diff --git a/engine/CMakeLists.txt b/engine/CMakeLists.txt
index e2373e837..62b4c78cf 100644
--- a/engine/CMakeLists.txt
+++ b/engine/CMakeLists.txt
@@ -44,6 +44,7 @@ add_subdirectory(timeline)
add_subdirectory(tool)
add_subdirectory(ui)
add_subdirectory(undo)
+add_subdirectory(src/capi)
add_library(oakengine SHARED
${OLIVE_SOURCES}
@@ -225,4 +226,11 @@ if (BUILD_TESTS)
endfunction()
make_oakengine_test(oakengine_ipc_test)
+
+ make_oakengine_test(oakengine_init_test)
+ # Resolves the real test assets (tests/demo.mp4, the footage fixture
+ # project) relative to the repository root, like tests/gtest does.
+ target_compile_definitions(oakengine_init_test PRIVATE
+ OAK_TEST_SOURCE_DIR="${CMAKE_SOURCE_DIR}"
+ )
endif ()
diff --git a/engine/include/oakengine/init.h b/engine/include/oakengine/init.h
new file mode 100644
index 000000000..6d771c7af
--- /dev/null
+++ b/engine/include/oakengine/init.h
@@ -0,0 +1,125 @@
+/***
+
+ 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 .
+
+***/
+
+#ifndef OAKENGINE_INIT_H
+#define OAKENGINE_INIT_H
+
+#include "export.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file init.h
+ * @brief C ABI for engine process initialization and shutdown
+ *
+ * oakengine_init() brings up the UI-independent engine services a consumer of
+ * liboakengine needs before touching projects or timelines. It never creates
+ * any UI: no QApplication, no main window, no display connection. When no
+ * application object exists yet, an offscreen QGuiApplication is created (Qt
+ * requires exactly one application object; it is leaked intentionally because
+ * Qt cannot safely re-create one). A QGuiApplication -- not a plain
+ * QCoreApplication -- is required because EngineCore's undo stack creates
+ * QActions in its constructor, and Qt6 QActions need QGuiApplication state;
+ * with the offscreen QPA plugin (the default, overridable through
+ * QT_QPA_PLATFORM) nothing graphical ever happens.
+ *
+ * The flag mask selects the service set:
+ *
+ * - OAKENGINE_INIT_HEADLESS: Config, NodeFactory, ColorManager, TaskManager,
+ * ConformManager, ProxyManager, FrameManager, DiskManager,
+ * ProjectSerializer and a process-wide EngineCore shell (holds the global
+ * undo stack and the EngineCore::instance() pointer engine code
+ * dereferences). DiskManager is not part of EngineCore::start() but is
+ * required because loading a project touches PlaybackCache state which
+ * dereferences DiskManager::instance(). Everything here runs headless;
+ * no GL is required.
+ *
+ * - OAKENGINE_INIT_RENDER: additionally creates the RenderManager. Only
+ * with this bit may a consumer end up needing a GL context (the actual
+ * render backends are dynamic engine plugins loaded on demand).
+ *
+ * Initialization is modelled on the render worker's headless bootstrap
+ * (worker/workermain.cpp) rather than EngineCore::start(), because start()
+ * unconditionally creates the RenderManager, starts the autorecovery timer
+ * and reads the recent-projects list -- application behavior that does not
+ * belong behind a library boundary.
+ *
+ * Conventions:
+ * - Return codes: 0 (OAKENGINE_OK) on success, a negative OAKENGINE_E_*
+ * error code on failure.
+ * - oakengine_init() is idempotent: calling it again is a no-op for flag
+ * bits already initialized and only brings up the missing bits (e.g.
+ * upgrading HEADLESS to HEADLESS|RENDER).
+ * - oakengine_shutdown() pairs with oakengine_init() and tears down the
+ * initialized services in reverse order. The QCoreApplication and the
+ * EngineCore shell are kept alive (see above), so oakengine_init() may be
+ * called again afterwards.
+ */
+
+/**
+ * @brief Status and error codes shared by the init/project/timeline families.
+ */
+#define OAKENGINE_OK 0 /**< Success. */
+#define OAKENGINE_E_INVALID (-1) /**< NULL handle or invalid argument. */
+#define OAKENGINE_E_STATE (-2) /**< Call not valid in the current state. */
+#define OAKENGINE_E_FAILED (-3) /**< The engine reported a failure. */
+#define OAKENGINE_E_NOT_FOUND (-4) /**< Index out of range / entry not found. */
+
+/** @brief Base headless engine services (no GL required). */
+#define OAKENGINE_INIT_HEADLESS 0x01
+/** @brief Render services on top of HEADLESS (may require GL). */
+#define OAKENGINE_INIT_RENDER 0x02
+
+/**
+ * @brief Initialize the engine services selected by `flags`.
+ *
+ * `flags` is a bitmask of OAKENGINE_INIT_HEADLESS and/or
+ * OAKENGINE_INIT_RENDER; 0 is invalid. Repeated calls are idempotent and may
+ * add the RENDER bit to a running HEADLESS instance.
+ *
+ * @return OAKENGINE_OK on success, OAKENGINE_E_INVALID for an empty mask.
+ */
+OAKENGINE_API int oakengine_init(int flags);
+
+/**
+ * @brief Tear down the services brought up by oakengine_init().
+ *
+ * Safe to call when not initialized (a no-op then). The QCoreApplication and
+ * the EngineCore shell survive shutdown intentionally.
+ *
+ * @return OAKENGINE_OK.
+ */
+OAKENGINE_API int oakengine_shutdown(void);
+
+/**
+ * @brief Current initialization state as a flag bitmask (0 = not initialized).
+ *
+ * Only services that are actually up are reported, e.g. after upgrading a
+ * HEADLESS instance with the RENDER bit the result includes both bits.
+ */
+OAKENGINE_API int oakengine_init_flags(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKENGINE_INIT_H */
diff --git a/engine/include/oakengine/project.h b/engine/include/oakengine/project.h
new file mode 100644
index 000000000..758e2d7ef
--- /dev/null
+++ b/engine/include/oakengine/project.h
@@ -0,0 +1,202 @@
+/***
+
+ 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 .
+
+***/
+
+#ifndef OAKENGINE_PROJECT_H
+#define OAKENGINE_PROJECT_H
+
+#include "export.h"
+#include "init.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file project.h
+ * @brief C ABI for Oak project files (.ove)
+ *
+ * An OakEngineProject wraps the engine's olive::Project node graph. Projects
+ * are created empty with oakengine_project_create() and must then be given
+ * content exactly once: either oakengine_project_new() for a blank project or
+ * oakengine_project_load() to read a project file (the engine's project
+ * serializers require a fresh, uninitialized project, so loading into a
+ * project that already has content is rejected with OAKENGINE_E_STATE).
+ *
+ * Sequences are owned by their project through Qt's QObject parent chain;
+ * OakEngineSequence handles are borrowed views whose lifetime follows the
+ * project. See timeline.h for the sequence function family.
+ *
+ * Conventions (matching oakengine/ipc.h):
+ * - Booleans are int (1/0).
+ * - Return codes: 0 (OAKENGINE_OK) on success, negative OAKENGINE_E_* on
+ * failure.
+ * - String output uses the buf/size convention: the return value is the
+ * number of characters that would have been written excluding the NUL,
+ * so buf == NULL or a short buffer queries the required size. The output
+ * is NUL-terminated whenever buf_size > 0. A negative return value is an
+ * OAKENGINE_E_* error code.
+ * - NULL handles are accepted everywhere and yield a no-op / zero result /
+ * OAKENGINE_E_INVALID.
+ *
+ * Undo/redo note: the engine's undo stack is a process-wide singleton held by
+ * EngineCore (EngineCore::undo_stack()), not a per-project object. The
+ * project_undo/project_redo family therefore operates on that global stack
+ * and is not scoped to `self`; oakengine_project_new() and
+ * oakengine_project_load() clear it, matching the application's
+ * new/open-project behavior.
+ */
+
+/**
+ * @brief Opaque project handle. Owned by the caller; release with
+ * oakengine_project_free().
