle(oakcore_audioparams_time_base(handle_));
 	}
 
 	void set_time_base(const Rational &timebase)
 	{
-		timebase_ = timebase;
+		oakcore_audioparams_set_time_base(handle_, timebase.handle());
 	}
 
 	Rational sample_rate_as_time_base() const
 	{
-		return Rational(1, sample_rate());
+		return Rational::from_handle(
+			oakcore_audioparams_sample_rate_as_time_base(handle_));
 	}
 
 	SampleFormat format() const
 	{
-		return format_;
+		return SampleFormat(
+			static_cast<SampleFormat::Format>(oakcore_audioparams_format(handle_)));
 	}
 
 	void set_format(SampleFormat format)
 	{
-		format_ = format;
+		oakcore_audioparams_set_format(handle_, format);
 	}
 
 	bool enabled() const
 	{
-		return enabled_;
+		return oakcore_audioparams_enabled(handle_) != 0;
 	}
 
 	void set_enabled(bool e)
 	{
-		enabled_ = e;
+		oakcore_audioparams_set_enabled(handle_, e ? 1 : 0);
 	}
 
 	int stream_index() const
 	{
-		return stream_index_;
+		return oakcore_audioparams_stream_index(handle_);
 	}
 
 	void set_stream_index(int s)
 	{
-		stream_index_ = s;
+		oakcore_audioparams_set_stream_index(handle_, s);
 	}
 
 	int64_t duration() const
 	{
-		return duration_;
+		return oakcore_audioparams_duration(handle_);
 	}
 
 	void set_duration(int64_t duration)
 	{
-		duration_ = duration;
+		oakcore_audioparams_set_duration(handle_, duration);
 	}
 
-	int64_t time_to_bytes(const double &time) const;
-	int64_t time_to_bytes(const Rational &time) const;
-	int64_t time_to_bytes_per_channel(const double &time) const;
-	int64_t time_to_bytes_per_channel(const Rational &time) const;
-	int64_t time_to_samples(const double &time) const;
-	int64_t time_to_samples(const Rational &time) const;
-	int64_t samples_to_bytes(const int64_t &samples) const;
-	int64_t samples_to_bytes_per_channel(const int64_t &samples) const;
-	Rational samples_to_time(const int64_t &samples) const;
-	int64_t bytes_to_samples(const int64_t &bytes) const;
-	Rational bytes_to_time(const int64_t &bytes) const;
-	Rational bytes_per_channel_to_time(const int64_t &bytes) const;
-	int channel_count() const;
-	int bytes_per_sample_per_channel() const;
-	int bits_per_sample() const;
-	bool is_valid() const;
+	int64_t time_to_bytes(const double &time) const
+	{
+		return oakcore_audioparams_time_to_bytes(handle_, time);
+	}
 
-	bool operator==(const AudioParams &other) const;
-	bool operator!=(const AudioParams &other) const;
+	int64_t time_to_bytes(const Rational &time) const
+	{
+		return oakcore_audioparams_time_to_bytes_rational(handle_, time.handle());
+	}
+
+	int64_t time_to_bytes_per_channel(const double &time) const
+	{
+		return oakcore_audioparams_time_to_bytes_per_channel(handle_, time);
+	}
+
+	int64_t time_to_bytes_per_channel(const Rational &time) const
+	{
+		return oakcore_audioparams_time_to_bytes_per_channel_rational(handle_,
+																	  time.handle());
+	}
+
+	int64_t time_to_samples(const double &time) const
+	{
+		return oakcore_audioparams_time_to_samples(handle_, time);
+	}
+
+	int64_t time_to_samples(const Rational &time) const
+	{
+		return oakcore_audioparams_time_to_samples_rational(handle_, time.handle());
+	}
+
+	int64_t samples_to_bytes(const int64_t &samples) const
+	{
+		return oakcore_audioparams_samples_to_bytes(handle_, samples);
+	}
+
+	int64_t samples_to_bytes_per_channel(const int64_t &samples) const
+	{
+		return oakcore_audioparams_samples_to_bytes_per_channel(handle_, samples);
+	}
+
+	Rational samples_to_time(const int64_t &samples) const
+	{
+		return Rational::from_handle(
+			oakcore_audioparams_samples_to_time(handle_, samples));
+	}
+
+	int64_t bytes_to_samples(const int64_t &bytes) const
+	{
+		return oakcore_audioparams_bytes_to_samples(handle_, bytes);
+	}
+
+	Rational bytes_to_time(const int64_t &bytes) const
+	{
+		return Rational::from_handle(
+			oakcore_audioparams_bytes_to_time(handle_, bytes));
+	}
+
+	Rational bytes_per_channel_to_time(const int64_t &bytes) const
+	{
+		return Rational::from_handle(
+			oakcore_audioparams_bytes_per_channel_to_time(handle_, bytes));
+	}
+
+	int channel_count() const
+	{
+		return oakcore_audioparams_channel_count(handle_);
+	}
+
+	int bytes_per_sample_per_channel() const
+	{
+		return oakcore_audioparams_bytes_per_sample_per_channel(handle_);
+	}
+
+	int bits_per_sample() const
+	{
+		return oakcore_audioparams_bits_per_sample(handle_);
+	}
+
+	bool is_valid() const
+	{
+		return oakcore_audioparams_is_valid(handle_) != 0;
+	}
+
+	bool operator==(const AudioParams &other) const
+	{
+		return oakcore_audioparams_equals(handle_, other.handle_) != 0;
+	}
+
+	bool operator!=(const AudioParams &other) const
+	{
+		return !(*this == other);
+	}
 
 	static const std::vector<uint64_t> k_supported_channel_layouts;
 	static const std::vector<int> k_supported_sample_rates;
 
-private:
-	void set_default_footage_parameters()
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakAudioParams *handle() const
 	{
-		enabled_ = true;
-		stream_index_ = 0;
-		duration_ = 0;
+		return handle_;
 	}
 
 	/**
-	 * @brief Updates channel_count_ from the current channel_layout_mask_
-	 * Called after any channel layout modification.
+	 * @brief Wraps an owned C handle (takes ownership)
 	 */
-	void calculate_channel_count();
+	static AudioParams from_handle(OakAudioParams *handle)
+	{
+		return AudioParams(handle);
+	}
 
-	int sample_rate_;                    ///< Audio sample rate in Hz (e.g., 48000)
+private:
+	explicit AudioParams(OakAudioParams *handle)
+		: handle_(handle)
+	{
+	}
 
-	/**
-	 * @brief Channel layout mask (0 if unspecified)
-	 *
-	 * Plain value type mirroring FFmpeg's AV_CH_LAYOUT_* masks; no dynamic
-	 * memory is involved, so copies are trivially safe.
-	 */
-	uint64_t channel_layout_mask_;
-
-	int channel_count_;                  ///< Cached channel count from layout
-
-	SampleFormat format_;                ///< Audio sample format
-
-	// Footage-specific parameters (serialized with footage metadata)
-	int enabled_; // Using int instead of bool fixes GCC 11 stringop-overflow issue (byte alignment)
-	int stream_index_;                   ///< Index in the source file's stream list
-	int64_t duration_;                   ///< Stream duration in timebase units
-	Rational timebase_;                  ///< Timebase for this audio stream
+	OakAudioParams *handle_;
 };
 
+inline const std::vector<uint64_t> AudioParams::k_supported_channel_layouts = [] {
+	std::vector<uint64_t> v;
+	const int n = oakcore_audioparams_supported_channel_layout_count();
+	v.reserve(size_t(n));
+	for (int i = 0; i < n; i++) {
+		v.push_back(oakcore_audioparams_supported_channel_layout_at(i));
+	}
+	return v;
+}();
+
+inline const std::vector<int> AudioParams::k_supported_sample_rates = [] {
+	std::vector<int> v;
+	const int n = oakcore_audioparams_supported_sample_rate_count();
+	v.reserve(size_t(n));
+	for (int i = 0; i < n; i++) {
+		v.push_back(oakcore_audioparams_supported_sample_rate_at(i));
+	}
+	return v;
+}();
+
 }
 
 #endif // OAK_LIBOLIVECORE_AUDIOPARAMS_H

core/include/olive/core/render/samplebuffer.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,11 +22,11 @@
 #ifndef OAK_LIBOLIVECORE_SAMPLEBUFFER_H
 #define OAK_LIBOLIVECORE_SAMPLEBUFFER_H
 
-#include <memory>
 #include <vector>
 
-#include "audioparams.h"
-#include "../util/rational.h"
+#include "olive/core/oakcore/samplebuffer.h"
+#include "olive/core/render/audioparams.h"
+#include "olive/core/util/rational.h"
 
 namespace olive::core
 {
@@ -34,102 +34,265 @@ namespace olive::core
 /**
  * @brief A buffer of audio samples
  *
- * Audio samples in this structure are always stored in PLANAR (separated by channel). This is done to simplify audio
- * rendering code. This replaces the old system of using QByteArrays (containing packed audio) and while SampleBuffer
- * replaces many of those in the rendering/processing side of things, QByteArrays are currently still in use for
- * playback, including reading to and from the cache.
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakSampleBuffer handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation, except that
+ * the getters return AudioParams/size_t by value instead of by const
+ * reference.
+ *
+ * Audio samples in this structure are always stored in PLANAR (separated by
+ * channel). This is done to simplify audio rendering code. This replaces the
+ * old system of using QByteArrays (containing packed audio) and while
+ * SampleBuffer replaces many of those in the rendering/processing side of
+ * things, QByteArrays are currently still in use for playback, including
+ * reading to and from the cache.
  */
 class SampleBuffer {
 public:
-	SampleBuffer();
-	SampleBuffer(const AudioParams &audio_params, const Rational &length);
-	SampleBuffer(const AudioParams &audio_params, size_t samples_per_channel);
-
-	SampleBuffer rip_channel(int channel) const;
-	std::vector<float> rip_channel_vector(int channel) const;
-
-	const AudioParams &audio_params() const;
-	void set_audio_params(const AudioParams &params);
-
-	const size_t &sample_count() const
+	SampleBuffer()
+		: handle_(oakcore_samplebuffer_create())
 	{
-		return sample_count_per_channel_;
 	}
-	void set_sample_count(const size_t &sample_count);
+
+	SampleBuffer(const AudioParams &audio_params, const Rational &length)
+		: handle_(oakcore_samplebuffer_create_length(audio_params.handle(),
+													 length.handle()))
+	{
+	}
+
+	SampleBuffer(const AudioParams &audio_params, size_t samples_per_channel)
+		: handle_(oakcore_samplebuffer_create_samples(audio_params.handle(),
+													  samples_per_channel))
+	{
+	}
+
+	SampleBuffer(const SampleBuffer &rhs)
+		: handle_(oakcore_samplebuffer_copy(rhs.handle_))
+	{
+	}
+
+	SampleBuffer(SampleBuffer &&rhs) noexcept
+		: handle_(rhs.handle_)
+	{
+		rhs.handle_ = nullptr;
+	}
+
+	~SampleBuffer()
+	{
+		oakcore_samplebuffer_free(handle_);
+	}
+
+	SampleBuffer &operator=(const SampleBuffer &rhs)
+	{
+		if (this != &rhs) {
+			oakcore_samplebuffer_free(handle_);
+			handle_ = oakcore_samplebuffer_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	SampleBuffer &operator=(SampleBuffer &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakcore_samplebuffer_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
+
+	SampleBuffer rip_channel(int channel) const
+	{
+		return from_handle(oakcore_samplebuffer_rip_channel(handle_, channel));
+	}
+
+	std::vector<float> rip_channel_vector(int channel) const
+	{
+		const int size = oakcore_samplebuffer_rip_channel_vector(
+			handle_, channel, nullptr, 0);
+		std::vector<float> v(static_cast<size_t>(size));
+		if (size > 0) {
+			oakcore_samplebuffer_rip_channel_vector(handle_, channel, v.data(),
+													size);
+		}
+		return v;
+	}
+
+	AudioParams audio_params() const
+	{
+		return AudioParams::from_handle(
+			oakcore_samplebuffer_audio_params(handle_));
+	}
+
+	void set_audio_params(const AudioParams &params)
+	{
+		oakcore_samplebuffer_set_audio_params(handle_, params.handle());
+	}
+
+	size_t sample_count() const
+	{
+		return oakcore_samplebuffer_sample_count(handle_);
+	}
+
+	void set_sample_count(const size_t &sample_count)
+	{
+		oakcore_samplebuffer_set_sample_count(handle_, sample_count);
+	}
+
 	void set_sample_count(const Rational &length)
 	{
-		set_sample_count(audio_params_.time_to_samples(length));
+		oakcore_samplebuffer_set_sample_count_length(handle_,
+													 length.handle());
 	}
 
 	float *data(int channel)
 	{
-		return data_[channel].data();
+		return oakcore_samplebuffer_data(handle_, channel);
 	}
 
 	const float *data(int channel) const
 	{
-		return data_.at(channel).data();
+		return oakcore_samplebuffer_data(handle_, channel);
 	}
 
 	std::vector<float *> to_raw_ptrs()
 	{
-		std::vector<float *> r(data_.size());
-		for (size_t i = 0; i < r.size(); i++) {
-			r[i] = data_[i].data();
+		std::vector<float *> r(static_cast<size_t>(channel_count()));
+		if (!r.empty()) {
+			oakcore_samplebuffer_to_raw_ptrs(handle_, r.data());
 		}
 		return r;
 	}
 
 	int channel_count() const
 	{
-		return data_.size();
+		return oakcore_samplebuffer_channel_count(handle_);
 	}
 
 	bool is_allocated() const
 	{
-		return !data_.empty();
+		return oakcore_samplebuffer_is_allocated(handle_) != 0;
 	}
-	void allocate();
-	void destroy();
 
-	void reverse();
-	void speed(double speed);
+	void allocate()
+	{
+		oakcore_samplebuffer_allocate(handle_);
+	}
+
+	void destroy()
+	{
+		oakcore_samplebuffer_destroy(handle_);
+	}
+
+	void reverse()
+	{
+		oakcore_samplebuffer_reverse(handle_);
+	}
+
+	void speed(double speed)
+	{
+		oakcore_samplebuffer_speed(handle_, speed);
+	}
+
+	void transform_volume(float f)
+	{
+		oakcore_samplebuffer_transform_volume(handle_, f);
+	}
+
+	void transform_volume_for_channel(int channel, float volume)
+	{
+		oakcore_samplebuffer_transform_volume_for_channel(handle_, channel,
+														  volume);
+	}
 
-	void transform_volume(float f);
-	void transform_volume_for_channel(int channel, float volume);
 	static void transform_volume(float f, const SampleBuffer *input,
-								 SampleBuffer *output);
+								 SampleBuffer *output)
+	{
+		oakcore_samplebuffer_transform_volume_to(f, input->handle_,
+												 output->handle_);
+	}
+
 	static void transform_volume_for_channel(int channel, float volume,
 											 const SampleBuffer *input,
-											 SampleBuffer *output);
+											 SampleBuffer *output)
+	{
+		oakcore_samplebuffer_transform_volume_for_channel_to(
+			channel, volume, input->handle_, output->handle_);
+	}
+
+	void transform_volume_for_sample(size_t sample_index, float volume)
+	{
+		oakcore_samplebuffer_transform_volume_for_sample(handle_, sample_index,
+														 volume);
+	}
 
-	void transform_volume_for_sample(size_t sample_index, float volume);
 	void transform_volume_for_sample_on_channel(size_t sample_index,
-												int channel, float volume);
+												int channel, float volume)
+	{
+		oakcore_samplebuffer_transform_volume_for_sample_on_channel(
+			handle_, sample_index, channel, volume);
+	}
 
-	void clamp();
+	void clamp()
+	{
+		oakcore_samplebuffer_clamp(handle_);
+	}
 
-	void silence();
-	void silence(size_t start_sample, size_t end_sample);
-	void silence_bytes(size_t start_byte, size_t end_byte);
+	void silence()
+	{
+		oakcore_samplebuffer_silence(handle_);
+	}
+
+	void silence(size_t start_sample, size_t end_sample)
+	{
+		oakcore_samplebuffer_silence_range(handle_, start_sample, end_sample);
+	}
+
+	void silence_bytes(size_t start_byte, size_t end_byte)
+	{
+		oakcore_samplebuffer_silence_bytes(handle_, start_byte, end_byte);
+	}
 
 	void set(int channel, const float *data, size_t sample_offset,
-			 size_t sample_length);
+			 size_t sample_length)
+	{
+		oakcore_samplebuffer_set(handle_, channel, data, sample_offset,
+								 sample_length);
+	}
+
 	void set(int channel, const float *data, size_t sample_length)
 	{
 		set(channel, data, 0, sample_length);
 	}
 
-	void fast_set(const SampleBuffer &other, int to, int from = -1);
+	void fast_set(const SampleBuffer &other, int to, int from = -1)
+	{
+		oakcore_samplebuffer_fast_set(handle_, other.handle_, to, from);
+	}
+
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakSampleBuffer *handle() const
+	{
+		return handle_;
+	}
+
+	/**
+	 * @brief Wraps an owned C handle (takes ownership)
+	 */
+	static SampleBuffer from_handle(OakSampleBuffer *handle)
+	{
+		return SampleBuffer(handle);
+	}
 
 private:
-	void clamp_channel(int channel);
+	explicit SampleBuffer(OakSampleBuffer *handle)
+		: handle_(handle)
+	{
+	}
 
-	AudioParams audio_params_;
-
-	size_t sample_count_per_channel_;
-
-	std::vector<std::vector<float>> data_;
+	OakSampleBuffer *handle_;
 };
 
 }

core/include/olive/core/util/bezier.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,113 +24,193 @@
 
 #include <Imath/ImathVec.h>
 
+#include "olive/core/oakcore/bezier.h"
+
 namespace olive::core
 {
 
+/**
+ * @brief Keyframe easing bezier curve value type
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakBezier handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation.
+ */
 class Bezier {
 public:
-	Bezier();
-	Bezier(double x, double y);
-	Bezier(double x, double y, double cp1_x, double cp1_y, double cp2_x,
-		   double cp2_y);
+	Bezier()
+		: handle_(oakcore_bezier_create())
+	{
+	}
 
-	const double &x() const
+	Bezier(double x, double y)
+		: handle_(oakcore_bezier_create_xy(x, y))
 	{
-		return x_;
 	}
-	const double &y() const
+
+	Bezier(double x, double y, double cp1_x, double cp1_y, double cp2_x,
+		   double cp2_y)
+		: handle_(
+			oakcore_bezier_create_full(x, y, cp1_x, cp1_y, cp2_x, cp2_y))
 	{
-		return y_;
 	}
-	const double &cp1_x() const
+
+	Bezier(const Bezier &rhs)
+		: handle_(oakcore_bezier_copy(rhs.handle_))
 	{
-		return cp1_x_;
 	}
-	const double &cp1_y() const
+
+	Bezier(Bezier &&rhs) noexcept
+		: handle_(rhs.handle_)
 	{
-		return cp1_y_;
+		rhs.handle_ = nullptr;
 	}
-	const double &cp2_x() const
+
+	~Bezier()
 	{
-		return cp2_x_;
+		oakcore_bezier_free(handle_);
 	}
-	const double &cp2_y() const
+
+	Bezier &operator=(const Bezier &rhs)
 	{
-		return cp2_y_;
+		if (this != &rhs) {
+			oakcore_bezier_free(handle_);
+			handle_ = oakcore_bezier_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	Bezier &operator=(Bezier &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakcore_bezier_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
+
+	double x() const
+	{
+		return oakcore_bezier_x(handle_);
+	}
+	double y() const
+	{
+		return oakcore_bezier_y(handle_);
+	}
+	double cp1_x() const
+	{
+		return oakcore_bezier_cp1_x(handle_);
+	}
+	double cp1_y() const
+	{
+		return oakcore_bezier_cp1_y(handle_);
+	}
+	double cp2_x() const
+	{
+		return oakcore_bezier_cp2_x(handle_);
+	}
+	double cp2_y() const
+	{
+		return oakcore_bezier_cp2_y(handle_);
 	}
 
 	Imath::V2d to_vec() const
 	{
-		return Imath::V2d(x_, y_);
+		return Imath::V2d(x(), y());
 	}
 
 	Imath::V2d control_point_1_to_vec() const
 	{
-		return Imath::V2d(cp1_x_, cp1_y_);
+		return Imath::V2d(cp1_x(), cp1_y());
 	}
 
 	Imath::V2d control_point_2_to_vec() const
 	{
-		return Imath::V2d(cp2_x_, cp2_y_);
+		return Imath::V2d(cp2_x(), cp2_y());
 	}
 
 	void set_x(const double &x)
 	{
-		x_ = x;
+		oakcore_bezier_set_x(handle_, x);
 	}
 	void set_y(const double &y)
 	{
-		y_ = y;
+		oakcore_bezier_set_y(handle_, y);
 	}
 	void set_cp1_x(const double &cp1_x)
 	{
-		cp1_x_ = cp1_x;
+		oakcore_bezier_set_cp1_x(handle_, cp1_x);
 	}
 	void set_cp1_y(const double &cp1_y)
 	{
-		cp1_y_ = cp1_y;
+		oakcore_bezier_set_cp1_y(handle_, cp1_y);
 	}
 	void set_cp2_x(const double &cp2_x)
 	{
-		cp2_x_ = cp2_x;
+		oakcore_bezier_set_cp2_x(handle_, cp2_x);
 	}
 	void set_cp2_y(const double &cp2_y)
 	{
-		cp2_y_ = cp2_y;
+		oakcore_bezier_set_cp2_y(handle_, cp2_y);
 	}
 
-	static double quadratic_xto_t(double x, double a, double b, double c);
+	static double quadratic_xto_t(double x, double a, double b, double c)
+	{
+		return oakcore_bezier_quadratic_xto_t(x, a, b, c);
+	}
 
-	static double quadratic_tto_y(double a, double b, double c, double t);
+	static double quadratic_tto_y(double a, double b, double c, double t)
+	{
+		return oakcore_bezier_quadratic_tto_y(a, b, c, t);
+	}
 
 	static double quadratic_xto_y(double x, const Imath::V2d &a,
-								const Imath::V2d &b, const Imath::V2d &c)
+								  const Imath::V2d &b, const Imath::V2d &c)
 	{
 		return quadratic_tto_y(a.y, b.y, c.y, quadratic_xto_t(x, a.x, b.x, c.x));
 	}
 
-	static double cubic_xto_t(double x, double a, double b, double c, double d);
+	static double cubic_xto_t(double x, double a, double b, double c, double d)
+	{
+		return oakcore_bezier_cubic_xto_t(x, a, b, c, d);
+	}
 
-	static double cubic_tto_y(double a, double b, double c, double d, double t);
+	static double cubic_tto_y(double a, double b, double c, double d, double t)
+	{
+		return oakcore_bezier_cubic_tto_y(a, b, c, d, t);
+	}
 
 	static double cubic_xto_y(double x, const Imath::V2d &a, const Imath::V2d &b,
-							const Imath::V2d &c, const Imath::V2d &d)
+							  const Imath::V2d &c, const Imath::V2d &d)
 	{
-		return cubic_tto_y(a.y, b.y, c.y, d.y, cubic_xto_t(x, a.x, b.x, c.x, d.x));
+		return cubic_tto_y(a.y, b.y, c.y, d.y,
+						   cubic_xto_t(x, a.x, b.x, c.x, d.x));
+	}
+
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakBezier *handle() const
+	{
+		return handle_;
+	}
+
+	/**
+	 * @brief Wraps an owned C handle (takes ownership)
+	 */
+	static Bezier from_handle(OakBezier *handle)
+	{
+		return Bezier(handle);
 	}
 
 private:
-	static double calculate_t_from_x(bool cubic, double x, double a, double b,
-								  double c, double d);
+	explicit Bezier(OakBezier *handle)
+		: handle_(handle)
+	{
+	}
 
-	double x_;
-	double y_;
-
-	double cp1_x_;
-	double cp1_y_;
-
-	double cp2_x_;
-	double cp2_y_;
+	OakBezier *handle_;
 };
 
 }

core/include/olive/core/util/color.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,6 +22,7 @@
 #ifndef OAK_LIBOLIVECORE_COLOR_H
 #define OAK_LIBOLIVECORE_COLOR_H
 
+#include "olive/core/oakcore/color.h"
 #include "../render/pixelformat.h"
 
 namespace olive::core
@@ -29,6 +30,10 @@ namespace olive::core
 
 /**
  * @brief High precision 32-bit DataType based RGBA color value
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakColor handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation.
  */
 class Color {
 public:
@@ -36,22 +41,55 @@ public:
 	static constexpr unsigned int rgba = 4;
 
 	Color()
+		: handle_(oakcore_color_create())
 	{
-		for (unsigned int i = 0; i < rgba; i++) {
-			data_[i] = 0.0;
-		}
 	}
 
 	Color(const DataType &r, const DataType &g, const DataType &b,
 		  const DataType &a = 1.0f)
+		: handle_(oakcore_color_create_rgba(r, g, b, a))
 	{
-		data_[0] = r;
-		data_[1] = g;
-		data_[2] = b;
-		data_[3] = a;
 	}
 
-	Color(const char *data, const PixelFormat &format, int ch_layout);
+	Color(const char *data, const PixelFormat &format, int ch_layout)
+		: handle_(oakcore_color_from_data(data, format, ch_layout))
+	{
+	}
+
+	Color(const Color &rhs)
+		: handle_(oakcore_color_copy(rhs.handle_))
+	{
+	}
+
+	Color(Color &&rhs) noexcept
+		: handle_(rhs.handle_)
+	{
+		rhs.handle_ = nullptr;
+	}
+
+	~Color()
+	{
+		oakcore_color_free(handle_);
+	}
+
+	Color &operator=(const Color &rhs)
+	{
+		if (this != &rhs) {
+			oakcore_color_free(handle_);
+			handle_ = oakcore_color_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	Color &operator=(Color &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakcore_color_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
 
 	/**
    * @brief Creates a Color struct from hue/saturation/value
@@ -59,78 +97,143 @@ public:
    * Hue expects a value between 0.0 and 360.0. Saturation and Value expect a value between 0.0 and 1.0.
    */
 	static Color from_hsv(const DataType &h, const DataType &s,
-						 const DataType &v);
-
-	const DataType &red() const
+						 const DataType &v)
 	{
-		return data_[0];
-	}
-	const DataType &green() const
-	{
-		return data_[1];
-	}
-	const DataType &blue() const
-	{
-		return data_[2];
-	}
-	const DataType &alpha() const
-	{
-		return data_[3];
+		return from_handle(oakcore_color_from_hsv(h, s, v));
 	}
 
-	void to_hsv(DataType *hue, DataType *sat, DataType *val) const;
-	DataType hsv_hue() const;
-	DataType hsv_saturation() const;
-	DataType value() const;
+	DataType red() const
+	{
+		return oakcore_color_red(handle_);
+	}
+	DataType green() const
+	{
+		return oakcore_color_green(handle_);
+	}
+	DataType blue() const
+	{
+		return oakcore_color_blue(handle_);
+	}
+	DataType alpha() const
+	{
+		return oakcore_color_alpha(handle_);
+	}
 
-	void to_hsl(DataType *hue, DataType *sat, DataType *lightness) const;
-	DataType hsl_hue() const;
-	DataType hsl_saturation() const;
-	DataType lightness() const;
+	void to_hsv(DataType *hue, DataType *sat, DataType *val) const
+	{
+		oakcore_color_to_hsv(handle_, hue, sat, val);
+	}
+	DataType hsv_hue() const
+	{
+		return oakcore_color_hsv_hue(handle_);
+	}
+	DataType hsv_saturation() const
+	{
+		return oakcore_color_hsv_saturation(handle_);
+	}
+	DataType value() const
+	{
+		return oakcore_color_value(handle_);
+	}
+
+	void to_hsl(DataType *hue, DataType *sat, DataType *lightness) const
+	{
+		oakcore_color_to_hsl(handle_, hue, sat, lightness);
+	}
+	DataType hsl_hue() const
+	{
+		return oakcore_color_hsl_hue(handle_);
+	}
+	DataType hsl_saturation() const
+	{
+		return oakcore_color_hsl_saturation(handle_);
+	}
+	DataType lightness() const
+	{
+		return oakcore_color_lightness(handle_);
+	}
 
 	void set_red(const DataType &red)
 	{
-		data_[0] = red;
+		oakcore_color_set_red(handle_, red);
 	}
 	void set_green(const DataType &green)
 	{
-		data_[1] = green;
+		oakcore_color_set_green(handle_, green);
 	}
 	void set_blue(const DataType &blue)
 	{
-		data_[2] = blue;
+		oakcore_color_set_blue(handle_, blue);
 	}
 	void set_alpha(const DataType &alpha)
 	{
-		data_[3] = alpha;
+		oakcore_color_set_alpha(handle_, alpha);
 	}
 
 	DataType *data()
 	{
-		return data_;
+		return oakcore_color_data(handle_);
 	}
 	const DataType *data() const
 	{
-		return data_;
+		return oakcore_color_const_data(handle_);
 	}
 
 	void to_data(char *out, const PixelFormat &format,
-				unsigned int nb_channels) const;
+				unsigned int nb_channels) const
+	{
+		oakcore_color_to_data(handle_, out, format, int(nb_channels));
+	}
 
 	static Color from_data(const char *in, const PixelFormat &format,
-						  unsigned int nb_channels);
+						  unsigned int nb_channels)
+	{
+		return from_handle(oakcore_color_from_data(in, format, int(nb_channels)));
+	}
 
 	// Suuuuper rough luminance value mostly used for UI (determining whether to overlay with black
 	// or white text)
-	DataType get_rough_luminance() const;
+	DataType get_rough_luminance() const
+	{
+		return oakcore_color_get_rough_luminance(handle_);
+	}
 
 	// Assignment math operators
-	Color &operator+=(const Color &rhs);
-	Color &operator-=(const Color &rhs);
-	Color &operator+=(const DataType &rhs);
-	Color &operator-=(const DataType &rhs);
-	Color &operator*=(const DataType &rhs);
-	Color &operator/=(const DataType &rhs);
+	Color &operator+=(const Color &rhs)
+	{
+		oakcore_color_add_assign(handle_, rhs.handle_);
+		return *this;
+	}
+
+	Color &operator-=(const Color &rhs)
+	{
+		oakcore_color_sub_assign(handle_, rhs.handle_);
+		return *this;
+	}
+
+	Color &operator+=(const DataType &rhs)
+	{
+		oakcore_color_add_scalar_assign(handle_, rhs);
+		return *this;
+	}
+
+	Color &operator-=(const DataType &rhs)
+	{
+		oakcore_color_sub_scalar_assign(handle_, rhs);
+		return *this;
+	}
+
+	Color &operator*=(const DataType &rhs)
+	{
+		oakcore_color_mul_scalar_assign(handle_, rhs);
+		return *this;
+	}
+
+	Color &operator/=(const DataType &rhs)
+	{
+		oakcore_color_div_scalar_assign(handle_, rhs);
+		return *this;
+	}
 
