From 22c6251d37911a11e322bf7518e6a992ea0bb6c7 Mon Sep 17 00:00:00 2001
From: Good Guy <good1.2guy@gmail.com>
Date: Wed, 2 Sep 2020 19:16:24 -0600
Subject: [PATCH 1/1] add ids to auto/labels, fix awdw gui deadlock, fix
 fourier bfr bug, fix cache critical section, rework normalize_speed, fix
 delete_track gang bug

---
 cinelerra-5.1/cinelerra/auto.C           |   8 +-
 cinelerra-5.1/cinelerra/auto.h           |   3 +-
 cinelerra-5.1/cinelerra/autos.C          |   6 ++
 cinelerra-5.1/cinelerra/autos.h          |   1 +
 cinelerra-5.1/cinelerra/awindowgui.C     |  10 +-
 cinelerra-5.1/cinelerra/edits.C          |   7 ++
 cinelerra-5.1/cinelerra/edits.h          |   1 +
 cinelerra-5.1/cinelerra/fourier.C        |   6 +-
 cinelerra-5.1/cinelerra/labels.C         |  15 ++-
 cinelerra-5.1/cinelerra/labels.h         |   2 +
 cinelerra-5.1/cinelerra/mwindow.C        |  24 ++---
 cinelerra-5.1/cinelerra/mwindowedit.C    | 113 ++++++++++-------------
 cinelerra-5.1/cinelerra/playbackengine.C |   4 +
 cinelerra-5.1/cinelerra/playbackengine.h |   2 +
 cinelerra-5.1/cinelerra/tracks.C         |   3 +-
 15 files changed, 112 insertions(+), 93 deletions(-)

diff --git a/cinelerra-5.1/cinelerra/auto.C b/cinelerra-5.1/cinelerra/auto.C
index 4171fa83..03d4aa01 100644
--- a/cinelerra-5.1/cinelerra/auto.C
+++ b/cinelerra-5.1/cinelerra/auto.C
@@ -21,6 +21,7 @@
 
 #include "auto.h"
 #include "autos.h"
+#include "edl.h"
 #include "filexml.h"
 
 Auto::Auto()
@@ -29,10 +30,11 @@ Auto::Auto()
 	this->edl = 0;
 	this->autos = 0;
 	position = 0;
-	skip = 0;
 	WIDTH = xS(10);
 	HEIGHT = yS(10);
 	is_default = 0;
+	id = EDL::next_id();
+	orig_id = id;
 }
 
 Auto::Auto(EDL *edl, Autos *autos)
@@ -41,10 +43,11 @@ Auto::Auto(EDL *edl, Autos *autos)
 	this->edl = edl;
 	this->autos = autos;
 	position = 0;
-	skip = 0;
 	WIDTH = xS(10);
 	HEIGHT = yS(10);
 	is_default = 0;
+	id = EDL::next_id();
+	orig_id = id;
 }
 
 Auto& Auto::operator=(Auto& that)
@@ -66,6 +69,7 @@ void Auto::copy(int64_t start, int64_t end, FileXML *file, int default_only)
 
 void Auto::copy_from(Auto *that)
 {
+	this->orig_id = orig_id;
 	this->position = that->position;
 }
 
diff --git a/cinelerra-5.1/cinelerra/auto.h b/cinelerra-5.1/cinelerra/auto.h
index f91451ef..63309524 100644
--- a/cinelerra-5.1/cinelerra/auto.h
+++ b/cinelerra-5.1/cinelerra/auto.h
@@ -57,10 +57,9 @@ public:
 
 	virtual void get_caption(char *string) {};
 
-
-	int skip;       // if added by selection event for moves
 	EDL *edl;
 	Autos *autos;
+	int id, orig_id;
 	int WIDTH, HEIGHT;
 // Units native to the track
 	int is_default;
diff --git a/cinelerra-5.1/cinelerra/autos.C b/cinelerra-5.1/cinelerra/autos.C
index a2914d82..a48afbb5 100644
--- a/cinelerra-5.1/cinelerra/autos.C
+++ b/cinelerra-5.1/cinelerra/autos.C
@@ -274,6 +274,12 @@ Auto* Autos::get_auto_at_position(double position)
 	return 0;
 }
 