+ */
+typedef struct OakEngineProject OakEngineProject;
+
+/**
+ * @brief Opaque sequence (timeline) handle.
+ *
+ * Typedef'd here so project.h and timeline.h can be included in any order.
+ * Handles are borrowed from their owning OakEngineProject (QObject parent
+ * chain) and must NOT be freed; they become invalid when the project is
+ * freed. The sequence function family lives in oakengine/timeline.h.
+ */
+typedef struct OakEngineSequence OakEngineSequence;
+
+/**
+ * @brief Allocate an empty project shell. Owned by the caller.
+ *
+ * The project has no content until exactly one of oakengine_project_new() or
+ * oakengine_project_load() succeeds on it.
+ */
+OAKENGINE_API OakEngineProject *oakengine_project_create(void);
+
+/**
+ * @brief Destroy a project and everything it owns (including sequences).
+ * NULL-safe.
+ */
+OAKENGINE_API void oakengine_project_free(OakEngineProject *self);
+
+/**
+ * @brief Initialize `self` as a new, blank project (untitled, not modified).
+ *
+ * Clears the global undo stack. Returns OAKENGINE_E_STATE if the project
+ * already has content (new/load may only be applied once).
+ */
+OAKENGINE_API int oakengine_project_new(OakEngineProject *self);
+
+/**
+ * @brief Load project content from a .ove file.
+ *
+ * On success the project's filename is set to `path` and the modified flag is
+ * cleared; the global undo stack is cleared. Footage is validated like the
+ * engine does (EngineCore::validate_footage_in_loaded_project): files that
+ * moved together with the project are resolved relatively; missing footage is
+ * tolerated (no relink UI exists at this layer, so the project is accepted
+ * as-is). On failure a human-readable reason is written to `err` using the
+ * buf/size convention (err may be NULL) and a negative code is returned.
+ */
+OAKENGINE_API int oakengine_project_load(OakEngineProject *self,
+ const char *path, char *err,
+ int err_size);
+
+/**
+ * @brief Save the project to `path`.
+ *
+ * `path` == NULL saves under the project's current filename
+ * (Project::filename()); saving an untitled project without a path fails with
+ * OAKENGINE_E_INVALID. Files are gzip-compressed unless the target name ends
+ * in ".ovexml" (mirrors the application behavior). On success the project's
+ * filename is set to the target and the modified flag is cleared
+ * (EngineCore::on_project_saved() semantics, minus the UI recent-list).
+ */
+OAKENGINE_API int oakengine_project_save(OakEngineProject *self,
+ const char *path);
+
+OAKENGINE_API int oakengine_project_is_modified(const OakEngineProject *self);
+
+/**
+ * @brief Set the project modified flag (Project::set_modified).
+ */
+OAKENGINE_API int oakengine_project_set_modified(OakEngineProject *self,
+ int modified);
+
+/**
+ * @brief Project display name (Project::name(): the filename's base name, or
+ * "(untitled)"). Uses the buf/size convention.
+ */
+OAKENGINE_API int oakengine_project_name(const OakEngineProject *self,
+ char *buf, int buf_size);
+
+/**
+ * @brief Full path the project was loaded from / saved to, or "" if untitled
+ * (Project::filename()). Uses the buf/size convention.
+ */
+OAKENGINE_API int oakengine_project_filename(const OakEngineProject *self,
+ char *buf, int buf_size);
+
+/**
+ * @brief Number of footage items in the project.
+ */
+OAKENGINE_API int oakengine_project_footage_count(const OakEngineProject *self);
+
+/**
+ * @brief Stored filename of the footage item at `index` (Footage::filename(),
+ * as recorded in the project file; may be relative). Uses the buf/size
+ * convention; returns OAKENGINE_E_NOT_FOUND for an out-of-range index.
+ */
+OAKENGINE_API int oakengine_project_footage_filename(
+ const OakEngineProject *self, int index, char *buf, int buf_size);
+
+/**
+ * @brief 1 if the footage file at `index` exists on disk, 0 if not.
+ *
+ * Mirrors the engine's validation rule: the stored path is checked as-is
+ * first, then resolved relative to the project file's directory (footage
+ * that moved together with the project stays online). Returns
+ * OAKENGINE_E_NOT_FOUND for an out-of-range index.
+ */
+OAKENGINE_API int
+oakengine_project_footage_is_online(const OakEngineProject *self, int index);
+
+/* ---- Undo (global singleton stack, see the file comment above) ---------- */
+
+OAKENGINE_API int oakengine_project_can_undo(const OakEngineProject *self);
+OAKENGINE_API int oakengine_project_can_redo(const OakEngineProject *self);
+OAKENGINE_API int oakengine_project_undo(OakEngineProject *self);
+OAKENGINE_API int oakengine_project_redo(OakEngineProject *self);
+
+/**
+ * @brief Number of sequences (timelines) in the project.
+ */
+OAKENGINE_API int
+oakengine_project_sequence_count(const OakEngineProject *self);
+
+/**
+ * @brief Borrowed handle of the sequence at `index`, or NULL when out of
+ * range. Do NOT free; the sequence is owned by the project.
+ */
+OAKENGINE_API OakEngineSequence *
+oakengine_project_sequence_at(const OakEngineProject *self, int index);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKENGINE_PROJECT_H */
diff --git a/engine/include/oakengine/timeline.h b/engine/include/oakengine/timeline.h
new file mode 100644
index 000000000..91284b814
--- /dev/null
+++ b/engine/include/oakengine/timeline.h
@@ -0,0 +1,185 @@
+/***
+
+ 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 .
+
+***/
+
+#ifndef OAKENGINE_TIMELINE_H
+#define OAKENGINE_TIMELINE_H
+
+#include
+
+#include "export.h"
+#include "init.h"
+#include "project.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @file timeline.h
+ * @brief C ABI for sequences (Oak timelines)
+ *
+ * An OakEngineSequence wraps the engine's olive::Sequence node
+ * (engine/node/project/sequence/sequence.h, a ViewerOutput). This family is
+ * intentionally read-mostly this round: playhead and workarea are simple
+ * writes, everything else is inspection. Clip/track editing is a later
+ * milestone.
+ *
+ * Handles are borrowed from their owning OakEngineProject (Qt QObject parent
+ * chain; sequences are added to the project graph which becomes their
+ * parent). There is deliberately no oakengine_sequence_free(): a sequence
+ * handle becomes invalid when its project is freed. Sequences created with
+ * oakengine_sequence_new() are additionally undoable -- undoing the creation
+ * removes the sequence from the project (but keeps it alive under the undo
+ * command), redoing brings it back.
+ *
+ * Time is exposed in the two representations used across the engine
+ * (olive::core::Timecode terminology, core/util/timecodefunctions.h):
+ *
+ * - seconds: a plain double (`*_seconds` accessors), or a rational seconds
+ * value as a numerator/denominator int pair (`*_rational`);
+ *
+ * - timestamp: an int64 count of timebase units, where the timebase is the
+ * sequence's frame duration (the frame rate flipped, e.g. 1001/30000 for
+ * a 30000/1001 sequence) -- i.e. a frame number. This matches how the
+ * engine converts between Rational times and frame timestamps
+ * (Timecode::time_to_timestamp / timestamp_to_time).
+ *
+ * Conventions match oakengine/project.h: booleans are int, 0
+ * (OAKENGINE_OK)/negative OAKENGINE_E_* return codes, buf/size string output,
+ * NULL handles yield no-ops or OAKENGINE_E_INVALID.
+ */
+
+/**
+ * @brief Create a new sequence named `name` in `project` and return its
+ * borrowed handle (NULL on failure; `project` NULL -> NULL).
+ *
+ * The sequence gets the application's default parameters
+ * (ViewerOutput::set_default_parameters(): width/height/pixel aspect/
+ * interlacing/audio layout from Config, frame rate from the
+ * DefaultSequenceFrameRate config entry, 30000/1001 by default) and starts
+ * with zero tracks. The creation is pushed onto the global undo stack like
+ * the application's "Create New Sequence" action (minus opening a viewer).