 	// Binary math operators
 	Color operator+(const Color &rhs) const
@@ -175,8 +278,29 @@ public:
 		return c;
 	}
 
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakColor *handle() const
+	{
+		return handle_;
+	}
+
+	/**
+	 * @brief Wraps an owned C handle (takes ownership)
+	 */
+	static Color from_handle(OakColor *handle)
+	{
+		return Color(handle);
+	}
+
 private:
-	DataType data_[rgba];
+	explicit Color(OakColor *handle)
+		: handle_(handle)
+	{
+	}
+
+	OakColor *handle_;
 };
 
 }

core/include/olive/core/util/fractionutils.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,14 +24,20 @@
 
 #include <stdint.h>
 
+#include "olive/core/oakcore/fractionutils.h"
+
 namespace olive::core
 {
 
 /**
- * @brief Rounding modes for RescaleRnd()
+ * @brief Rounding modes for rescale_rnd()
  *
  * Mirrors the FFmpeg AVRounding modes that this codebase used before the
  * FFmpeg dependency was removed from core.
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: every function forwards
+ * across the C boundary. The public API is unchanged from the original
+ * implementation.
  */
 enum class FractionRounding {
 	/**
@@ -55,7 +61,10 @@ enum class FractionRounding {
  *
  * A zero denominator is preserved (with the numerator set to zero).
  */
-void reduce_fraction(int64_t &num, int64_t &den, int64_t max);
+inline void reduce_fraction(int64_t &num, int64_t &den, int64_t max)
+{
+	oakcore_fractionutils_reduce_fraction(&num, &den, max);
+}
 
 /**
  * @brief Compare two fractions
@@ -64,7 +73,10 @@ void reduce_fraction(int64_t &num, int64_t &den, int64_t max);
  * 0 if a == b, 1 if a > b, and INT_MIN when the comparison is meaningless
  * (degenerate zero-denominator fractions).
  */
-int compare_fractions(int an, int ad, int bn, int bd);
+inline int compare_fractions(int an, int ad, int bn, int bd)
+{
+	return oakcore_fractionutils_compare_fractions(an, ad, bn, bd);
+}
 
 /**
  * @brief Rescale `a` by the fraction b/c: returns a * b / c
@@ -73,7 +85,11 @@ int compare_fractions(int an, int ad, int bn, int bd);
  * product is computed with 128-bit arithmetic where available so that no
  * precision is lost for large timestamps.
  */
-int64_t rescale_rnd(int64_t a, int64_t b, int64_t c, FractionRounding rnd);
+inline int64_t rescale_rnd(int64_t a, int64_t b, int64_t c, FractionRounding rnd)
+{
+	return oakcore_fractionutils_rescale_rnd(a, b, c,
+											 static_cast<OakFractionRounding>(rnd));
+}
 
 }
 

core/include/olive/core/util/rational.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -24,131 +24,295 @@
 
 #include <climits>
 #include <iostream>
+#include <string>
 
 #ifdef USE_OTIO
 #include <opentime/rationalTime.h>
 #endif
 
+#include "olive/core/oakcore/rational.h"
+
 namespace olive::core
 {
 
+/**
+ * @brief Rational number value type
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakRational handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation.
+ */
 class Rational {
 public:
 	Rational(const int &numerator = 0)
+		: handle_(oakcore_rational_create(numerator))
 	{
-		num_ = numerator;
-		den_ = 1;
 	}
 
 	Rational(const int &numerator, const int &denominator)
+		: handle_(oakcore_rational_create_nd(numerator, denominator))
 	{
-		num_ = numerator;
-		den_ = denominator;
-
-		fix_signs();
-		reduce();
 	}
 
-	Rational(const Rational &rhs) = default;
+	Rational(const Rational &rhs)
+		: handle_(oakcore_rational_copy(rhs.handle_))
+	{
+	}
 
-	static Rational from_double(const double &flt, bool *ok = nullptr);
-	static Rational from_string(const std::string &str, bool *ok = nullptr);
+	Rational(Rational &&rhs) noexcept
+		: handle_(rhs.handle_)
+	{
+		rhs.handle_ = nullptr;
+	}
+
+	~Rational()
+	{
+		oakcore_rational_free(handle_);
+	}
+
+	static Rational from_double(const double &flt, bool *ok = nullptr)
+	{
+		int c_ok = 0;
+		Rational r(from_handle(oakcore_rational_from_double(flt, &c_ok)));
+		if (ok) {
+			*ok = (c_ok != 0);
+		}
+		return r;
+	}
+
+	static Rational from_string(const std::string &str, bool *ok = nullptr)
+	{
+		int c_ok = 0;
+		Rational r(
+			from_handle(oakcore_rational_from_string(str.c_str(), &c_ok)));
+		if (ok) {
+			*ok = (c_ok != 0);
+		}
+		return r;
+	}
 
 	static const Rational na_n;
 
 	//Assignment Operators
-	const Rational &operator=(const Rational &rhs);
-	const Rational &operator+=(const Rational &rhs);
-	const Rational &operator-=(const Rational &rhs);
-	const Rational &operator/=(const Rational &rhs);
-	const Rational &operator*=(const Rational &rhs);
+	Rational &operator=(const Rational &rhs)
+	{
+		if (this != &rhs) {
+			oakcore_rational_free(handle_);
+			handle_ = oakcore_rational_copy(rhs.handle_);
+		}
+		return *this;
+	}
+
+	Rational &operator=(Rational &&rhs) noexcept
+	{
+		if (this != &rhs) {
+			oakcore_rational_free(handle_);
+			handle_ = rhs.handle_;
+			rhs.handle_ = nullptr;
+		}
+		return *this;
+	}
+
+	Rational &operator+=(const Rational &rhs)
+	{
+		oakcore_rational_add_assign(handle_, rhs.handle_);
+		return *this;
+	}
+
+	Rational &operator-=(const Rational &rhs)
+	{
+		oakcore_rational_sub_assign(handle_, rhs.handle_);
+		return *this;
+	}
+
+	Rational &operator/=(const Rational &rhs)
+	{
+		oakcore_rational_div_assign(handle_, rhs.handle_);
+		return *this;
+	}
+
+	Rational &operator*=(const Rational &rhs)
+	{
+		oakcore_rational_mul_assign(handle_, rhs.handle_);
+		return *this;
+	}
 
 	//Binary math operators
-	Rational operator+(const Rational &rhs) const;
-	Rational operator-(const Rational &rhs) const;
-	Rational operator/(const Rational &rhs) const;
-	Rational operator*(const Rational &rhs) const;
+	Rational operator+(const Rational &rhs) const
+	{
+		Rational answer(*this);
+		answer += rhs;
+		return answer;
+	}
+
+	Rational operator-(const Rational &rhs) const
+	{
+		Rational answer(*this);
+		answer -= rhs;
+		return answer;
+	}
+
+	Rational operator/(const Rational &rhs) const
+	{
+		Rational answer(*this);
+		answer /= rhs;
+		return answer;
+	}
+
+	Rational operator*(const Rational &rhs) const
+	{
+		Rational answer(*this);
+		answer *= rhs;
+		return answer;
+	}
 
 	//Relational and equality operators
-	bool operator<(const Rational &rhs) const;
-	bool operator<=(const Rational &rhs) const;
-	bool operator>(const Rational &rhs) const;
-	bool operator>=(const Rational &rhs) const;
-	bool operator==(const Rational &rhs) const;
-	bool operator!=(const Rational &rhs) const;
+	bool operator<(const Rational &rhs) const
+	{
+		return oakcore_rational_compare(handle_, rhs.handle_) < 0;
+	}
+
+	bool operator<=(const Rational &rhs) const
+	{
+		return oakcore_rational_compare(handle_, rhs.handle_) <= 0;
+	}
+
+	bool operator>(const Rational &rhs) const
+	{
+		return oakcore_rational_compare(handle_, rhs.handle_) > 0;
+	}
+
+	bool operator>=(const Rational &rhs) const
+	{
+		return oakcore_rational_compare(handle_, rhs.handle_) >= 0;
+	}
+
+	bool operator==(const Rational &rhs) const
+	{
+		return oakcore_rational_compare(handle_, rhs.handle_) == 0;
+	}
+
+	bool operator!=(const Rational &rhs) const
+	{
+		return !(*this == rhs);
+	}
 
 	//Unary operators
-	const Rational &operator+() const
+	Rational operator+() const
 	{
 		return *this;
 	}
+
 	Rational operator-() const
 	{
-		return Rational(num_, -den_);
+		return Rational(numerator(), -denominator());
 	}
+
 	bool operator!() const
 	{
-		return !num_;
+		return numerator() == 0;
 	}
 
 	//Function: convert to double
-	double to_double() const;
+	double to_double() const
+	{
+		return oakcore_rational_to_double(handle_);
+	}
 
 #ifdef USE_OTIO
 	static Rational fromRationalTime(const opentime::RationalTime &t)
 	{
-		// Is this the best way to do this?
-		return fromDouble(t.to_seconds());
+		return from_double(t.to_seconds());
 	}
 
-	// Convert Olive rationals to opentime rationals with the given framerate (defaults to 24)
-	opentime::RationalTime toRationalTime(double framerate = 24) const;
+	opentime::RationalTime toRationalTime(double framerate = 24) const
+	{
+		// Olive can store rationals as 0/0 which causes errors in OTIO
+		const int den = denominator();
+		opentime::RationalTime time(numerator(), den == 0 ? 1 : den);
+		return time.rescaled_to(framerate);
+	}
 #endif
 
 	// Produce "flipped" version
-	Rational flipped() const;
-	void flip();
+	Rational flipped() const
+	{
+		return from_handle(oakcore_rational_flipped(handle_));
+	}
+
+	void flip()
+	{
+		oakcore_rational_flip(handle_);
+	}
 
 	// Returns whether the Rational is valid but equal to zero or not
 	//
 	// A NaN is always a null, but a null is not always a NaN
 	bool isNull() const
 	{
-		return num_ == 0;
+		return oakcore_rational_is_null(handle_) != 0;
 	}
 
 	// Returns whether this Rational is not a valid number (denominator == 0)
 	bool isNaN() const
 	{
-		return den_ == 0;
+		return oakcore_rational_is_nan(handle_) != 0;
 	}
 
-	const int &numerator() const
+	int numerator() const
 	{
-		return num_;
-	}
-	const int &denominator() const
-	{
-		return den_;
+		return oakcore_rational_numerator(handle_);
 	}
 
-	std::string to_string() const;
+	int denominator() const
+	{
+		return oakcore_rational_denominator(handle_);
+	}
+
+	std::string to_string() const
+	{
+		const int size = oakcore_rational_to_string(handle_, nullptr, 0);
+		std::string s(size_t(size) + 1, '\0');
+		oakcore_rational_to_string(handle_, s.data(), size + 1);
+		s.resize(size_t(size));
+		return s;
+	}
 
 	friend std::ostream &operator<<(std::ostream &out, const Rational &value)
 	{
-		out << value.num_ << '/' << value.den_;
+		out << value.numerator() << '/' << value.denominator();
 
 		return out;
 	}
 
-private:
-	void fix_signs();
-	void reduce();
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakRational *handle() const
+	{
+		return handle_;
+	}
 
-	int num_;
-	int den_;
+	/**
+	 * @brief Wraps an owned C handle (takes ownership)
+	 */
+	static Rational from_handle(OakRational *handle)
+	{
+		return Rational(handle);
+	}
+
+private:
+	explicit Rational(OakRational *handle)
+		: handle_(handle)
+	{
+	}
+
+	OakRational *handle_;
 };
 
+inline const Rational Rational::na_n =
+	Rational::from_handle(oakcore_rational_create_nan());
+
 #define RATIONAL_MIN Rational(INT_MIN)
 #define RATIONAL_MAX Rational(INT_MAX)
 

core/include/olive/core/util/stringutils.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -23,13 +23,24 @@
 #define OAK_LIBOLIVECORE_STRINGUTILS_H
 
 #include <algorithm>
+#include <cstdarg>
 #include <regex>
 #include <vector>
 #include <string>
 
+#include "olive/core/oakcore/stringutils.h"
+
 namespace olive::core
 {
 
+/**
+ * @brief String utility functions
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: every non-inlined call
+ * is forwarded across the C boundary. The public API is unchanged from the
+ * original implementation. The class has static members only, so there is
+ * no opaque handle.
+ */
 class StringUtils {
 public:
 	/**
@@ -47,7 +58,20 @@ public:
    *
    * A vector of strings split by the specified delimiter.
    */
-	static std::vector<std::string> split(const std::string &s, char separator);
+	static std::vector<std::string> split(const std::string &s, char separator)
+	{
+		int count = 0;
+		char **arr = oakcore_stringutils_split(s.c_str(), separator, &count);
+		std::vector<std::string> output;
+		if (arr) {
+			output.reserve(size_t(count));
+			for (int i = 0; i < count; i++) {
+				output.emplace_back(arr[i]);
+			}
+			oakcore_stringutils_free_string_array(arr, count);
+		}
+		return output;
+	}
 
 	/**
    * @brief Splits a string into a list of strings using regular expressions.
@@ -65,10 +89,26 @@ public:
    * A vector of strings split wherever the regular expression matched.
    */
 	static std::vector<std::string> split_regex(const std::string &s,
-												const std::regex &regex);
+												const std::regex &regex)
+	{
+		// std::regex cannot cross the C ABI, so this overload is implemented
+		// inline here with only standard library facilities, exactly like the
+		// original. The C ABI exposes the same functionality as
+		// oakcore_stringutils_split_regex() taking a pattern string.
+		std::vector<std::string> output;
+
+		std::sregex_token_iterator iter(s.begin(), s.end(), regex, -1);
+		std::sregex_token_iterator end;
+		for (; iter != end; iter++) {
+			output.push_back(*iter);
+		}
+
+		return output;
+	}
 
 	/**
-   * @brief Convert a string to int using a bool pointer to determine success rather than an exception
+   * @brief Convert a string to int using a bool pointer to determine
+   * success rather than an exception
    *
    * @param s
    *
@@ -86,7 +126,15 @@ public:
    *
    * Either the int parsed from the string, or 0 (with *ok set to false) on parser error.
    */
-	static int to_int(const std::string &s, int base, bool *ok = nullptr);
+	static int to_int(const std::string &s, int base, bool *ok = nullptr)
+	{
+		int c_ok = 0;
+		const int x = oakcore_stringutils_to_int(s.c_str(), base, &c_ok);
+		if (ok) {
+			*ok = (c_ok != 0);
+		}
+		return x;
+	}
 
 	/**
    * @brief Overloaded function
@@ -157,7 +205,28 @@ public:
    *
    * A formatted string in std::string form.
    */
-	static std::string format(const char *fmt, ...);
+	static std::string format(const char *fmt, ...)
+	{
+		va_list ap1, ap2;
+		va_start(ap1, fmt);
+
+		// Need to duplicate because the va_list is consumed by each C API call
+		va_copy(ap2, ap1);
+
+		const int size = oakcore_stringutils_format_v(nullptr, 0, fmt, ap1);
+
+		// Create string with size, adding 1 for the null terminator
+		std::string r(size_t(size) + 1, '\0');
+		oakcore_stringutils_format_v(r.data(), size + 1, fmt, ap2);
+
+		va_end(ap2);
+		va_end(ap1);
+
+		// Pop null terminator
+		r.pop_back();
+
+		return r;
+	}
 
 	// trim from start (in place)
 	static inline void ltrim(std::string &s)

core/include/olive/core/util/timecodefunctions.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -25,6 +25,9 @@
 #include "rational.h"
 
 #include <cstdint>
+#include <string>
+
+#include "olive/core/oakcore/timecodefunctions.h"
 
 namespace olive::core
 {
@@ -32,11 +35,17 @@ namespace olive::core
 /**
  * @brief Functions for converting times/timecodes/timestamps
  *
+ * Consumer-side wrapper over the liboakcore C ABI: the class is all-static
+ * and every call is forwarded across the C boundary (times and timebases
+ * cross it as borrowed Rational handles). The public API is unchanged from
+ * the original implementation.
+ *
  * Olive uses the following terminology through its code:
  *
  * `time` - time in seconds presented in a Rational form
  * `timebase` - the base time unit of an audio/video stream in seconds
- * `timestamp` - an integer representation of a time in timebase units (in many cases is used like a frame number)
+ * `timestamp` - an integer representation of a time in timebase units
+ * (in many cases is used like a frame number)
  * `timecode` a user-friendly string representation of a time according to Timecode::Display
  */
 class Timecode {
@@ -52,40 +61,104 @@ public:
 	enum Rounding { k_ceil, k_floor, k_round };
 
 	/**
-   * @brief Convert a timestamp (according to a Rational timebase) to a user-friendly string representation
+   * @brief Convert a timestamp (according to a Rational timebase) to a
+   * user-friendly string representation
    */
 	static std::string time_to_timecode(const Rational &time,
 										const Rational &timebase,
 										const Display &display,
-										bool show_plus_if_positive = false);
+										bool show_plus_if_positive = false)
+	{
+		const OakTimecodeDisplay c_display =
+			static_cast<OakTimecodeDisplay>(display);
+		const int c_show_plus = show_plus_if_positive ? 1 : 0;
+		const int size = oakcore_timecode_time_to_timecode(
+			time.handle(), timebase.handle(), c_display, c_show_plus, nullptr,
+			0);
+		std::string s(size_t(size) + 1, '\0');
+		oakcore_timecode_time_to_timecode(time.handle(), timebase.handle(),
+										  c_display, c_show_plus, s.data(),
+										  size + 1);
+		s.resize(size_t(size));
+		return s;
+	}
+
 	static Rational timecode_to_time(std::string timecode,
 									 const Rational &timebase,
 									 const Display &display,
-									 bool *ok = nullptr);
+									 bool *ok = nullptr)
+	{
+		int c_ok = 0;
+		Rational r = Rational::from_handle(oakcore_timecode_timecode_to_time(
+			timecode.c_str(), timebase.handle(),
+			static_cast<OakTimecodeDisplay>(display), &c_ok));
+		if (ok) {
+			*ok = (c_ok != 0);
+		}
+		return r;
+	}
 
-	static std::string time_to_string(int64_t ms);
+	static std::string time_to_string(int64_t ms)
+	{
+		const int size = oakcore_timecode_time_to_string(ms, nullptr, 0);
+		std::string s(size_t(size) + 1, '\0');
+		oakcore_timecode_time_to_string(ms, s.data(), size + 1);
+		s.resize(size_t(size));
+		return s;
+	}
 
 	static Rational snap_time_to_timebase(const Rational &time,
 										  const Rational &timebase,
-										  Rounding floor = k_round);
+										  Rounding floor = k_round)
+	{
+		return Rational::from_handle(oakcore_timecode_snap_time_to_timebase(
+			time.handle(), timebase.handle(),
+			static_cast<OakTimecodeRounding>(floor)));
+	}
 
 	static int64_t time_to_timestamp(const Rational &time,
 									 const Rational &timebase,
-									 Rounding floor = k_round);
+									 Rounding floor = k_round)
+	{
+		return oakcore_timecode_time_to_timestamp(
+			time.handle(), timebase.handle(),
+			static_cast<OakTimecodeRounding>(floor));
+	}
+
 	static int64_t time_to_timestamp(const double &time,
 									 const Rational &timebase,
-									 Rounding floor = k_round);
+									 Rounding floor = k_round)
+	{
+		return oakcore_timecode_time_to_timestamp_d(
+			time, timebase.handle(), static_cast<OakTimecodeRounding>(floor));
+	}
 
 	static int64_t rescale_timestamp(const int64_t &ts, const Rational &source,
-									 const Rational &dest);
+									 const Rational &dest)
+	{
+		return oakcore_timecode_rescale_timestamp(ts, source.handle(),
+												  dest.handle());
+	}
+
 	static int64_t rescale_timestamp_ceil(const int64_t &ts,
 										  const Rational &source,
-										  const Rational &dest);
+										  const Rational &dest)
+	{
+		return oakcore_timecode_rescale_timestamp_ceil(ts, source.handle(),
+													   dest.handle());
+	}
 
 	static Rational timestamp_to_time(const int64_t &timestamp,
-									  const Rational &timebase);
+									  const Rational &timebase)
+	{
+		return Rational::from_handle(oakcore_timecode_timestamp_to_time(
+			timestamp, timebase.handle()));
+	}
 
-	static bool timebase_is_drop_frame(const Rational &timebase);
+	static bool timebase_is_drop_frame(const Rational &timebase)
+	{
+		return oakcore_timecode_timebase_is_drop_frame(timebase.handle()) != 0;
+	}
 };
 
 }

core/include/olive/core/util/timerange.h

@@ -2,7 +2,7 @@
 
   Olive - Non-Linear Video Editor
   Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
+  Modifications Copyright (C) 2026 Oak Team
 
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -22,67 +22,223 @@
 #ifndef OAK_LIBOLIVECORE_TIMERANGE_H
 #define OAK_LIBOLIVECORE_TIMERANGE_H
 
+#include <algorithm>
+#include <cstdint>
+#include <iostream>
 #include <list>
 #include <vector>
 
+#include "olive/core/oakcore/timerange.h"
 #include "rational.h"
+#include "timecodefunctions.h"
 
 namespace olive::core
 {
 
+/**
+ * @brief A range of time, normalized so that in() <= out()
+ *
+ * Consumer-side wrapper over the liboakcore C ABI: the object only holds an
+ * opaque OakTimeRange handle and forwards every call across the C boundary.
+ * The public API is unchanged from the original implementation, except that
+ * the getters return Rational by value instead of by const reference.
+ */
 class TimeRange {
 public:
-	TimeRange() = default;
-	TimeRange(const Rational &in, const Rational &out);
-	TimeRange(const TimeRange &r)
-		: TimeRange(r.in(), r.out())
+	TimeRange()
+		: handle_(oakcore_timerange_create())
 	{
 	}
 
+	TimeRange(const Rational &in, const Rational &out)
+		: handle_(oakcore_timerange_create_io(in.handle(), out.handle()))
+	{
+	}
+
+	TimeRange(const TimeRange &r)
+		: handle_(oakcore_timerange_copy(r.handle_))
+	{
+	}
+
+	TimeRange(TimeRange &&r) noexcept
+		: handle_(r.handle_)
+	{
+		r.handle_ = nullptr;
+	}
+
+	~TimeRange()
+	{
+		oakcore_timerange_free(handle_);
+	}
+
 	TimeRange &operator=(const TimeRange &r)
 	{
-		set_range(r.in(), r.out());
+		if (this != &r) {
+			oakcore_timerange_free(handle_);
+			handle_ = oakcore_timerange_copy(r.handle_);
+		}
 		return *this;
 	}
 
-	const Rational &in() const;
-	const Rational &out() const;
-	const Rational &length() const;
+	TimeRange &operator=(TimeRange &&r) noexcept
+	{
+		if (this != &r) {
+			oakcore_timerange_free(handle_);
+			handle_ = r.handle_;
+			r.handle_ = nullptr;
+		}
+		return *this;
+	}
 
-	void set_in(const Rational &in);
-	void set_out(const Rational &out);
-	void set_range(const Rational &in, const Rational &out);
+	Rational in() const
+	{
+		return Rational::from_handle(oakcore_timerange_in(handle_));
+	}
 
-	bool operator==(const TimeRange &r) const;
-	bool operator!=(const TimeRange &r) const;
+	Rational out() const
+	{
+		return Rational::from_handle(oakcore_timerange_out(handle_));
+	}
+
+	Rational length() const
+	{
+		return Rational::from_handle(oakcore_timerange_length(handle_));
+	}
+
+	void set_in(const Rational &in)
+	{
+		oakcore_timerange_set_in(handle_, in.handle());
+	}
+
+	void set_out(const Rational &out)
+	{
+		oakcore_timerange_set_out(handle_, out.handle());
+	}
+
+	void set_range(const Rational &in, const Rational &out)
+	{
+		oakcore_timerange_set_range(handle_, in.handle(), out.handle());
+	}
+
+	bool operator==(const TimeRange &r) const
+	{
+		return oakcore_timerange_equal(handle_, r.handle_) != 0;
+	}
+
+	bool operator!=(const TimeRange &r) const
+	{
+		return !(*this == r);
+	}
 
 	bool overlaps_with(const TimeRange &a, bool in_inclusive = true,
-					  bool out_inclusive = true) const;
+					  bool out_inclusive = true) const
+	{
+		return oakcore_timerange_overlaps_with(handle_, a.handle_,
+											   in_inclusive ? 1 : 0,
+											   out_inclusive ? 1 : 0) != 0;
+	}
+
 	bool contains(const TimeRange &a, bool in_inclusive = true,
-				  bool out_inclusive = true) const;
-	bool contains(const Rational &r) const;
+				  bool out_inclusive = true) const
+	{
+		return oakcore_timerange_contains_range(handle_, a.handle_,
+												in_inclusive ? 1 : 0,
+												out_inclusive ? 1 : 0) != 0;
+	}
 
-	TimeRange combined(const TimeRange &a) const;
-	static TimeRange combine(const TimeRange &a, const TimeRange &b);
-	TimeRange intersected(const TimeRange &a) const;
-	static TimeRange intersect(const TimeRange &a, const TimeRange &b);
+	bool contains(const Rational &r) const
+	{
+		return oakcore_timerange_contains_time(handle_, r.handle()) != 0;
+	}
 
-	TimeRange operator+(const Rational &rhs) const;
-	TimeRange operator-(const Rational &rhs) const;
+	TimeRange combined(const TimeRange &a) const
+	{
+		return from_handle(oakcore_timerange_combined(handle_, a.handle_));
+	}
 
-	const TimeRange &operator+=(const Rational &rhs);
-	const TimeRange &operator-=(const Rational &rhs);
+	static TimeRange combine(const TimeRange &a, const TimeRange &b)
+	{
+		return from_handle(oakcore_timerange_combine(a.handle_, b.handle_));
+	}
 
-	std::list<TimeRange> split(const int &chunk_size) const;
+	TimeRange intersected(const TimeRange &a) const
+	{
+		return from_handle(oakcore_timerange_intersected(handle_, a.handle_));
+	}
+
+	static TimeRange intersect(const TimeRange &a, const TimeRange &b)
+	{
+		return from_handle(oakcore_timerange_intersect(a.handle_, b.handle_));
+	}
+
+	TimeRange operator+(const Rational &rhs) const
+	{
+		return from_handle(oakcore_timerange_add(handle_, rhs.handle()));
+	}
+
+	TimeRange operator-(const Rational &rhs) const
+	{
+		return from_handle(oakcore_timerange_sub(handle_, rhs.handle()));
+	}
+
+	const TimeRange &operator+=(const Rational &rhs)
+	{
+		oakcore_timerange_add_assign(handle_, rhs.handle());
+		return *this;
+	}
+
+	const TimeRange &operator-=(const Rational &rhs)
+	{
+		oakcore_timerange_sub_assign(handle_, rhs.handle());
+		return *this;
+	}
+
+	std::list<TimeRange> split(const int &chunk_size) const
+	{
+		const int count = oakcore_timerange_split_count(handle_, chunk_size);
+		std::vector<OakTimeRange *> handles{size_t(count)};
+		oakcore_timerange_split(handle_, chunk_size, handles.data(), count);
+
+		std::list<TimeRange> ranges;
+		for (OakTimeRange *h : handles) {
+			ranges.push_back(from_handle(h));
+		}
+		return ranges;
+	}
+
+	/**
+	 * @brief The wrapped C handle, for cross-type wrappers and direct C API use
+	 */
+	OakTimeRange *handle() const
+	{
+		return handle_;
+	}
+
+	/**
+	 * @brief Wraps an owned C handle (takes ownership)
+	 */
+	static TimeRange from_handle(OakTimeRange *handle)
+	{
+		return TimeRange(handle);
+	}
 
 private:
-	void normalize();
+	explicit TimeRange(OakTimeRange *handle)
+		: handle_(handle)
+	{
+	}
 
-	Rational in_;
-	Rational out_;
-	Rational length_;
+	OakTimeRange *handle_;
 };
 
+/**
+ * @brief A list of TimeRanges, kept merged and non-overlapping on insert()
+ *
+ * Consumer-side inline reimplementation over the wrapped TimeRange: every
+ * operation is expressed through the public API of olive::core::TimeRange
+ * and olive::core::Rational, so a container like this needs no C ABI surface
+ * of its own. The public API is unchanged from the original implementation.
+ */
 class TimeRangeList {
 public:
 	TimeRangeList() = default;
@@ -92,11 +248,46 @@ public:
 	{
 	}
 
-	void insert(const TimeRangeList &list_to_add);
-	void insert(TimeRange range_to_add);
+	void insert(const TimeRangeList &list_to_add)
+	{
+		for (auto it = list_to_add.cbegin(); it != list_to_add.cend(); it++) {
+			insert(*it);
+		}
+	}
 
-	void remove(const TimeRange &remove);
-	void remove(const TimeRangeList &list);
+	void insert(TimeRange range_to_add)
+	{
+		// See if list contains this range
+		if (contains(range_to_add)) {
+			return;
+		}
+
+		// Does not contain range, so we'll almost certainly be adding it in some way
+		for (auto it = array_.begin(); it != array_.end();) {
+			const TimeRange &compare = *it;
+
+			if (compare.overlaps_with(range_to_add)) {
+				range_to_add = TimeRange::combine(range_to_add, compare);
+				it = array_.erase(it);
+			} else {
+				it++;
+			}
+		}
+
+		array_.push_back(range_to_add);
+	}
+
+	void remove(const TimeRange &remove)
+	{
+		util_remove(&array_, remove);
+	}
+
+	void remove(const TimeRangeList &list)
+	{
+		for (const TimeRange &r : list) {
+			remove(r);
+		}
+	}
 
 	template <typename T>
 	static void util_remove(std::vector<T> *list, const TimeRange &remove)
@@ -138,7 +329,16 @@ public:
 	}
 
 	bool contains(const TimeRange &range, bool in_inclusive = true,
-				  bool out_inclusive = true) const;
+				  bool out_inclusive = true) const
+	{
+		for (int i = 0; i < size(); i++) {
+			if (array_.at(i).contains(range, in_inclusive, out_inclusive)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
 
 	bool contains(const Rational &r) const
 	{
@@ -178,13 +378,62 @@ public:
 		return array_.size();
 	}
 