+Auto* Autos::get_auto(int id)
+{
+	Auto *current = first;
+	while( current && current->orig_id != id ) current = NEXT;
+	return current;
+}
 
 Auto* Autos::get_auto_for_editing(double position, int create)
 {
diff --git a/cinelerra-5.1/cinelerra/autos.h b/cinelerra-5.1/cinelerra/autos.h
index ee53f63a..dcb997d8 100644
--- a/cinelerra-5.1/cinelerra/autos.h
+++ b/cinelerra-5.1/cinelerra/autos.h
@@ -61,6 +61,7 @@ public:
 	int auto_exists_for_editing(double position);
 // Returns auto at exact position, null if non-existent. ignores autokeyframming and align on frames
 	Auto* get_auto_at_position(double position = -1);
+	Auto* get_auto(int id);
 
 // Get keyframe for editing with creation
 // create: <0: always new keyframe, =0: no new keyframe, >0: auto keyframe
diff --git a/cinelerra-5.1/cinelerra/awindowgui.C b/cinelerra-5.1/cinelerra/awindowgui.C
index 4688e7bc..c9a9a898 100644
--- a/cinelerra-5.1/cinelerra/awindowgui.C
+++ b/cinelerra-5.1/cinelerra/awindowgui.C
@@ -945,6 +945,11 @@ void AssetPicon::create_objects()
 		if( asset->video_data ) {
 			if( mwindow->preferences->use_thumbnails ) {
 				gui->unlock_window();
+				char string[BCTEXTLEN];
+				sprintf(string, _("Reading %s"), name);
+				mwindow->gui->lock_window("AssetPicon::create_objects");
+				mwindow->gui->show_message(string);
+				mwindow->gui->unlock_window();
 				File *file = mwindow->video_cache->check_out(asset,
 					mwindow->edl,
 					1);
@@ -968,11 +973,6 @@ void AssetPicon::create_objects()
 							asset->width, asset->height,
 							BC_RGB888, -1);
 					}
-					{ char string[BCTEXTLEN];
-					sprintf(string, _("Reading %s"), name);
-					mwindow->gui->lock_window("AssetPicon::create_objects");
-					mwindow->gui->show_message(string);
-					mwindow->gui->unlock_window(); }
 					file->read_frame(gui->temp_picon);
 					mwindow->video_cache->check_in(asset);
 
diff --git a/cinelerra-5.1/cinelerra/edits.C b/cinelerra-5.1/cinelerra/edits.C
index cec86c84..71dd3b18 100644
--- a/cinelerra-5.1/cinelerra/edits.C
+++ b/cinelerra-5.1/cinelerra/edits.C
@@ -560,6 +560,13 @@ Edit* Edits::editof(int64_t position, int direction, int use_nudge)
 	return 0;     // return 0 on failure
 }
 
+Edit* Edits::get_edit(int id)
+{
+	Edit *current = first;
+	while( current && current->orig_id != id ) current = NEXT;
+	return current;
+}
+
 Edit* Edits::get_playable_edit(int64_t position, int use_nudge)
 {
 	Edit *current;
diff --git a/cinelerra-5.1/cinelerra/edits.h b/cinelerra-5.1/cinelerra/edits.h
index bd73e4e7..5550cb55 100644
--- a/cinelerra-5.1/cinelerra/edits.h
+++ b/cinelerra-5.1/cinelerra/edits.h
@@ -109,6 +109,7 @@ public:
 // ==================================== accounting
 
 	Edit* editof(int64_t position, int direction, int use_nudge);
+	Edit* get_edit(int id);
 // Return an edit if position is over an edit and the edit has a source file
 	Edit* get_playable_edit(int64_t position, int use_nudge);
 //	int64_t total_length();
diff --git a/cinelerra-5.1/cinelerra/fourier.C b/cinelerra-5.1/cinelerra/fourier.C
index f78a45bd..7f52fe0c 100644
--- a/cinelerra-5.1/cinelerra/fourier.C
+++ b/cinelerra-5.1/cinelerra/fourier.C
@@ -429,9 +429,11 @@ int CrossfadeFFT::process_buffer(int64_t output_sample,
 	}
 