+ */
+OAKENGINE_API OakEngineSequence *
+oakengine_sequence_new(OakEngineProject *project, const char *name);
+
+/**
+ * @brief Sequence name (Node::get_label()). Uses the buf/size convention.
+ */
+OAKENGINE_API int oakengine_sequence_name(const OakEngineSequence *self,
+ char *buf, int buf_size);
+
+/**
+ * @brief Length of the sequence content in seconds
+ * (ViewerOutput::get_length()). 0 for an empty sequence.
+ */
+OAKENGINE_API int oakengine_sequence_get_length(const OakEngineSequence *self,
+ double *seconds);
+
+/**
+ * @brief Length of the sequence content as rational seconds
+ * (ViewerOutput::get_length().numerator()/denominator()).
+ */
+OAKENGINE_API int
+oakengine_sequence_get_length_rational(const OakEngineSequence *self, int *num,
+ int *den);
+
+/**
+ * @brief Sequence frame rate as a num/den pair, e.g. 30000/1001
+ * (ViewerOutput::get_video_params().frame_rate()).
+ */
+OAKENGINE_API int
+oakengine_sequence_get_frame_rate(const OakEngineSequence *self, int *num,
+ int *den);
+
+/**
+ * @brief Number of tracks per track type (Sequence::track_list(type)->
+ * get_track_count()). Any of `video`/`audio`/`subtitle` may be NULL.
+ */
+OAKENGINE_API int oakengine_sequence_track_count(const OakEngineSequence *self,
+ int *video, int *audio,
+ int *subtitle);
+
+/**
+ * @brief Playhead position as a timestamp in timebase units (frame number;
+ * ViewerOutput::get_playhead() rescaled to the frame-rate timebase).
+ */
+OAKENGINE_API int
+oakengine_sequence_get_playhead(const OakEngineSequence *self,
+ int64_t *timestamp);
+
+/**
+ * @brief Move the playhead to `timestamp` (frame number;
+ * ViewerOutput::set_playhead()).
+ */
+OAKENGINE_API int oakengine_sequence_set_playhead(OakEngineSequence *self,
+ int64_t timestamp);
+
+/**
+ * @brief Playhead position in seconds.
+ */
+OAKENGINE_API int
+oakengine_sequence_get_playhead_seconds(const OakEngineSequence *self,
+ double *seconds);
+
+/**
+ * @brief 1 if the workarea (in/out range) is enabled
+ * (TimelineWorkArea::enabled()).
+ */
+OAKENGINE_API int
+oakengine_sequence_workarea_is_enabled(const OakEngineSequence *self);
+
+/**
+ * @brief Workarea in/out points as timestamps in timebase units
+ * (TimelineWorkArea::in()/out()). Either pointer may be NULL.
+ */
+OAKENGINE_API int
+oakengine_sequence_get_workarea(const OakEngineSequence *self, int64_t *in,
+ int64_t *out);
+
+/**
+ * @brief Set the workarea: enable flag plus in/out timestamps in timebase
+ * units (TimelineWorkArea::set_enabled()/set_range()).
+ */
+OAKENGINE_API int oakengine_sequence_set_workarea(OakEngineSequence *self,
+ int enabled, int64_t in,
+ int64_t out);
+
+/**
+ * @brief Number of timeline markers (TimelineMarkerList::size()).
+ */
+OAKENGINE_API int
+oakengine_sequence_marker_count(const OakEngineSequence *self);
+
+/**
+ * @brief Marker at `index`: `time` receives its in-point as a timestamp in
+ * timebase units (may be NULL), `name` its label using the buf/size
+ * truncation convention (may be NULL to only fetch the time). Returns
+ * OAKENGINE_OK on success, OAKENGINE_E_NOT_FOUND for an out-of-range index.
+ */
+OAKENGINE_API int oakengine_sequence_marker_at(const OakEngineSequence *self,
+ int index, int64_t *time,
+ char *name, int name_size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* OAKENGINE_TIMELINE_H */
diff --git a/engine/src/capi/CMakeLists.txt b/engine/src/capi/CMakeLists.txt
new file mode 100644
index 000000000..7d7e95914
--- /dev/null
+++ b/engine/src/capi/CMakeLists.txt
@@ -0,0 +1,32 @@
+# 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 .
+
+# C ABI facade of liboakengine (mirrors the pattern documented in
+# render/ipc/CMakeLists.txt):
+# - include/oakengine/*.h public C API
+# - src/capi/*.cpp C ABI implementations
+# The init/project/timeline families wrap the engine core, the project
+# serializer and the sequence/viewer timeline objects.
+set(OLIVE_SOURCES
+ ${OLIVE_SOURCES}
+ include/oakengine/init.h
+ include/oakengine/project.h
+ include/oakengine/timeline.h
+ src/capi/init.cpp
+ src/capi/project.cpp
+ src/capi/timeline.cpp
+ PARENT_SCOPE
+)
diff --git a/engine/src/capi/init.cpp b/engine/src/capi/init.cpp
new file mode 100644
index 000000000..2bf115c18
--- /dev/null
+++ b/engine/src/capi/init.cpp
@@ -0,0 +1,163 @@
+/***
+
+ 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 .
+
+***/
+
+#include "oakengine/init.h"
+
+#include
+#include
+
+#include "codec/conformmanager.h"
+#include "codec/proxymanager.h"
+#include "config/config.h"
+#include "coreengine.h"
+#include "node/color/colormanager/colormanager.h"
+#include "node/factory.h"
+#include "node/project/serializer/serializer.h"
+#include "render/diskmanager.h"
+#include "render/framemanager.h"
+#include "render/rendermanager.h"
+#include "task/taskmanager.h"
+
+namespace
+{
+
+// Currently initialized OAKENGINE_INIT_* bits.
+int g_flags = 0;
+
+// Qt requires exactly one application object for the process and cannot
+// safely destroy and re-create one, so when the library has to create it the
+// object (and its argv storage) is leaked intentionally.
+//
+// This is a QGuiApplication, not a plain QCoreApplication: EngineCore's
+// UndoStack member creates QActions in its constructor, and Qt6 QActions
+// dereference QGuiApplication private state (they crash without one). A
+// QGuiApplication is still a QCoreApplication, and with the offscreen QPA
+// plugin (defaulted below, overridable by the caller) no display
+// connection, window or other UI is ever created.
+void ensure_qcoreapplication()
+{
+ if (QCoreApplication::instance()) {
+ return;
+ }
+
+ // Same default as the gtest harness (tests/gtest/main.cpp).
+ if (qEnvironmentVariableIsEmpty("QT_QPA_PLATFORM")) {
+ qputenv("QT_QPA_PLATFORM", "offscreen");
+ }
+
+ static int argc = 1;
+ static char app_name[] = "oakengine";
+ static char *argv[] = { app_name, nullptr };
+ new QGuiApplication(argc, argv);
+
+ // Same identity as the editor (app/main.cpp) so Config and friends land
+ // in the same locations.
+ QCoreApplication::setOrganizationName(QStringLiteral("oakvideoeditor.org"));
+ QCoreApplication::setApplicationName(QStringLiteral("Oak Video Editor"));
+}
+
+} // namespace
+
+extern "C"
+{
+
+int oakengine_init(int flags)
+{
+ if (flags == 0 || (flags & ~(OAKENGINE_INIT_HEADLESS | OAKENGINE_INIT_RENDER)) != 0) {
+ return OAKENGINE_E_INVALID;
+ }
+
+ if ((flags & OAKENGINE_INIT_HEADLESS) != 0 &&
+ (g_flags & OAKENGINE_INIT_HEADLESS) == 0) {
+ ensure_qcoreapplication();
+
+ // EngineCore shell: provides EngineCore::instance() and the global
+ // undo stack. Never deleted -- EngineCore does not reset instance_ in
+ // its destructor, so deleting would leave a dangling singleton. This
+ // mirrors the render worker's headless bootstrap.
+ if (!olive::EngineCore::instance()) {
+ new olive::EngineCore(olive::EngineCore::CoreParams());
+ }
+
+ olive::Config::load();
+ olive::NodeFactory::initialize();
+ olive::ColorManager::set_up_default_config();
+ olive::TaskManager::create_instance();
+ olive::ConformManager::create_instance();
+ olive::ProxyManager::create_instance();
+ olive::FrameManager::create_instance();
+ // Not in EngineCore::start(), but required headless: loading a project
+ // touches PlaybackCache::load_state() which dereferences
+ // DiskManager::instance() (the render worker creates it for the same
+ // reason).