-	void shift(const Rational &diff);
+	void shift(const Rational &diff)
+	{
+		for (int i = 0; i < array_.size(); i++) {
+			array_[i] += diff;
+		}
+	}
 
-	void trim_in(const Rational &diff);
+	void trim_in(const Rational &diff)
+	{
+		// Re-do list since we want to handle overlaps
+		TimeRangeList temp = *this;
 
-	void trim_out(const Rational &diff);
+		clear();
 
-	TimeRangeList intersects(const TimeRange &range) const;
+		for (auto it = temp.array_.begin(); it != temp.array_.end(); it++) {
+			TimeRange &r = *it;
+			r.set_in(r.in() + diff);
+			insert(r);
+		}
+	}
+
+	void trim_out(const Rational &diff)
+	{
+		// Re-do list since we want to handle overlaps
+		TimeRangeList temp = *this;
+
+		clear();
+
+		for (auto it = temp.array_.begin(); it != temp.array_.end(); it++) {
+			TimeRange &r = *it;
+			r.set_out(r.out() + diff);
+			insert(r);
+		}
+	}
+
+	TimeRangeList intersects(const TimeRange &range) const
+	{
+		TimeRangeList intersect_list;
+
+		for (int i = 0; i < size(); i++) {
+			const TimeRange &compare = array_.at(i);
+
+			if (compare.out() <= range.in() || compare.in() >= range.out()) {
+				// No intersect
+				continue;
+			} else {
+				// Crop the time range to the range and add it to the list
+				TimeRange cropped(std::max(range.in(), compare.in()),
+								  std::min(range.out(), compare.out()));
+
+				intersect_list.insert(cropped);
+			}
+		}
+
+		return intersect_list;
+	}
 
 	using const_iterator = std::vector<TimeRange>::const_iterator;
 
@@ -237,17 +486,70 @@ private:
 	std::vector<TimeRange> array_;
 };
 
+/**
+ * @brief Steps through a TimeRangeList frame by frame at a given timebase
+ *
+ * Consumer-side inline reimplementation: frame snapping and timestamp
+ * conversion go through the wrapped olive::core::Timecode functions, the
+ * range storage through the wrapped olive::core::TimeRangeList above. The
+ * public API is unchanged from the original implementation.
+ */
 class TimeRangeListFrameIterator {
 public:
-	TimeRangeListFrameIterator();
+	TimeRangeListFrameIterator()
+		: TimeRangeListFrameIterator(TimeRangeList(), Rational::na_n)
+	{
+	}
+
 	TimeRangeListFrameIterator(const TimeRangeList &list,
-							   const Rational &timebase);
+							   const Rational &timebase)
+		: list_(list)
+		, timebase_(timebase)
+		, range_index_(-1)
+		, size_(-1)
+		, frame_index_(0)
+		, custom_range_(false)
+	{
+		if (!list_.isEmpty() && timebase_.isNull()) {
+			std::cerr
+				<< "TimeRangeListFrameIterator created with null timebase but "
+				   "non-empty list, this will likely lead to infinite loops"
+				<< std::endl;
+		}
 
-	Rational snap(const Rational &r) const;
+		update_index_if_necessary();
+	}
 
-	bool get_next(Rational *out);
+	Rational snap(const Rational &r) const
+	{
+		return Timecode::snap_time_to_timebase(r, timebase_, Timecode::k_floor);
+	}
 
-	bool has_next() const;
+	bool get_next(Rational *out)
+	{
+		if (!has_next()) {
+			return false;
+		}
+
+		// Output current value
+		*out = current_;
+
+		// Determine next value by adding timebase
+		current_ += timebase_;
+
+		// If this time is outside the current range, jump to the next one
+		update_index_if_necessary();
+
+		// Increment frame index
+		frame_index_++;
+
+		return true;
+	}
+
+	bool has_next() const
+	{
+		return range_index_ < list_.size();
+	}
 
 	std::vector<Rational> to_vector() const
 	{
@@ -260,7 +562,31 @@ public:
 		return times;
 	}
 
-	int size();
+	int size()
+	{
+		if (size_ == -1) {
+			// Size isn't calculated automatically for optimization, so we'll calculate it now
+			size_ = 0;
+
+			for (const TimeRange &range : list_) {
+				Rational start = snap(range.in());
+				Rational end = Timecode::snap_time_to_timebase(
+					range.out(), timebase_, Timecode::k_floor);
+
+				if (end == range.out()) {
+					end -= timebase_;
+				}
+
+				int64_t start_ts =
+					Timecode::time_to_timestamp(start, timebase_);
+				int64_t end_ts = Timecode::time_to_timestamp(end, timebase_);
+
+				size_ += 1 + (end_ts - start_ts);
+			}
+		}
+
+		return size_;
+	}
 
 	void reset()
 	{
@@ -293,7 +619,18 @@ public:
 	}
 
 private:
-	void update_index_if_necessary();
+	void update_index_if_necessary()
+	{
+		while (range_index_ < list_.size() &&
+			   (range_index_ == -1 ||
+				current_ >= list_.at(range_index_).out())) {
+			range_index_++;
+
+			if (range_index_ < list_.size()) {
+				current_ = snap(list_.at(range_index_).in());
+			}
+		}
+	}
 
 	TimeRangeList list_;
 

core/src/capi/audioparams.cpp

@@ -0,0 +1,315 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/audioparams.h"
+
+#include "render/audioparams.h"
+
+namespace
+{
+
+olive::core::internal::AudioParams *impl(OakAudioParams *h)
+{
+	return reinterpret_cast<olive::core::internal::AudioParams *>(h);
+}
+
+const olive::core::internal::AudioParams *impl(const OakAudioParams *h)
+{
+	return reinterpret_cast<const olive::core::internal::AudioParams *>(h);
+}
+
+OakAudioParams *wrap(olive::core::internal::AudioParams *p)
+{
+	return reinterpret_cast<OakAudioParams *>(p);
+}
+
+const olive::core::internal::Rational *impl(const OakRational *h)
+{
+	return reinterpret_cast<const olive::core::internal::Rational *>(h);
+}
+
+OakRational *wrap(olive::core::internal::Rational *r)
+{
+	return reinterpret_cast<OakRational *>(r);
+}
+
+olive::core::SampleFormat to_format(int f)
+{
+	return olive::core::SampleFormat(
+		static_cast<olive::core::SampleFormat::Format>(f));
+}
+
+// The supported channel layouts / sample rates as constant data. These
+// mirror AudioParams::k_supported_channel_layouts /
+// k_supported_sample_rates (src/render/audioparams.cpp) and must be kept in
+// sync with them. The C API serves these instead of reading the
+// implementation's std::vector statics directly so that the functions are
+// safe to call during a consumer's static initialization even when
+// liboakcore is linked statically (cross-TU static init order is
+// unspecified; the implementation's vectors may not be constructed yet).
+constexpr uint64_t k_supported_channel_layouts[] = {
+	olive::core::k_channel_layout_mono,
+	olive::core::k_channel_layout_stereo,
+	olive::core::k_channel_layout2_1,
+	olive::core::k_channel_layout5_point1,
+	olive::core::k_channel_layout7_point1,
+};
+
+constexpr int k_supported_sample_rates[] = {
+	8000, 11025, 16000, 22050, 24000, 32000, 44100, 48000, 88200, 96000,
+};
+
+template <typename T, size_t N>
+T at_or_zero(const T (&arr)[N], int index)
+{
+	if (index < 0 || size_t(index) >= N) {
+		return 0;
+	}
+	return arr[index];
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakAudioParams *oakcore_audioparams_create(int sample_rate,
+										   uint64_t channel_layout, int format)
+{
+	return wrap(new olive::core::internal::AudioParams(
+		sample_rate, channel_layout, to_format(format)));
+}
+
+OakAudioParams *oakcore_audioparams_create_invalid(void)
+{
+	return wrap(new olive::core::internal::AudioParams());
+}
+
+OakAudioParams *oakcore_audioparams_copy(const OakAudioParams *self)
+{
+	return wrap(new olive::core::internal::AudioParams(*impl(self)));
+}
+
+void oakcore_audioparams_free(OakAudioParams *self)
+{
+	delete impl(self);
+}
+
+int oakcore_audioparams_sample_rate(const OakAudioParams *self)
+{
+	return impl(self)->sample_rate();
+}
+
+void oakcore_audioparams_set_sample_rate(OakAudioParams *self, int sample_rate)
+{
+	impl(self)->set_sample_rate(sample_rate);
+}
+
+uint64_t oakcore_audioparams_channel_layout(const OakAudioParams *self)
+{
+	return impl(self)->channel_layout();
+}
+
+void oakcore_audioparams_set_channel_layout(OakAudioParams *self, uint64_t mask)
+{
+	impl(self)->set_channel_layout(mask);
+}
+
+OakRational *oakcore_audioparams_time_base(const OakAudioParams *self)
+{
+	return wrap(new olive::core::internal::Rational(impl(self)->time_base()));
+}
+
+void oakcore_audioparams_set_time_base(OakAudioParams *self,
+									   const OakRational *timebase)
+{
+	impl(self)->set_time_base(*impl(timebase));
+}
+
+OakRational *oakcore_audioparams_sample_rate_as_time_base(
+	const OakAudioParams *self)
+{
+	return wrap(
+		new olive::core::internal::Rational(impl(self)->sample_rate_as_time_base()));
+}
+
+int oakcore_audioparams_format(const OakAudioParams *self)
+{
+	return int(impl(self)->format());
+}
+
+void oakcore_audioparams_set_format(OakAudioParams *self, int format)
+{
+	impl(self)->set_format(to_format(format));
+}
+
+int oakcore_audioparams_enabled(const OakAudioParams *self)
+{
+	return impl(self)->enabled() ? 1 : 0;
+}
+
+void oakcore_audioparams_set_enabled(OakAudioParams *self, int enabled)
+{
+	impl(self)->set_enabled(enabled != 0);
+}
+
+int oakcore_audioparams_stream_index(const OakAudioParams *self)
+{
+	return impl(self)->stream_index();
+}
+
+void oakcore_audioparams_set_stream_index(OakAudioParams *self, int stream_index)
+{
+	impl(self)->set_stream_index(stream_index);
+}
+
+int64_t oakcore_audioparams_duration(const OakAudioParams *self)
+{
+	return impl(self)->duration();
+}
+
+void oakcore_audioparams_set_duration(OakAudioParams *self, int64_t duration)
+{
+	impl(self)->set_duration(duration);
+}
+
+int64_t oakcore_audioparams_time_to_bytes(const OakAudioParams *self, double time)
+{
+	return impl(self)->time_to_bytes(time);
+}
+
+int64_t oakcore_audioparams_time_to_bytes_rational(const OakAudioParams *self,
+												   const OakRational *time)
+{
+	return impl(self)->time_to_bytes(*impl(time));
+}
+
+int64_t oakcore_audioparams_time_to_bytes_per_channel(const OakAudioParams *self,
+													  double time)
+{
+	return impl(self)->time_to_bytes_per_channel(time);
+}
+
+int64_t oakcore_audioparams_time_to_bytes_per_channel_rational(
+	const OakAudioParams *self, const OakRational *time)
+{
+	return impl(self)->time_to_bytes_per_channel(*impl(time));
+}
+
+int64_t oakcore_audioparams_time_to_samples(const OakAudioParams *self,
+											double time)
+{
+	return impl(self)->time_to_samples(time);
+}
+
+int64_t oakcore_audioparams_time_to_samples_rational(const OakAudioParams *self,
+													 const OakRational *time)
+{
+	return impl(self)->time_to_samples(*impl(time));
+}
+
+int64_t oakcore_audioparams_samples_to_bytes(const OakAudioParams *self,
+											 int64_t samples)
+{
+	return impl(self)->samples_to_bytes(samples);
+}
+
+int64_t oakcore_audioparams_samples_to_bytes_per_channel(
+	const OakAudioParams *self, int64_t samples)
+{
+	return impl(self)->samples_to_bytes_per_channel(samples);
+}
+
+OakRational *oakcore_audioparams_samples_to_time(const OakAudioParams *self,
+												 int64_t samples)
+{
+	return wrap(
+		new olive::core::internal::Rational(impl(self)->samples_to_time(samples)));
+}
+
+int64_t oakcore_audioparams_bytes_to_samples(const OakAudioParams *self,
+											 int64_t bytes)
+{
+	return impl(self)->bytes_to_samples(bytes);
+}
+
+OakRational *oakcore_audioparams_bytes_to_time(const OakAudioParams *self,
+											   int64_t bytes)
+{
+	return wrap(
+		new olive::core::internal::Rational(impl(self)->bytes_to_time(bytes)));
+}
+
+OakRational *oakcore_audioparams_bytes_per_channel_to_time(
+	const OakAudioParams *self, int64_t bytes)
+{
+	return wrap(new olive::core::internal::Rational(
+		impl(self)->bytes_per_channel_to_time(bytes)));
+}
+
+int oakcore_audioparams_channel_count(const OakAudioParams *self)
+{
+	return impl(self)->channel_count();
+}
+
+int oakcore_audioparams_bytes_per_sample_per_channel(const OakAudioParams *self)
+{
+	return impl(self)->bytes_per_sample_per_channel();
+}
+
+int oakcore_audioparams_bits_per_sample(const OakAudioParams *self)
+{
+	return impl(self)->bits_per_sample();
+}
+
+int oakcore_audioparams_is_valid(const OakAudioParams *self)
+{
+	return impl(self)->is_valid() ? 1 : 0;
+}
+
+int oakcore_audioparams_equals(const OakAudioParams *self,
+							   const OakAudioParams *other)
+{
+	return (*impl(self) == *impl(other)) ? 1 : 0;
+}
+
+int oakcore_audioparams_supported_channel_layout_count(void)
+{
+	return int(sizeof(k_supported_channel_layouts) /
+			   sizeof(k_supported_channel_layouts[0]));
+}
+
+uint64_t oakcore_audioparams_supported_channel_layout_at(int index)
+{
+	return at_or_zero(k_supported_channel_layouts, index);
+}
+
+int oakcore_audioparams_supported_sample_rate_count(void)
+{
+	return int(sizeof(k_supported_sample_rates) /
+			   sizeof(k_supported_sample_rates[0]));
+}
+
+int oakcore_audioparams_supported_sample_rate_at(int index)
+{
+	return at_or_zero(k_supported_sample_rates, index);
+}
+
+} // extern "C"

core/src/capi/bezier.cpp

@@ -0,0 +1,157 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/bezier.h"
+
+#include "util/bezier.h"
+
+namespace
+{
+
+olive::core::internal::Bezier *impl(OakBezier *h)
+{
+	return reinterpret_cast<olive::core::internal::Bezier *>(h);
+}
+
+const olive::core::internal::Bezier *impl(const OakBezier *h)
+{
+	return reinterpret_cast<const olive::core::internal::Bezier *>(h);
+}
+
+OakBezier *wrap(olive::core::internal::Bezier *b)
+{
+	return reinterpret_cast<OakBezier *>(b);
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakBezier *oakcore_bezier_create(void)
+{
+	return wrap(new olive::core::internal::Bezier());
+}
+
+OakBezier *oakcore_bezier_create_xy(double x, double y)
+{
+	return wrap(new olive::core::internal::Bezier(x, y));
+}
+
+OakBezier *oakcore_bezier_create_full(double x, double y, double cp1_x,
+									  double cp1_y, double cp2_x, double cp2_y)
+{
+	return wrap(new olive::core::internal::Bezier(x, y, cp1_x, cp1_y, cp2_x,
+												  cp2_y));
+}
+
+OakBezier *oakcore_bezier_copy(const OakBezier *self)
+{
+	return wrap(new olive::core::internal::Bezier(*impl(self)));
+}
+
+void oakcore_bezier_free(OakBezier *self)
+{
+	delete impl(self);
+}
+
+double oakcore_bezier_x(const OakBezier *self)
+{
+	return impl(self)->x();
+}
+
+double oakcore_bezier_y(const OakBezier *self)
+{
+	return impl(self)->y();
+}
+
+double oakcore_bezier_cp1_x(const OakBezier *self)
+{
+	return impl(self)->cp1_x();
+}
+
+double oakcore_bezier_cp1_y(const OakBezier *self)
+{
+	return impl(self)->cp1_y();
+}
+
+double oakcore_bezier_cp2_x(const OakBezier *self)
+{
+	return impl(self)->cp2_x();
+}
+
+double oakcore_bezier_cp2_y(const OakBezier *self)
+{
+	return impl(self)->cp2_y();
+}
+
+void oakcore_bezier_set_x(OakBezier *self, double x)
+{
+	impl(self)->set_x(x);
+}
+
+void oakcore_bezier_set_y(OakBezier *self, double y)
+{
+	impl(self)->set_y(y);
+}
+
+void oakcore_bezier_set_cp1_x(OakBezier *self, double cp1_x)
+{
+	impl(self)->set_cp1_x(cp1_x);
+}
+
+void oakcore_bezier_set_cp1_y(OakBezier *self, double cp1_y)
+{
+	impl(self)->set_cp1_y(cp1_y);
+}
+
+void oakcore_bezier_set_cp2_x(OakBezier *self, double cp2_x)
+{
+	impl(self)->set_cp2_x(cp2_x);
+}
+
+void oakcore_bezier_set_cp2_y(OakBezier *self, double cp2_y)
+{
+	impl(self)->set_cp2_y(cp2_y);
+}
+
+double oakcore_bezier_quadratic_xto_t(double x, double a, double b, double c)
+{
+	return olive::core::internal::Bezier::quadratic_xto_t(x, a, b, c);
+}
+
+double oakcore_bezier_quadratic_tto_y(double a, double b, double c, double t)
+{
+	return olive::core::internal::Bezier::quadratic_tto_y(a, b, c, t);
+}
+
+double oakcore_bezier_cubic_xto_t(double x, double a, double b, double c,
+								  double d)
+{
+	return olive::core::internal::Bezier::cubic_xto_t(x, a, b, c, d);
+}
+
+double oakcore_bezier_cubic_tto_y(double a, double b, double c, double d,
+								  double t)
+{
+	return olive::core::internal::Bezier::cubic_tto_y(a, b, c, d, t);
+}
+
+} // extern "C"

core/src/capi/color.cpp

@@ -0,0 +1,220 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/color.h"
+
+#include "util/color.h"
+
+namespace
+{
+
+olive::core::internal::Color *impl(OakColor *h)
+{
+	return reinterpret_cast<olive::core::internal::Color *>(h);
+}
+
+const olive::core::internal::Color *impl(const OakColor *h)
+{
+	return reinterpret_cast<const olive::core::internal::Color *>(h);
+}
+
+OakColor *wrap(olive::core::internal::Color *c)
+{
+	return reinterpret_cast<OakColor *>(c);
+}
+
+olive::core::PixelFormat to_format(int f)
+{
+	return olive::core::PixelFormat(
+		static_cast<olive::core::PixelFormat::Format>(f));
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakColor *oakcore_color_create(void)
+{
+	return wrap(new olive::core::internal::Color());
+}
+
+OakColor *oakcore_color_create_rgba(float r, float g, float b, float a)
+{
+	return wrap(new olive::core::internal::Color(r, g, b, a));
+}
+
+OakColor *oakcore_color_copy(const OakColor *self)
+{
+	return wrap(new olive::core::internal::Color(*impl(self)));
+}
+
+void oakcore_color_free(OakColor *self)
+{
+	delete impl(self);
+}
+
+OakColor *oakcore_color_from_hsv(float h, float s, float v)
+{
+	return wrap(
+		new olive::core::internal::Color(olive::core::internal::Color::from_hsv(h, s, v)));
+}
+
+OakColor *oakcore_color_from_data(const char *data, int format, int nb_channels)
+{
+	return wrap(new olive::core::internal::Color(
+		olive::core::internal::Color::from_data(data, to_format(format),
+												static_cast<unsigned int>(nb_channels))));
+}
+
+float oakcore_color_red(const OakColor *self)
+{
+	return impl(self)->red();
+}
+
+float oakcore_color_green(const OakColor *self)
+{
+	return impl(self)->green();
+}
+
+float oakcore_color_blue(const OakColor *self)
+{
+	return impl(self)->blue();
+}
+
+float oakcore_color_alpha(const OakColor *self)
+{
+	return impl(self)->alpha();
+}
+
+void oakcore_color_set_red(OakColor *self, float red)
+{
+	impl(self)->set_red(red);
+}
+
+void oakcore_color_set_green(OakColor *self, float green)
+{
+	impl(self)->set_green(green);
+}
+
+void oakcore_color_set_blue(OakColor *self, float blue)
+{
+	impl(self)->set_blue(blue);
+}
+
+void oakcore_color_set_alpha(OakColor *self, float alpha)
+{
+	impl(self)->set_alpha(alpha);
+}
+
+void oakcore_color_to_hsv(const OakColor *self, float *hue, float *sat, float *val)
+{
+	impl(self)->to_hsv(hue, sat, val);
+}
+
+float oakcore_color_hsv_hue(const OakColor *self)
+{
+	return impl(self)->hsv_hue();
+}
+
+float oakcore_color_hsv_saturation(const OakColor *self)
+{
+	return impl(self)->hsv_saturation();
+}
+
+float oakcore_color_value(const OakColor *self)
+{
+	return impl(self)->value();
+}
+
+void oakcore_color_to_hsl(const OakColor *self, float *hue, float *sat,
+						  float *lightness)
+{
+	impl(self)->to_hsl(hue, sat, lightness);
+}
+
+float oakcore_color_hsl_hue(const OakColor *self)
+{
+	return impl(self)->hsl_hue();
+}
+
+float oakcore_color_hsl_saturation(const OakColor *self)
+{
+	return impl(self)->hsl_saturation();
+}
+
+float oakcore_color_lightness(const OakColor *self)
+{
+	return impl(self)->lightness();
+}
+
+float *oakcore_color_data(OakColor *self)
+{
+	return impl(self)->data();
+}
+
+const float *oakcore_color_const_data(const OakColor *self)
+{
+	return impl(self)->data();
+}
+
+void oakcore_color_to_data(const OakColor *self, char *out, int format,
+						   int nb_channels)
+{
+	impl(self)->to_data(out, to_format(format),
+						static_cast<unsigned int>(nb_channels));
+}
+
+float oakcore_color_get_rough_luminance(const OakColor *self)
+{
+	return impl(self)->get_rough_luminance();
+}
+
+void oakcore_color_add_assign(OakColor *self, const OakColor *other)
+{
+	*impl(self) += *impl(other);
+}
+
+void oakcore_color_sub_assign(OakColor *self, const OakColor *other)
+{
+	*impl(self) -= *impl(other);
+}
+
+void oakcore_color_add_scalar_assign(OakColor *self, float value)
+{
+	*impl(self) += value;
+}
+
+void oakcore_color_sub_scalar_assign(OakColor *self, float value)
+{
+	*impl(self) -= value;
+}
+
+void oakcore_color_mul_scalar_assign(OakColor *self, float value)
+{
+	*impl(self) *= value;
+}
+
+void oakcore_color_div_scalar_assign(OakColor *self, float value)
+{
+	*impl(self) /= value;
+}
+
+} // extern "C"

core/src/capi/fractionutils.cpp

@@ -0,0 +1,53 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/fractionutils.h"
+
+#include "util/fractionutils.h"
+
+namespace
+{
+
+olive::core::internal::FractionRounding impl(OakFractionRounding rnd)
+{
+	return static_cast<olive::core::internal::FractionRounding>(rnd);
+}
+
+} // namespace
+
+extern "C"
+{
+
+void oakcore_fractionutils_reduce_fraction(int64_t *num, int64_t *den, int64_t max)
+{
+	olive::core::internal::reduce_fraction(*num, *den, max);
+}
+
+int oakcore_fractionutils_compare_fractions(int an, int ad, int bn, int bd)
+{
+	return olive::core::internal::compare_fractions(an, ad, bn, bd);
+}
+
+int64_t oakcore_fractionutils_rescale_rnd(int64_t a, int64_t b, int64_t c, OakFractionRounding rnd)
+{
+	return olive::core::internal::rescale_rnd(a, b, c, impl(rnd));
+}
+
+} // extern "C"

core/src/capi/rational.cpp

@@ -0,0 +1,172 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/rational.h"
+
+#include <stdio.h>
+
+#include "util/rational.h"
+
+namespace
+{
+
+olive::core::internal::Rational *impl(OakRational *h)
+{
+	return reinterpret_cast<olive::core::internal::Rational *>(h);
+}
+
+const olive::core::internal::Rational *impl(const OakRational *h)
+{
+	return reinterpret_cast<const olive::core::internal::Rational *>(h);
+}
+
+OakRational *wrap(olive::core::internal::Rational *r)
+{
+	return reinterpret_cast<OakRational *>(r);
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakRational *oakcore_rational_create(int numerator)
+{
+	return wrap(new olive::core::internal::Rational(numerator));
+}
+
+OakRational *oakcore_rational_create_nd(int numerator, int denominator)
+{
+	return wrap(new olive::core::internal::Rational(numerator, denominator));
+}
+
+OakRational *oakcore_rational_create_nan(void)
+{
+	return wrap(new olive::core::internal::Rational(olive::core::internal::Rational::na_n));
+}
+
+OakRational *oakcore_rational_copy(const OakRational *self)
+{
+	return wrap(new olive::core::internal::Rational(*impl(self)));
+}
+
+void oakcore_rational_free(OakRational *self)
+{
+	delete impl(self);
+}
+
+int oakcore_rational_numerator(const OakRational *self)
+{
+	return impl(self)->numerator();
+}
+
+int oakcore_rational_denominator(const OakRational *self)
+{
+	return impl(self)->denominator();
+}
+
+double oakcore_rational_to_double(const OakRational *self)
+{
+	return impl(self)->to_double();
+}
+
+int oakcore_rational_to_string(const OakRational *self, char *buf, int buf_size)
+{
+	const std::string s = impl(self)->to_string();
+	if (buf && buf_size > 0) {
+		snprintf(buf, size_t(buf_size), "%s", s.c_str());
+	}
+	return int(s.size());
+}
+
+OakRational *oakcore_rational_from_double(double value, int *ok)
+{
+	bool b = false;
+	olive::core::internal::Rational *r =
+		new olive::core::internal::Rational(olive::core::internal::Rational::from_double(value, &b));
+	if (ok) {
+		*ok = b ? 1 : 0;
+	}
+	return wrap(r);
+}
+
+OakRational *oakcore_rational_from_string(const char *str, int *ok)
+{
+	bool b = false;
+	olive::core::internal::Rational *r = new olive::core::internal::Rational(
+		olive::core::internal::Rational::from_string(str ? str : "", &b));
+	if (ok) {
+		*ok = b ? 1 : 0;
+	}
+	return wrap(r);
+}
+
+int oakcore_rational_is_null(const OakRational *self)
+{
+	return impl(self)->isNull() ? 1 : 0;
+}
+
+int oakcore_rational_is_nan(const OakRational *self)
+{
+	return impl(self)->isNaN() ? 1 : 0;
+}
+
+OakRational *oakcore_rational_flipped(const OakRational *self)
+{
+	return wrap(new olive::core::internal::Rational(impl(self)->flipped()));
+}
+
+void oakcore_rational_flip(OakRational *self)
+{
+	impl(self)->flip();
+}
+
+void oakcore_rational_add_assign(OakRational *self, const OakRational *other)
+{
+	*impl(self) += *impl(other);
+}
+
+void oakcore_rational_sub_assign(OakRational *self, const OakRational *other)
+{
+	*impl(self) -= *impl(other);
+}
+
+void oakcore_rational_mul_assign(OakRational *self, const OakRational *other)
+{
+	*impl(self) *= *impl(other);
+}
+
+void oakcore_rational_div_assign(OakRational *self, const OakRational *other)
+{
+	*impl(self) /= *impl(other);
+}
+
+int oakcore_rational_compare(const OakRational *self, const OakRational *other)
+{
+	if (*impl(self) < *impl(other)) {
+		return -1;
+	}
+	if (*impl(other) < *impl(self)) {
+		return 1;
+	}
+	return 0;
+}
+
+} // extern "C"