 	input_buffer->set_offset(input_size);
-	result = read_samples(input_sample, need_samples-input_size, input_buffer);
+	if( need_samples > input_size ) {
+		result = read_samples(input_sample, need_samples-input_size, input_buffer);
+		input_sample += step * (need_samples - input_size);
+	}
 	input_buffer->set_offset(0);
-	input_sample += step * (need_samples - input_size);
 	input_size = need_samples;
 
 
diff --git a/cinelerra-5.1/cinelerra/labels.C b/cinelerra-5.1/cinelerra/labels.C
index 211b8767..ad3626bf 100644
--- a/cinelerra-5.1/cinelerra/labels.C
+++ b/cinelerra-5.1/cinelerra/labels.C
@@ -272,7 +272,9 @@ void Labels::copy_from(Labels *labels)
 
 	for(Label *current = labels->first; current; current = NEXT)
 	{
-		append(new Label(edl, this, current->position, current->textstr));
+		Label *new_label = new Label(edl, this, current->position, current->textstr);
+		new_label->orig_id = current->orig_id;
+		append(new_label);
 	}
 }
 
@@ -460,6 +462,13 @@ Label* Labels::next_label(double position)
 	return current;
 }
 
+Label* Labels::get_label(int id)
+{
+	Label *current = first;
+	while( current && current->orig_id != id ) current = NEXT;
+	return current;
+}
+
 int Labels::insert(double start, double length)
 {      // shift every label including the first one back
 	Label *current;
@@ -541,6 +550,8 @@ Label* Labels::label_of(double position)
 Label::Label()
  : ListItem<Label>()
 {
+	id = EDL::next_id();
+	orig_id = id;
 }
 
 Label::Label(EDL *edl, Labels *labels, double position, const char *textstr)
@@ -550,6 +561,8 @@ Label::Label(EDL *edl, Labels *labels, double position, const char *textstr)
 	this->labels = labels;
 	this->position = position;
 	strcpy(this->textstr, textstr ? textstr : "");
+	id = EDL::next_id();
+	orig_id = id;
 }
 
 
diff --git a/cinelerra-5.1/cinelerra/labels.h b/cinelerra-5.1/cinelerra/labels.h
index 31015ea4..e648de5a 100644
--- a/cinelerra-5.1/cinelerra/labels.h
+++ b/cinelerra-5.1/cinelerra/labels.h
@@ -60,6 +60,7 @@ public:
 	char textstr[BCTEXTLEN];
 // Seconds
 	double position;
+	int id, orig_id;
 };
 
 class Labels : public List<Label>
@@ -98,6 +99,7 @@ public:
 // Get nearest labels or 0 if start or end of timeline
 	Label* prev_label(double position);
 	Label* next_label(double position);
+	Label* get_label(int id);
 
 	Label* label_of(double position); // first label on or after position
 	TimeBar *timebar;
diff --git a/cinelerra-5.1/cinelerra/mwindow.C b/cinelerra-5.1/cinelerra/mwindow.C
index 4afbd818..8319bfbd 100644
--- a/cinelerra-5.1/cinelerra/mwindow.C
+++ b/cinelerra-5.1/cinelerra/mwindow.C
@@ -4480,26 +4480,20 @@ void MWindow::reset_caches()
 	int locked  = gui->get_window_lock();
 	if( locked ) gui->unlock_window();
 	awindow->gui->stop_vicon_drawing(1);
-	frame_cache->remove_all();
-	wave_cache->remove_all();
-	audio_cache->remove_all();
-	video_cache->remove_all();
-	if( cwindow->playback_engine ) {
-		if( cwindow->playback_engine->audio_cache )
-			cwindow->playback_engine->audio_cache->remove_all();
-		if( cwindow->playback_engine->video_cache )
-			cwindow->playback_engine->video_cache->remove_all();
-	}
+	if( cwindow->playback_engine )
+		cwindow->playback_engine->create_cache();
 	for(int i = 0; i < vwindows.size(); i++) {
 		VWindow *vwindow = vwindows[i];
 		if( !vwindow->is_running() ) continue;
 		if( !vwindow->playback_engine ) continue;
-		if( vwindow->playback_engine->audio_cache )
-			vwindow->playback_engine->audio_cache->remove_all();
-		if( vwindow->playback_engine->video_cache )
-			vwindow->playback_engine->video_cache->remove_all();
+		vwindow->playback_engine->create_cache();
 	}
-	if( locked ) gui->lock_window("MWindow::reset_caches");
+	gui->lock_window("MWindow::reset_caches");
+	frame_cache->remove_all();
+	wave_cache->remove_all();
+	audio_cache->remove_all();
+	video_cache->remove_all();
+	if( !locked ) gui->unlock_window();
 }
 