+ olive::DiskManager::create_instance();
+ olive::ProjectSerializer::initialize();
+
+ g_flags |= OAKENGINE_INIT_HEADLESS;
+ }
+
+ if ((flags & OAKENGINE_INIT_RENDER) != 0 &&
+ (g_flags & OAKENGINE_INIT_RENDER) == 0) {
+ olive::RenderManager::create_instance();
+
+ g_flags |= OAKENGINE_INIT_RENDER;
+ }
+
+ return OAKENGINE_OK;
+}
+
+int oakengine_shutdown(void)
+{
+ // Reverse of oakengine_init(), mirroring EngineCore::stop(). The
+ // QCoreApplication and the EngineCore shell intentionally survive (see
+ // oakengine_init()).
+ if ((g_flags & OAKENGINE_INIT_RENDER) != 0) {
+ olive::RenderManager::destroy_instance();
+ }
+
+ if ((g_flags & OAKENGINE_INIT_HEADLESS) != 0) {
+ olive::Config::save();
+
+ olive::ProjectSerializer::destroy();
+
+ olive::DiskManager::destroy_instance();
+
+ olive::ConformManager::destroy_instance();
+
+ olive::ProxyManager::destroy_instance();
+
+ olive::FrameManager::destroy_instance();
+
+ olive::TaskManager::destroy_instance();
+
+ olive::NodeFactory::destroy();
+ }
+
+ g_flags = 0;
+
+ return OAKENGINE_OK;
+}
+
+int oakengine_init_flags(void)
+{
+ return g_flags;
+}
+
+} // extern "C"
diff --git a/engine/src/capi/project.cpp b/engine/src/capi/project.cpp
new file mode 100644
index 000000000..e818bd305
--- /dev/null
+++ b/engine/src/capi/project.cpp
@@ -0,0 +1,391 @@
+/***
+
+ 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 .
+
+***/
+
+#include "oakengine/project.h"
+
+#include
+#include
+
+#include
+#include
+#include
+
+#include "coreengine.h"
+#include "node/project.h"
+#include "node/project/footage/footage.h"
+#include "node/project/sequence/sequence.h"
+#include "node/project/serializer/serializer.h"
+#include "undo/undostack.h"
+
+namespace
+{
+
+olive::Project *impl(OakEngineProject *h)
+{
+ return reinterpret_cast(h);
+}
+
+const olive::Project *impl(const OakEngineProject *h)
+{
+ return reinterpret_cast(h);
+}
+
+OakEngineProject *wrap(olive::Project *p)
+{
+ return reinterpret_cast(p);
+}
+
+OakEngineSequence *wrap_seq(olive::Sequence *s)
+{
+ return reinterpret_cast(s);
+}
+
+// buf/size convention: returns the would-be length excluding the NUL.
+int string_to_buf(const QString &s, char *buf, int buf_size)
+{
+ const QByteArray utf = s.toUtf8();
+ if (buf && buf_size > 0) {
+ snprintf(buf, size_t(buf_size), "%s", utf.constData());
+ }
+ return int(utf.size());
+}
+
+// The footage node at `index` in iteration order over the graph, or nullptr.
+olive::Footage *footage_at(const olive::Project *p, int index)
+{
+ if (index < 0) {
+ return nullptr;
+ }
+ int i = 0;
+ for (olive::Node *n : p->nodes()) {
+ if (olive::Footage *f = dynamic_cast(n)) {
+ if (i == index) {
+ return f;
+ }
+ i++;
+ }
+ }
+ return nullptr;
+}
+
+// The sequence node at `index` in iteration order over the graph, or nullptr.
+olive::Sequence *sequence_at(const olive::Project *p, int index)
+{
+ if (index < 0) {
+ return nullptr;
+ }
+ int i = 0;
+ for (olive::Node *n : p->nodes()) {
+ if (olive::Sequence *s = dynamic_cast(n)) {
+ if (i == index) {
+ return s;
+ }
+ i++;
+ }
+ }
+ return nullptr;
+}
+
+int node_count_of_type(const olive::Project *p, bool sequences)
+{
+ int count = 0;
+ for (olive::Node *n : p->nodes()) {
+ const bool match = sequences ?
+ (dynamic_cast(n) != nullptr) :
+ (dynamic_cast(n) != nullptr);
+ if (match) {
+ count++;
+ }
+ }
+ return count;
+}
+
+// Human-readable text for a failed project load, mirroring the messages in
+// ProjectLoadTask::run() (task/project/load/load.cpp).
+QString load_error_string(olive::ProjectSerializer::ResultCode code,
+ const QString &details, const QString &filename)
+{
+ switch (code) {
+ case olive::ProjectSerializer::k_project_too_old:
+ return QStringLiteral(
+ "This project is from a version of Oak Video Editor that is no "
+ "longer supported in this version.");
+ case olive::ProjectSerializer::k_project_too_new:
+ return QStringLiteral(
+ "This project is from a newer version of Oak Video Editor and "
+ "cannot be opened in this version.");
+ case olive::ProjectSerializer::k_unknown_version:
+ return QStringLiteral("Failed to determine project version.");
+ case olive::ProjectSerializer::k_file_error:
+ return QStringLiteral("Failed to read file \"%1\" for reading.")
+ .arg(filename);
+ case olive::ProjectSerializer::k_xml_error:
+ return QStringLiteral(
+ "Failed to read XML document. File may be corrupt. Error was: %1")
+ .arg(details);
+ case olive::ProjectSerializer::k_no_data:
+ return QStringLiteral("Failed to find any data to parse.");
+ case olive::ProjectSerializer::k_success:
+ case olive::ProjectSerializer::k_overwrite_error:
+ break;
+ }
+ return QStringLiteral("Unknown error.");
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakEngineProject *oakengine_project_create(void)
+{
+ // Not initialized on purpose: the project serializers require a fresh
+ // project (root folder unset), so oakengine_project_new() and
+ // oakengine_project_load() perform the one-time content setup.
+ return wrap(new olive::Project());
+}
+
+void oakengine_project_free(OakEngineProject *self)
+{
+ delete impl(self);
+}
+
+int oakengine_project_new(OakEngineProject *self)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ if (impl(self)->root() != nullptr) {
+ return OAKENGINE_E_STATE;
+ }
+ impl(self)->initialize();
+ if (olive::EngineCore::instance()) {
+ olive::EngineCore::instance()->undo_stack()->clear();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_project_load(OakEngineProject *self, const char *path,
+ char *err, int err_size)
+{
+ if (!self || !path) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Project *project = impl(self);
+ if (project->root() != nullptr) {
+ return OAKENGINE_E_STATE;
+ }
+
+ const QString filename = QString::fromUtf8(path);
+ project->set_filename(filename);
+
+ olive::ProjectSerializer::Result result = olive::ProjectSerializer::load(
+ project, filename, olive::ProjectSerializer::k_project);
+ if (result != olive::ProjectSerializer::k_success) {
+ // The project may be partially loaded; the handle should be freed
+ // (loading again is rejected above because root is set by then).
+ string_to_buf(load_error_string(result.code(), result.get_details(),
+ filename),
+ err, err_size);
+ return OAKENGINE_E_FAILED;
+ }
+
+ // Validate footage like the application does: resolve files that moved
+ // together with the project. Without a relink handler (none exists at
+ // this layer) the project is accepted as-is.