core/src/capi/samplebuffer.cpp

@@ -0,0 +1,272 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/samplebuffer.h"
+
+#include <algorithm>
+#include <vector>
+
+#include "render/audioparams.h"
+#include "render/samplebuffer.h"
+#include "util/rational.h"
+
+namespace
+{
+
+olive::core::internal::SampleBuffer *impl(OakSampleBuffer *h)
+{
+	return reinterpret_cast<olive::core::internal::SampleBuffer *>(h);
+}
+
+const olive::core::internal::SampleBuffer *impl(const OakSampleBuffer *h)
+{
+	return reinterpret_cast<const olive::core::internal::SampleBuffer *>(h);
+}
+
+OakSampleBuffer *wrap(olive::core::internal::SampleBuffer *b)
+{
+	return reinterpret_cast<OakSampleBuffer *>(b);
+}
+
+const olive::core::internal::AudioParams *apimpl(const OakAudioParams *h)
+{
+	return reinterpret_cast<const olive::core::internal::AudioParams *>(h);
+}
+
+OakAudioParams *apwrap(olive::core::internal::AudioParams *p)
+{
+	return reinterpret_cast<OakAudioParams *>(p);
+}
+
+const olive::core::internal::Rational *rimpl(const OakRational *h)
+{
+	return reinterpret_cast<const olive::core::internal::Rational *>(h);
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakSampleBuffer *oakcore_samplebuffer_create(void)
+{
+	return wrap(new olive::core::internal::SampleBuffer());
+}
+
+OakSampleBuffer *oakcore_samplebuffer_create_length(
+	const OakAudioParams *params, const OakRational *length)
+{
+	return wrap(new olive::core::internal::SampleBuffer(*apimpl(params),
+														*rimpl(length)));
+}
+
+OakSampleBuffer *oakcore_samplebuffer_create_samples(
+	const OakAudioParams *params, size_t samples_per_channel)
+{
+	return wrap(new olive::core::internal::SampleBuffer(*apimpl(params),
+														samples_per_channel));
+}
+
+OakSampleBuffer *oakcore_samplebuffer_copy(const OakSampleBuffer *self)
+{
+	return wrap(new olive::core::internal::SampleBuffer(*impl(self)));
+}
+
+void oakcore_samplebuffer_free(OakSampleBuffer *self)
+{
+	delete impl(self);
+}
+
+OakSampleBuffer *oakcore_samplebuffer_rip_channel(const OakSampleBuffer *self,
+												  int channel)
+{
+	return wrap(
+		new olive::core::internal::SampleBuffer(impl(self)->rip_channel(channel)));
+}
+
+int oakcore_samplebuffer_rip_channel_vector(const OakSampleBuffer *self,
+											int channel, float *out,
+											int out_size)
+{
+	const std::vector<float> v = impl(self)->rip_channel_vector(channel);
+	if (out && out_size > 0) {
+		const size_t n = std::min(v.size(), size_t(out_size));
+		std::copy(v.begin(), v.begin() + n, out);
+	}
+	return int(v.size());
+}
+
+OakAudioParams *oakcore_samplebuffer_audio_params(const OakSampleBuffer *self)
+{
+	return apwrap(
+		new olive::core::internal::AudioParams(impl(self)->audio_params()));
+}
+
+void oakcore_samplebuffer_set_audio_params(OakSampleBuffer *self,
+										   const OakAudioParams *params)
+{
+	impl(self)->set_audio_params(*apimpl(params));
+}
+
+size_t oakcore_samplebuffer_sample_count(const OakSampleBuffer *self)
+{
+	return impl(self)->sample_count();
+}
+
+void oakcore_samplebuffer_set_sample_count(OakSampleBuffer *self,
+										   size_t sample_count)
+{
+	impl(self)->set_sample_count(sample_count);
+}
+
+void oakcore_samplebuffer_set_sample_count_length(OakSampleBuffer *self,
+												  const OakRational *length)
+{
+	impl(self)->set_sample_count(*rimpl(length));
+}
+
+float *oakcore_samplebuffer_data(OakSampleBuffer *self, int channel)
+{
+	if (!impl(self)->is_allocated() || channel < 0 ||
+		channel >= impl(self)->channel_count()) {
+		return nullptr;
+	}
+	return impl(self)->data(channel);
+}
+
+void oakcore_samplebuffer_to_raw_ptrs(OakSampleBuffer *self, float **out)
+{
+	if (!out) {
+		return;
+	}
+	const std::vector<float *> ptrs = impl(self)->to_raw_ptrs();
+	std::copy(ptrs.begin(), ptrs.end(), out);
+}
+
+int oakcore_samplebuffer_channel_count(const OakSampleBuffer *self)
+{
+	return impl(self)->channel_count();
+}
+
+int oakcore_samplebuffer_is_allocated(const OakSampleBuffer *self)
+{
+	return impl(self)->is_allocated() ? 1 : 0;
+}
+
+void oakcore_samplebuffer_allocate(OakSampleBuffer *self)
+{
+	impl(self)->allocate();
+}
+
+void oakcore_samplebuffer_destroy(OakSampleBuffer *self)
+{
+	impl(self)->destroy();
+}
+
+void oakcore_samplebuffer_reverse(OakSampleBuffer *self)
+{
+	impl(self)->reverse();
+}
+
+void oakcore_samplebuffer_speed(OakSampleBuffer *self, double speed)
+{
+	impl(self)->speed(speed);
+}
+
+void oakcore_samplebuffer_transform_volume(OakSampleBuffer *self, float f)
+{
+	impl(self)->transform_volume(f);
+}
+
+void oakcore_samplebuffer_transform_volume_for_channel(OakSampleBuffer *self,
+													   int channel,
+													   float volume)
+{
+	impl(self)->transform_volume_for_channel(channel, volume);
+}
+
+void oakcore_samplebuffer_transform_volume_to(float f,
+											  const OakSampleBuffer *input,
+											  OakSampleBuffer *output)
+{
+	olive::core::internal::SampleBuffer::transform_volume(f, impl(input),
+														  impl(output));
+}
+
+void oakcore_samplebuffer_transform_volume_for_channel_to(
+	int channel, float volume, const OakSampleBuffer *input,
+	OakSampleBuffer *output)
+{
+	olive::core::internal::SampleBuffer::transform_volume_for_channel(
+		channel, volume, impl(input), impl(output));
+}
+
+void oakcore_samplebuffer_transform_volume_for_sample(OakSampleBuffer *self,
+													  size_t sample_index,
+													  float volume)
+{
+	impl(self)->transform_volume_for_sample(sample_index, volume);
+}
+
+void oakcore_samplebuffer_transform_volume_for_sample_on_channel(
+	OakSampleBuffer *self, size_t sample_index, int channel, float volume)
+{
+	impl(self)->transform_volume_for_sample_on_channel(sample_index, channel,
+													   volume);
+}
+
+void oakcore_samplebuffer_clamp(OakSampleBuffer *self)
+{
+	impl(self)->clamp();
+}
+
+void oakcore_samplebuffer_silence(OakSampleBuffer *self)
+{
+	impl(self)->silence();
+}
+
+void oakcore_samplebuffer_silence_range(OakSampleBuffer *self,
+										size_t start_sample,
+										size_t end_sample)
+{
+	impl(self)->silence(start_sample, end_sample);
+}
+
+void oakcore_samplebuffer_silence_bytes(OakSampleBuffer *self,
+										size_t start_byte, size_t end_byte)
+{
+	impl(self)->silence_bytes(start_byte, end_byte);
+}
+
+void oakcore_samplebuffer_set(OakSampleBuffer *self, int channel,
+							  const float *data, size_t sample_offset,
+							  size_t sample_length)
+{
+	impl(self)->set(channel, data, sample_offset, sample_length);
+}
+
+void oakcore_samplebuffer_fast_set(OakSampleBuffer *self,
+								   const OakSampleBuffer *other, int to,
+								   int from)
+{
+	impl(self)->fast_set(*impl(other), to, from);
+}
+
+} // extern "C"

core/src/capi/stringutils.cpp

@@ -0,0 +1,123 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/stringutils.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <regex>
+#include <string>
+#include <vector>
+
+#include "util/stringutils.h"
+
+namespace
+{
+
+char **copy_string_vector(const std::vector<std::string> &v, int *count)
+{
+	char **arr = static_cast<char **>(malloc(sizeof(char *) * v.size()));
+	if (!arr) {
+		*count = 0;
+		return nullptr;
+	}
+	for (size_t i = 0; i < v.size(); i++) {
+		arr[i] = static_cast<char *>(malloc(v[i].size() + 1));
+		if (!arr[i]) {
+			for (size_t j = 0; j < i; j++) {
+				free(arr[j]);
+			}
+			free(arr);
+			*count = 0;
+			return nullptr;
+		}
+		memcpy(arr[i], v[i].c_str(), v[i].size() + 1);
+	}
+	*count = int(v.size());
+	return arr;
+}
+
+} // namespace
+
+extern "C"
+{
+
+char **oakcore_stringutils_split(const char *s, char separator, int *count)
+{
+	const std::vector<std::string> v =
+		olive::core::internal::StringUtils::split(s ? s : "", separator);
+	return copy_string_vector(v, count);
+}
+
+char **oakcore_stringutils_split_regex(const char *s, const char *pattern,
+									   int *count)
+{
+	const std::vector<std::string> v =
+		olive::core::internal::StringUtils::split_regex(
+			s ? s : "", std::regex(pattern ? pattern : ""));
+	return copy_string_vector(v, count);
+}
+
+void oakcore_stringutils_free_string_array(char **arr, int count)
+{
+	if (!arr) {
+		return;
+	}
+	for (int i = 0; i < count; i++) {
+		free(arr[i]);
+	}
+	free(arr);
+}
+
+int oakcore_stringutils_to_int(const char *s, int base, int *ok)
+{
+	bool b = false;
+	const int x = olive::core::internal::StringUtils::to_int(s ? s : "", base, &b);
+	if (ok) {
+		*ok = b ? 1 : 0;
+	}
+	return x;
+}
+
+int oakcore_stringutils_format(char *buf, int buf_size, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	const int r = oakcore_stringutils_format_v(buf, buf_size, fmt, args);
+	va_end(args);
+	return r;
+}
+
+int oakcore_stringutils_format_v(char *buf, int buf_size, const char *fmt,
+								 va_list args)
+{
+	// The implementation class only exposes a variadic format(), so the
+	// va_list form applies the same vsnprintf semantics directly here.
+	va_list copy;
+	va_copy(copy, args);
+	const int needed =
+		vsnprintf(buf, buf_size > 0 ? size_t(buf_size) : 0, fmt, copy);
+	va_end(copy);
+	return needed;
+}
+
+} // extern "C"

core/src/capi/timecodefunctions.cpp

@@ -0,0 +1,157 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/timecodefunctions.h"
+
+#include <stdio.h>
+
+#include <string>
+
+#include "util/rational.h"
+#include "util/timecodefunctions.h"
+
+namespace
+{
+
+const olive::core::internal::Rational *impl(const OakRational *h)
+{
+	return reinterpret_cast<const olive::core::internal::Rational *>(h);
+}
+
+OakRational *wrap(olive::core::internal::Rational *r)
+{
+	return reinterpret_cast<OakRational *>(r);
+}
+
+olive::core::internal::Timecode::Display to_display(OakTimecodeDisplay d)
+{
+	return static_cast<olive::core::internal::Timecode::Display>(d);
+}
+
+olive::core::internal::Timecode::Rounding to_rounding(OakTimecodeRounding r)
+{
+	return static_cast<olive::core::internal::Timecode::Rounding>(r);
+}
+
+int write_string(const std::string &s, char *buf, int buf_size)
+{
+	if (buf && buf_size > 0) {
+		snprintf(buf, size_t(buf_size), "%s", s.c_str());
+	}
+	return int(s.size());
+}
+
+} // namespace
+
+extern "C"
+{
+
+int oakcore_timecode_time_to_timecode(const OakRational *time,
+									  const OakRational *timebase,
+									  OakTimecodeDisplay display,
+									  int show_plus_if_positive, char *buf,
+									  int buf_size)
+{
+	const std::string s = olive::core::internal::Timecode::time_to_timecode(
+		*impl(time), *impl(timebase), to_display(display),
+		show_plus_if_positive != 0);
+	return write_string(s, buf, buf_size);
+}
+
+OakRational *oakcore_timecode_timecode_to_time(const char *timecode,
+											   const OakRational *timebase,
+											   OakTimecodeDisplay display,
+											   int *ok)
+{
+	bool b = false;
+	olive::core::internal::Rational *r = new olive::core::internal::Rational(
+		olive::core::internal::Timecode::timecode_to_time(
+			timecode ? timecode : "", *impl(timebase), to_display(display),
+			&b));
+	if (ok) {
+		*ok = b ? 1 : 0;
+	}
+	return wrap(r);
+}
+
+int oakcore_timecode_time_to_string(int64_t ms, char *buf, int buf_size)
+{
+	return write_string(olive::core::internal::Timecode::time_to_string(ms),
+						buf, buf_size);
+}
+
+OakRational *oakcore_timecode_snap_time_to_timebase(const OakRational *time,
+													const OakRational *timebase,
+													OakTimecodeRounding rounding)
+{
+	return wrap(new olive::core::internal::Rational(
+		olive::core::internal::Timecode::snap_time_to_timebase(
+			*impl(time), *impl(timebase), to_rounding(rounding))));
+}
+
+int64_t oakcore_timecode_time_to_timestamp(const OakRational *time,
+										   const OakRational *timebase,
+										   OakTimecodeRounding rounding)
+{
+	return olive::core::internal::Timecode::time_to_timestamp(
+		*impl(time), *impl(timebase), to_rounding(rounding));
+}
+
+int64_t oakcore_timecode_time_to_timestamp_d(double time,
+											 const OakRational *timebase,
+											 OakTimecodeRounding rounding)
+{
+	return olive::core::internal::Timecode::time_to_timestamp(
+		time, *impl(timebase), to_rounding(rounding));
+}
+
+int64_t oakcore_timecode_rescale_timestamp(int64_t ts,
+										   const OakRational *source,
+										   const OakRational *dest)
+{
+	return olive::core::internal::Timecode::rescale_timestamp(
+		ts, *impl(source), *impl(dest));
+}
+
+int64_t oakcore_timecode_rescale_timestamp_ceil(int64_t ts,
+												const OakRational *source,
+												const OakRational *dest)
+{
+	return olive::core::internal::Timecode::rescale_timestamp_ceil(
+		ts, *impl(source), *impl(dest));
+}
+
+OakRational *oakcore_timecode_timestamp_to_time(int64_t timestamp,
+												const OakRational *timebase)
+{
+	return wrap(new olive::core::internal::Rational(
+		olive::core::internal::Timecode::timestamp_to_time(timestamp,
+														   *impl(timebase))));
+}
+
+int oakcore_timecode_timebase_is_drop_frame(const OakRational *timebase)
+{
+	return olive::core::internal::Timecode::timebase_is_drop_frame(
+			   *impl(timebase))
+			   ? 1
+			   : 0;
+}
+
+} // extern "C"

core/src/capi/timerange.cpp

@@ -0,0 +1,221 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/timerange.h"
+
+#include <list>
+
+#include "util/rational.h"
+#include "util/timerange.h"
+
+namespace
+{
+
+olive::core::internal::TimeRange *impl(OakTimeRange *h)
+{
+	return reinterpret_cast<olive::core::internal::TimeRange *>(h);
+}
+
+const olive::core::internal::TimeRange *impl(const OakTimeRange *h)
+{
+	return reinterpret_cast<const olive::core::internal::TimeRange *>(h);
+}
+
+OakTimeRange *wrap(olive::core::internal::TimeRange *r)
+{
+	return reinterpret_cast<OakTimeRange *>(r);
+}
+
+const olive::core::internal::Rational *rimpl(const OakRational *h)
+{
+	return reinterpret_cast<const olive::core::internal::Rational *>(h);
+}
+
+OakRational *rwrap(olive::core::internal::Rational *r)
+{
+	return reinterpret_cast<OakRational *>(r);
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakTimeRange *oakcore_timerange_create(void)
+{
+	return wrap(new olive::core::internal::TimeRange());
+}
+
+OakTimeRange *oakcore_timerange_create_io(const OakRational *in,
+										  const OakRational *out)
+{
+	return wrap(
+		new olive::core::internal::TimeRange(*rimpl(in), *rimpl(out)));
+}
+
+OakTimeRange *oakcore_timerange_copy(const OakTimeRange *self)
+{
+	return wrap(new olive::core::internal::TimeRange(*impl(self)));
+}
+
+void oakcore_timerange_free(OakTimeRange *self)
+{
+	delete impl(self);
+}
+
+OakRational *oakcore_timerange_in(const OakTimeRange *self)
+{
+	return rwrap(new olive::core::internal::Rational(impl(self)->in()));
+}
+
+OakRational *oakcore_timerange_out(const OakTimeRange *self)
+{
+	return rwrap(new olive::core::internal::Rational(impl(self)->out()));
+}
+
+OakRational *oakcore_timerange_length(const OakTimeRange *self)
+{
+	return rwrap(new olive::core::internal::Rational(impl(self)->length()));
+}
+
+void oakcore_timerange_set_in(OakTimeRange *self, const OakRational *in)
+{
+	impl(self)->set_in(*rimpl(in));
+}
+
+void oakcore_timerange_set_out(OakTimeRange *self, const OakRational *out)
+{
+	impl(self)->set_out(*rimpl(out));
+}
+
+void oakcore_timerange_set_range(OakTimeRange *self, const OakRational *in,
+								 const OakRational *out)
+{
+	impl(self)->set_range(*rimpl(in), *rimpl(out));
+}
+
+int oakcore_timerange_equal(const OakTimeRange *self,
+							const OakTimeRange *other)
+{
+	return *impl(self) == *impl(other) ? 1 : 0;
+}
+
+int oakcore_timerange_overlaps_with(const OakTimeRange *self,
+									const OakTimeRange *other,
+									int in_inclusive, int out_inclusive)
+{
+	return impl(self)
+				   ->overlaps_with(*impl(other), in_inclusive != 0,
+								   out_inclusive != 0) ?
+			   1 :
+			   0;
+}
+
+int oakcore_timerange_contains_range(const OakTimeRange *self,
+									 const OakTimeRange *other,
+									 int in_inclusive, int out_inclusive)
+{
+	return impl(self)
+				   ->contains(*impl(other), in_inclusive != 0,
+							  out_inclusive != 0) ?
+			   1 :
+			   0;
+}
+
+int oakcore_timerange_contains_time(const OakTimeRange *self,
+									const OakRational *time)
+{
+	return impl(self)->contains(*rimpl(time)) ? 1 : 0;
+}
+
+OakTimeRange *oakcore_timerange_combined(const OakTimeRange *self,
+										 const OakTimeRange *other)
+{
+	return wrap(
+		new olive::core::internal::TimeRange(impl(self)->combined(*impl(other))));
+}
+
+OakTimeRange *oakcore_timerange_combine(const OakTimeRange *a,
+										const OakTimeRange *b)
+{
+	return wrap(new olive::core::internal::TimeRange(
+		olive::core::internal::TimeRange::combine(*impl(a), *impl(b))));
+}
+
+OakTimeRange *oakcore_timerange_intersected(const OakTimeRange *self,
+											const OakTimeRange *other)
+{
+	return wrap(new olive::core::internal::TimeRange(
+		impl(self)->intersected(*impl(other))));
+}
+
+OakTimeRange *oakcore_timerange_intersect(const OakTimeRange *a,
+										  const OakTimeRange *b)
+{
+	return wrap(new olive::core::internal::TimeRange(
+		olive::core::internal::TimeRange::intersect(*impl(a), *impl(b))));
+}
+
+OakTimeRange *oakcore_timerange_add(const OakTimeRange *self,
+									const OakRational *rhs)
+{
+	return wrap(
+		new olive::core::internal::TimeRange(*impl(self) + *rimpl(rhs)));
+}
+
+OakTimeRange *oakcore_timerange_sub(const OakTimeRange *self,
+									const OakRational *rhs)
+{
+	return wrap(
+		new olive::core::internal::TimeRange(*impl(self) - *rimpl(rhs)));
+}
+
+void oakcore_timerange_add_assign(OakTimeRange *self, const OakRational *rhs)
+{
+	*impl(self) += *rimpl(rhs);
+}
+
+void oakcore_timerange_sub_assign(OakTimeRange *self, const OakRational *rhs)
+{
+	*impl(self) -= *rimpl(rhs);
+}
+
+int oakcore_timerange_split_count(const OakTimeRange *self, int chunk_size)
+{
+	return int(impl(self)->split(chunk_size).size());
+}
+
+int oakcore_timerange_split(const OakTimeRange *self, int chunk_size,
+							OakTimeRange **out_ranges, int out_size)
+{
+	const std::list<olive::core::internal::TimeRange> ranges =
+		impl(self)->split(chunk_size);
+	int n = 0;
+	for (const olive::core::internal::TimeRange &r : ranges) {
+		if (out_ranges && n < out_size) {
+			out_ranges[n] =
+				wrap(new olive::core::internal::TimeRange(r));
+		}
+		n++;
+	}
+	return n;
+}
+
+} // extern "C"

core/src/oliveimpl/render/audioparams.h

@@ -0,0 +1,217 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_AUDIOPARAMS_H
+#define OAK_LIBOLIVECORE_AUDIOPARAMS_H
+#include <cstring>
+
+#include <assert.h>
+#include <vector>
+
+#include "render/channellayout.h"
+#include "render/sampleformat.h"
+#include "../util/rational.h"
+
+namespace olive::core::internal
+{
+
+/**
+ * @brief Audio parameters class managing audio stream configuration
+ *
+ * Channel layouts are stored as plain 64-bit masks (see channellayout.h).
+ * Because the mask is a simple value type, AudioParams has value semantics
+ * and can be copied freely.
+ */
+class AudioParams {
+public:
+	/**
+	 * @brief Default constructor creates invalid AudioParams
+	 * sample_rate=0, channel_layout empty, format=INVALID
+	 */
+	AudioParams()
+		: sample_rate_(0)
+		, channel_layout_mask_(0)
+		, channel_count_(0)
+		, format_(SampleFormat::invalid)
+	{
+		set_default_footage_parameters();
+	}
+
+	/**
+	 * @brief Constructor from channel layout mask
+	 * @param sample_rate Audio sample rate
+	 * @param channel_layout Channel layout mask (e.g., kChannelLayoutStereo)
+	 * @param format Sample format
+	 */
+	AudioParams(const int &sample_rate, uint64_t channel_layout,
+				const SampleFormat &format)
+		: sample_rate_(sample_rate)
+		, channel_layout_mask_(channel_layout)
+		, channel_count_(0)
+		, format_(format)
+	{
+		set_default_footage_parameters();
+		timebase_ = sample_rate_as_time_base();
+		calculate_channel_count();
+	}
+	int sample_rate() const
+	{
+		return sample_rate_;
+	}
+
+	void set_sample_rate(int sample_rate)
+	{
+		sample_rate_ = sample_rate;
+	}
+
+	/**
+	 * @brief Channel layout as a 64-bit mask (0 if unspecified)
+	 */
+	const uint64_t &channel_layout() const
+	{
+		return channel_layout_mask_;
+	}
+
+	/**
+	 * @brief Set channel layout from mask
+	 * @param mask Channel layout mask (e.g., kChannelLayoutStereo)
+	 */
+	void set_channel_layout(uint64_t mask)
+	{
+		channel_layout_mask_ = mask;
+		calculate_channel_count();
+	}
+	Rational time_base() const
+	{
+		return timebase_;
+	}
+
+	void set_time_base(const Rational &timebase)
+	{
+		timebase_ = timebase;
+	}
+
+	Rational sample_rate_as_time_base() const
+	{
+		return Rational(1, sample_rate());
+	}
+
+	SampleFormat format() const
+	{
+		return format_;
+	}
+
+	void set_format(SampleFormat format)
+	{
+		format_ = format;
+	}
+
+	bool enabled() const
+	{
+		return enabled_;
+	}
+
+	void set_enabled(bool e)
+	{
+		enabled_ = e;
+	}
+
+	int stream_index() const
+	{
+		return stream_index_;
+	}
+
+	void set_stream_index(int s)
+	{
+		stream_index_ = s;
+	}
+
+	int64_t duration() const
+	{
+		return duration_;
+	}
+
+	void set_duration(int64_t duration)
+	{
+		duration_ = duration;
+	}
+
+	int64_t time_to_bytes(const double &time) const;
+	int64_t time_to_bytes(const Rational &time) const;
+	int64_t time_to_bytes_per_channel(const double &time) const;
+	int64_t time_to_bytes_per_channel(const Rational &time) const;
+	int64_t time_to_samples(const double &time) const;
+	int64_t time_to_samples(const Rational &time) const;
+	int64_t samples_to_bytes(const int64_t &samples) const;
+	int64_t samples_to_bytes_per_channel(const int64_t &samples) const;
+	Rational samples_to_time(const int64_t &samples) const;
+	int64_t bytes_to_samples(const int64_t &bytes) const;
+	Rational bytes_to_time(const int64_t &bytes) const;
+	Rational bytes_per_channel_to_time(const int64_t &bytes) const;
+	int channel_count() const;
+	int bytes_per_sample_per_channel() const;
+	int bits_per_sample() const;
+	bool is_valid() const;
+
+	bool operator==(const AudioParams &other) const;
+	bool operator!=(const AudioParams &other) const;
+
+	static const std::vector<uint64_t> k_supported_channel_layouts;
+	static const std::vector<int> k_supported_sample_rates;
+
+private:
+	void set_default_footage_parameters()
+	{
+		enabled_ = true;
+		stream_index_ = 0;
+		duration_ = 0;
+	}
+
+	/**
+	 * @brief Updates channel_count_ from the current channel_layout_mask_
+	 * Called after any channel layout modification.
+	 */
+	void calculate_channel_count();
+
+	int sample_rate_;                    ///< Audio sample rate in Hz (e.g., 48000)
+
+	/**
+	 * @brief Channel layout mask (0 if unspecified)
+	 *
+	 * Plain value type mirroring FFmpeg's AV_CH_LAYOUT_* masks; no dynamic
+	 * memory is involved, so copies are trivially safe.
+	 */
+	uint64_t channel_layout_mask_;
+
+	int channel_count_;                  ///< Cached channel count from layout
+
+	SampleFormat format_;                ///< Audio sample format
+
+	// Footage-specific parameters (serialized with footage metadata)
+	int enabled_; // Using int instead of bool fixes GCC 11 stringop-overflow issue (byte alignment)
+	int stream_index_;                   ///< Index in the source file's stream list
+	int64_t duration_;                   ///< Stream duration in timebase units
+	Rational timebase_;                  ///< Timebase for this audio stream
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_AUDIOPARAMS_H

core/src/oliveimpl/render/samplebuffer.h

@@ -0,0 +1,137 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_SAMPLEBUFFER_H
+#define OAK_LIBOLIVECORE_SAMPLEBUFFER_H
+
+#include <memory>
+#include <vector>
+
+#include "audioparams.h"
+#include "../util/rational.h"
+
+namespace olive::core::internal
+{
+
+/**
+ * @brief A buffer of audio samples
+ *
+ * Audio samples in this structure are always stored in PLANAR (separated by channel). This is done to simplify audio
+ * rendering code. This replaces the old system of using QByteArrays (containing packed audio) and while SampleBuffer
+ * replaces many of those in the rendering/processing side of things, QByteArrays are currently still in use for
+ * playback, including reading to and from the cache.
+ */
+class SampleBuffer {
+public:
+	SampleBuffer();
+	SampleBuffer(const AudioParams &audio_params, const Rational &length);
+	SampleBuffer(const AudioParams &audio_params, size_t samples_per_channel);
+
+	SampleBuffer rip_channel(int channel) const;
+	std::vector<float> rip_channel_vector(int channel) const;
+
+	const AudioParams &audio_params() const;
+	void set_audio_params(const AudioParams &params);
+
+	const size_t &sample_count() const
+	{
+		return sample_count_per_channel_;
+	}
+	void set_sample_count(const size_t &sample_count);
+	void set_sample_count(const Rational &length)
+	{
+		set_sample_count(audio_params_.time_to_samples(length));
+	}
+
+	float *data(int channel)
+	{
+		return data_[channel].data();
+	}
+
+	const float *data(int channel) const
+	{
+		return data_.at(channel).data();
+	}
+
+	std::vector<float *> to_raw_ptrs()
+	{
+		std::vector<float *> r(data_.size());
+		for (size_t i = 0; i < r.size(); i++) {
+			r[i] = data_[i].data();
+		}
+		return r;
+	}
+
+	int channel_count() const
+	{
+		return data_.size();
+	}
+
+	bool is_allocated() const
+	{
+		return !data_.empty();
+	}
+	void allocate();
+	void destroy();
+
+	void reverse();
+	void speed(double speed);
+
+	void transform_volume(float f);
+	void transform_volume_for_channel(int channel, float volume);
+	static void transform_volume(float f, const SampleBuffer *input,
+								 SampleBuffer *output);
+	static void transform_volume_for_channel(int channel, float volume,
+											 const SampleBuffer *input,
+											 SampleBuffer *output);
+
+	void transform_volume_for_sample(size_t sample_index, float volume);
+	void transform_volume_for_sample_on_channel(size_t sample_index,
+												int channel, float volume);
+
+	void clamp();
+
+	void silence();
+	void silence(size_t start_sample, size_t end_sample);
+	void silence_bytes(size_t start_byte, size_t end_byte);
+
+	void set(int channel, const float *data, size_t sample_offset,
+			 size_t sample_length);
+	void set(int channel, const float *data, size_t sample_length)
+	{
+		set(channel, data, 0, sample_length);
+	}
+
+	void fast_set(const SampleBuffer &other, int to, int from = -1);
+
+private:
+	void clamp_channel(int channel);
+
+	AudioParams audio_params_;
+
+	size_t sample_count_per_channel_;
+
+	std::vector<std::vector<float>> data_;
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_SAMPLEBUFFER_H

core/src/oliveimpl/util/bezier.h

@@ -0,0 +1,138 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_BEZIER_H
+#define OAK_LIBOLIVECORE_BEZIER_H
+
+#include <Imath/ImathVec.h>
+
+namespace olive::core::internal
+{
+
+class Bezier {
+public:
+	Bezier();
+	Bezier(double x, double y);
+	Bezier(double x, double y, double cp1_x, double cp1_y, double cp2_x,
+		   double cp2_y);
+
+	const double &x() const
+	{
+		return x_;
+	}
+	const double &y() const
+	{
+		return y_;
+	}
+	const double &cp1_x() const
+	{
+		return cp1_x_;
+	}
+	const double &cp1_y() const
+	{
+		return cp1_y_;
+	}
+	const double &cp2_x() const
+	{
+		return cp2_x_;
+	}
+	const double &cp2_y() const
+	{
+		return cp2_y_;
+	}
+
+	Imath::V2d to_vec() const
+	{
+		return Imath::V2d(x_, y_);
+	}
+
+	Imath::V2d control_point_1_to_vec() const
+	{
+		return Imath::V2d(cp1_x_, cp1_y_);
+	}
+
+	Imath::V2d control_point_2_to_vec() const
+	{
+		return Imath::V2d(cp2_x_, cp2_y_);
+	}
+
+	void set_x(const double &x)
+	{
+		x_ = x;
+	}
+	void set_y(const double &y)
+	{
+		y_ = y;
+	}
+	void set_cp1_x(const double &cp1_x)
+	{
+		cp1_x_ = cp1_x;
+	}
+	void set_cp1_y(const double &cp1_y)
+	{
+		cp1_y_ = cp1_y;
+	}
+	void set_cp2_x(const double &cp2_x)
+	{
+		cp2_x_ = cp2_x;
+	}
+	void set_cp2_y(const double &cp2_y)
+	{
+		cp2_y_ = cp2_y;
+	}
+
+	static double quadratic_xto_t(double x, double a, double b, double c);
+
+	static double quadratic_tto_y(double a, double b, double c, double t);
+
+	static double quadratic_xto_y(double x, const Imath::V2d &a,
+								const Imath::V2d &b, const Imath::V2d &c)
+	{
+		return quadratic_tto_y(a.y, b.y, c.y, quadratic_xto_t(x, a.x, b.x, c.x));
+	}
+
+	static double cubic_xto_t(double x, double a, double b, double c, double d);
+
+	static double cubic_tto_y(double a, double b, double c, double d, double t);
+
+	static double cubic_xto_y(double x, const Imath::V2d &a, const Imath::V2d &b,
+							const Imath::V2d &c, const Imath::V2d &d)
+	{
+		return cubic_tto_y(a.y, b.y, c.y, d.y, cubic_xto_t(x, a.x, b.x, c.x, d.x));
+	}
+
+private:
+	static double calculate_t_from_x(bool cubic, double x, double a, double b,
+								  double c, double d);
+
+	double x_;
+	double y_;
+
+	double cp1_x_;
+	double cp1_y_;
+
+	double cp2_x_;
+	double cp2_y_;
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_BEZIER_H