 void MWindow::remove_from_caches(Indexable *idxbl)
diff --git a/cinelerra-5.1/cinelerra/mwindowedit.C b/cinelerra-5.1/cinelerra/mwindowedit.C
index 7b359ce2..f75896d7 100644
--- a/cinelerra-5.1/cinelerra/mwindowedit.C
+++ b/cinelerra-5.1/cinelerra/mwindowedit.C
@@ -2602,56 +2602,46 @@ int MWindow::normalize_speed(EDL *old_edl, EDL *new_edl, int edit_speed)
 			old_speed = (FloatAuto *)old_speed->next;
 			new_speed = (FloatAuto *)new_speed->next;
 		}
+		if( !old_speed && !new_speed ) continue;
+		result = 1;
 		if( edit_speed ) {
 			Autos *old_autos = old_track->automation->autos[AUTOMATION_SPEED];
 			Autos *new_autos = new_track->automation->autos[AUTOMATION_SPEED];
 			Auto *old_auto = old_autos ? old_autos->first : 0;
-			Auto *new_auto = new_autos ? new_autos->first : 0;
-			while( old_auto && new_auto ) {
+			for( ; old_auto; old_auto=old_auto->next ) {
+				Auto *new_auto = new_autos->get_auto(old_auto->orig_id);
+				if( !new_auto ) continue;
 				int64_t auto_pos = old_auto->position;
-				if( old_speed || new_speed ) {
-					double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
-					auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
-					result = 1;
-				}
+				double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
+				auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
 				new_auto->position = auto_pos;
-				old_auto = old_auto->next;
-				new_auto = new_auto->next;
 			}
 		}
 		Edit *old_edit = old_track->edits->first;
-		Edit *new_edit = new_track->edits->first;
-		while( old_edit && new_edit ) {
+		for( ; old_edit; old_edit=old_edit->next ) {
+			Edit *new_edit = new_track->edits->get_edit(old_edit->orig_id);
+			if( !new_edit ) continue;
 			int64_t edit_start = old_edit->startproject;
 			int64_t edit_end = edit_start + old_edit->length;
-			if( old_speed || new_speed ) {
-				double orig_start = old_speeds->automation_integral(0, edit_start, PLAY_FORWARD);
-				double orig_end   = old_speeds->automation_integral(0, edit_end, PLAY_FORWARD);
-				edit_start = new_track->frame_align(new_speeds->speed_position(orig_start), 1);
-				edit_end = new_track->frame_align(new_speeds->speed_position(orig_end), 1);
-				result = 1;
-			}
+			double orig_start = old_speeds->automation_integral(0, edit_start, PLAY_FORWARD);
+			double orig_end   = old_speeds->automation_integral(0, edit_end, PLAY_FORWARD);
+			edit_start = new_track->frame_align(new_speeds->speed_position(orig_start), 1);
+			edit_end = new_track->frame_align(new_speeds->speed_position(orig_end), 1);
 			new_edit->startproject = edit_start;
 			new_edit->length = edit_end - edit_start;
-			old_edit = old_edit->next;
-			new_edit = new_edit->next;
 		}
 		if( first_track && old_track->is_armed() ) {
-			if( edit_labels ) {
-				Labels *old_labels = old_edl->labels;
-				Labels *new_labels = new_edl->labels;
-				Label *old_label = old_labels ? old_labels->first : 0;
-				Label *new_label = new_labels ? new_labels->first : 0;
-				while( old_label && new_label ) {
+			Labels *old_labels = old_edl->labels;
+			Labels *new_labels = new_edl->labels;
+			if( edit_labels && old_labels && new_labels ) {
+				Label *old_label = old_labels->first;
+				for( ; old_label; old_label=old_label->next ) {
+					Label *new_label = new_labels->get_label(old_label->orig_id);
+					if( !new_label ) continue;
 					int64_t label_pos = old_track->to_units(old_label->position, 1);
-					if( old_speed || new_speed ) {
-						double orig_pos = old_speeds->automation_integral(0, label_pos, PLAY_FORWARD);
-						label_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
-						result = 1;
-					}
+					double orig_pos = old_speeds->automation_integral(0, label_pos, PLAY_FORWARD);
+					label_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
 					new_label->position = new_track->from_units(label_pos);
-					old_label = old_label->next;
-					new_label = new_label->next;
 				}
 			}
 			first_track = 0;
@@ -2662,59 +2652,54 @@ int MWindow::normalize_speed(EDL *old_edl, EDL *new_edl, int edit_speed)
 			int n = bmin(old_size, new_size);
 			for( int i=0; i<n; ++i ) {
 				PluginSet *old_plugin_set = old_track->plugin_set[i];
-				Plugin *old_plugin = (Plugin *)(old_plugin_set ? old_plugin_set->first : 0);
+				if( !old_plugin_set ) continue;
 				PluginSet *new_plugin_set = new_track->plugin_set[i];