+ if (olive::EngineCore::instance()) {
+ olive::EngineCore::instance()->validate_footage_in_loaded_project(
+ project, project->get_saved_url());
+ olive::EngineCore::instance()->undo_stack()->clear();
+ }
+
+ project->set_modified(false);
+ if (err && err_size > 0) {
+ err[0] = '\0';
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_project_save(OakEngineProject *self, const char *path)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Project *project = impl(self);
+
+ QString filename = path ? QString::fromUtf8(path) : project->filename();
+ if (filename.isEmpty()) {
+ return OAKENGINE_E_INVALID;
+ }
+
+ olive::ProjectSerializer::SaveData data(olive::ProjectSerializer::k_project,
+ project, filename);
+ const bool compress = !filename.endsWith(QStringLiteral(".ovexml"),
+ Qt::CaseInsensitive);
+ olive::ProjectSerializer::Result result =
+ olive::ProjectSerializer::save(data, compress);
+
+ switch (result.code()) {
+ case olive::ProjectSerializer::k_success:
+ project->set_filename(filename);
+ project->set_modified(false);
+ return OAKENGINE_OK;
+ case olive::ProjectSerializer::k_overwrite_error:
+ // The file could not be replaced and the project was written to a
+ // temporary name instead; the engine counts this as a success.
+ project->set_filename(result.get_details());
+ project->set_modified(false);
+ return OAKENGINE_OK;
+ default:
+ return OAKENGINE_E_FAILED;
+ }
+}
+
+int oakengine_project_is_modified(const OakEngineProject *self)
+{
+ return self && impl(self)->is_modified() ? 1 : 0;
+}
+
+int oakengine_project_set_modified(OakEngineProject *self, int modified)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ impl(self)->set_modified(modified != 0);
+ return OAKENGINE_OK;
+}
+
+int oakengine_project_name(const OakEngineProject *self, char *buf,
+ int buf_size)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ return string_to_buf(impl(self)->name(), buf, buf_size);
+}
+
+int oakengine_project_filename(const OakEngineProject *self, char *buf,
+ int buf_size)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ return string_to_buf(impl(self)->filename(), buf, buf_size);
+}
+
+int oakengine_project_footage_count(const OakEngineProject *self)
+{
+ return self ? node_count_of_type(impl(self), false) : 0;
+}
+
+int oakengine_project_footage_filename(const OakEngineProject *self, int index,
+ char *buf, int buf_size)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Footage *f = footage_at(impl(self), index);
+ if (!f) {
+ return OAKENGINE_E_NOT_FOUND;
+ }
+ return string_to_buf(f->filename(), buf, buf_size);
+}
+
+int oakengine_project_footage_is_online(const OakEngineProject *self,
+ int index)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ const olive::Project *project = impl(self);
+ olive::Footage *f = footage_at(project, index);
+ if (!f) {
+ return OAKENGINE_E_NOT_FOUND;
+ }
+ const QString filename = f->filename();
+ if (QFileInfo::exists(filename)) {
+ return 1;
+ }
+ // Footage that moved together with the project file: resolve relative
+ // paths against the project's directory (same rule as
+ // EngineCore::validate_footage_in_loaded_project()).
+ if (QFileInfo(filename).isRelative() && !project->filename().isEmpty()) {
+ const QString resolved =
+ QFileInfo(project->filename()).dir().filePath(filename);
+ if (QFileInfo::exists(resolved)) {
+ return 1;
+ }
+ }
+ return 0;
+}
+
+int oakengine_project_can_undo(const OakEngineProject *self)
+{
+ if (!self || !olive::EngineCore::instance()) {
+ return 0;
+ }
+ return olive::EngineCore::instance()->undo_stack()->can_undo() ? 1 : 0;
+}
+
+int oakengine_project_can_redo(const OakEngineProject *self)
+{
+ if (!self || !olive::EngineCore::instance()) {
+ return 0;
+ }
+ return olive::EngineCore::instance()->undo_stack()->can_redo() ? 1 : 0;
+}
+
+int oakengine_project_undo(OakEngineProject *self)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ if (olive::EngineCore::instance()) {
+ olive::EngineCore::instance()->undo_stack()->undo();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_project_redo(OakEngineProject *self)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ if (olive::EngineCore::instance()) {
+ olive::EngineCore::instance()->undo_stack()->redo();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_project_sequence_count(const OakEngineProject *self)
+{
+ return self ? node_count_of_type(impl(self), true) : 0;
+}
+
+OakEngineSequence *oakengine_project_sequence_at(const OakEngineProject *self,
+ int index)
+{
+ if (!self) {
+ return nullptr;
+ }
+ return wrap_seq(sequence_at(impl(self), index));
+}
+
+} // extern "C"
diff --git a/engine/src/capi/timeline.cpp b/engine/src/capi/timeline.cpp
new file mode 100644
index 000000000..7717bfd61
--- /dev/null
+++ b/engine/src/capi/timeline.cpp
@@ -0,0 +1,326 @@
+/***
+
+ 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 .
+
+***/
+
+#include "oakengine/timeline.h"
+
+#include
+#include
+
+#include
+#include
+
+#include "coreengine.h"
+#include "node/nodeundo.h"
+#include "node/project.h"
+#include "node/project/folder/folder.h"
+#include "node/project/sequence/sequence.h"
+#include "timeline/timelinemarker.h"
+#include "timeline/timelineworkarea.h"
+#include "undo/undocommand.h"
+#include "undo/undostack.h"
+
+namespace
+{
+
+olive::Sequence *impl(OakEngineSequence *h)
+{
+ return reinterpret_cast(h);
+}
+
+const olive::Sequence *impl(const OakEngineSequence *h)
+{
+ return reinterpret_cast(h);
+}
+
+OakEngineSequence *wrap(olive::Sequence *s)
+{
+ return reinterpret_cast(s);
+}
+
+// ViewerOutput::get_playhead() is not a const method in the engine; the
+// facade keeps const-correct handles and casts locally.
+olive::Sequence *mutable_impl(const OakEngineSequence *h)
+{
+ return const_cast(
+ reinterpret_cast(h));
+}
+
+// buf/size convention: returns the would-be length excluding the NUL.
+int string_to_buf(const QString &s, char *buf, int buf_size)
+{
+ const QByteArray utf = s.toUtf8();
+ if (buf && buf_size > 0) {
+ snprintf(buf, size_t(buf_size), "%s", utf.constData());
+ }
+ return int(utf.size());
+}
+
+// Copy a QString into a fixed-capacity C buffer, always NUL-terminating and
+// truncating what does not fit.
+void copy_to_buf(const QString &s, char *dst, size_t cap)
+{
+ const QByteArray utf = s.toUtf8();
+ const size_t n = qMin(size_t(utf.size()), cap - 1);
+ memcpy(dst, utf.constData(), n);
+ dst[n] = '\0';
+}
+
+// The sequence's frame duration as a Rational timebase (frame rate flipped).
+// Returns false when the sequence has no valid frame rate (no video params).
+bool time_base_of(const olive::Sequence *s, olive::Rational *out)
+{
+ const olive::Rational frame_rate = s->get_video_params().frame_rate();
+ if (frame_rate.isNull() || frame_rate.isNaN()) {
+ return false;
+ }
+ *out = frame_rate.flipped();
+ return true;
+}
+
+// Rational seconds -> timestamp in timebase units, like
+// Timecode::time_to_timestamp with k_round rounding.
+int64_t time_to_ts(const olive::Rational &time, const olive::Rational &tb)
+{
+ return olive::core::Timecode::time_to_timestamp(
+ time, tb, olive::core::Timecode::k_round);
+}
+
+} // namespace
+
+extern "C"
+{
+
+OakEngineSequence *oakengine_sequence_new(OakEngineProject *project,
+ const char *name)
+{
+ olive::Project *p = reinterpret_cast(project);
+ if (!p || !p->root()) {
+ return nullptr;
+ }
+
+ olive::Sequence *sequence = new olive::Sequence();
+ sequence->set_default_parameters();
+ sequence->set_label(QString::fromUtf8(name ? name : ""));
+
+ // Same undoable creation as the application's "Create New Sequence"
+ // action (app/core.cpp), minus opening a viewer. Without an EngineCore
+ // (library not initialized) the command is executed non-undoably.