core/src/oliveimpl/util/color.h

@@ -0,0 +1,184 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_COLOR_H
+#define OAK_LIBOLIVECORE_COLOR_H
+
+#include "render/pixelformat.h"
+
+namespace olive::core::internal
+{
+
+/**
+ * @brief High precision 32-bit DataType based RGBA color value
+ */
+class Color {
+public:
+	using DataType = float;
+	static constexpr unsigned int rgba = 4;
+
+	Color()
+	{
+		for (unsigned int i = 0; i < rgba; i++) {
+			data_[i] = 0.0;
+		}
+	}
+
+	Color(const DataType &r, const DataType &g, const DataType &b,
+		  const DataType &a = 1.0f)
+	{
+		data_[0] = r;
+		data_[1] = g;
+		data_[2] = b;
+		data_[3] = a;
+	}
+
+	Color(const char *data, const PixelFormat &format, int ch_layout);
+
+	/**
+   * @brief Creates a Color struct from hue/saturation/value
+   *
+   * Hue expects a value between 0.0 and 360.0. Saturation and Value expect a value between 0.0 and 1.0.
+   */
+	static Color from_hsv(const DataType &h, const DataType &s,
+						 const DataType &v);
+
+	const DataType &red() const
+	{
+		return data_[0];
+	}
+	const DataType &green() const
+	{
+		return data_[1];
+	}
+	const DataType &blue() const
+	{
+		return data_[2];
+	}
+	const DataType &alpha() const
+	{
+		return data_[3];
+	}
+
+	void to_hsv(DataType *hue, DataType *sat, DataType *val) const;
+	DataType hsv_hue() const;
+	DataType hsv_saturation() const;
+	DataType value() const;
+
+	void to_hsl(DataType *hue, DataType *sat, DataType *lightness) const;
+	DataType hsl_hue() const;
+	DataType hsl_saturation() const;
+	DataType lightness() const;
+
+	void set_red(const DataType &red)
+	{
+		data_[0] = red;
+	}
+	void set_green(const DataType &green)
+	{
+		data_[1] = green;
+	}
+	void set_blue(const DataType &blue)
+	{
+		data_[2] = blue;
+	}
+	void set_alpha(const DataType &alpha)
+	{
+		data_[3] = alpha;
+	}
+
+	DataType *data()
+	{
+		return data_;
+	}
+	const DataType *data() const
+	{
+		return data_;
+	}
+
+	void to_data(char *out, const PixelFormat &format,
+				unsigned int nb_channels) const;
+
+	static Color from_data(const char *in, const PixelFormat &format,
+						  unsigned int nb_channels);
+
+	// Suuuuper rough luminance value mostly used for UI (determining whether to overlay with black
+	// or white text)
+	DataType get_rough_luminance() const;
+
+	// Assignment math operators
+	Color &operator+=(const Color &rhs);
+	Color &operator-=(const Color &rhs);
+	Color &operator+=(const DataType &rhs);
+	Color &operator-=(const DataType &rhs);
+	Color &operator*=(const DataType &rhs);
+	Color &operator/=(const DataType &rhs);
+
+	// Binary math operators
+	Color operator+(const Color &rhs) const
+	{
+		Color c(*this);
+		c += rhs;
+		return c;
+	}
+
+	Color operator-(const Color &rhs) const
+	{
+		Color c(*this);
+		c -= rhs;
+		return c;
+	}
+
+	Color operator+(const DataType &rhs) const
+	{
+		Color c(*this);
+		c += rhs;
+		return c;
+	}
+
+	Color operator-(const DataType &rhs) const
+	{
+		Color c(*this);
+		c -= rhs;
+		return c;
+	}
+
+	Color operator*(const DataType &rhs) const
+	{
+		Color c(*this);
+		c *= rhs;
+		return c;
+	}
+
+	Color operator/(const DataType &rhs) const
+	{
+		Color c(*this);
+		c /= rhs;
+		return c;
+	}
+
+private:
+	DataType data_[rgba];
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_COLOR_H

core/src/oliveimpl/util/fractionutils.h

@@ -0,0 +1,80 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_FRACTIONUTILS_H
+#define OAK_LIBOLIVECORE_FRACTIONUTILS_H
+
+#include <stdint.h>
+
+namespace olive::core::internal
+{
+
+/**
+ * @brief Rounding modes for RescaleRnd()
+ *
+ * Mirrors the FFmpeg AVRounding modes that this codebase used before the
+ * FFmpeg dependency was removed from core.
+ */
+enum class FractionRounding {
+	/**
+	 * Round to the nearest value; halfway cases are rounded away from zero.
+	 * Equivalent to FFmpeg's AV_ROUND_NEAR_INF.
+	 */
+	k_near_inf,
+
+	/**
+	 * Round toward positive infinity. Equivalent to FFmpeg's AV_ROUND_UP.
+	 */
+	k_up
+};
+
+/**
+ * @brief Reduce a fraction so that numerator and denominator fit within `max`
+ *
+ * Native re-implementation of FFmpeg's av_reduce(): divides out the greatest
+ * common divisor and, if the values still do not fit within `max`, finds the
+ * closest approximation using continued fractions.
+ *
+ * A zero denominator is preserved (with the numerator set to zero).
+ */
+void reduce_fraction(int64_t &num, int64_t &den, int64_t max);
+
+/**
+ * @brief Compare two fractions
+ *
+ * Native re-implementation of FFmpeg's av_cmp_q(): returns -1 if a < b,
+ * 0 if a == b, 1 if a > b, and INT_MIN when the comparison is meaningless
+ * (degenerate zero-denominator fractions).
+ */
+int compare_fractions(int an, int ad, int bn, int bd);
+
+/**
+ * @brief Rescale `a` by the fraction b/c: returns a * b / c
+ *
+ * Native re-implementation of FFmpeg's av_rescale_rnd(). The intermediate
+ * product is computed with 128-bit arithmetic where available so that no
+ * precision is lost for large timestamps.
+ */
+int64_t rescale_rnd(int64_t a, int64_t b, int64_t c, FractionRounding rnd);
+
+}
+
+#endif // OAK_LIBOLIVECORE_FRACTIONUTILS_H

core/src/oliveimpl/util/rational.h

@@ -0,0 +1,157 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_RATIONAL_H
+#define OAK_LIBOLIVECORE_RATIONAL_H
+
+#include <climits>
+#include <iostream>
+
+#ifdef USE_OTIO
+#include <opentime/rationalTime.h>
+#endif
+
+namespace olive::core::internal
+{
+
+class Rational {
+public:
+	Rational(const int &numerator = 0)
+	{
+		num_ = numerator;
+		den_ = 1;
+	}
+
+	Rational(const int &numerator, const int &denominator)
+	{
+		num_ = numerator;
+		den_ = denominator;
+
+		fix_signs();
+		reduce();
+	}
+
+	Rational(const Rational &rhs) = default;
+
+	static Rational from_double(const double &flt, bool *ok = nullptr);
+	static Rational from_string(const std::string &str, bool *ok = nullptr);
+
+	static const Rational na_n;
+
+	//Assignment Operators
+	const Rational &operator=(const Rational &rhs);
+	const Rational &operator+=(const Rational &rhs);
+	const Rational &operator-=(const Rational &rhs);
+	const Rational &operator/=(const Rational &rhs);
+	const Rational &operator*=(const Rational &rhs);
+
+	//Binary math operators
+	Rational operator+(const Rational &rhs) const;
+	Rational operator-(const Rational &rhs) const;
+	Rational operator/(const Rational &rhs) const;
+	Rational operator*(const Rational &rhs) const;
+
+	//Relational and equality operators
+	bool operator<(const Rational &rhs) const;
+	bool operator<=(const Rational &rhs) const;
+	bool operator>(const Rational &rhs) const;
+	bool operator>=(const Rational &rhs) const;
+	bool operator==(const Rational &rhs) const;
+	bool operator!=(const Rational &rhs) const;
+
+	//Unary operators
+	const Rational &operator+() const
+	{
+		return *this;
+	}
+	Rational operator-() const
+	{
+		return Rational(num_, -den_);
+	}
+	bool operator!() const
+	{
+		return !num_;
+	}
+
+	//Function: convert to double
+	double to_double() const;
+
+#ifdef USE_OTIO
+	static Rational fromRationalTime(const opentime::RationalTime &t)
+	{
+		// Is this the best way to do this?
+		return fromDouble(t.to_seconds());
+	}
+
+	// Convert Olive rationals to opentime rationals with the given framerate (defaults to 24)
+	opentime::RationalTime toRationalTime(double framerate = 24) const;
+#endif
+
+	// Produce "flipped" version
+	Rational flipped() const;
+	void flip();
+
+	// Returns whether the Rational is valid but equal to zero or not
+	//
+	// A NaN is always a null, but a null is not always a NaN
+	bool isNull() const
+	{
+		return num_ == 0;
+	}
+
+	// Returns whether this Rational is not a valid number (denominator == 0)
+	bool isNaN() const
+	{
+		return den_ == 0;
+	}
+
+	const int &numerator() const
+	{
+		return num_;
+	}
+	const int &denominator() const
+	{
+		return den_;
+	}
+
+	std::string to_string() const;
+
+	friend std::ostream &operator<<(std::ostream &out, const Rational &value)
+	{
+		out << value.num_ << '/' << value.den_;
+
+		return out;
+	}
+
+private:
+	void fix_signs();
+	void reduce();
+
+	int num_;
+	int den_;
+};
+
+#define RATIONAL_MIN Rational(INT_MIN)
+#define RATIONAL_MAX Rational(INT_MAX)
+
+}
+
+#endif // OAK_LIBOLIVECORE_RATIONAL_H

core/src/oliveimpl/util/stringutils.h

@@ -0,0 +1,211 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_STRINGUTILS_H
+#define OAK_LIBOLIVECORE_STRINGUTILS_H
+
+#include <algorithm>
+#include <regex>
+#include <vector>
+#include <string>
+
+namespace olive::core::internal
+{
+
+class StringUtils {
+public:
+	/**
+   * @brief Split a string into a list of strings using a specific delimiter
+   *
+   * @param s
+   *
+   * The string to split.
+   *
+   * @param separator
+   *
+   * The character to split the string on.
+   *
+   * @return
+   *
+   * A vector of strings split by the specified delimiter.
+   */
+	static std::vector<std::string> split(const std::string &s, char separator);
+
+	/**
+   * @brief Splits a string into a list of strings using regular expressions.
+   *
+   * @param s
+   *
+   * The string to split.
+   *
+   * @param regex
+   *
+   * The regular expression to split the string on.
+   *
+   * @return
+   *
+   * A vector of strings split wherever the regular expression matched.
+   */
+	static std::vector<std::string> split_regex(const std::string &s,
+												const std::regex &regex);
+
+	/**
+   * @brief Convert a string to int using a bool pointer to determine success rather than an exception
+   *
+   * @param s
+   *
+   * The string to parse an int from.
+   *
+   * @param base
+   *
+   * The base of the number in the string (usually 10, or 16 for hex).
+   *
+   * @param ok
+   *
+   * (Optional) a boolean output parameter specifying whether the conversion was successful or not.
+   *
+   * @return
+   *
+   * Either the int parsed from the string, or 0 (with *ok set to false) on parser error.
+   */
+	static int to_int(const std::string &s, int base, bool *ok = nullptr);
+
+	/**
+   * @brief Overloaded function
+   *
+   * @param s
+   *
+   * The string to parse an int from.
+   *
+   * @param ok
+   *
+   * (Optional) a boolean output parameter specifying whether the conversion was successful or not.
+   *
+   * @return
+   *
+   * Either the int parsed from the string, or 0 (with *ok set to false) on parser error.
+   */
+	static int to_int(const std::string &s, bool *ok = nullptr)
+	{
+		return to_int(s, 10, ok);
+	}
+
+	/**
+   * @brief Convert a number to a string with left padding
+   *
+   * Usually used for converting a number to a string with leading zeroes.
+   *
+   * @param val
+   *
+   * The number to convert. This is a templated function and will accept any type, e.g.
+   * int/long/float/double/etc.
+   *
+   * @param padding
+   *
+   * Total desired length of the string. For example, setting this to `2` will ensure the string
+   * is at least 2 characters in size, using `c` to pad the left side where necessary.
+   *
+   * @param c
+   *
+   * The character to pad with. This defaults to `0` assuming you'll be using this function to
+   * create leading zeroes.
+   *
+   * @return
+   *
+   * The padded string.
+   */
+	template <typename T>
+	static std::string to_string_leftpad(T val, size_t padding, char c = '0')
+	{
+		std::string s = std::to_string(val);
+
+		if (s.size() < padding) {
+			s.insert(0, padding - s.size(), c);
+		}
+
+		return s;
+	}
+
+	/**
+   * @brief Format a string
+   *
+   * A sprintf wrapper that returns a std::string.
+   *
+   * @param fmt
+   *
+   * The format to use.
+   *
+   * @return
+   *
+   * A formatted string in std::string form.
+   */
+	static std::string format(const char *fmt, ...);
+
+	// trim from start (in place)
+	static inline void ltrim(std::string &s)
+	{
+		s.erase(s.begin(),
+				std::find_if(s.begin(), s.end(), [](unsigned char ch) {
+					return !std::isspace(ch);
+				}));
+	}
+
+	// trim from end (in place)
+	static inline void rtrim(std::string &s)
+	{
+		s.erase(std::find_if(s.rbegin(), s.rend(),
+							 [](unsigned char ch) { return !std::isspace(ch); })
+					.base(),
+				s.end());
+	}
+
+	// trim from both ends (in place)
+	static inline void trim(std::string &s)
+	{
+		rtrim(s);
+		ltrim(s);
+	}
+
+	// trim from start (copying)
+	static inline std::string ltrimmed(std::string s)
+	{
+		ltrim(s);
+		return s;
+	}
+
+	// trim from end (copying)
+	static inline std::string rtrimmed(std::string s)
+	{
+		rtrim(s);
+		return s;
+	}
+
+	// trim from both ends (copying)
+	static inline std::string trimmed(std::string s)
+	{
+		trim(s);
+		return s;
+	}
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_STRINGUTILS_H

core/src/oliveimpl/util/timecodefunctions.h

@@ -0,0 +1,93 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_TIMECODEFUNCTIONS_H
+#define OAK_LIBOLIVECORE_TIMECODEFUNCTIONS_H
+
+#include "rational.h"
+
+#include <cstdint>
+
+namespace olive::core::internal
+{
+
+/**
+ * @brief Functions for converting times/timecodes/timestamps
+ *
+ * Olive uses the following terminology through its code:
+ *
+ * `time` - time in seconds presented in a Rational form
+ * `timebase` - the base time unit of an audio/video stream in seconds
+ * `timestamp` - an integer representation of a time in timebase units (in many cases is used like a frame number)
+ * `timecode` a user-friendly string representation of a time according to Timecode::Display
+ */
+class Timecode {
+public:
+	enum Display {
+		k_timecode_drop_frame,
+		k_timecode_non_drop_frame,
+		k_timecode_seconds,
+		k_frames,
+		k_milliseconds
+	};
+
+	enum Rounding { k_ceil, k_floor, k_round };
+
+	/**
+   * @brief Convert a timestamp (according to a Rational timebase) to a user-friendly string representation
+   */
+	static std::string time_to_timecode(const Rational &time,
+										const Rational &timebase,
+										const Display &display,
+										bool show_plus_if_positive = false);
+	static Rational timecode_to_time(std::string timecode,
+									 const Rational &timebase,
+									 const Display &display,
+									 bool *ok = nullptr);
+
+	static std::string time_to_string(int64_t ms);
+
+	static Rational snap_time_to_timebase(const Rational &time,
+										  const Rational &timebase,
+										  Rounding floor = k_round);
+
+	static int64_t time_to_timestamp(const Rational &time,
+									 const Rational &timebase,
+									 Rounding floor = k_round);
+	static int64_t time_to_timestamp(const double &time,
+									 const Rational &timebase,
+									 Rounding floor = k_round);
+
+	static int64_t rescale_timestamp(const int64_t &ts, const Rational &source,
+									 const Rational &dest);
+	static int64_t rescale_timestamp_ceil(const int64_t &ts,
+										  const Rational &source,
+										  const Rational &dest);
+
+	static Rational timestamp_to_time(const int64_t &timestamp,
+									  const Rational &timebase);
+
+	static bool timebase_is_drop_frame(const Rational &timebase);
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_TIMECODEFUNCTIONS_H

core/src/oliveimpl/util/timerange.h

@@ -0,0 +1,315 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2023 Olive Studios LLC
+  Modifications Copyright (C) 2025 mikesolar
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef OAK_LIBOLIVECORE_TIMERANGE_H
+#define OAK_LIBOLIVECORE_TIMERANGE_H
+
+#include <list>
+#include <vector>
+
+#include "rational.h"
+
+namespace olive::core::internal
+{
+
+class TimeRange {
+public:
+	TimeRange() = default;
+	TimeRange(const Rational &in, const Rational &out);
+	TimeRange(const TimeRange &r)
+		: TimeRange(r.in(), r.out())
+	{
+	}
+
+	TimeRange &operator=(const TimeRange &r)
+	{
+		set_range(r.in(), r.out());
+		return *this;
+	}
+
+	const Rational &in() const;
+	const Rational &out() const;
+	const Rational &length() const;
+
+	void set_in(const Rational &in);
+	void set_out(const Rational &out);
+	void set_range(const Rational &in, const Rational &out);
+
+	bool operator==(const TimeRange &r) const;
+	bool operator!=(const TimeRange &r) const;
+
+	bool overlaps_with(const TimeRange &a, bool in_inclusive = true,
+					  bool out_inclusive = true) const;
+	bool contains(const TimeRange &a, bool in_inclusive = true,
+				  bool out_inclusive = true) const;
+	bool contains(const Rational &r) const;
+
+	TimeRange combined(const TimeRange &a) const;
+	static TimeRange combine(const TimeRange &a, const TimeRange &b);
+	TimeRange intersected(const TimeRange &a) const;
+	static TimeRange intersect(const TimeRange &a, const TimeRange &b);
+
+	TimeRange operator+(const Rational &rhs) const;
+	TimeRange operator-(const Rational &rhs) const;
+
+	const TimeRange &operator+=(const Rational &rhs);
+	const TimeRange &operator-=(const Rational &rhs);
+
+	std::list<TimeRange> split(const int &chunk_size) const;
+
+private:
+	void normalize();
+
+	Rational in_;
+	Rational out_;
+	Rational length_;
+};
+
+class TimeRangeList {
+public:
+	TimeRangeList() = default;
+
+	TimeRangeList(std::initializer_list<TimeRange> r)
+		: array_(r)
+	{
+	}
+
+	void insert(const TimeRangeList &list_to_add);
+	void insert(TimeRange range_to_add);
+
+	void remove(const TimeRange &remove);
+	void remove(const TimeRangeList &list);
+
+	template <typename T>
+	static void util_remove(std::vector<T> *list, const TimeRange &remove)
+	{
+		std::vector<T> additions;
+
+		for (auto it = list->begin(); it != list->end();) {
+			T &compare = *it;
+
+			if (remove.contains(compare)) {
+				// This element is entirely encompassed in this range, remove it
+				it = list->erase(it);
+			} else {
+				if (compare.contains(remove, false, false)) {
+					// The remove range is within this element, only choice is to split the element into two
+					T new_range = compare;
+					new_range.set_in(remove.out());
+					compare.set_out(remove.in());
+
+					additions.push_back(new_range);
+					break;
+				} else {
+					if (compare.in() < remove.in() &&
+						compare.out() > remove.in()) {
+						// This element's out point overlaps the range's in, we'll trim it
+						compare.set_out(remove.in());
+					} else if (compare.in() < remove.out() &&
+							   compare.out() > remove.out()) {
+						// This element's in point overlaps the range's out, we'll trim it
+						compare.set_in(remove.out());
+					}
+
+					it++;
+				}
+			}
+		}
+
+		list->insert(list->end(), additions.begin(), additions.end());
+	}
+
+	bool contains(const TimeRange &range, bool in_inclusive = true,
+				  bool out_inclusive = true) const;
+
+	bool contains(const Rational &r) const
+	{
+		for (const TimeRange &range : array_) {
+			if (range.contains(r)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	bool overlaps_with(const TimeRange &r, bool in_inclusive = true,
+					  bool out_inclusive = true) const
+	{
+		for (const TimeRange &range : array_) {
+			if (range.overlaps_with(r, in_inclusive, out_inclusive)) {
+				return true;
+			}
+		}
+
+		return false;
+	}
+
+	bool isEmpty() const
+	{
+		return array_.empty();
+	}
+
+	void clear()
+	{
+		array_.clear();
+	}
+
+	int size() const
+	{
+		return array_.size();
+	}
+
+	void shift(const Rational &diff);
+
+	void trim_in(const Rational &diff);
+
+	void trim_out(const Rational &diff);
+
+	TimeRangeList intersects(const TimeRange &range) const;
+
+	using const_iterator = std::vector<TimeRange>::const_iterator;
+
+	const_iterator begin() const
+	{
+		return array_.cbegin();
+	}
+
+	const_iterator end() const
+	{
+		return array_.cend();
+	}
+
+	const_iterator cbegin() const
+	{
+		return begin();
+	}
+
+	const_iterator cend() const
+	{
+		return end();
+	}
+
+	const TimeRange &first() const
+	{
+		return array_.front();
+	}
+
+	const TimeRange &last() const
+	{
+		return array_.back();
+	}
+
+	const TimeRange &at(int index) const
+	{
+		return array_.at(index);
+	}
+
+	const std::vector<TimeRange> &internal_array() const
+	{
+		return array_;
+	}
+
+	bool operator==(const TimeRangeList &rhs) const
+	{
+		return array_ == rhs.array_;
+	}
+
+private:
+	std::vector<TimeRange> array_;
+};
+
+class TimeRangeListFrameIterator {
+public:
+	TimeRangeListFrameIterator();
+	TimeRangeListFrameIterator(const TimeRangeList &list,
+							   const Rational &timebase);
+
+	Rational snap(const Rational &r) const;
+
+	bool get_next(Rational *out);
+
+	bool has_next() const;
+
+	std::vector<Rational> to_vector() const
+	{
+		TimeRangeListFrameIterator copy(list_, timebase_);
+		std::vector<Rational> times;
+		Rational r;
+		while (copy.get_next(&r)) {
+			times.push_back(r);
+		}
+		return times;
+	}
+
+	int size();
+
+	void reset()
+	{
+		*this = TimeRangeListFrameIterator();
+	}
+
+	void insert(const TimeRange &range)
+	{
+		list_.insert(range);
+	}
+
+	void insert(const TimeRangeList &list)
+	{
+		list_.insert(list);
+	}
+
+	bool is_custom_range() const
+	{
+		return custom_range_;
+	}
+
+	void set_custom_range(bool e)
+	{
+		custom_range_ = e;
+	}
+
+	int frame_index() const
+	{
+		return frame_index_;
+	}
+
+private:
+	void update_index_if_necessary();
+
+	TimeRangeList list_;
+
+	Rational timebase_;
+
+	Rational current_;
+
+	int range_index_;
+
+	int size_;
+
+	int frame_index_;
+
+	bool custom_range_;
+};
+
+}
+
+#endif // OAK_LIBOLIVECORE_TIMERANGE_H

core/src/oliveimpl/util/value.h

@@ -28,7 +28,7 @@
 #include <string.h>
 #include <vector>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 /**

core/src/render/audioparams.cpp

@@ -23,7 +23,7 @@
 
 #include <cmath>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 const std::vector<int> AudioParams::k_supported_sample_rates = {

core/src/render/samplebuffer.cpp

@@ -29,7 +29,7 @@
 #include "util/cpuoptimize.h"
 #include "util/log.h"
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 SampleBuffer::SampleBuffer()

core/src/util/bezier.cpp

@@ -23,7 +23,7 @@
 
 #include <algorithm>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 Bezier::Bezier()

core/src/util/color.cpp

@@ -27,7 +27,7 @@
 #include <math.h>
 #include <stdint.h>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 Color Color::from_hsv(const DataType &h, const DataType &s, const DataType &v)

core/src/util/fractionutils.cpp

@@ -27,7 +27,7 @@
 
 #include <limits>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 namespace

core/src/util/rational.cpp

@@ -31,7 +31,7 @@
 #include "util/fractionutils.h"
 #include "util/stringutils.h"
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 const Rational Rational::na_n = Rational(0, 0);

core/src/util/stringutils.cpp

@@ -24,7 +24,7 @@
 #include <stdarg.h>
 #include <stdexcept>
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 std::vector<std::string> StringUtils::split(const std::string &s,

core/src/util/timecodefunctions.cpp

@@ -27,7 +27,7 @@
 #include "util/fractionutils.h"
 #include "util/stringutils.h"
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 std::string Timecode::time_to_timecode(const Rational &time,

core/src/util/timerange.cpp

@@ -27,7 +27,7 @@
 
 #include "util/timecodefunctions.h"
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 TimeRange::TimeRange(const Rational &in, const Rational &out)

core/src/util/value.cpp

@@ -21,7 +21,7 @@
 
 #include "util/value.h"
 