-				Plugin *new_plugin = (Plugin *)(new_plugin_set ? new_plugin_set->first : 0);
-				while( old_plugin && new_plugin ) {
+				if( !new_plugin_set ) continue;
+				Plugin *old_plugin = (Plugin *)old_plugin_set->first;
+				for( ; old_plugin; old_plugin=(Plugin *)old_plugin->next ) {
+					Plugin *new_plugin = (Plugin *)new_plugin_set->get_edit(old_plugin->orig_id);
+					if( !new_plugin ) continue;
 					int64_t plugin_start = old_plugin->startproject;
 					int64_t plugin_end = plugin_start + old_plugin->length;
-					if( old_speed || new_speed ) {
-						double orig_start = old_speeds->automation_integral(0, plugin_start, PLAY_FORWARD);
-						double orig_end   = old_speeds->automation_integral(0, plugin_end, PLAY_FORWARD);
-						plugin_start = new_track->frame_align(new_speeds->speed_position(orig_start), 1);
-						plugin_end = new_track->frame_align(new_speeds->speed_position(orig_end), 1);
-						result = 1;
-					}
+					double orig_start = old_speeds->automation_integral(0, plugin_start, PLAY_FORWARD);
+					double orig_end   = old_speeds->automation_integral(0, plugin_end, PLAY_FORWARD);
+					plugin_start = new_track->frame_align(new_speeds->speed_position(orig_start), 1);
+					plugin_end = new_track->frame_align(new_speeds->speed_position(orig_end), 1);
 					new_plugin->startproject = plugin_start;
 					new_plugin->length = plugin_end - plugin_start;
 					if( edit_autos ) {
 						KeyFrames *old_keyframes = old_plugin->keyframes;
-						Auto *old_auto = old_keyframes ? old_keyframes->first : 0;
+						if( !old_keyframes ) continue;
 						KeyFrames *new_keyframes = new_plugin->keyframes;
-						Auto *new_auto = new_keyframes ? new_keyframes->first : 0;
-						while( old_auto && new_auto ) {
+						if( !new_keyframes ) continue;
+						Auto *old_auto = old_keyframes->first;
+						for( ; old_auto; old_auto=old_auto->next ) {
+							Auto *new_auto = new_keyframes->get_auto(old_auto->orig_id);
+							if( !new_auto ) continue;
 							int64_t auto_pos = old_auto->position;
-							if( old_speed || new_speed ) {
-								double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
-								auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
-								result = 1;
-							}
+							double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
+							auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
 							new_auto->position = auto_pos;
 							old_auto = old_auto->next;
-							new_auto = new_auto->next;
 						}
 					}
-					old_plugin = (Plugin *)old_plugin->next;
-					new_plugin = (Plugin *)new_plugin->next;
 				}
 			}
 		}
 		if( edit_autos ) { // speed must be last
 			for( int i=0; i<AUTOMATION_SPEED; ++i ) {
 				Autos *old_autos = old_track->automation->autos[i];
+				if( !old_autos ) continue;
 				Autos *new_autos = new_track->automation->autos[i];
-				Auto *old_auto = old_autos ? old_autos->first : 0;
-				Auto *new_auto = new_autos ? new_autos->first : 0;
-				while( old_auto && new_auto ) {
+				if( !new_autos ) continue;
+				Auto *old_auto = old_autos->first;
+				for( ; old_auto; old_auto=old_auto->next ) {
+					Auto *new_auto = new_autos->get_auto(old_auto->orig_id);
+					if( !new_auto ) continue;
 					int64_t auto_pos = old_auto->position;
-					if( old_speed || new_speed ) {
-						double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
-						auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
-						result = 1;
-					}
+					double orig_pos = old_speeds->automation_integral(0, auto_pos, PLAY_FORWARD);
+					auto_pos = new_track->frame_align(new_speeds->speed_position(orig_pos), 1);
 					new_auto->position = auto_pos;
-					old_auto = old_auto->next;
-					new_auto = new_auto->next;
 				}
 			}
 		}
diff --git a/cinelerra-5.1/cinelerra/playbackengine.C b/cinelerra-5.1/cinelerra/playbackengine.C
index 82bd7bb6..b15edd62 100644
--- a/cinelerra-5.1/cinelerra/playbackengine.C
+++ b/cinelerra-5.1/cinelerra/playbackengine.C
@@ -71,6 +71,7 @@ PlaybackEngine::PlaybackEngine(MWindow *mwindow, Canvas *output)
 	tracking_done = new Condition(1, "PlaybackEngine::tracking_done");
 	pause_lock = new Condition(0, "PlaybackEngine::pause_lock");
 	start_lock = new Condition(0, "PlaybackEngine::start_lock");
+	cache_lock = new Mutex("PlaybackEngine::cache_lock");
 	input_lock = new Condition(1, "PlaybackEngine::input_lock");
 	output_lock = new Condition(0, "PlaybackEngine::output_lock", 1);
 