+ olive::MultiUndoCommand *command = new olive::MultiUndoCommand();
+ command->add_child(new olive::NodeAddCommand(p, sequence));
+ command->add_child(new olive::FolderAddChild(p->root(), sequence));
+
+ if (olive::EngineCore::instance()) {
+ olive::EngineCore::instance()->undo_stack()->push(
+ command, QStringLiteral("Create Sequence"));
+ } else {
+ command->redo_now();
+ delete command;
+ }
+
+ return wrap(sequence);
+}
+
+int oakengine_sequence_name(const OakEngineSequence *self, char *buf,
+ int buf_size)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ return string_to_buf(impl(self)->get_label(), buf, buf_size);
+}
+
+int oakengine_sequence_get_length(const OakEngineSequence *self,
+ double *seconds)
+{
+ if (!self || !seconds) {
+ return OAKENGINE_E_INVALID;
+ }
+ *seconds = impl(self)->get_length().to_double();
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_get_length_rational(const OakEngineSequence *self,
+ int *num, int *den)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ const olive::Rational length = impl(self)->get_length();
+ if (num) {
+ *num = length.numerator();
+ }
+ if (den) {
+ *den = length.denominator();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_get_frame_rate(const OakEngineSequence *self, int *num,
+ int *den)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ const olive::Rational frame_rate = impl(self)->get_video_params().frame_rate();
+ if (frame_rate.isNull() || frame_rate.isNaN()) {
+ return OAKENGINE_E_STATE;
+ }
+ if (num) {
+ *num = frame_rate.numerator();
+ }
+ if (den) {
+ *den = frame_rate.denominator();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_track_count(const OakEngineSequence *self, int *video,
+ int *audio, int *subtitle)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ const olive::Sequence *s = impl(self);
+ if (video) {
+ *video = s->track_list(olive::Track::k_video)->get_track_count();
+ }
+ if (audio) {
+ *audio = s->track_list(olive::Track::k_audio)->get_track_count();
+ }
+ if (subtitle) {
+ *subtitle = s->track_list(olive::Track::k_subtitle)->get_track_count();
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_get_playhead(const OakEngineSequence *self,
+ int64_t *timestamp)
+{
+ if (!self || !timestamp) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Rational tb;
+ if (!time_base_of(impl(self), &tb)) {
+ return OAKENGINE_E_STATE;
+ }
+ *timestamp = time_to_ts(mutable_impl(self)->get_playhead(), tb);
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_set_playhead(OakEngineSequence *self, int64_t timestamp)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Rational tb;
+ if (!time_base_of(impl(self), &tb)) {
+ return OAKENGINE_E_STATE;
+ }
+ impl(self)->set_playhead(
+ olive::core::Timecode::timestamp_to_time(timestamp, tb));
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_get_playhead_seconds(const OakEngineSequence *self,
+ double *seconds)
+{
+ if (!self || !seconds) {
+ return OAKENGINE_E_INVALID;
+ }
+ *seconds = mutable_impl(self)->get_playhead().to_double();
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_workarea_is_enabled(const OakEngineSequence *self)
+{
+ return self && impl(self)->get_work_area()->enabled() ? 1 : 0;
+}
+
+int oakengine_sequence_get_workarea(const OakEngineSequence *self, int64_t *in,
+ int64_t *out)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Rational tb;
+ if (!time_base_of(impl(self), &tb)) {
+ return OAKENGINE_E_STATE;
+ }
+ const olive::TimelineWorkArea *workarea = impl(self)->get_work_area();
+ if (in) {
+ *in = time_to_ts(workarea->in(), tb);
+ }
+ if (out) {
+ *out = time_to_ts(workarea->out(), tb);
+ }
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_set_workarea(OakEngineSequence *self, int enabled,
+ int64_t in, int64_t out)
+{
+ if (!self) {
+ return OAKENGINE_E_INVALID;
+ }
+ olive::Rational tb;
+ if (!time_base_of(impl(self), &tb)) {
+ return OAKENGINE_E_STATE;
+ }
+ olive::TimelineWorkArea *workarea = impl(self)->get_work_area();
+ workarea->set_enabled(enabled != 0);
+ workarea->set_range(
+ olive::TimeRange(olive::core::Timecode::timestamp_to_time(in, tb),
+ olive::core::Timecode::timestamp_to_time(out, tb)));
+ return OAKENGINE_OK;
+}
+
+int oakengine_sequence_marker_count(const OakEngineSequence *self)
+{
+ if (!self) {
+ return 0;
+ }
+ return int(impl(self)->get_markers()->size());
+}
+
+int oakengine_sequence_marker_at(const OakEngineSequence *self, int index,
+ int64_t *time, char *name, int name_size)
+{
+ if (!self || index < 0) {
+ return OAKENGINE_E_INVALID;
+ }
+ const olive::TimelineMarkerList *markers = impl(self)->get_markers();
+ if (size_t(index) >= markers->size()) {
+ return OAKENGINE_E_NOT_FOUND;
+ }
+ const olive::TimelineMarker *marker = *(markers->cbegin() + index);
+ if (time) {
+ olive::Rational tb;
+ if (!time_base_of(impl(self), &tb)) {
+ return OAKENGINE_E_STATE;
+ }
+ *time = time_to_ts(marker->time().in(), tb);
+ }
+ if (name && name_size > 0) {
+ copy_to_buf(marker->name(), name, size_t(name_size));
+ }
+ return OAKENGINE_OK;
+}
+
+} // extern "C"
diff --git a/engine/tests/oakengine_init_test.cpp b/engine/tests/oakengine_init_test.cpp
new file mode 100644
index 000000000..fa705d49a
--- /dev/null
+++ b/engine/tests/oakengine_init_test.cpp
@@ -0,0 +1,420 @@
+/***
+
+ 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 .
+
+***/
+
+// Pure C ABI test for the liboakengine init/project/timeline facade.
+// Exercises engine init/shutdown, project create/new/save/load round-trips,
+// the global undo stack, sequence inspection (length, frame rate, tracks,
+// playhead, workarea, markers) and a fixture project with real footage
+// (tests/demo.mp4). No Qt, no GL: oakengine_init() creates the
+// QCoreApplication itself when needed.
+
+#include
+#include
+#include
+#include
+#include
+
+#if defined(_WIN32)
+#include
+#include
+#else
+#include
+#endif
+
+#include "oakengine/init.h"
+#include "oakengine/project.h"
+#include "oakengine/timeline.h"
+
+#ifndef OAK_TEST_SOURCE_DIR
+#define OAK_TEST_SOURCE_DIR "."
+#endif
+
+static char g_tmpdir[4096];
+
+static void make_tmpdir(void)
+{
+#if defined(_WIN32)
+ char base[MAX_PATH];
+ const DWORD len = GetTempPathA(MAX_PATH, base);
+ assert(len > 0 && len < MAX_PATH);
+ snprintf(g_tmpdir, sizeof(g_tmpdir), "%soakengine_init_test_%lu", base,
+ (unsigned long)GetCurrentProcessId());
+ assert(_mkdir(g_tmpdir) == 0);
+#else
+ strcpy(g_tmpdir, "/tmp/oakengine_init_test_XXXXXX");
+ assert(mkdtemp(g_tmpdir) != NULL);
+#endif
+}
+
+static void make_path(char *dst, size_t cap, const char *filename)
+{
+ const int n = snprintf(dst, cap, "%s/%s", g_tmpdir, filename);
+ assert(n > 0 && (size_t)n < cap);
+}
+
+static int file_exists(const char *path)
+{
+ FILE *f = fopen(path, "rb");
+ if (!f) {
+ return 0;
+ }
+ fclose(f);
+ return 1;
+}
+
+static void test_init(void)
+{
+ assert(oakengine_init(0) == OAKENGINE_E_INVALID);
+ assert(oakengine_init(4) == OAKENGINE_E_INVALID); // unknown bit
+
+ assert(oakengine_init(OAKENGINE_INIT_HEADLESS) == OAKENGINE_OK);
+ assert(oakengine_init_flags() == OAKENGINE_INIT_HEADLESS);
+
+ // Repeated init is idempotent.
+ assert(oakengine_init(OAKENGINE_INIT_HEADLESS) == OAKENGINE_OK);
+ assert(oakengine_init_flags() == OAKENGINE_INIT_HEADLESS);
+}
+
+static void test_project_basics(void)
+{
+ OakEngineProject *p = oakengine_project_create();
+ assert(p != NULL);
+
+ // Fresh shell: untitled, unmodified, empty.