-namespace olive::core
+namespace olive::core::internal
 {
 
 }

core/tests/oakcore_audioparams_test.cpp

@@ -0,0 +1,247 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+// Pure C API test for oakcore/audioparams.h: no gtest, no C++ wrappers.
+// oakcore/audioparams.h includes oakcore/rational.h for the OakRational
+// handles crossing the boundary.
+
+#include <cassert>
+#include <cstdint>
+#include <cstdio>
+
+#include "olive/core/oakcore/audioparams.h"
+
+// Mirror of render/channellayout.h values, spelled out so this test only
+// includes the C API header.
+static const uint64_t k_layout_mono = 0x4;
+static const uint64_t k_layout_stereo = 0x3;
+static const uint64_t k_layout_2_1 = 0x103;
+static const uint64_t k_layout_5_point1 = 0x60F;
+static const uint64_t k_layout_7_point1 = 0x63F;
+
+// Mirror of render/sampleformat.h enum values.
+static const int k_format_invalid = -1;
+static const int k_format_u8_p = 0;
+static const int k_format_f32_p = 4;
+static const int k_format_s16 = 7;
+static const int k_format_f64 = 11;
+
+int main()
+{
+	// Default constructor: invalid parameters with footage defaults
+	{
+		OakAudioParams *p = oakcore_audioparams_create_invalid();
+		assert(p != nullptr);
+		assert(oakcore_audioparams_is_valid(p) == 0);
+		assert(oakcore_audioparams_sample_rate(p) == 0);
+		assert(oakcore_audioparams_channel_layout(p) == 0);
+		assert(oakcore_audioparams_channel_count(p) == 0);
+		assert(oakcore_audioparams_format(p) == k_format_invalid);
+		assert(oakcore_audioparams_bytes_per_sample_per_channel(p) == 0);
+		assert(oakcore_audioparams_bits_per_sample(p) == 0);
+		assert(oakcore_audioparams_enabled(p) == 1);
+		assert(oakcore_audioparams_stream_index(p) == 0);
+		assert(oakcore_audioparams_duration(p) == 0);
+
+		OakRational *tb = oakcore_audioparams_time_base(p);
+		assert(oakcore_rational_is_null(tb) == 1);
+		oakcore_rational_free(tb);
+
+		oakcore_audioparams_free(p);
+	}
+
+	// Full constructor: 48000 Hz stereo s16
+	OakAudioParams *p =
+		oakcore_audioparams_create(48000, k_layout_stereo, k_format_s16);
+	assert(p != nullptr);
+	assert(oakcore_audioparams_is_valid(p) == 1);
+	assert(oakcore_audioparams_sample_rate(p) == 48000);
+	assert(oakcore_audioparams_channel_layout(p) == k_layout_stereo);
+	assert(oakcore_audioparams_channel_count(p) == 2);
+	assert(oakcore_audioparams_format(p) == k_format_s16);
+	assert(oakcore_audioparams_bytes_per_sample_per_channel(p) == 2);
+	assert(oakcore_audioparams_bits_per_sample(p) == 16);
+	assert(oakcore_audioparams_enabled(p) == 1);
+	assert(oakcore_audioparams_stream_index(p) == 0);
+	assert(oakcore_audioparams_duration(p) == 0);
+
+	// Timebase defaults to 1/sample_rate
+	{
+		OakRational *tb = oakcore_audioparams_time_base(p);
+		assert(oakcore_rational_numerator(tb) == 1);
+		assert(oakcore_rational_denominator(tb) == 48000);
+		oakcore_rational_free(tb);
+
+		OakRational *srtb = oakcore_audioparams_sample_rate_as_time_base(p);
+		assert(oakcore_rational_numerator(srtb) == 1);
+		assert(oakcore_rational_denominator(srtb) == 48000);
+		oakcore_rational_free(srtb);
+	}
+
+	// Setters / getters
+	oakcore_audioparams_set_sample_rate(p, 44100);
+	assert(oakcore_audioparams_sample_rate(p) == 44100);
+	oakcore_audioparams_set_sample_rate(p, 48000);
+	assert(oakcore_audioparams_sample_rate(p) == 48000);
+
+	// Changing the layout recalculates the channel count
+	oakcore_audioparams_set_channel_layout(p, k_layout_mono);
+	assert(oakcore_audioparams_channel_layout(p) == k_layout_mono);
+	assert(oakcore_audioparams_channel_count(p) == 1);
+	oakcore_audioparams_set_channel_layout(p, k_layout_5_point1);
+	assert(oakcore_audioparams_channel_count(p) == 6);
+	oakcore_audioparams_set_channel_layout(p, k_layout_stereo);
+	assert(oakcore_audioparams_channel_count(p) == 2);
+
+	{
+		OakRational *tb = oakcore_rational_create_nd(1, 1000);
+		oakcore_audioparams_set_time_base(p, tb);
+		oakcore_rational_free(tb);
+
+		OakRational *got = oakcore_audioparams_time_base(p);
+		assert(oakcore_rational_numerator(got) == 1);
+		assert(oakcore_rational_denominator(got) == 1000);
+		oakcore_rational_free(got);
+
+		// Restore the default 1/48000 timebase
+		tb = oakcore_rational_create_nd(1, 48000);
+		oakcore_audioparams_set_time_base(p, tb);
+		oakcore_rational_free(tb);
+	}
+
+	oakcore_audioparams_set_format(p, k_format_f32_p);
+	assert(oakcore_audioparams_format(p) == k_format_f32_p);
+	assert(oakcore_audioparams_bytes_per_sample_per_channel(p) == 4);
+	assert(oakcore_audioparams_bits_per_sample(p) == 32);
+	oakcore_audioparams_set_format(p, k_format_s16);
+	assert(oakcore_audioparams_bytes_per_sample_per_channel(p) == 2);
+
+	oakcore_audioparams_set_enabled(p, 0);
+	assert(oakcore_audioparams_enabled(p) == 0);
+	oakcore_audioparams_set_enabled(p, 1);
+	assert(oakcore_audioparams_enabled(p) == 1);
+
+	oakcore_audioparams_set_stream_index(p, 3);
+	assert(oakcore_audioparams_stream_index(p) == 3);
+	oakcore_audioparams_set_stream_index(p, 0);
+
+	const int64_t big_duration = int64_t(1) << 40;
+	oakcore_audioparams_set_duration(p, big_duration);
+	assert(oakcore_audioparams_duration(p) == big_duration);
+	oakcore_audioparams_set_duration(p, 0);
+
+	// Time/sample/byte conversions (48000 Hz, 2 channels, 2 bytes/sample)
+	assert(oakcore_audioparams_time_to_samples(p, 1.0) == 48000);
+	assert(oakcore_audioparams_time_to_samples(p, 0.5) == 24000);
+	assert(oakcore_audioparams_time_to_samples(p, -1.0) == -48000);
+	assert(oakcore_audioparams_time_to_samples(p, 0.0) == 0);
+
+	assert(oakcore_audioparams_samples_to_bytes_per_channel(p, 100) == 200);
+	assert(oakcore_audioparams_samples_to_bytes(p, 100) == 400);
+	assert(oakcore_audioparams_samples_to_bytes(p, 0) == 0);
+
+	assert(oakcore_audioparams_time_to_bytes_per_channel(p, 1.0) == 96000);
+	assert(oakcore_audioparams_time_to_bytes(p, 1.0) == 192000);
+
+	assert(oakcore_audioparams_bytes_to_samples(p, 400) == 100);
+	assert(oakcore_audioparams_bytes_to_samples(p, 0) == 0);
+
+	// Rational-taking overloads
+	{
+		OakRational *half = oakcore_rational_create_nd(1, 2);
+		assert(oakcore_audioparams_time_to_samples_rational(p, half) == 24000);
+		assert(oakcore_audioparams_time_to_bytes_rational(p, half) == 96000);
+		assert(oakcore_audioparams_time_to_bytes_per_channel_rational(p, half) ==
+			   48000);
+		oakcore_rational_free(half);
+	}
+
+	// Rational-returning conversions
+	{
+		OakRational *t = oakcore_audioparams_samples_to_time(p, 48000);
+		assert(oakcore_rational_numerator(t) == 1);
+		assert(oakcore_rational_denominator(t) == 1);
+		oakcore_rational_free(t);
+
+		t = oakcore_audioparams_samples_to_time(p, 24000);
+		assert(oakcore_rational_numerator(t) == 1);
+		assert(oakcore_rational_denominator(t) == 2);
+		oakcore_rational_free(t);
+
+		t = oakcore_audioparams_bytes_to_time(p, 192000);
+		assert(oakcore_rational_numerator(t) == 1);
+		assert(oakcore_rational_denominator(t) == 1);
+		oakcore_rational_free(t);
+
+		t = oakcore_audioparams_bytes_per_channel_to_time(p, 96000);
+		assert(oakcore_rational_numerator(t) == 1);
+		assert(oakcore_rational_denominator(t) == 1);
+		oakcore_rational_free(t);
+	}
+
+	// Copy + equality
+	{
+		OakAudioParams *copy = oakcore_audioparams_copy(p);
+		assert(copy != nullptr);
+		assert(oakcore_audioparams_equals(p, copy) == 1);
+		assert(oakcore_audioparams_equals(copy, copy) == 1);
+
+		oakcore_audioparams_set_sample_rate(copy, 96000);
+		assert(oakcore_audioparams_equals(p, copy) == 0);
+		oakcore_audioparams_set_sample_rate(copy, 48000);
+		assert(oakcore_audioparams_equals(p, copy) == 1);
+
+		OakAudioParams *invalid = oakcore_audioparams_create_invalid();
+		assert(oakcore_audioparams_equals(p, invalid) == 0);
+		assert(oakcore_audioparams_equals(invalid, invalid) == 1);
+		oakcore_audioparams_free(invalid);
+
+		oakcore_audioparams_free(copy);
+	}
+
+	// Supported channel layouts / sample rates
+	{
+		assert(oakcore_audioparams_supported_channel_layout_count() == 5);
+		assert(oakcore_audioparams_supported_channel_layout_at(0) == k_layout_mono);
+		assert(oakcore_audioparams_supported_channel_layout_at(1) ==
+			   k_layout_stereo);
+		assert(oakcore_audioparams_supported_channel_layout_at(2) == k_layout_2_1);
+		assert(oakcore_audioparams_supported_channel_layout_at(3) ==
+			   k_layout_5_point1);
+		assert(oakcore_audioparams_supported_channel_layout_at(4) ==
+			   k_layout_7_point1);
+		// Out-of-range indices return 0
+		assert(oakcore_audioparams_supported_channel_layout_at(-1) == 0);
+		assert(oakcore_audioparams_supported_channel_layout_at(5) == 0);
+
+		assert(oakcore_audioparams_supported_sample_rate_count() == 10);
+		assert(oakcore_audioparams_supported_sample_rate_at(0) == 8000);
+		assert(oakcore_audioparams_supported_sample_rate_at(6) == 44100);
+		assert(oakcore_audioparams_supported_sample_rate_at(7) == 48000);
+		assert(oakcore_audioparams_supported_sample_rate_at(9) == 96000);
+		assert(oakcore_audioparams_supported_sample_rate_at(-1) == 0);
+		assert(oakcore_audioparams_supported_sample_rate_at(10) == 0);
+	}
+
+	oakcore_audioparams_free(p);
+
+	std::printf("oakcore_audioparams_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_bezier_test.cpp

@@ -0,0 +1,144 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+
+#include "olive/core/oakcore/bezier.h"
+
+static int double_eq(double a, double b)
+{
+	return fabs(a - b) < 1e-9;
+}
+
+int main(void)
+{
+	// Default constructor: everything zeroed
+	OakBezier *b = oakcore_bezier_create();
+	assert(b != NULL);
+	assert(double_eq(oakcore_bezier_x(b), 0.0));
+	assert(double_eq(oakcore_bezier_y(b), 0.0));
+	assert(double_eq(oakcore_bezier_cp1_x(b), 0.0));
+	assert(double_eq(oakcore_bezier_cp1_y(b), 0.0));
+	assert(double_eq(oakcore_bezier_cp2_x(b), 0.0));
+	assert(double_eq(oakcore_bezier_cp2_y(b), 0.0));
+
+	// Setters write through to the getters
+	oakcore_bezier_set_x(b, 1.5);
+	oakcore_bezier_set_y(b, -2.25);
+	oakcore_bezier_set_cp1_x(b, 0.1);
+	oakcore_bezier_set_cp1_y(b, 0.2);
+	oakcore_bezier_set_cp2_x(b, 0.3);
+	oakcore_bezier_set_cp2_y(b, 0.4);
+	assert(double_eq(oakcore_bezier_x(b), 1.5));
+	assert(double_eq(oakcore_bezier_y(b), -2.25));
+	assert(double_eq(oakcore_bezier_cp1_x(b), 0.1));
+	assert(double_eq(oakcore_bezier_cp1_y(b), 0.2));
+	assert(double_eq(oakcore_bezier_cp2_x(b), 0.3));
+	assert(double_eq(oakcore_bezier_cp2_y(b), 0.4));
+
+	// x/y constructor: control points stay zeroed
+	OakBezier *xy = oakcore_bezier_create_xy(3.0, 4.0);
+	assert(double_eq(oakcore_bezier_x(xy), 3.0));
+	assert(double_eq(oakcore_bezier_y(xy), 4.0));
+	assert(double_eq(oakcore_bezier_cp1_x(xy), 0.0));
+	assert(double_eq(oakcore_bezier_cp1_y(xy), 0.0));
+	assert(double_eq(oakcore_bezier_cp2_x(xy), 0.0));
+	assert(double_eq(oakcore_bezier_cp2_y(xy), 0.0));
+
+	// Full constructor
+	OakBezier *full =
+		oakcore_bezier_create_full(1.0, 2.0, 0.25, 0.5, 0.75, 1.0);
+	assert(double_eq(oakcore_bezier_x(full), 1.0));
+	assert(double_eq(oakcore_bezier_y(full), 2.0));
+	assert(double_eq(oakcore_bezier_cp1_x(full), 0.25));
+	assert(double_eq(oakcore_bezier_cp1_y(full), 0.5));
+	assert(double_eq(oakcore_bezier_cp2_x(full), 0.75));
+	assert(double_eq(oakcore_bezier_cp2_y(full), 1.0));
+
+	// Copy: same values, independent storage
+	OakBezier *dup = oakcore_bezier_copy(full);
+	assert(double_eq(oakcore_bezier_x(dup), 1.0));
+	assert(double_eq(oakcore_bezier_cp2_y(dup), 1.0));
+	oakcore_bezier_set_x(dup, 9.0);
+	oakcore_bezier_set_cp1_y(dup, 8.0);
+	assert(double_eq(oakcore_bezier_x(full), 1.0));
+	assert(double_eq(oakcore_bezier_cp1_y(full), 0.5));
+
+	// Quadratic evaluation: endpoints and x->t->y round trip
+	assert(double_eq(oakcore_bezier_quadratic_tto_y(0.0, 0.5, 1.0, 0.0), 0.0));
+	assert(double_eq(oakcore_bezier_quadratic_tto_y(0.0, 0.5, 1.0, 1.0), 1.0));
+	{
+		const double x = 0.3;
+		const double t =
+			oakcore_bezier_quadratic_xto_t(x, 0.0, 0.25, 1.0);
+		const double y =
+			oakcore_bezier_quadratic_tto_y(0.0, 0.75, 1.0, t);
+		assert(t >= 0.0 && t <= 1.0);
+		// xto_t solves on the x curve; feeding the same x back must hold
+		assert(fabs(oakcore_bezier_quadratic_tto_y(0.0, 0.25, 1.0, t) - x) <
+			   1e-5);
+		(void) y;
+	}
+	// xto_t clamps x into [a, c] instead of diverging
+	{
+		const double t_lo = oakcore_bezier_quadratic_xto_t(-5.0, 0.0, 0.5, 1.0);
+		const double t_hi = oakcore_bezier_quadratic_xto_t(5.0, 0.0, 0.5, 1.0);
+		assert(t_lo >= 0.0 && t_lo <= 1.0);
+		assert(t_hi >= 0.0 && t_hi <= 1.0);
+	}
+
+	// Cubic evaluation: endpoints and x->t->y round trip
+	assert(double_eq(oakcore_bezier_cubic_tto_y(0.0, 0.25, 0.75, 1.0, 0.0),
+					 0.0));
+	assert(double_eq(oakcore_bezier_cubic_tto_y(0.0, 0.25, 0.75, 1.0, 1.0),
+					 1.0));
+	{
+		const double x = 0.6;
+		const double t =
+			oakcore_bezier_cubic_xto_t(x, 0.0, 0.1, 0.9, 1.0);
+		const double y =
+			oakcore_bezier_cubic_tto_y(0.0, 0.8, 0.2, 1.0, t);
+		assert(t >= 0.0 && t <= 1.0);
+		assert(fabs(oakcore_bezier_cubic_tto_y(0.0, 0.1, 0.9, 1.0, t) - x) <
+			   1e-5);
+		(void) y;
+	}
+	// xto_t clamps x into [a, d] instead of diverging
+	{
+		const double t_lo =
+			oakcore_bezier_cubic_xto_t(-5.0, 0.0, 0.25, 0.75, 1.0);
+		const double t_hi =
+			oakcore_bezier_cubic_xto_t(5.0, 0.0, 0.25, 0.75, 1.0);
+		assert(t_lo >= 0.0 && t_lo <= 1.0);
+		assert(t_hi >= 0.0 && t_hi <= 1.0);
+	}
+
+	// Ownership: every handle released exactly once
+	oakcore_bezier_free(b);
+	oakcore_bezier_free(xy);
+	oakcore_bezier_free(full);
+	oakcore_bezier_free(dup);
+	oakcore_bezier_free(NULL);
+
+	printf("oakcore_bezier_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_color_test.cpp

@@ -0,0 +1,351 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+/**
+ * @file oakcore_color_test.cpp
+ * @brief Pure C API test for the OakColor ABI
+ *
+ * Exercises every function of oakcore/color.h through the C boundary only:
+ * no C++ wrapper, no test framework, just main() + assert().
+ */
+
+#include "olive/core/oakcore/color.h"
+
+#include <assert.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+
+/* PixelFormat::Format values (render/pixelformat.h) */
+enum { PF_U8 = 0, PF_U10 = 1, PF_U16 = 2, PF_F16 = 3, PF_F32 = 4 };
+
+static int feq(float a, float b)
+{
+	return fabsf(a - b) < 1e-5f;
+}
+
+static void test_create_and_channels(void)
+{
+	/* Default construction: all channels zero */
+	OakColor *c = oakcore_color_create();
+	assert(c != NULL);
+	assert(feq(oakcore_color_red(c), 0.0f));
+	assert(feq(oakcore_color_green(c), 0.0f));
+	assert(feq(oakcore_color_blue(c), 0.0f));
+	assert(feq(oakcore_color_alpha(c), 0.0f));
+	oakcore_color_free(c);
+
+	/* RGBA construction + getters */
+	c = oakcore_color_create_rgba(0.25f, 0.5f, 0.75f, 1.0f);
+	assert(feq(oakcore_color_red(c), 0.25f));
+	assert(feq(oakcore_color_green(c), 0.5f));
+	assert(feq(oakcore_color_blue(c), 0.75f));
+	assert(feq(oakcore_color_alpha(c), 1.0f));
+
+	/* Setters, including out-of-gamut HDR values */
+	oakcore_color_set_red(c, -0.5f);
+	oakcore_color_set_green(c, 2.0f);
+	oakcore_color_set_blue(c, 0.0f);
+	oakcore_color_set_alpha(c, 0.125f);
+	assert(feq(oakcore_color_red(c), -0.5f));
+	assert(feq(oakcore_color_green(c), 2.0f));
+	assert(feq(oakcore_color_blue(c), 0.0f));
+	assert(feq(oakcore_color_alpha(c), 0.125f));
+	oakcore_color_free(c);
+}
+
+static void test_copy_and_ownership(void)
+{
+	OakColor *c = oakcore_color_create_rgba(0.1f, 0.2f, 0.3f, 0.4f);
+	OakColor *copy = oakcore_color_copy(c);
+	assert(copy != NULL);
+	assert(feq(oakcore_color_red(copy), 0.1f));
+	assert(feq(oakcore_color_green(copy), 0.2f));
+	assert(feq(oakcore_color_blue(copy), 0.3f));
+	assert(feq(oakcore_color_alpha(copy), 0.4f));
+
+	/* The copy is independent from the original */
+	oakcore_color_set_red(copy, 0.9f);
+	assert(feq(oakcore_color_red(copy), 0.9f));
+	assert(feq(oakcore_color_red(c), 0.1f));
+
+	oakcore_color_free(copy);
+	oakcore_color_free(c);
+
+	/* Releasing a NULL handle must be safe */
+	oakcore_color_free(NULL);
+}
+
+static void test_hsv(void)
+{
+	/* Primary colors from HSV */
+	OakColor *c = oakcore_color_from_hsv(0.0f, 1.0f, 1.0f);
+	assert(feq(oakcore_color_red(c), 1.0f));
+	assert(feq(oakcore_color_green(c), 0.0f));
+	assert(feq(oakcore_color_blue(c), 0.0f));
+	assert(feq(oakcore_color_alpha(c), 1.0f));
+	oakcore_color_free(c);
+
+	c = oakcore_color_from_hsv(120.0f, 1.0f, 1.0f);
+	assert(feq(oakcore_color_red(c), 0.0f));
+	assert(feq(oakcore_color_green(c), 1.0f));
+	assert(feq(oakcore_color_blue(c), 0.0f));
+	oakcore_color_free(c);
+
+	c = oakcore_color_from_hsv(240.0f, 1.0f, 0.5f);
+	assert(feq(oakcore_color_red(c), 0.0f));
+	assert(feq(oakcore_color_green(c), 0.0f));
+	assert(feq(oakcore_color_blue(c), 0.5f));
+	oakcore_color_free(c);
+
+	/* to_hsv of pure red and gray */
+	c = oakcore_color_create_rgba(1.0f, 0.0f, 0.0f, 1.0f);
+	float h = -1.0f, s = -1.0f, v = -1.0f;
+	oakcore_color_to_hsv(c, &h, &s, &v);
+	assert(feq(h, 0.0f));
+	assert(feq(s, 1.0f));
+	assert(feq(v, 1.0f));
+	assert(feq(oakcore_color_hsv_hue(c), h));
+	assert(feq(oakcore_color_hsv_saturation(c), s));
+	assert(feq(oakcore_color_value(c), v));
+	oakcore_color_free(c);
+
+	c = oakcore_color_create_rgba(0.5f, 0.5f, 0.5f, 1.0f);
+	oakcore_color_to_hsv(c, &h, &s, &v);
+	assert(feq(h, 0.0f));
+	assert(feq(s, 0.0f));
+	assert(feq(v, 0.5f));
+	oakcore_color_free(c);
+
+	/* Roundtrip: color -> hsv -> color */
+	c = oakcore_color_create_rgba(0.2f, 0.4f, 0.8f, 1.0f);
+	oakcore_color_to_hsv(c, &h, &s, &v);
+	assert(feq(h, 220.0f));
+	assert(feq(s, 0.75f));
+	assert(feq(v, 0.8f));
+	OakColor *rt = oakcore_color_from_hsv(h, s, v);
+	assert(feq(oakcore_color_red(rt), 0.2f));
+	assert(feq(oakcore_color_green(rt), 0.4f));
+	assert(feq(oakcore_color_blue(rt), 0.8f));
+	oakcore_color_free(rt);
+	oakcore_color_free(c);
+}
+
+static void test_hsl(void)
+{
+	/* Pure red: l = 0.5, s = 1, h = 0 */
+	OakColor *c = oakcore_color_create_rgba(1.0f, 0.0f, 0.0f, 1.0f);
+	float h = -1.0f, s = -1.0f, l = -1.0f;
+	oakcore_color_to_hsl(c, &h, &s, &l);
+	assert(feq(h, 0.0f));
+	assert(feq(s, 1.0f));
+	assert(feq(l, 0.5f));
+	assert(feq(oakcore_color_hsl_hue(c), h));
+	assert(feq(oakcore_color_hsl_saturation(c), s));
+	assert(feq(oakcore_color_lightness(c), l));
+	oakcore_color_free(c);
+
+	/* Gray: zero saturation */
+	c = oakcore_color_create_rgba(0.5f, 0.5f, 0.5f, 1.0f);
+	oakcore_color_to_hsl(c, &h, &s, &l);
+	assert(feq(h, 0.0f));
+	assert(feq(s, 0.0f));
+	assert(feq(l, 0.5f));
+	oakcore_color_free(c);
+
+	/* Arbitrary color */
+	c = oakcore_color_create_rgba(0.2f, 0.4f, 0.8f, 1.0f);
+	oakcore_color_to_hsl(c, &h, &s, &l);
+	assert(feq(h, 220.0f));
+	assert(feq(s, 0.6f));
+	assert(feq(l, 0.5f));
+	oakcore_color_free(c);
+}
+
+static void test_data_access(void)
+{
+	OakColor *c = oakcore_color_create_rgba(0.1f, 0.2f, 0.3f, 0.4f);
+
+	/* Const read access */
+	const float *cd = oakcore_color_const_data(c);
+	assert(cd != NULL);
+	assert(feq(cd[0], 0.1f));
+	assert(feq(cd[1], 0.2f));
+	assert(feq(cd[2], 0.3f));
+	assert(feq(cd[3], 0.4f));
+
+	/* Mutable write access */
+	float *d = oakcore_color_data(c);
+	assert(d != NULL);
+	d[0] = 0.125f;
+	d[3] = 1.0f;
+	assert(feq(oakcore_color_red(c), 0.125f));
+	assert(feq(oakcore_color_alpha(c), 1.0f));
+
+	oakcore_color_free(c);
+}
+
+static void test_pixel_data(void)
+{
+	char buf[16];
+	memset(buf, 0, sizeof(buf));
+
+	/* u8 roundtrip, 4 channels */
+	OakColor *c = oakcore_color_create_rgba(1.0f, 0.0f, 1.0f, 1.0f);
+	oakcore_color_to_data(c, buf, PF_U8, 4);
+	assert((uint8_t)buf[0] == 255);
+	assert((uint8_t)buf[1] == 0);
+	assert((uint8_t)buf[2] == 255);
+	assert((uint8_t)buf[3] == 255);
+	OakColor *back = oakcore_color_from_data(buf, PF_U8, 4);
+	assert(feq(oakcore_color_red(back), 1.0f));
+	assert(feq(oakcore_color_green(back), 0.0f));
+	assert(feq(oakcore_color_blue(back), 1.0f));
+	assert(feq(oakcore_color_alpha(back), 1.0f));
+	oakcore_color_free(back);
+
+	/* u8 with only 3 channels: alpha stays 0 */
+	oakcore_color_to_data(c, buf, PF_U8, 3);
+	back = oakcore_color_from_data(buf, PF_U8, 3);
+	assert(feq(oakcore_color_red(back), 1.0f));
+	assert(feq(oakcore_color_green(back), 0.0f));
+	assert(feq(oakcore_color_blue(back), 1.0f));
+	assert(feq(oakcore_color_alpha(back), 0.0f));
+	oakcore_color_free(back);
+
+	/* u16 roundtrip */
+	oakcore_color_to_data(c, buf, PF_U16, 4);
+	assert(((uint16_t *)buf)[0] == 65535);
+	assert(((uint16_t *)buf)[1] == 0);
+	back = oakcore_color_from_data(buf, PF_U16, 4);
+	assert(feq(oakcore_color_red(back), 1.0f));
+	assert(feq(oakcore_color_green(back), 0.0f));
+	assert(feq(oakcore_color_alpha(back), 1.0f));
+	oakcore_color_free(back);
+	oakcore_color_free(c);
+
+	/* f32 roundtrip, exact */
+	c = oakcore_color_create_rgba(0.25f, 0.5f, 0.75f, 1.0f);
+	oakcore_color_to_data(c, buf, PF_F32, 4);
+	assert(feq(((float *)buf)[0], 0.25f));
+	assert(feq(((float *)buf)[3], 1.0f));
+	back = oakcore_color_from_data(buf, PF_F32, 4);
+	assert(feq(oakcore_color_red(back), 0.25f));
+	assert(feq(oakcore_color_green(back), 0.5f));
+	assert(feq(oakcore_color_blue(back), 0.75f));
+	assert(feq(oakcore_color_alpha(back), 1.0f));
+	oakcore_color_free(back);
+
+	/* f16 roundtrip: 1.0 = 0x3C00, 0.5 = 0x3800 in IEEE half */
+	c = oakcore_color_create_rgba(1.0f, 0.5f, 0.0f, 1.0f);
+	oakcore_color_to_data(c, buf, PF_F16, 4);
+	assert(((uint16_t *)buf)[0] == 0x3C00);
+	assert(((uint16_t *)buf)[1] == 0x3800);
+	back = oakcore_color_from_data(buf, PF_F16, 4);
+	assert(feq(oakcore_color_red(back), 1.0f));
+	assert(feq(oakcore_color_green(back), 0.5f));
+	assert(feq(oakcore_color_blue(back), 0.0f));
+	assert(feq(oakcore_color_alpha(back), 1.0f));
+	oakcore_color_free(back);
+
+	/* u10 packed 4-channel roundtrip: all ones packs to 0xFFFFFFFF */
+	c = oakcore_color_create_rgba(1.0f, 1.0f, 1.0f, 1.0f);
+	oakcore_color_to_data(c, buf, PF_U10, 4);
+	assert(((uint32_t *)buf)[0] == 0xFFFFFFFFu);
+	back = oakcore_color_from_data(buf, PF_U10, 4);
+	assert(feq(oakcore_color_red(back), 1.0f));
+	assert(feq(oakcore_color_green(back), 1.0f));
+	assert(feq(oakcore_color_blue(back), 1.0f));
+	assert(feq(oakcore_color_alpha(back), 1.0f));
+	oakcore_color_free(back);
+	oakcore_color_free(c);
+}
+
+static void test_luminance(void)
+{
+	/* (2r + b + 3g) / 6 */
+	OakColor *c = oakcore_color_create_rgba(1.0f, 1.0f, 1.0f, 1.0f);
+	assert(feq(oakcore_color_get_rough_luminance(c), 1.0f));
+	oakcore_color_free(c);
+
+	c = oakcore_color_create_rgba(0.5f, 0.5f, 0.5f, 1.0f);
+	assert(feq(oakcore_color_get_rough_luminance(c), 0.5f));
+	oakcore_color_free(c);
+
+	c = oakcore_color_create_rgba(0.6f, 0.2f, 0.4f, 1.0f);
+	assert(feq(oakcore_color_get_rough_luminance(c),
+			   (2.0f * 0.6f + 0.4f + 3.0f * 0.2f) / 6.0f));
+	oakcore_color_free(c);
+}
+
+static void test_math(void)
+{
+	OakColor *a = oakcore_color_create_rgba(0.1f, 0.2f, 0.3f, 0.4f);
+	OakColor *b = oakcore_color_create_rgba(0.4f, 0.3f, 0.2f, 0.1f);
+
+	/* Color +=/-= Color */
+	oakcore_color_add_assign(a, b);
+	assert(feq(oakcore_color_red(a), 0.5f));
+	assert(feq(oakcore_color_green(a), 0.5f));
+	assert(feq(oakcore_color_blue(a), 0.5f));
+	assert(feq(oakcore_color_alpha(a), 0.5f));
+	oakcore_color_sub_assign(a, b);
+	assert(feq(oakcore_color_red(a), 0.1f));
+	assert(feq(oakcore_color_green(a), 0.2f));
+	assert(feq(oakcore_color_blue(a), 0.3f));
+	assert(feq(oakcore_color_alpha(a), 0.4f));
+
+	/* Scalar assign operators (apply to all channels) */
+	oakcore_color_add_scalar_assign(a, 1.0f);
+	assert(feq(oakcore_color_red(a), 1.1f));
+	assert(feq(oakcore_color_alpha(a), 1.4f));
+	oakcore_color_sub_scalar_assign(a, 0.6f);
+	assert(feq(oakcore_color_red(a), 0.5f));
+	assert(feq(oakcore_color_alpha(a), 0.8f));
+	oakcore_color_mul_scalar_assign(a, 2.0f);
+	assert(feq(oakcore_color_red(a), 1.0f));
+	assert(feq(oakcore_color_green(a), 1.2f));
+	assert(feq(oakcore_color_blue(a), 1.4f));
+	assert(feq(oakcore_color_alpha(a), 1.6f));
+	oakcore_color_div_scalar_assign(a, 4.0f);
+	assert(feq(oakcore_color_red(a), 0.25f));
+	assert(feq(oakcore_color_green(a), 0.3f));
+	assert(feq(oakcore_color_blue(a), 0.35f));
+	assert(feq(oakcore_color_alpha(a), 0.4f));
+
+	oakcore_color_free(b);
+	oakcore_color_free(a);
+}
+
+int main(void)
+{
+	test_create_and_channels();
+	test_copy_and_ownership();
+	test_hsv();
+	test_hsl();
+	test_data_access();
+	test_pixel_data();
+	test_luminance();
+	test_math();
+
+	printf("oakcore_color_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_fractionutils_test.cpp

@@ -0,0 +1,126 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include "oakcore/fractionutils.h"
+
+#include <assert.h>
+#include <limits.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+
+/**
+ * @file oakcore_fractionutils_test.cpp
+ * @brief Pure C API test for the fraction utility functions
+ *
+ * Exercises every oakcore_fractionutils_* function directly, without the
+ * C++ wrapper and without a test framework.
+ */
+int main()
+{
+	// reduce_fraction: greatest common divisor is divided out
+	{
+		int64_t num = 6, den = 9;
+		oakcore_fractionutils_reduce_fraction(&num, &den, INT64_MAX);
+		assert(num == 2 && den == 3);
+	}
+
+	// reduce_fraction: the sign is normalized into the numerator
+	{
+		int64_t num = -6, den = 9;
+		oakcore_fractionutils_reduce_fraction(&num, &den, INT64_MAX);
+		assert(num == -2 && den == 3);
+	}
+	{
+		int64_t num = 6, den = -9;
+		oakcore_fractionutils_reduce_fraction(&num, &den, INT64_MAX);
+		assert(num == -2 && den == 3);
+	}
+
+	// reduce_fraction: a zero denominator is preserved, numerator zeroed
+	{
+		int64_t num = 42, den = 0;
+		oakcore_fractionutils_reduce_fraction(&num, &den, INT64_MAX);
+		assert(num == 0 && den == 0);
+	}
+
+	// reduce_fraction: a zero numerator reduces to 0/1
+	{
+		int64_t num = 0, den = 7;
+		oakcore_fractionutils_reduce_fraction(&num, &den, INT64_MAX);
+		assert(num == 0 && den == 1);
+	}
+
+	// reduce_fraction: exact reduction well within max
+	{
+		int64_t num = 1000000, den = 1000000;
+		oakcore_fractionutils_reduce_fraction(&num, &den, 100);
+		assert(num == 1 && den == 1);
+	}
+
+	// reduce_fraction: continued-fraction approximation respects max
+	{
+		int64_t num = 1048576, den = 1000000;
+		oakcore_fractionutils_reduce_fraction(&num, &den, 10000);
+		assert(num > 0 && num <= 10000 && den > 0 && den <= 10000);
+		const double approx = double(num) / double(den);
+		assert(fabs(approx - 1.048576) < 0.001);
+	}
+
+	// compare_fractions: three-way result -1 / 0 / 1
+	assert(oakcore_fractionutils_compare_fractions(1, 3, 1, 2) == -1);
+	assert(oakcore_fractionutils_compare_fractions(1, 2, 2, 4) == 0);
+	assert(oakcore_fractionutils_compare_fractions(2, 3, 1, 2) == 1);
+
+	// compare_fractions: meaningless degenerate comparison returns INT_MIN
+	assert(oakcore_fractionutils_compare_fractions(0, 0, 0, 5) == INT_MIN);
+
+	// rescale_rnd: exact division needs no rounding
+	assert(oakcore_fractionutils_rescale_rnd(100, 3, 4,
+											 OAK_FRACTION_ROUNDING_NEAR_INF) == 75);
+
+	// rescale_rnd: round to nearest, halfway cases away from zero
+	assert(oakcore_fractionutils_rescale_rnd(5, 1, 2,
+											 OAK_FRACTION_ROUNDING_NEAR_INF) == 3);
+	assert(oakcore_fractionutils_rescale_rnd(-5, 1, 2,
+											 OAK_FRACTION_ROUNDING_NEAR_INF) == -3);
+	assert(oakcore_fractionutils_rescale_rnd(7, 1, 2,
+											 OAK_FRACTION_ROUNDING_NEAR_INF) == 4);
+
+	// rescale_rnd: round toward positive infinity
+	assert(oakcore_fractionutils_rescale_rnd(5, 1, 2,
+											 OAK_FRACTION_ROUNDING_UP) == 3);
+	assert(oakcore_fractionutils_rescale_rnd(-5, 1, 2,
+											 OAK_FRACTION_ROUNDING_UP) == -2);
+	assert(oakcore_fractionutils_rescale_rnd(4, 1, 2,
+											 OAK_FRACTION_ROUNDING_UP) == 2);
+
+	// rescale_rnd: a negative divisor is normalized into the multiplier
+	assert(oakcore_fractionutils_rescale_rnd(10, 1, -2,
+											 OAK_FRACTION_ROUNDING_NEAR_INF) == -5);
+
+	// rescale_rnd: large intermediates stay exact (128-bit path)
+	assert(oakcore_fractionutils_rescale_rnd(INT64_MAX / 2, 4, 2,
+											 OAK_FRACTION_ROUNDING_NEAR_INF)
+		   == INT64_MAX - 1);
+
+	printf("oakcore_fractionutils_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_rational_test.cpp