@@ -93,6 +94,7 @@ PlaybackEngine::~PlaybackEngine()
 	delete tracking_done;
 	delete pause_lock;
 	delete start_lock;
+	delete cache_lock;
 	delete renderengine_lock;
 	delete command;
 	delete next_command;
@@ -164,12 +166,14 @@ void PlaybackEngine::wait_render_engine()
 
 void PlaybackEngine::create_cache()
 {
+	cache_lock->lock("PlaybackEngine::create_cache");
 	if( audio_cache )
 		audio_cache->remove_user();
 	if( video_cache )
 		video_cache->remove_user();
 	audio_cache = new CICache(preferences);
 	video_cache = new CICache(preferences);
+	cache_lock->unlock();
 }
 
 
diff --git a/cinelerra-5.1/cinelerra/playbackengine.h b/cinelerra-5.1/cinelerra/playbackengine.h
index ee27ff19..65935c2b 100644
--- a/cinelerra-5.1/cinelerra/playbackengine.h
+++ b/cinelerra-5.1/cinelerra/playbackengine.h
@@ -106,6 +106,8 @@ public:
 	Condition *pause_lock;
 // Wait until thread has started
 	Condition *start_lock;
+// Reinit caches
+	Mutex *cache_lock;
 
 	MWindow *mwindow;
 	Canvas *output;
diff --git a/cinelerra-5.1/cinelerra/tracks.C b/cinelerra-5.1/cinelerra/tracks.C
index 73e7706d..d8357e2f 100644
--- a/cinelerra-5.1/cinelerra/tracks.C
+++ b/cinelerra-5.1/cinelerra/tracks.C
@@ -336,8 +336,7 @@ int Tracks::delete_track(Track *track, int gang)
 		gang = edl->session->gang_tracks != GANG_NONE ? 1 : 0;
 	Track *nxt = track->next;
 	if( gang ) {
-		while( track && !track->master && track->previous )
-			track = track->previous;
+		track = track->gang_master();
 		while( nxt && !nxt->master )
 			nxt = nxt->next;
 	}
-- 
2.26.2