+ assert(oakengine_project_is_modified(p) == 0);
+ assert(oakengine_project_footage_count(p) == 0);
+ assert(oakengine_project_sequence_count(p) == 0);
+ assert(oakengine_project_can_undo(p) == 0);
+ assert(oakengine_project_can_redo(p) == 0);
+
+ assert(oakengine_project_new(p) == OAKENGINE_OK);
+ // Content setup may only happen once.
+ assert(oakengine_project_new(p) == OAKENGINE_E_STATE);
+
+ // An untitled project reports the engine's "(untitled)" name and an
+ // empty filename.
+ char name[64];
+ const int name_len = oakengine_project_name(p, NULL, 0);
+ assert(name_len > 0);
+ assert(oakengine_project_name(p, name, sizeof(name)) == name_len);
+ assert((int)strlen(name) == name_len);
+ assert(strcmp(name, "(untitled)") == 0);
+ // buf/size truncation: reports the full size, writes what fits.
+ char tiny[4];
+ assert(oakengine_project_name(p, tiny, sizeof(tiny)) == name_len);
+ assert(strlen(tiny) == sizeof(tiny) - 1);
+
+ char filename[16];
+ assert(oakengine_project_filename(p, filename, sizeof(filename)) == 0);
+ assert(filename[0] == '\0');
+
+ // Modified flag round-trips.
+ assert(oakengine_project_set_modified(p, 1) == OAKENGINE_OK);
+ assert(oakengine_project_is_modified(p) == 1);
+ assert(oakengine_project_set_modified(p, 0) == OAKENGINE_OK);
+ assert(oakengine_project_is_modified(p) == 0);
+
+ // Saving an untitled project without a path fails.
+ assert(oakengine_project_save(p, NULL) == OAKENGINE_E_INVALID);
+
+ oakengine_project_free(p);
+}
+
+static void test_sequence_and_save_load(void)
+{
+ char path[4096];
+ make_path(path, sizeof(path), "roundtrip.ove");
+
+ OakEngineProject *p = oakengine_project_create();
+ assert(p != NULL);
+ assert(oakengine_project_new(p) == OAKENGINE_OK);
+
+ // Create a sequence through the facade; it is owned by the project.
+ OakEngineSequence *seq = oakengine_sequence_new(p, "Main");
+ assert(seq != NULL);
+ assert(oakengine_project_sequence_count(p) == 1);
+ assert(oakengine_project_sequence_at(p, 0) == seq);
+ assert(oakengine_project_sequence_at(p, 1) == NULL);
+ assert(oakengine_project_sequence_at(p, -1) == NULL);
+
+ // The creation went onto the global undo stack and marked the project.
+ assert(oakengine_project_can_undo(p) == 1);
+ assert(oakengine_project_is_modified(p) == 1);
+
+ // Sequence name round-trips.
+ char name[64];
+ const int name_len = oakengine_sequence_name(seq, NULL, 0);
+ assert(name_len == 4);
+ assert(oakengine_sequence_name(seq, name, sizeof(name)) == 4);
+ assert(strcmp(name, "Main") == 0);
+
+ // Empty sequence: zero length.
+ double seconds = -1.0;
+ assert(oakengine_sequence_get_length(seq, &seconds) == OAKENGINE_OK);
+ assert(seconds == 0.0);
+ int num = -1, den = -1;
+ assert(oakengine_sequence_get_length_rational(seq, &num, &den) ==
+ OAKENGINE_OK);
+ assert(num == 0);
+
+ // Default frame rate from Config's DefaultSequenceFrameRate entry
+ // (time base 1001/30000 -> frame rate 30000/1001).
+ num = den = -1;
+ assert(oakengine_sequence_get_frame_rate(seq, &num, &den) == OAKENGINE_OK);
+ assert(num == 30000 && den == 1001);
+
+ // Fresh sequences have no tracks.
+ int video = -1, audio = -1, subtitle = -1;
+ assert(oakengine_sequence_track_count(seq, &video, &audio, &subtitle) ==
+ OAKENGINE_OK);
+ assert(video == 0 && audio == 0 && subtitle == 0);
+
+ // Playhead starts at zero and accepts frame timestamps.
+ int64_t ts = -1;
+ assert(oakengine_sequence_get_playhead(seq, &ts) == OAKENGINE_OK);
+ assert(ts == 0);
+ assert(oakengine_sequence_set_playhead(seq, 30) == OAKENGINE_OK);
+ ts = -1;
+ assert(oakengine_sequence_get_playhead(seq, &ts) == OAKENGINE_OK);
+ assert(ts == 30);
+ // 30 frames at 1001/30000 per frame = 1.001 seconds.
+ seconds = -1.0;
+ assert(oakengine_sequence_get_playhead_seconds(seq, &seconds) ==
+ OAKENGINE_OK);
+ assert(fabs(seconds - 1.001) < 1e-9);
+
+ // Workarea: disabled by default, then set + read back.
+ assert(oakengine_sequence_workarea_is_enabled(seq) == 0);
+ assert(oakengine_sequence_set_workarea(seq, 1, 10, 40) == OAKENGINE_OK);
+ assert(oakengine_sequence_workarea_is_enabled(seq) == 1);
+ int64_t in = -1, out = -1;
+ assert(oakengine_sequence_get_workarea(seq, &in, &out) == OAKENGINE_OK);
+ assert(in == 10 && out == 40);
+
+ // No markers on a fresh sequence.
+ assert(oakengine_sequence_marker_count(seq) == 0);
+ assert(oakengine_sequence_marker_at(seq, 0, NULL, NULL, 0) ==
+ OAKENGINE_E_NOT_FOUND);
+
+ // Save; the modified flag clears and the filename is adopted.
+ assert(oakengine_project_save(p, path) == OAKENGINE_OK);
+ assert(oakengine_project_is_modified(p) == 0);
+ assert(file_exists(path));
+ char filename[4096];
+ assert(oakengine_project_filename(p, filename, sizeof(filename)) ==
+ (int)strlen(path));
+ assert(strcmp(filename, path) == 0);
+
+ // Undo removes the sequence, redo brings the same object back.
+ assert(oakengine_project_undo(p) == OAKENGINE_OK);
+ assert(oakengine_project_sequence_count(p) == 0);
+ assert(oakengine_project_can_redo(p) == 1);
+ assert(oakengine_project_redo(p) == OAKENGINE_OK);
+ assert(oakengine_project_sequence_count(p) == 1);
+ assert(oakengine_project_sequence_at(p, 0) == seq);
+ oakengine_project_free(p);
+
+ // Load the saved file into a fresh project.
+ OakEngineProject *q = oakengine_project_create();
+ assert(q != NULL);
+ char err[512];
+ assert(oakengine_project_load(q, path, err, sizeof(err)) == OAKENGINE_OK);
+ assert(oakengine_project_is_modified(q) == 0);
+ assert(oakengine_project_can_undo(q) == 0); // load clears the undo stack
+ assert(oakengine_project_can_redo(q) == 0);
+
+ // Project name derives from the file's base name.
+ const int qname_len = oakengine_project_name(q, NULL, 0);
+ assert(qname_len == (int)strlen("roundtrip"));
+ assert(oakengine_project_name(q, name, sizeof(name)) == qname_len);
+ assert(strcmp(name, "roundtrip") == 0);
+ assert(oakengine_project_filename(q, filename, sizeof(filename)) ==
+ (int)strlen(path));
+ assert(strcmp(filename, path) == 0);
+
+ // The sequence survived the round trip, workarea included (the workarea
+ // is serialized by ViewerOutput::save_custom()).