@@ -0,0 +1,110 @@
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "olive/core/oakcore/rational.h"
+
+int main()
+{
+	// create_nd reduces and normalizes signs
+	OakRational *r = oakcore_rational_create_nd(2, 4);
+	assert(r != NULL);
+	assert(oakcore_rational_numerator(r) == 1);
+	assert(oakcore_rational_denominator(r) == 2);
+
+	OakRational *neg = oakcore_rational_create_nd(1, -2);
+	assert(oakcore_rational_numerator(neg) == -1);
+	assert(oakcore_rational_denominator(neg) == 2);
+	oakcore_rational_free(neg);
+
+	// create defaults to n/1
+	OakRational *five = oakcore_rational_create(5);
+	assert(oakcore_rational_numerator(five) == 5);
+	assert(oakcore_rational_denominator(five) == 1);
+	oakcore_rational_free(five);
+
+	// NaN
+	OakRational *nan = oakcore_rational_create_nan();
+	assert(oakcore_rational_is_nan(nan) == 1);
+	assert(oakcore_rational_is_null(nan) == 1);
+	assert(isnan(oakcore_rational_to_double(nan)));
+	oakcore_rational_free(nan);
+
+	// copy is deep
+	OakRational *copy = oakcore_rational_copy(r);
+	assert(copy != r);
+	assert(oakcore_rational_compare(copy, r) == 0);
+	oakcore_rational_add_assign(copy, r);
+	assert(oakcore_rational_numerator(copy) == 1);
+	assert(oakcore_rational_denominator(copy) == 1);
+	assert(oakcore_rational_numerator(r) == 1);
+	assert(oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(copy);
+
+	// to_double / to_string
+	assert(fabs(oakcore_rational_to_double(r) - 0.5) < 1e-12);
+	char buf[32];
+	int needed = oakcore_rational_to_string(r, NULL, 0);
+	assert(needed == 3);
+	assert(oakcore_rational_to_string(r, buf, sizeof(buf)) == 3);
+	assert(strcmp(buf, "1/2") == 0);
+	assert(oakcore_rational_to_string(r, buf, 2) == 3); // truncated write
+	assert(strcmp(buf, "1") == 0);
+
+	// from_double / from_string
+	int ok = 0;
+	OakRational *half = oakcore_rational_from_double(0.5, &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_compare(half, r) == 0);
+	oakcore_rational_free(half);
+
+	OakRational *bad = oakcore_rational_from_double(NAN, &ok);
+	assert(ok == 0);
+	assert(oakcore_rational_is_nan(bad));
+	oakcore_rational_free(bad);
+
+	OakRational *parsed = oakcore_rational_from_string("3/4", &ok);
+	assert(ok == 1);
+	assert(fabs(oakcore_rational_to_double(parsed) - 0.75) < 1e-12);
+	oakcore_rational_free(parsed);
+
+	OakRational *unparsed = oakcore_rational_from_string("1/2/3", &ok);
+	assert(ok == 0);
+	oakcore_rational_free(unparsed);
+
+	// flip
+	OakRational *flip = oakcore_rational_flipped(r);
+	assert(oakcore_rational_numerator(flip) == 2);
+	assert(oakcore_rational_denominator(flip) == 1);
+	oakcore_rational_flip(flip);
+	assert(oakcore_rational_compare(flip, r) == 0);
+	oakcore_rational_free(flip);
+
+	// arithmetic assignments
+	OakRational *a = oakcore_rational_create_nd(1, 3);
+	OakRational *b = oakcore_rational_create_nd(1, 6);
+	oakcore_rational_add_assign(a, b);
+	assert(oakcore_rational_numerator(a) == 1);
+	assert(oakcore_rational_denominator(a) == 2);
+	oakcore_rational_sub_assign(a, b);
+	assert(oakcore_rational_numerator(a) == 1);
+	assert(oakcore_rational_denominator(a) == 3);
+	oakcore_rational_mul_assign(a, b);
+	assert(oakcore_rational_numerator(a) == 1);
+	assert(oakcore_rational_denominator(a) == 18);
+	oakcore_rational_div_assign(a, b);
+	assert(oakcore_rational_numerator(a) == 1);
+	assert(oakcore_rational_denominator(a) == 3);
+
+	// compare ordering
+	assert(oakcore_rational_compare(b, a) < 0);
+	assert(oakcore_rational_compare(a, b) > 0);
+
+	oakcore_rational_free(a);
+	oakcore_rational_free(b);
+	oakcore_rational_free(r);
+
+	printf("oakcore_rational_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_samplebuffer_test.cpp

@@ -0,0 +1,359 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include <assert.h>
+#include <math.h>
+#include <stdint.h>
+#include <stdio.h>
+
+#include "olive/core/oakcore/samplebuffer.h"
+
+/* These functions are declared in oakcore/audioparams.h (a parallel
+ * delivery); they are re-declared here so that this test only includes the
+ * samplebuffer C header it is meant to exercise. */
+extern "C" {
+OakAudioParams *oakcore_audioparams_create(int sample_rate,
+										   uint64_t channel_layout,
+										   int format);
+void oakcore_audioparams_free(OakAudioParams *self);
+int oakcore_audioparams_sample_rate(const OakAudioParams *self);
+int oakcore_audioparams_channel_count(const OakAudioParams *self);
+}
+
+/* Values mirror render/channellayout.h (k_channel_layout_stereo) and
+ * render/sampleformat.h (SampleFormat::f32_p) on the library side. */
+#define SAMPLE_RATE 48000
+#define CHANNEL_LAYOUT_STEREO 0x3
+#define FORMAT_F32P 4
+
+static int float_eq(float a, float b)
+{
+	return fabsf(a - b) < 1e-6f;
+}
+
+int main(void)
+{
+	/* --- Default construction: empty, unallocated --- */
+	OakSampleBuffer *def = oakcore_samplebuffer_create();
+	assert(def != NULL);
+	assert(oakcore_samplebuffer_is_allocated(def) == 0);
+	assert(oakcore_samplebuffer_sample_count(def) == 0);
+	assert(oakcore_samplebuffer_channel_count(def) == 0);
+	assert(oakcore_samplebuffer_data(def, 0) == NULL);
+
+	/* audio_params() hands back an owned copy of the (invalid) defaults */
+	OakAudioParams *def_params = oakcore_samplebuffer_audio_params(def);
+	assert(def_params != NULL);
+	assert(oakcore_audioparams_sample_rate(def_params) == 0);
+	oakcore_audioparams_free(def_params);
+
+	/* Operations that need an allocation warn and leave the buffer alone */
+	oakcore_samplebuffer_allocate(def);
+	assert(oakcore_samplebuffer_is_allocated(def) == 0);
+	oakcore_samplebuffer_silence(def);
+	oakcore_samplebuffer_reverse(def);
+	assert(oakcore_samplebuffer_is_allocated(def) == 0);
+	oakcore_samplebuffer_free(def);
+
+	/* --- Construction from audio params + sample count --- */
+	OakAudioParams *stereo = oakcore_audioparams_create(
+		SAMPLE_RATE, CHANNEL_LAYOUT_STEREO, FORMAT_F32P);
+	assert(stereo != NULL);
+
+	OakSampleBuffer *buf = oakcore_samplebuffer_create_samples(stereo, 100);
+	assert(oakcore_samplebuffer_is_allocated(buf) == 1);
+	assert(oakcore_samplebuffer_sample_count(buf) == 100);
+	assert(oakcore_samplebuffer_channel_count(buf) == 2);
+
+	/* A fresh allocation is silent */
+	for (int ch = 0; ch < 2; ch++) {
+		const float *d = oakcore_samplebuffer_data(buf, ch);
+		assert(d != NULL);
+		for (int i = 0; i < 100; i++) {
+			assert(float_eq(d[i], 0.0f));
+		}
+	}
+
+	/* audio_params() copy reflects the construction parameters */
+	OakAudioParams *p = oakcore_samplebuffer_audio_params(buf);
+	assert(oakcore_audioparams_sample_rate(p) == SAMPLE_RATE);
+	assert(oakcore_audioparams_channel_count(p) == 2);
+	oakcore_audioparams_free(p);
+
+	/* data() rejects out-of-range channels */
+	assert(oakcore_samplebuffer_data(buf, -1) == NULL);
+	assert(oakcore_samplebuffer_data(buf, 2) == NULL);
+
+	/* --- Construction from audio params + rational length (0.5s) --- */
+	OakRational *half_sec = oakcore_rational_create_nd(1, 2);
+	OakSampleBuffer *timed =
+		oakcore_samplebuffer_create_length(stereo, half_sec);
+	assert(oakcore_samplebuffer_is_allocated(timed) == 1);
+	assert(oakcore_samplebuffer_sample_count(timed) == 24000);
+	oakcore_rational_free(half_sec);
+	oakcore_samplebuffer_free(timed);
+
+	/* --- Manual lifecycle: params + count + allocate, destroy, repeat --- */
+	OakSampleBuffer *manual = oakcore_samplebuffer_create();
+	oakcore_samplebuffer_set_audio_params(manual, stereo);
+	oakcore_samplebuffer_set_sample_count(manual, 50);
+	oakcore_samplebuffer_allocate(manual);
+	assert(oakcore_samplebuffer_is_allocated(manual) == 1);
+	assert(oakcore_samplebuffer_sample_count(manual) == 50);
+	assert(oakcore_samplebuffer_channel_count(manual) == 2);
+
+	oakcore_samplebuffer_destroy(manual);
+	assert(oakcore_samplebuffer_is_allocated(manual) == 0);
+	assert(oakcore_samplebuffer_channel_count(manual) == 0);
+	assert(oakcore_samplebuffer_data(manual, 0) == NULL);
+
+	oakcore_samplebuffer_set_sample_count(manual, 30);
+	oakcore_samplebuffer_allocate(manual);
+	assert(oakcore_samplebuffer_is_allocated(manual) == 1);
+	assert(oakcore_samplebuffer_sample_count(manual) == 30);
+	oakcore_samplebuffer_free(manual);
+
+	/* set_sample_count via a rational length: 0.001s at 48kHz = 48 samples */
+	OakSampleBuffer *manual2 = oakcore_samplebuffer_create();
+	oakcore_samplebuffer_set_audio_params(manual2, stereo);
+	OakRational *one_ms = oakcore_rational_create_nd(1, 1000);
+	oakcore_samplebuffer_set_sample_count_length(manual2, one_ms);
+	oakcore_rational_free(one_ms);
+	oakcore_samplebuffer_allocate(manual2);
+	assert(oakcore_samplebuffer_sample_count(manual2) == 48);
+	oakcore_samplebuffer_free(manual2);
+
+	/* --- data() direct access, set(), to_raw_ptrs() --- */
+	float *ch0 = oakcore_samplebuffer_data(buf, 0);
+	float *ch1 = oakcore_samplebuffer_data(buf, 1);
+	for (int i = 0; i < 100; i++) {
+		ch0[i] = (float)i;       /* ramp 0..99 on channel 0 */
+		ch1[i] = (float)(i * 10); /* ramp 0..990 on channel 1 */
+	}
+
+	const float ins[4] = { -1.0f, -2.0f, -3.0f, -4.0f };
+	oakcore_samplebuffer_set(buf, 0, ins, 10, 4); /* write at offset 10 */
+	for (int k = 0; k < 4; k++) {
+		assert(float_eq(ch0[10 + k], ins[k]));
+	}
+	assert(float_eq(ch0[9], 9.0f)); /* neighbours untouched */
+	assert(float_eq(ch0[14], 14.0f));
+
+	oakcore_samplebuffer_set(buf, 1, ins, 0, 4); /* write at offset 0 */
+	for (int k = 0; k < 4; k++) {
+		assert(float_eq(ch1[k], ins[k]));
+	}
+	for (int k = 0; k < 4; k++) { /* restore the channel 1 ramp */
+		ch1[k] = (float)(k * 10);
+	}
+
+	float *ptrs[2] = { NULL, NULL };
+	oakcore_samplebuffer_to_raw_ptrs(buf, ptrs);
+	assert(ptrs[0] == ch0);
+	assert(ptrs[1] == ch1);
+	ptrs[1][50] = 123.0f; /* writes through the raw pointer land in the buffer */
+	assert(float_eq(oakcore_samplebuffer_data(buf, 1)[50], 123.0f));
+	ch1[50] = 500.0f; /* restore ramp value (50 * 10) */
+
+	/* --- copy: an independent deep copy --- */
+	OakSampleBuffer *cp = oakcore_samplebuffer_copy(buf);
+	assert(oakcore_samplebuffer_is_allocated(cp) == 1);
+	assert(oakcore_samplebuffer_sample_count(cp) == 100);
+	assert(oakcore_samplebuffer_channel_count(cp) == 2);
+	assert(float_eq(oakcore_samplebuffer_data(cp, 0)[9], 9.0f));
+
+	/* --- transform_volume (in place, all channels) --- */
+	oakcore_samplebuffer_transform_volume(cp, 2.0f);
+	assert(float_eq(oakcore_samplebuffer_data(cp, 0)[9], 18.0f));
+	assert(float_eq(oakcore_samplebuffer_data(cp, 1)[9], 180.0f));
+	assert(float_eq(oakcore_samplebuffer_data(buf, 0)[9], 9.0f)); /* source keeps its data */
+
+	/* --- transform_volume_for_channel (in place, one channel) --- */
+	oakcore_samplebuffer_transform_volume_for_channel(cp, 1, 0.5f);
+	assert(float_eq(oakcore_samplebuffer_data(cp, 1)[9], 90.0f));
+	assert(float_eq(oakcore_samplebuffer_data(cp, 0)[9], 18.0f)); /* other channel untouched */
+	oakcore_samplebuffer_free(cp);
+
+	/* --- static-style transforms: input -> output --- */
+	OakSampleBuffer *tin = oakcore_samplebuffer_create_samples(stereo, 10);
+	OakSampleBuffer *tout = oakcore_samplebuffer_create_samples(stereo, 10);
+	for (int i = 0; i < 10; i++) {
+		oakcore_samplebuffer_data(tin, 0)[i] = (float)i;
+		oakcore_samplebuffer_data(tin, 1)[i] = (float)(100 + i);
+	}
+
+	oakcore_samplebuffer_transform_volume_to(0.5f, tin, tout);
+	for (int i = 0; i < 10; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(tout, 0)[i], (float)i * 0.5f));
+		assert(float_eq(oakcore_samplebuffer_data(tout, 1)[i],
+						(float)(100 + i) * 0.5f));
+		assert(float_eq(oakcore_samplebuffer_data(tin, 0)[i], (float)i)); /* input unchanged */
+	}
+
+	oakcore_samplebuffer_silence(tout);
+	oakcore_samplebuffer_transform_volume_for_channel_to(1, 2.0f, tin, tout);
+	for (int i = 0; i < 10; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(tout, 1)[i],
+						(float)(100 + i) * 2.0f));
+		assert(float_eq(oakcore_samplebuffer_data(tout, 0)[i], 0.0f)); /* channel 0 untouched */
+	}
+
+	/* --- per-sample volume transforms --- */
+	oakcore_samplebuffer_transform_volume_for_sample(tin, 3, 10.0f);
+	assert(float_eq(oakcore_samplebuffer_data(tin, 0)[3], 30.0f));
+	assert(float_eq(oakcore_samplebuffer_data(tin, 1)[3], 1030.0f));
+
+	oakcore_samplebuffer_transform_volume_for_sample_on_channel(tin, 4, 0,
+																100.0f);
+	assert(float_eq(oakcore_samplebuffer_data(tin, 0)[4], 400.0f));
+	assert(float_eq(oakcore_samplebuffer_data(tin, 1)[4], 104.0f)); /* channel 1 untouched */
+	oakcore_samplebuffer_free(tin);
+	oakcore_samplebuffer_free(tout);
+
+	/* --- clamp() limits every channel to [-1, 1] --- */
+	OakSampleBuffer *cl = oakcore_samplebuffer_create_samples(stereo, 4);
+	oakcore_samplebuffer_data(cl, 0)[0] = 2.5f;
+	oakcore_samplebuffer_data(cl, 0)[1] = -2.5f;
+	oakcore_samplebuffer_data(cl, 1)[0] = 42.0f;
+	oakcore_samplebuffer_data(cl, 1)[1] = 0.25f;
+	oakcore_samplebuffer_clamp(cl);
+	assert(float_eq(oakcore_samplebuffer_data(cl, 0)[0], 1.0f));
+	assert(float_eq(oakcore_samplebuffer_data(cl, 0)[1], -1.0f));
+	assert(float_eq(oakcore_samplebuffer_data(cl, 1)[0], 1.0f));
+	assert(float_eq(oakcore_samplebuffer_data(cl, 1)[1], 0.25f));
+	oakcore_samplebuffer_free(cl);
+
+	/* --- silence / silence_range / silence_bytes --- */
+	OakSampleBuffer *si = oakcore_samplebuffer_create_samples(stereo, 10);
+	for (int ch = 0; ch < 2; ch++) {
+		for (int i = 0; i < 10; i++) {
+			oakcore_samplebuffer_data(si, ch)[i] = 1.0f;
+		}
+	}
+
+	oakcore_samplebuffer_silence_range(si, 2, 5); /* samples [2, 5) */
+	for (int ch = 0; ch < 2; ch++) {
+		const float *d = oakcore_samplebuffer_data(si, ch);
+		assert(float_eq(d[1], 1.0f));
+		assert(float_eq(d[2], 0.0f));
+		assert(float_eq(d[4], 0.0f));
+		assert(float_eq(d[5], 1.0f));
+	}
+
+	oakcore_samplebuffer_silence_bytes(si, 0, 2 * sizeof(float)); /* samples [0, 2) */
+	for (int ch = 0; ch < 2; ch++) {
+		const float *d = oakcore_samplebuffer_data(si, ch);
+		assert(float_eq(d[0], 0.0f));
+		assert(float_eq(d[1], 0.0f));
+		assert(float_eq(d[5], 1.0f));
+	}
+
+	oakcore_samplebuffer_silence(si); /* everything */
+	for (int ch = 0; ch < 2; ch++) {
+		const float *d = oakcore_samplebuffer_data(si, ch);
+		for (int i = 0; i < 10; i++) {
+			assert(float_eq(d[i], 0.0f));
+		}
+	}
+	oakcore_samplebuffer_free(si);
+
+	/* --- reverse() flips every channel --- */
+	OakSampleBuffer *rv = oakcore_samplebuffer_create_samples(stereo, 5);
+	for (int i = 0; i < 5; i++) {
+		oakcore_samplebuffer_data(rv, 0)[i] = (float)i;
+		oakcore_samplebuffer_data(rv, 1)[i] = (float)(10 * i);
+	}
+	oakcore_samplebuffer_reverse(rv);
+	for (int i = 0; i < 5; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(rv, 0)[i], (float)(4 - i)));
+		assert(float_eq(oakcore_samplebuffer_data(rv, 1)[i],
+						(float)(10 * (4 - i))));
+	}
+	oakcore_samplebuffer_free(rv);
+
+	/* --- speed(2.0) halves the sample count, sampling the ramp exactly --- */
+	OakSampleBuffer *sp = oakcore_samplebuffer_create_samples(stereo, 100);
+	for (int i = 0; i < 100; i++) {
+		oakcore_samplebuffer_data(sp, 0)[i] = (float)i;
+	}
+	oakcore_samplebuffer_speed(sp, 2.0);
+	assert(oakcore_samplebuffer_sample_count(sp) == 50);
+	for (int i = 0; i < 50; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(sp, 0)[i], (float)(2 * i)));
+	}
+	oakcore_samplebuffer_free(sp);
+
+	/* --- fast_set(): channel copy between buffers --- */
+	OakSampleBuffer *fa = oakcore_samplebuffer_create_samples(stereo, 10);
+	OakSampleBuffer *fb = oakcore_samplebuffer_create_samples(stereo, 10);
+	for (int i = 0; i < 10; i++) {
+		oakcore_samplebuffer_data(fa, 0)[i] = (float)i;
+		oakcore_samplebuffer_data(fa, 1)[i] = (float)(100 + i);
+	}
+
+	oakcore_samplebuffer_fast_set(fb, fa, 1, 0); /* fb channel 1 <- fa channel 0 */
+	for (int i = 0; i < 10; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(fb, 1)[i], (float)i));
+		assert(float_eq(oakcore_samplebuffer_data(fb, 0)[i], 0.0f));
+	}
+
+	oakcore_samplebuffer_fast_set(fb, fa, 0, -1); /* from == -1 mirrors to */
+	for (int i = 0; i < 10; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(fb, 0)[i], (float)i));
+	}
+	oakcore_samplebuffer_free(fa);
+	oakcore_samplebuffer_free(fb);
+
+	/* --- rip_channel(): a new mono buffer with one channel's samples --- */
+	OakSampleBuffer *rip = oakcore_samplebuffer_rip_channel(buf, 1);
+	assert(oakcore_samplebuffer_is_allocated(rip) == 1);
+	assert(oakcore_samplebuffer_channel_count(rip) == 1);
+	assert(oakcore_samplebuffer_sample_count(rip) == 100);
+	for (int i = 0; i < 100; i++) {
+		assert(float_eq(oakcore_samplebuffer_data(rip, 0)[i], (float)(i * 10)));
+	}
+	OakAudioParams *rip_params = oakcore_samplebuffer_audio_params(rip);
+	assert(oakcore_audioparams_sample_rate(rip_params) == SAMPLE_RATE);
+	assert(oakcore_audioparams_channel_count(rip_params) == 1);
+	oakcore_audioparams_free(rip_params);
+	oakcore_samplebuffer_free(rip);
+
+	/* --- rip_channel_vector(): query size, partial copy, full copy --- */
+	assert(oakcore_samplebuffer_rip_channel_vector(buf, 1, NULL, 0) == 100);
+
+	float partial[4] = { 0.0f, 0.0f, 0.0f, 0.0f };
+	assert(oakcore_samplebuffer_rip_channel_vector(buf, 1, partial, 4) == 100);
+	for (int k = 0; k < 4; k++) {
+		assert(float_eq(partial[k], (float)(k * 10)));
+	}
+
+	float full[100];
+	assert(oakcore_samplebuffer_rip_channel_vector(buf, 1, full, 100) == 100);
+	for (int i = 0; i < 100; i++) {
+		assert(float_eq(full[i], (float)(i * 10)));
+	}
+
+	/* --- Ownership: everything released --- */
+	oakcore_samplebuffer_free(buf);
+	oakcore_audioparams_free(stereo);
+
+	printf("oakcore_samplebuffer_test: all assertions passed\n");
+	return 0;
+}

core/tests/oakcore_stringutils_test.cpp

@@ -0,0 +1,174 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+/**
+ * @file oakcore_stringutils_test.cpp
+ * @brief Pure C API test for oakcore/stringutils.h
+ *
+ * Exercises every C function directly (no C++ wrapper, no test framework).
+ */
+
+#include <assert.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "olive/core/oakcore/stringutils.h"
+
+static void test_split()
+{
+	int count = 0;
+
+	// Basic split
+	char **arr = oakcore_stringutils_split("a,b,c", ',', &count);
+	assert(arr != NULL);
+	assert(count == 3);
+	assert(strcmp(arr[0], "a") == 0);
+	assert(strcmp(arr[1], "b") == 0);
+	assert(strcmp(arr[2], "c") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// No separator present: single element equal to the whole string
+	arr = oakcore_stringutils_split("abc", ',', &count);
+	assert(arr != NULL);
+	assert(count == 1);
+	assert(strcmp(arr[0], "abc") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// Trailing separator yields a trailing empty string
+	arr = oakcore_stringutils_split("a,", ',', &count);
+	assert(arr != NULL);
+	assert(count == 2);
+	assert(strcmp(arr[0], "a") == 0);
+	assert(strcmp(arr[1], "") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// Empty string yields one empty string
+	arr = oakcore_stringutils_split("", ',', &count);
+	assert(arr != NULL);
+	assert(count == 1);
+	assert(strcmp(arr[0], "") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// NULL string behaves like an empty string
+	arr = oakcore_stringutils_split(NULL, ',', &count);
+	assert(arr != NULL);
+	assert(count == 1);
+	assert(strcmp(arr[0], "") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+}
+
+static void test_split_regex()
+{
+	int count = 0;
+
+	// Split on runs of digits
+	char **arr = oakcore_stringutils_split_regex("a1b22c", "[0-9]+", &count);
+	assert(arr != NULL);
+	assert(count == 3);
+	assert(strcmp(arr[0], "a") == 0);
+	assert(strcmp(arr[1], "b") == 0);
+	assert(strcmp(arr[2], "c") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// Pattern that never matches yields the whole string
+	arr = oakcore_stringutils_split_regex("abc", "[0-9]+", &count);
+	assert(arr != NULL);
+	assert(count == 1);
+	assert(strcmp(arr[0], "abc") == 0);
+	oakcore_stringutils_free_string_array(arr, count);
+
+	// Freeing NULL is safe
+	oakcore_stringutils_free_string_array(NULL, 0);
+}
+
+static void test_to_int()
+{
+	int ok = 0;
+
+	// Base 10
+	assert(oakcore_stringutils_to_int("42", 10, &ok) == 42);
+	assert(ok == 1);
+
+	// Negative
+	assert(oakcore_stringutils_to_int("-17", 10, &ok) == -17);
+	assert(ok == 1);
+
+	// Base 16
+	assert(oakcore_stringutils_to_int("ff", 16, &ok) == 255);
+	assert(ok == 1);
+
+	// Parser error: returns 0 and reports failure
+	assert(oakcore_stringutils_to_int("xyz", 10, &ok) == 0);
+	assert(ok == 0);
+
+	// ok output parameter is optional
+	assert(oakcore_stringutils_to_int("7", 10, NULL) == 7);
+}
+
+/* Variadic forwarder to exercise oakcore_stringutils_format_v() */
+static int format_forward(char *buf, int buf_size, const char *fmt, ...)
+{
+	va_list args;
+	va_start(args, fmt);
+	const int r = oakcore_stringutils_format_v(buf, buf_size, fmt, args);
+	va_end(args);
+	return r;
+}
+
+static void test_format()
+{
+	char buf[64];
+
+	// Format with mixed argument types
+	const int needed = oakcore_stringutils_format(buf, sizeof(buf), "%d-%s-%.2f",
+												  42, "mid", 1.5);
+	assert(needed == 11);
+	assert(strcmp(buf, "42-mid-1.50") == 0);
+
+	// NULL buffer queries the required size
+	assert(oakcore_stringutils_format(NULL, 0, "%d-%s-%.2f", 42, "mid",
+									  1.5) == needed);
+
+	// Too-small buffer truncates but still reports the full required size
+	char small[5];
+	const int needed2 =
+		oakcore_stringutils_format(small, sizeof(small), "%s", "abcdefgh");
+	assert(needed2 == 8);
+	assert(strcmp(small, "abcd") == 0);
+
+	// va_list form produces identical results
+	char buf2[64];
+	const int needed3 = format_forward(buf2, sizeof(buf2), "%d-%s-%.2f", 42,
+									   "mid", 1.5);
+	assert(needed3 == needed);
+	assert(strcmp(buf2, buf) == 0);
+}
+
+int main()
+{
+	test_split();
+	test_split_regex();
+	test_to_int();
+	test_format();
+
+	printf("oakcore_stringutils_test: all tests passed\n");
+	return 0;
+}

