Make ppqPos in VST sync sample accurate

Author: DomClark

include/VstSyncController.h

@@ -39,7 +39,7 @@ class VstSyncController : public QObject
 	VstSyncController();
 	~VstSyncController();
 
-	void setAbsolutePosition( int ticks );
+	void setAbsolutePosition( double ticks );
 
 	void setPlaybackState( bool enabled )
 	{
@@ -77,7 +77,7 @@ private slots:
 	struct VstSyncData
 	{
 		bool isPlaying;
-		float ppqPos;
+		double ppqPos;
 		int timeSigNumer;
 		int timeSigDenom;
 		bool isCycle;

include/VstSyncData.h

@@ -42,7 +42,7 @@
 struct VstSyncData
 {
 	bool isPlaying;
-	float ppqPos;
+	double ppqPos;
 	int timeSigNumer;
 	int timeSigDenom;
 	bool isCycle;

plugins/vst_base/RemoteVstPlugin.cpp

@@ -395,8 +395,8 @@ class RemoteVstPlugin : public RemotePluginClient
 	// host to plugin synchronisation data structure
 	struct in
 	{
-		float lastppqPos;
-		float m_Timestamp;
+		double lastppqPos;
+		double m_Timestamp;
 		int32_t m_lastFlags;
 	} ;
 
@@ -1605,10 +1605,20 @@ intptr_t RemoteVstPlugin::hostCallback( AEffect * _effect, int32_t _opcode,
 			}
 			else if( __plugin->m_vstSyncData->isPlaying )
 			{
-				__plugin->m_in->lastppqPos += (
-							__plugin->m_vstSyncData->hasSHM ?
-							__plugin->m_vstSyncData->m_bpm :
-							__plugin->m_bpm ) / (float)10340;
+				if( __plugin->m_vstSyncData->hasSHM )
+				{
+					__plugin->m_in->lastppqPos +=
+						__plugin->m_vstSyncData->m_bpm / 60.0
+						* __plugin->m_vstSyncData->m_bufferSize
+						/ __plugin->m_vstSyncData->m_sampleRate;
+				}
+				else
+				{
+					__plugin->m_in->lastppqPos +=
+						__plugin->m_bpm / 60.0
+						* __plugin->bufferSize()
+						/ __plugin->sampleRate();
+				}
 				_timeInfo.ppqPos = __plugin->m_in->lastppqPos;
 			}
 //			_timeInfo.ppqPos = __plugin->m_vstSyncData->ppqPos;

src/core/Song.cpp

@@ -265,8 +265,6 @@ void Song::processNextBuffer()
 			m_playPos[m_playMode].setTicks(
 						tl->loopBegin().getTicks() );
 
-			m_vstSyncController.setAbsolutePosition(
-						tl->loopBegin().getTicks() );
 			m_vstSyncController.setPlaybackJumped( true );
 
 			emit updateSampleTracks();
@@ -293,8 +291,6 @@ void Song::processNextBuffer()
 			int ticks = m_playPos[m_playMode].getTicks() + 
 				( int )( currentFrame / framesPerTick );
 
-			m_vstSyncController.setAbsolutePosition( ticks );
-
 			// did we play a whole tact?
 			if( ticks >= MidiTime::ticksPerTact() )
 			{
@@ -332,7 +328,6 @@ void Song::processNextBuffer()
 					m_elapsedMilliSeconds = 
 						( ticks * 60 * 1000 / 48 ) / getTempo();
 
-					m_vstSyncController.setAbsolutePosition( ticks );
 					m_vstSyncController.setPlaybackJumped( true );
 				}
 			}
@@ -354,7 +349,6 @@ void Song::processNextBuffer()
 					m_elapsedMilliSeconds =
 						( ticks * 60 * 1000 / 48 ) / getTempo();
 
-					m_vstSyncController.setAbsolutePosition( ticks );
 					m_vstSyncController.setPlaybackJumped( true );
 
 					emit updateSampleTracks();
@@ -369,6 +363,16 @@ void Song::processNextBuffer()
 			m_playPos[m_playMode].setCurrentFrame( currentFrame );
 		}
 
+		if( framesPlayed == 0 )
+		{
+			// update VST sync position after we've corrected frame/
+			// tick count but before actually playing any frames
+			m_vstSyncController.setAbsolutePosition(
+				m_playPos[m_playMode].getTicks()
+				+ m_playPos[m_playMode].currentFrame()
+				/ (double) framesPerTick );
+		}
+
 		f_cnt_t framesToPlay = 
 			Engine::mixer()->framesPerPeriod() - framesPlayed;
 
@@ -716,7 +720,10 @@ void Song::stop()
 	m_playPos[m_playMode].setCurrentFrame( 0 );
 
 	m_vstSyncController.setPlaybackState( m_exporting );
-	m_vstSyncController.setAbsolutePosition( m_playPos[m_playMode].getTicks() );
+	m_vstSyncController.setAbsolutePosition(
+		m_playPos[m_playMode].getTicks()
+		+ m_playPos[m_playMode].currentFrame()
+		/ (double) Engine::framesPerTick() );
 
 	// remove all note-play-handles that are active
 	Engine::mixer()->clear();

src/core/VstSyncController.cpp

@@ -136,12 +136,12 @@ VstSyncController::~VstSyncController()
 
 
 
-void VstSyncController::setAbsolutePosition( int ticks )
+void VstSyncController::setAbsolutePosition( double ticks )
 {
 #ifdef VST_SNC_LATENCY
-	m_syncData->ppqPos = ( ( ticks + 0 ) / (float)48 ) - m_syncData->m_latency;
+	m_syncData->ppqPos = ( ( ticks + 0 ) / 48.0 ) - m_syncData->m_latency;
 #else
-	m_syncData->ppqPos = ( ( ticks + 0 ) / (float)48 );
+	m_syncData->ppqPos = ( ( ticks + 0 ) / 48.0 );
 #endif
 }