+ assert(oakengine_project_sequence_count(q) == 1);
+ OakEngineSequence *loaded = oakengine_project_sequence_at(q, 0);
+ assert(loaded != NULL);
+ assert(oakengine_sequence_name(loaded, name, sizeof(name)) == 4);
+ assert(strcmp(name, "Main") == 0);
+ num = den = -1;
+ assert(oakengine_sequence_get_frame_rate(loaded, &num, &den) ==
+ OAKENGINE_OK);
+ assert(num == 30000 && den == 1001);
+ assert(oakengine_sequence_track_count(loaded, &video, &audio,
+ &subtitle) == OAKENGINE_OK);
+ assert(video == 0 && audio == 0 && subtitle == 0);
+ assert(oakengine_sequence_workarea_is_enabled(loaded) == 1);
+ in = out = -1;
+ assert(oakengine_sequence_get_workarea(loaded, &in, &out) == OAKENGINE_OK);
+ assert(in == 10 && out == 40);
+ assert(oakengine_project_footage_count(q) == 0);
+
+ // Saving with a NULL path reuses the project's current filename.
+ assert(oakengine_project_save(q, NULL) == OAKENGINE_OK);
+ assert(file_exists(path));
+ oakengine_project_free(q);
+
+ // Loading a missing file fails and reports a human-readable reason.
+ OakEngineProject *r = oakengine_project_create();
+ assert(r != NULL);
+ char missing[4096];
+ make_path(missing, sizeof(missing), "does-not-exist.ove");
+ assert(oakengine_project_load(r, missing, err, sizeof(err)) ==
+ OAKENGINE_E_FAILED);
+ assert(strlen(err) > 0);
+ // Loading into a project that already has content is rejected.
+ assert(oakengine_project_new(r) == OAKENGINE_OK);
+ assert(oakengine_project_load(r, missing, err, sizeof(err)) ==
+ OAKENGINE_E_STATE);
+ oakengine_project_free(r);
+}
+
+// tests/project_with_footage.ove is a small uncompressed project holding one
+// footage item whose stored filename is the relative path "demo.mp4" (the
+// real media file sits next to the fixture in tests/).
+static void test_footage_fixture(void)
+{
+ char fixture[4096];
+ const int n = snprintf(fixture, sizeof(fixture),
+ "%s/tests/project_with_footage.ove",
+ OAK_TEST_SOURCE_DIR);
+ assert(n > 0 && (size_t)n < sizeof(fixture));
+ assert(file_exists(fixture));
+
+ OakEngineProject *p = oakengine_project_create();
+ assert(p != NULL);
+ char err[512];
+ assert(oakengine_project_load(p, fixture, err, sizeof(err)) ==
+ OAKENGINE_OK);
+
+ assert(oakengine_project_footage_count(p) == 1);
+ char filename[256];
+ assert(oakengine_project_footage_filename(p, 0, filename,
+ sizeof(filename)) > 0);
+ assert(strcmp(filename, "demo.mp4") == 0);
+ // The stored relative path resolves against the project file's
+ // directory (tests/), where demo.mp4 exists.
+ assert(oakengine_project_footage_is_online(p, 0) == 1);
+ // Out-of-range footage indexes report OAKENGINE_E_NOT_FOUND.
+ assert(oakengine_project_footage_filename(p, 1, filename,
+ sizeof(filename)) ==
+ OAKENGINE_E_NOT_FOUND);
+ assert(oakengine_project_footage_is_online(p, -1) ==
+ OAKENGINE_E_NOT_FOUND);
+
+ assert(oakengine_project_sequence_count(p) == 1);
+ OakEngineSequence *seq = oakengine_project_sequence_at(p, 0);
+ assert(seq != NULL);
+ char name[64];
+ assert(oakengine_sequence_name(seq, name, sizeof(name)) > 0);
+ assert(strcmp(name, "Fixture Sequence") == 0);
+
+ oakengine_project_free(p);
+}
+
+static void test_null_safety(void)
+{
+ oakengine_project_free(NULL);
+ assert(oakengine_project_new(NULL) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_load(NULL, "/tmp/x.ove", NULL, 0) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_project_save(NULL, "/tmp/x.ove") == OAKENGINE_E_INVALID);
+ assert(oakengine_project_is_modified(NULL) == 0);
+ assert(oakengine_project_set_modified(NULL, 1) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_name(NULL, NULL, 0) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_filename(NULL, NULL, 0) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_footage_count(NULL) == 0);
+ assert(oakengine_project_footage_filename(NULL, 0, NULL, 0) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_project_footage_is_online(NULL, 0) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_project_can_undo(NULL) == 0);
+ assert(oakengine_project_can_redo(NULL) == 0);
+ assert(oakengine_project_undo(NULL) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_redo(NULL) == OAKENGINE_E_INVALID);
+ assert(oakengine_project_sequence_count(NULL) == 0);
+ assert(oakengine_project_sequence_at(NULL, 0) == NULL);
+
+ assert(oakengine_sequence_new(NULL, "x") == NULL);
+ assert(oakengine_sequence_name(NULL, NULL, 0) == OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_get_length(NULL, NULL) == OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_get_length_rational(NULL, NULL, NULL) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_get_frame_rate(NULL, NULL, NULL) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_track_count(NULL, NULL, NULL, NULL) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_get_playhead(NULL, NULL) == OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_set_playhead(NULL, 0) == OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_get_playhead_seconds(NULL, NULL) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_workarea_is_enabled(NULL) == 0);
+ assert(oakengine_sequence_get_workarea(NULL, NULL, NULL) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_set_workarea(NULL, 0, 0, 0) ==
+ OAKENGINE_E_INVALID);
+ assert(oakengine_sequence_marker_count(NULL) == 0);
+ assert(oakengine_sequence_marker_at(NULL, 0, NULL, NULL, 0) ==
+ OAKENGINE_E_INVALID);
+}
+
+static void test_shutdown_pairing(void)
+{
+ assert(oakengine_shutdown() == OAKENGINE_OK);
+ assert(oakengine_init_flags() == 0);
+
+ // Shutdown is idempotent.
+ assert(oakengine_shutdown() == OAKENGINE_OK);
+
+ // init may run again after a paired shutdown.
+ assert(oakengine_init(OAKENGINE_INIT_HEADLESS) == OAKENGINE_OK);
+ assert(oakengine_init_flags() == OAKENGINE_INIT_HEADLESS);
+ assert(oakengine_shutdown() == OAKENGINE_OK);
+ assert(oakengine_init_flags() == 0);
+}
+
+int main(void)
+{
+ make_tmpdir();
+
+ // Sandbox the config/cache/data locations so the engine never reads or
+ // writes the real user configuration. The engine's config path comes
+ // from QStandardPaths::AppDataLocation
+ // (FileFunctions::get_configuration_location()), which follows
+ // XDG_DATA_HOME on Linux; the other two are sandboxed for good measure.
+#if !defined(_WIN32)
+ assert(setenv("XDG_CONFIG_HOME", g_tmpdir, 1) == 0);
+ assert(setenv("XDG_CACHE_HOME", g_tmpdir, 1) == 0);
+ assert(setenv("XDG_DATA_HOME", g_tmpdir, 1) == 0);
+#endif
+
+ test_init();
+ test_project_basics();
+ test_sequence_and_save_load();
+ test_footage_fixture();
+ test_null_safety();
+ test_shutdown_pairing();
+
+ printf("oakengine_init_test: all assertions passed\n");
+ return 0;
+}
diff --git a/tests/project_with_footage.ove b/tests/project_with_footage.ove
new file mode 100644
index 000000000..70f50796a
--- /dev/null
+++ b/tests/project_with_footage.ove
@@ -0,0 +1,311 @@
+
+
+
+
+ {b9147285-72ca-4b6b-b980-ce1dfbec408f}
+
+
+
+
+
+ 0
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ {3f699391-032f-4b27-9ab9-297faa2781ba}
+ {a11aa028-d950-460f-a7a6-d71df445ce68}
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ 0
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ {d7346615-f439-4910-9c0b-c9b94df27883}
+ {7d154ff3-1794-451c-9495-528c5d5c4576}
+
+
+ 0
+
+
+ 0
+ 0/1
+ 0/1
+
+
+
+
+
+
+
+
+
+ 0
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+ {edd6c747-f4a8-4ecd-869c-e2d522ea648f}
+ {654584d4-b0c7-40d7-9c12-95971f981e69}
+
+
+
+ 0
+ 0/1
+ 0/1
+
+
+
+
+
+
+ scene_linear
+ Rec.709 OETF
+ 94695150158256
+
+
+
+
+
+
+
+
+
+
+