core/tests/oakcore_timecodefunctions_test.cpp

@@ -0,0 +1,254 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#include <assert.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "olive/core/oakcore/timecodefunctions.h"
+
+int main()
+{
+	char buf[64];
+	int ok = 0;
+	OakRational *r = NULL;
+
+	/* Common timebases: 30 fps non-drop, 29.97 drop-frame, 60 fps */
+	OakRational *tb_30 = oakcore_rational_create_nd(1, 30);
+	OakRational *tb_df = oakcore_rational_create_nd(1001, 30000);
+	OakRational *tb_60 = oakcore_rational_create_nd(1, 60);
+
+	/* oakcore_timecode_time_to_timecode: drop-frame ( Olive's own test case ) */
+	{
+		OakRational *time = oakcore_rational_create(1);
+		const int size = oakcore_timecode_time_to_timecode(
+			time, tb_df, OAK_TIMECODE_DISPLAY_DROP_FRAME, 0, NULL, 0);
+		assert(size == 11);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_df, OAK_TIMECODE_DISPLAY_DROP_FRAME, 0, buf,
+				   sizeof(buf)) == 11);
+		assert(strcmp(buf, "00:00:01;00") == 0);
+		/* Truncating buffer still reports the full required size */
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_df, OAK_TIMECODE_DISPLAY_DROP_FRAME, 0, buf,
+				   6) == 11);
+		assert(strcmp(buf, "00:00") == 0);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_time_to_timecode: invalid timebase */
+	{
+		OakRational *time = oakcore_rational_create(0);
+		OakRational *bizarre = oakcore_rational_create(156632219);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, bizarre, OAK_TIMECODE_DISPLAY_DROP_FRAME, 0, buf,
+				   sizeof(buf)) == 16);
+		assert(strcmp(buf, "INVALID TIMEBASE") == 0);
+		oakcore_rational_free(bizarre);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_time_to_timecode: non-drop, plus sign, negative */
+	{
+		OakRational *time = oakcore_rational_create_nd(3, 2);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_NON_DROP_FRAME, 0, buf,
+				   sizeof(buf)) == 11);
+		assert(strcmp(buf, "00:00:01:15") == 0);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_NON_DROP_FRAME, 1, buf,
+				   sizeof(buf)) == 12);
+		assert(strcmp(buf, "+00:00:01:15") == 0);
+		oakcore_rational_free(time);
+		time = oakcore_rational_create_nd(-3, 2);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_NON_DROP_FRAME, 0, buf,
+				   sizeof(buf)) == 12);
+		assert(strcmp(buf, "-00:00:01:15") == 0);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_time_to_timecode: seconds / frames / milliseconds */
+	{
+		OakRational *time = oakcore_rational_create_nd(123, 2); /* 61.5 s */
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_SECONDS, 0, buf,
+				   sizeof(buf)) == 12);
+		assert(strcmp(buf, "00:01:01.500") == 0);
+		oakcore_rational_free(time);
+		time = oakcore_rational_create_nd(3, 2);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_FRAMES, 0, buf,
+				   sizeof(buf)) == 2);
+		assert(strcmp(buf, "45") == 0);
+		assert(oakcore_timecode_time_to_timecode(
+				   time, tb_30, OAK_TIMECODE_DISPLAY_MILLISECONDS, 0, buf,
+				   sizeof(buf)) == 4);
+		assert(strcmp(buf, "1500") == 0);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_timecode_to_time: non-drop */
+	r = oakcore_timecode_timecode_to_time("00:00:01:15", tb_30,
+										  OAK_TIMECODE_DISPLAY_NON_DROP_FRAME,
+										  &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_numerator(r) == 3 &&
+		   oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(r);
+
+	/* oakcore_timecode_timecode_to_time: drop-frame */
+	r = oakcore_timecode_timecode_to_time("00:00:01;00", tb_df,
+										  OAK_TIMECODE_DISPLAY_DROP_FRAME,
+										  &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_numerator(r) == 1001 &&
+		   oakcore_rational_denominator(r) == 1000);
+	oakcore_rational_free(r);
+
+	/* oakcore_timecode_timecode_to_time: seconds / frames / milliseconds */
+	r = oakcore_timecode_timecode_to_time("00:00:01.5", tb_30,
+										  OAK_TIMECODE_DISPLAY_SECONDS, &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_numerator(r) == 3 &&
+		   oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(r);
+	r = oakcore_timecode_timecode_to_time("45", tb_30,
+										  OAK_TIMECODE_DISPLAY_FRAMES, &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_numerator(r) == 3 &&
+		   oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(r);
+	r = oakcore_timecode_timecode_to_time("1500", tb_30,
+										  OAK_TIMECODE_DISPLAY_MILLISECONDS,
+										  &ok);
+	assert(ok == 1);
+	assert(oakcore_rational_numerator(r) == 3 &&
+		   oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(r);
+
+	/* oakcore_timecode_timecode_to_time: invalid and NULL input */
+	r = oakcore_timecode_timecode_to_time("abc", tb_30,
+										  OAK_TIMECODE_DISPLAY_NON_DROP_FRAME,
+										  &ok);
+	assert(ok == 0);
+	assert(oakcore_rational_numerator(r) == 0);
+	oakcore_rational_free(r);
+	r = oakcore_timecode_timecode_to_time(NULL, tb_30,
+										  OAK_TIMECODE_DISPLAY_NON_DROP_FRAME,
+										  &ok);
+	assert(ok == 0);
+	oakcore_rational_free(r);
+	/* ok pointer itself may be NULL */
+	r = oakcore_timecode_timecode_to_time("45", tb_30,
+										  OAK_TIMECODE_DISPLAY_FRAMES, NULL);
+	assert(oakcore_rational_to_double(r) == 1.5);
+	oakcore_rational_free(r);
+
+	/* oakcore_timecode_time_to_string */
+	assert(oakcore_timecode_time_to_string(3661000, NULL, 0) == 8);
+	assert(oakcore_timecode_time_to_string(3661000, buf, sizeof(buf)) == 8);
+	assert(strcmp(buf, "01:01:01") == 0);
+	assert(oakcore_timecode_time_to_string(0, buf, sizeof(buf)) == 8);
+	assert(strcmp(buf, "00:00:00") == 0);
+
+	/* oakcore_timecode_snap_time_to_timebase */
+	{
+		OakRational *time = oakcore_rational_create_nd(102, 100); /* 1.02 s */
+		r = oakcore_timecode_snap_time_to_timebase(
+			time, tb_30, OAK_TIMECODE_ROUNDING_ROUND);
+		assert(oakcore_rational_numerator(r) == 31 &&
+			   oakcore_rational_denominator(r) == 30);
+		oakcore_rational_free(r);
+		oakcore_rational_free(time);
+		time = oakcore_rational_create_nd(151, 100); /* 1.51 s -> 45.3 frames */
+		r = oakcore_timecode_snap_time_to_timebase(
+			time, tb_30, OAK_TIMECODE_ROUNDING_FLOOR);
+		assert(oakcore_rational_numerator(r) == 3 &&
+			   oakcore_rational_denominator(r) == 2);
+		oakcore_rational_free(r);
+		r = oakcore_timecode_snap_time_to_timebase(
+			time, tb_30, OAK_TIMECODE_ROUNDING_CEIL);
+		assert(oakcore_rational_numerator(r) == 23 &&
+			   oakcore_rational_denominator(r) == 15);
+		oakcore_rational_free(r);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_time_to_timestamp (Rational) */
+	{
+		OakRational *time = oakcore_rational_create_nd(3, 2);
+		assert(oakcore_timecode_time_to_timestamp(
+				   time, tb_30, OAK_TIMECODE_ROUNDING_ROUND) == 45);
+		oakcore_rational_free(time);
+		time = oakcore_rational_create_nd(151, 100); /* 45.3 frames */
+		assert(oakcore_timecode_time_to_timestamp(
+				   time, tb_30, OAK_TIMECODE_ROUNDING_ROUND) == 45);
+		assert(oakcore_timecode_time_to_timestamp(
+				   time, tb_30, OAK_TIMECODE_ROUNDING_FLOOR) == 45);
+		assert(oakcore_timecode_time_to_timestamp(
+				   time, tb_30, OAK_TIMECODE_ROUNDING_CEIL) == 46);
+		oakcore_rational_free(time);
+	}
+
+	/* oakcore_timecode_time_to_timestamp_d (double) */
+	assert(oakcore_timecode_time_to_timestamp_d(1.5, tb_30,
+												OAK_TIMECODE_ROUNDING_ROUND) ==
+		   45);
+	assert(oakcore_timecode_time_to_timestamp_d(NAN, tb_30,
+												OAK_TIMECODE_ROUNDING_ROUND) ==
+		   0);
+
+	/* oakcore_timecode_rescale_timestamp */
+	assert(oakcore_timecode_rescale_timestamp(30, tb_30, tb_60) == 60);
+	assert(oakcore_timecode_rescale_timestamp(30, tb_30, tb_30) == 30);
+	{
+		/* 1 * (1*4) / (5*3) = 0.2666... -> nearest is 0 */
+		OakRational *src = oakcore_rational_create_nd(1, 5);
+		OakRational *dst = oakcore_rational_create_nd(3, 4);
+		assert(oakcore_timecode_rescale_timestamp(1, src, dst) == 0);
+		/* ... but ceil rounds up to 1 */
+		assert(oakcore_timecode_rescale_timestamp_ceil(1, src, dst) == 1);
+		oakcore_rational_free(dst);
+		oakcore_rational_free(src);
+	}
+	assert(oakcore_timecode_rescale_timestamp_ceil(30, tb_30, tb_60) == 60);
+
+	/* oakcore_timecode_timestamp_to_time */
+	r = oakcore_timecode_timestamp_to_time(45, tb_30);
+	assert(oakcore_rational_numerator(r) == 3 &&
+		   oakcore_rational_denominator(r) == 2);
+	oakcore_rational_free(r);
+	r = oakcore_timecode_timestamp_to_time(0, tb_30);
+	assert(oakcore_rational_to_double(r) == 0.0);
+	oakcore_rational_free(r);
+
+	/* oakcore_timecode_timebase_is_drop_frame */
+	assert(oakcore_timecode_timebase_is_drop_frame(tb_df) == 1);
+	assert(oakcore_timecode_timebase_is_drop_frame(tb_30) == 0);
+
+	oakcore_rational_free(tb_60);
+	oakcore_rational_free(tb_df);
+	oakcore_rational_free(tb_30);
+
+	printf("oakcore_timecodefunctions_test: all tests passed\n");
+	return 0;
+}

core/tests/oakcore_timerange_test.cpp

@@ -0,0 +1,352 @@
+/***
+
+  Oak - Non-Linear Video Editor
+  Copyright (C) 2026 Oak Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+/**
+ * @file oakcore_timerange_test.cpp
+ * @brief Smoke test for the OakTimeRange C ABI
+ *
+ * Pure C API test: no gtest, no C++ wrapper classes. Every allocated handle
+ * is released with the matching free function.
+ */
+
+#include <assert.h>
+#include <limits.h>
+#include <stdio.h>
+
+#include "olive/core/oakcore/timerange.h"
+
+static OakRational *mk_time(int n)
+{
+	return oakcore_rational_create(n);
+}
+
+static OakTimeRange *mk_range(int in, int out)
+{
+	OakRational *ri = mk_time(in);
+	OakRational *ro = mk_time(out);
+	OakTimeRange *r = oakcore_timerange_create_io(ri, ro);
+	oakcore_rational_free(ri);
+	oakcore_rational_free(ro);
+	return r;
+}
+
+static void expect_int_time(const OakRational *r, int expected)
+{
+	assert(oakcore_rational_numerator(r) == expected);
+	assert(oakcore_rational_denominator(r) == 1);
+}
+
+static void expect_range(const OakTimeRange *r, int in, int out)
+{
+	OakRational *ri = oakcore_timerange_in(r);
+	OakRational *ro = oakcore_timerange_out(r);
+	expect_int_time(ri, in);
+	expect_int_time(ro, out);
+	oakcore_rational_free(ri);
+	oakcore_rational_free(ro);
+}
+
+static void test_create_default(void)
+{
+	OakTimeRange *r = oakcore_timerange_create();
+	expect_range(r, 0, 0);
+
+	OakRational *length = oakcore_timerange_length(r);
+	expect_int_time(length, 0);
+	oakcore_rational_free(length);
+
+	oakcore_timerange_free(r);
+}
+
+static void test_create_and_getters(void)
+{
+	OakTimeRange *r = mk_range(10, 20);
+	expect_range(r, 10, 20);
+
+	OakRational *length = oakcore_timerange_length(r);
+	expect_int_time(length, 10);
+	oakcore_rational_free(length);
+
+	oakcore_timerange_free(r);
+}
+
+static void test_normalize_swaps_in_out(void)
+{
+	// out earlier than in must be swapped
+	OakTimeRange *r = mk_range(20, 10);
+	expect_range(r, 10, 20);
+
+	OakRational *length = oakcore_timerange_length(r);
+	expect_int_time(length, 10);
+	oakcore_rational_free(length);
+
+	oakcore_timerange_free(r);
+}
+
+static void test_length_nan_on_extremes(void)
+{
+	// RATIONAL_MIN/RATIONAL_MAX endpoints make the length NaN
+	OakTimeRange *r = mk_range(INT_MIN, 0);
+	OakRational *length = oakcore_timerange_length(r);
+	assert(oakcore_rational_is_nan(length) == 1);
+	oakcore_rational_free(length);
+	oakcore_timerange_free(r);
+
+	r = mk_range(0, INT_MAX);
+	length = oakcore_timerange_length(r);
+	assert(oakcore_rational_is_nan(length) == 1);
+	oakcore_rational_free(length);
+	oakcore_timerange_free(r);
+}
+
+static void test_copy_and_equal(void)
+{
+	OakTimeRange *r = mk_range(3, 7);
+	OakTimeRange *copy = oakcore_timerange_copy(r);
+
+	assert(oakcore_timerange_equal(r, copy) == 1);
+	expect_range(copy, 3, 7);
+
+	// Mutating the copy must not affect the original (deep ownership)
+	OakRational *nine = mk_time(9);
+	oakcore_timerange_set_in(copy, nine);
+	oakcore_rational_free(nine);
+
+	// set_in(9) with out==7 normalizes by swapping to (7, 9)
+	expect_range(copy, 7, 9);
+	assert(oakcore_timerange_equal(r, copy) == 0);
+	expect_range(r, 3, 7);
+
+	oakcore_timerange_free(copy);
+	oakcore_timerange_free(r);
+}
+
+static void test_setters(void)
+{
+	OakTimeRange *r = mk_range(0, 10);
+	OakRational *t = mk_time(5);
+
+	oakcore_timerange_set_in(r, t);
+	expect_range(r, 5, 10);
+
+	oakcore_timerange_set_out(r, t);
+	// set_out(5) with in==5 collapses to a zero-length range
+	expect_range(r, 5, 5);
+
+	{
+		OakRational *in = mk_time(30);
+		OakRational *out = mk_time(20);
+		oakcore_timerange_set_range(r, in, out);
+		oakcore_rational_free(in);
+		oakcore_rational_free(out);
+	}
+	// set_range also normalizes
+	expect_range(r, 20, 30);
+
+	oakcore_rational_free(t);
+	oakcore_timerange_free(r);
+}
+
+static void test_overlaps_with(void)
+{
+	OakTimeRange *a = mk_range(0, 10);
+	OakTimeRange *b = mk_range(10, 20);
+	OakTimeRange *c = mk_range(5, 15);
+
+	// Touching ranges (0,10) vs (10,20): in_inclusive governs the
+	// other.out-vs-self.in comparison, out_inclusive the other.in-vs-self.out
+	// one, so the results are asymmetric for mixed flags
+	assert(oakcore_timerange_overlaps_with(a, b, 1, 1) == 1);
+	assert(oakcore_timerange_overlaps_with(a, b, 0, 0) == 0);
+	assert(oakcore_timerange_overlaps_with(a, b, 1, 0) == 0);
+	assert(oakcore_timerange_overlaps_with(a, b, 0, 1) == 1);
+
+	// Genuinely overlapping ranges overlap under any inclusivity
+	assert(oakcore_timerange_overlaps_with(a, c, 1, 1) == 1);
+	assert(oakcore_timerange_overlaps_with(a, c, 0, 0) == 1);
+
+	oakcore_timerange_free(c);
+	oakcore_timerange_free(b);
+	oakcore_timerange_free(a);
+}
+
+static void test_contains_range(void)
+{
+	OakTimeRange *outer = mk_range(0, 30);
+	OakTimeRange *inner = mk_range(5, 10);
+	OakTimeRange *same = mk_range(0, 30);
+	OakTimeRange *partial = mk_range(5, 40);
+
+	assert(oakcore_timerange_contains_range(outer, inner, 1, 1) == 1);
+	assert(oakcore_timerange_contains_range(outer, inner, 0, 0) == 1);
+
+	// Identical ranges: contained inclusively, not exclusively
+	assert(oakcore_timerange_contains_range(outer, same, 1, 1) == 1);
+	assert(oakcore_timerange_contains_range(outer, same, 0, 0) == 0);
+
+	assert(oakcore_timerange_contains_range(outer, partial, 1, 1) == 0);
+	assert(oakcore_timerange_contains_range(inner, outer, 1, 1) == 0);
+
+	oakcore_timerange_free(partial);
+	oakcore_timerange_free(same);
+	oakcore_timerange_free(inner);
+	oakcore_timerange_free(outer);
+}
+
+static void test_contains_time(void)
+{
+	OakTimeRange *r = mk_range(0, 10);
+	OakRational *inside = mk_time(5);
+	OakRational *edge_in = mk_time(0);
+	OakRational *edge_out = mk_time(10);
+	OakRational *outside = mk_time(-1);
+
+	// contains(time) is in-inclusive but out-exclusive
+	assert(oakcore_timerange_contains_time(r, inside) == 1);
+	assert(oakcore_timerange_contains_time(r, edge_in) == 1);
+	assert(oakcore_timerange_contains_time(r, edge_out) == 0);
+	assert(oakcore_timerange_contains_time(r, outside) == 0);
+
+	oakcore_rational_free(outside);
+	oakcore_rational_free(edge_out);
+	oakcore_rational_free(edge_in);
+	oakcore_rational_free(inside);
+	oakcore_timerange_free(r);
+}
+
+static void test_combine_and_intersect(void)
+{
+	OakTimeRange *a = mk_range(0, 10);
+	OakTimeRange *b = mk_range(20, 30);
+
+	OakTimeRange *combined = oakcore_timerange_combined(a, b);
+	expect_range(combined, 0, 30);
+	oakcore_timerange_free(combined);
+
+	combined = oakcore_timerange_combine(b, a);
+	expect_range(combined, 0, 30);
+	oakcore_timerange_free(combined);
+
+	// Disjoint ranges intersect to (20, 10), which normalize() swaps to (10, 20)
+	OakTimeRange *intersected = oakcore_timerange_intersected(a, b);
+	expect_range(intersected, 10, 20);
+	oakcore_timerange_free(intersected);
+
+	oakcore_timerange_free(b);
+	oakcore_timerange_free(a);
+
+	a = mk_range(0, 20);
+	b = mk_range(10, 30);
+
+	intersected = oakcore_timerange_intersected(a, b);
+	expect_range(intersected, 10, 20);
+	oakcore_timerange_free(intersected);
+
+	intersected = oakcore_timerange_intersect(b, a);
+	expect_range(intersected, 10, 20);
+	oakcore_timerange_free(intersected);
+
+	oakcore_timerange_free(b);
+	oakcore_timerange_free(a);
+}
+
+static void test_arithmetic(void)
+{
+	OakTimeRange *r = mk_range(0, 10);
+	OakRational *five = mk_time(5);
+
+	OakTimeRange *shifted = oakcore_timerange_add(r, five);
+	expect_range(shifted, 5, 15);
+
+	OakTimeRange *back = oakcore_timerange_sub(shifted, five);
+	expect_range(back, 0, 10);
+	oakcore_timerange_free(back);
+	oakcore_timerange_free(shifted);
+
+	oakcore_timerange_add_assign(r, five);
+	expect_range(r, 5, 15);
+
+	oakcore_timerange_sub_assign(r, five);
+	expect_range(r, 0, 10);
+
+	OakRational *length = oakcore_timerange_length(r);
+	expect_int_time(length, 10);
+	oakcore_rational_free(length);
+
+	oakcore_rational_free(five);
+	oakcore_timerange_free(r);
+}
+
+static void test_split(void)
+{
+	OakTimeRange *r = mk_range(0, 10);
+
+	// Size query, both directly and through the NULL-buffer form
+	assert(oakcore_timerange_split_count(r, 4) == 3);
+	assert(oakcore_timerange_split(r, 4, NULL, 0) == 3);
+
+	// Full split: (0,4), (4,8), (8,10)
+	OakTimeRange *chunks[3];
+	assert(oakcore_timerange_split(r, 4, chunks, 3) == 3);
+	expect_range(chunks[0], 0, 4);
+	expect_range(chunks[1], 4, 8);
+	expect_range(chunks[2], 8, 10);
+	for (int i = 0; i < 3; i++) {
+		oakcore_timerange_free(chunks[i]);
+	}
+
+	// A too-small buffer receives a prefix, the return value is the total
+	OakTimeRange *prefix[2];
+	assert(oakcore_timerange_split(r, 4, prefix, 2) == 3);
+	expect_range(prefix[0], 0, 4);
+	expect_range(prefix[1], 4, 8);
+	oakcore_timerange_free(prefix[0]);
+	oakcore_timerange_free(prefix[1]);
+
+	// Zero-length range splits into exactly one chunk
+	OakTimeRange *zero = mk_range(5, 5);
+	assert(oakcore_timerange_split_count(zero, 4) == 1);
+	OakTimeRange *single = NULL;
+	assert(oakcore_timerange_split(zero, 4, &single, 1) == 1);
+	expect_range(single, 5, 5);
+	oakcore_timerange_free(single);
+	oakcore_timerange_free(zero);
+
+	oakcore_timerange_free(r);
+}
+
+int main(void)
+{
+	test_create_default();
+	test_create_and_getters();
+	test_normalize_swaps_in_out();
+	test_length_nan_on_extremes();
+	test_copy_and_equal();
+	test_setters();
+	test_overlaps_with();
+	test_contains_range();
+	test_contains_time();
+	test_combine_and_intersect();
+	test_arithmetic();
+	test_split();
+
+	printf("oakcore_timerange_test: all tests passed\n");
+	return 0;
+}

core/tests/rational-test.cpp

@@ -1,109 +0,0 @@
-/***
-
-  Olive - Non-Linear Video Editor
-  Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#include <cstring>
-
-#include "util/rational.h"
-#include "util/tests.h"
-
-using namespace olive::core;
-
-bool rational_to_from_string_test()
-{
-	Rational r(1, 30);
-
-	std::string s = r.toString();
-
-	Rational r2 = Rational::fromString(s);
-
-	return r == r2;
-}
-
-bool rational_to_from_string_test2()
-{
-	Rational r(69, 420);
-
-	std::string s = r.toString();
-
-	Rational r2 = Rational::fromString(s);
-
-	return r == r2;
-}
-
-bool rational_defaults()
-{
-	// By default, rationals are valid 0/1
-	Rational basic_constructor;
-
-	if (!basic_constructor.isNull()) {
-		return false;
-	}
-
-	if (basic_constructor.isNaN()) {
-		return false;
-	}
-
-	return true;
-}
-
-bool rational_nan()
-{
-	// Create a NaN with a 0 denominator
-	Rational nan = Rational(0, 0);
-	if (!nan.isNaN())
-		return false;
-	if (!nan.isNull())
-		return false;
-
-	// Create a non-NaN with a zero numerator
-	Rational zero_nonnan(0, 999);
-	if (!zero_nonnan.isNull())
-		return false;
-	if (zero_nonnan.isNaN())
-		return false;
-
-	// Create a non-NaN with a non-zero numerator
-	Rational nonzer_nonnan(1, 30);
-	if (nonzer_nonnan.isNull())
-		return false;
-	if (nonzer_nonnan.isNaN())
-		return false;
-
-	return true;
-}
-
-bool rational_nan_constant()
-{
-	return Rational::NaN.isNaN();
-}
-
-int main()
-{
-	Tester t;
-
-	t.add("Rational::defaults", rational_defaults);
-	t.add("Rational::NaN", rational_nan);
-	t.add("Rational::NaN_constant", rational_nan_constant);
-	t.add("Rational::toString/fromString", rational_to_from_string_test);
-	t.add("Rational::toString/fromString2", rational_to_from_string_test2);
-
-	return t.exec();
-}

core/tests/stringutils-test.cpp

@@ -1,47 +0,0 @@
-/***
-
-  Olive - Non-Linear Video Editor
-  Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#include <cstring>
-
-#include "util/stringutils.h"
-#include "util/tests.h"
-
-using namespace olive::core;
-
-bool stringutils_format_test()
-{
-	const char *expected = "Hello, world!";
-	std::string f = StringUtils::format("%s, %s!", "Hello", "world");
-	if (strcmp(f.c_str(), expected) != 0) {
-		return false;
-	}
-
-	return true;
-}
-
-int main()
-{
-	Tester t;
-
-	t.add("StringUtils::format", stringutils_format_test);
-
-	return t.exec();
-}

core/tests/timecode-test.cpp

@@ -1,65 +0,0 @@
-/***
-
-  Olive - Non-Linear Video Editor
-  Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#include <cstring>
-
-#include "util/timecodefunctions.h"
-#include "util/tests.h"
-
-using namespace olive::core;
-
-bool timecodefunctions_time_to_timecode_test()
-{
-	Rational drop_frame_30(1001, 30000);
-
-	std::string timecode = Timecode::time_to_timecode(
-		Rational(1), drop_frame_30, Timecode::kTimecodeDropFrame);
-	if (strcmp(timecode.c_str(), "00:00:01;00") != 0) {
-		return false;
-	}
-
-	return true;
-}
-
-bool timecodefunctions_time_to_timecode_test2()
-{
-	Rational bizarre_timebase(156632219);
-
-	std::string timecode = Timecode::time_to_timecode(
-		Rational(0), bizarre_timebase, Timecode::kTimecodeDropFrame);
-	if (strcmp(timecode.c_str(), "INVALID TIMEBASE") != 0) {
-		return false;
-	}
-
-	return true;
-}
-
-int main()
-{
-	Tester t;
-
-	t.add("Timecode::time_to_timecode",
-		  timecodefunctions_time_to_timecode_test);
-	t.add("Timecode::time_to_timecode2",
-		  timecodefunctions_time_to_timecode_test2);
-
-	return t.exec();
-}

core/tests/timerange-test.cpp

@@ -1,124 +0,0 @@
-/***
-
-  Olive - Non-Linear Video Editor
-  Copyright (C) 2023 Olive Studios LLC
-  Modifications Copyright (C) 2025 mikesolar
-
-  This program is free software: you can redistribute it and/or modify
-  it under the terms of the GNU General Public License as published by
-  the Free Software Foundation, either version 3 of the License, or
-  (at your option) any later version.
-
-  This program is distributed in the hope that it will be useful,
-  but WITHOUT ANY WARRANTY; without even the implied warranty of
-  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-  GNU General Public License for more details.
-
-  You should have received a copy of the GNU General Public License
-  along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-***/
-
-#include <cstring>
-
-#include "util/timerange.h"
-#include "util/tests.h"
-
-using namespace olive::core;
-
-bool timerangelist_remove_test()
-{
-	TimeRangeList t;
-
-	t.insert(TimeRange(0, 30));
-	t.remove(TimeRange(2, 5));
-
-	return true;
-}
-
-bool timerangelist_mergeadjacent_test()
-{
-	TimeRangeList t;
-
-	// TimeRangeList should merge 1 and 3 together since they're adjacent
-	t.insert(TimeRange(0, 6));
-	t.insert(TimeRange(20, 30));
-	t.insert(TimeRange(6, 10));
-
-	if (!(t.size() == 2)) {
-		return false;
-	}
-	if (!(t.first() == TimeRange(20, 30))) {
-		return false;
-	}
-	if (!(t.at(1) == TimeRange(0, 10))) {
-		return false;
-	}
-
-	// TimeRangeList should ignore these because it's already contained
-	TimeRangeList noop_test = t;
-
-	noop_test.insert(TimeRange(4, 7));
-	if (!(noop_test == t)) {
-		return false;
-	}
-
-	noop_test.insert(TimeRange(0, 3));
-	if (!(noop_test == t)) {
-		return false;
-	}
-
-	noop_test.insert(TimeRange(25, 30));
-	if (!(noop_test == t)) {
-		return false;
-	}
-
-	// TimeRangeList should combine all these together
-	TimeRangeList combine_test_no_overlap = t;
-	combine_test_no_overlap.insert(TimeRange(10, 20));
-	if (!(combine_test_no_overlap.size() == 1)) {
-		return false;
-	}
-	if (!(combine_test_no_overlap.first() == TimeRange(0, 30))) {
-		return false;
-	}
-
-	TimeRangeList combine_test_in_overlap = t;
-	combine_test_in_overlap.insert(TimeRange(9, 20));
-	if (!(combine_test_in_overlap.size() == 1)) {
-		return false;
-	}
-	if (!(combine_test_in_overlap.first() == TimeRange(0, 30))) {
-		return false;
-	}
-
-	TimeRangeList combine_test_out_overlap = t;
-	combine_test_out_overlap.insert(TimeRange(10, 21));
-	if (!(combine_test_out_overlap.size() == 1)) {
-		return false;
-	}
-	if (!(combine_test_out_overlap.first() == TimeRange(0, 30))) {
-		return false;
-	}
-
-	TimeRangeList combine_test_both_overlap = t;
-	combine_test_both_overlap.insert(TimeRange(9, 21));
-	if (!(combine_test_both_overlap.size() == 1)) {
-		return false;
-	}
-	if (!(combine_test_both_overlap.first() == TimeRange(0, 30))) {
-		return false;
-	}
-
-	return true;
-}
-
-int main()
-{
-	Tester t;
-
-	t.add("TimeRangeList::remove", timerangelist_remove_test);
-	t.add("TimeRangeList::merge_adjacent", timerangelist_mergeadjacent_test);
-
-	return t.exec();
-}

tests/gtest/CMakeLists.txt

@@ -198,8 +198,11 @@ else()
 endif()
 
 if (WIN32)
-  # Windows has no RPATH: ffmpeg_bridge.dll must sit next to the executable
+  # Windows has no RPATH: shared libraries must sit next to the executable
   add_custom_command(TARGET olive-gtest POST_BUILD
     COMMAND ${CMAKE_COMMAND} -E copy_if_different
       $<TARGET_FILE:ffmpeg_bridge> $<TARGET_FILE_DIR:olive-gtest>)
+  add_custom_command(TARGET olive-gtest POST_BUILD
+    COMMAND ${CMAKE_COMMAND} -E copy_if_different
+      $<TARGET_FILE:olivecore> $<TARGET_FILE_DIR:olive-gtest>)
 endif()

worker/CMakeLists.txt

@@ -70,6 +70,14 @@ endif ()
 # copies, Linux install() into the same bin directory)
 add_dependencies(olive-editor olive-render-worker)
 
+if (WIN32)
+    # Windows has no RPATH: shared libraries must sit next to the executable
+    add_custom_command(TARGET olive-render-worker POST_BUILD
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:ffmpeg_bridge> $<TARGET_FILE_DIR:olive-render-worker>
+            COMMAND ${CMAKE_COMMAND} -E copy_if_different $<TARGET_FILE:olivecore> $<TARGET_FILE_DIR:olive-render-worker>
+    )
+endif ()
+
 # Install the render worker alongside the editor on Linux.
 if (UNIX AND NOT APPLE)
     install(TARGETS olive-render-worker RUNTIME DESTINATION bin)