From 4b7e62ddb7b850cf3fce0301f5de3b8dd1cd317a Mon Sep 17 00:00:00 2001
From: itsmattkc <itsmattkc@gmail.com>
Date: Fri, 5 Oct 2018 11:02:04 +1000
Subject: [PATCH] added speed changes while maintaining audio pitch

---
 dialogs/speeddialog.cpp |  9 +++++++--
 dialogs/speeddialog.h   |  2 ++
 playback/cacher.cpp     | 21 ++++++++++++++++++---
 project/clip.cpp        |  3 ++-
 project/clip.h          |  4 ++--
 5 files changed, 31 insertions(+), 8 deletions(-)

diff --git a/dialogs/speeddialog.cpp b/dialogs/speeddialog.cpp
index b10aa2a7a..c4090e382 100644
--- a/dialogs/speeddialog.cpp
+++ b/dialogs/speeddialog.cpp
@@ -43,9 +43,12 @@ SpeedDialog::SpeedDialog(QWidget *parent) : QDialog(parent) {
 	main_layout->addLayout(grid);
 
 	reverse = new QCheckBox("Reverse");
+	maintain_pitch = new QCheckBox("Maintain Audio Pitch");
+	ripple = new QCheckBox("Ripple Changes");
+
 	main_layout->addWidget(reverse);
-	main_layout->addWidget(new QCheckBox("Maintain Audio Pitch"));
-	main_layout->addWidget(new QCheckBox("Ripple"));
+	main_layout->addWidget(maintain_pitch);
+	main_layout->addWidget(ripple);
 
 	QDialogButtonBox* buttonBox = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
 	buttonBox->setCenterButtons(true);
@@ -179,6 +182,8 @@ void SpeedDialog::accept() {
 		c->timeline_out = proposed_out;
 
 		c->recalculateMaxLength();
+
+		c->maintain_audio_pitch = maintain_pitch->isChecked();
 	}
 	panel_timeline->redraw_all_clips(true);
 	QDialog::accept();
diff --git a/dialogs/speeddialog.h b/dialogs/speeddialog.h
index e466cfc70..54f903ba3 100644
--- a/dialogs/speeddialog.h
+++ b/dialogs/speeddialog.h
@@ -26,6 +26,8 @@ private:
 	LabelSlider* frame_rate;
 
 	QCheckBox* reverse;
+	QCheckBox* maintain_pitch;
+	QCheckBox* ripple;
 
 	double default_frame_rate;
 	double current_frame_rate;
diff --git a/playback/cacher.cpp b/playback/cacher.cpp
index 440a71953..469637af0 100644
--- a/playback/cacher.cpp
+++ b/playback/cacher.cpp
@@ -490,13 +490,28 @@ void open_clip_worker(Clip* clip) {
 				qDebug() << "[ERROR] Could not set output sample format";
 			}
 
-			int sample_rates[] = { qRound(sequence->audio_frequency / clip->speed), 0 };
+			int target_sample_rate = sequence->audio_frequency;
+
+			if (qFuzzyCompare(clip->speed, 1.0)) {
+				avfilter_link(clip->buffersrc_ctx, 0, clip->buffersink_ctx, 0);
+			} else if (clip->maintain_audio_pitch) {
+				char speed_param[10];
+				snprintf(speed_param, sizeof(speed_param), "%f", clip->speed);
+
+				AVFilterContext* tempo_filter;
+				avfilter_graph_create_filter(&tempo_filter, avfilter_get_by_name("atempo"), "atempo", speed_param, NULL, clip->filter_graph);
+				avfilter_link(clip->buffersrc_ctx, 0, tempo_filter, 0);
+				avfilter_link(tempo_filter, 0, clip->buffersink_ctx, 0);
+			} else {
+				target_sample_rate = qRound(sequence->audio_frequency / clip->speed);
+				avfilter_link(clip->buffersrc_ctx, 0, clip->buffersink_ctx, 0);
+			}
+
+			int sample_rates[] = { target_sample_rate, 0 };
 			if (av_opt_set_int_list(clip->buffersink_ctx, "sample_rates", sample_rates, 0, AV_OPT_SEARCH_CHILDREN) < 0) {
 				qDebug() << "[ERROR] Could not set output sample rates";
 			}
 
-			avfilter_link(clip->buffersrc_ctx, 0, clip->buffersink_ctx, 0);
-
 			avfilter_graph_config(clip->filter_graph, NULL);
 
 			clip->audio_reset = true;
diff --git a/project/clip.cpp b/project/clip.cpp
index da1ef56aa..fd47c9c21 100644
--- a/project/clip.cpp
+++ b/project/clip.cpp
@@ -33,7 +33,8 @@ Clip::Clip(Sequence* s) :
 	filter_graph(NULL),
 	texture(NULL),
 	fbo(NULL),
-    autoscale(config.autoscale_by_default)
+	autoscale(config.autoscale_by_default),
+	maintain_audio_pitch(false)
 {
     reset();
 }
diff --git a/project/clip.h b/project/clip.h
index 19f5b8df8..ddcbbb7d5 100644
--- a/project/clip.h
+++ b/project/clip.h
@@ -116,8 +116,8 @@ struct Clip
     long texture_frame;
 	bool autoscale;
 
-    // audio playback variables
-//	SwrContext* swr_ctx;
+	// audio playback variables
+	bool maintain_audio_pitch;
     int frame_sample_index;
     int audio_buffer_write;
     bool audio_reset;