Implement VST latency reporting

include/aeffectx.h

@@ -238,13 +238,13 @@ class AEffect
 	int32_t numOutputs;
 	// flags 24-27
 	int32_t flags;
-	// Fill somewhere 28-2b
+	// Fill somewhere 28-2b 2c-2f
 	void *ptr1;
 	void *ptr2;
-	// 2c-2f
-	int latency;
-	// Zeroes 30-33 34-37
-	char empty3[4 + 4];
+	// latency(initial delay) 30-33
+	int initialDelay;
+	// Zeroes 34-37 38-3b
+	char empty2[4 + 4];
 	// 1.0f 3c-3f
 	float unknown_float;
 	// An object? pointer 40-43

plugins/Vestige/Vestige.cpp

@@ -374,6 +374,10 @@ void VestigeInstrument::loadFile( const QString & _file )
 		return;
 	}
 
+	connect(m_plugin, &VstPlugin::latencyChanged, [this]() {
+		setLatency(m_plugin->latency());
+	});
+
 	if ( !(instrumentTrack() != nullptr && instrumentTrack()->isPreviewMode()))
 	{
 		m_plugin->createUI(nullptr);

plugins/VstBase/RemoteVstPlugin.cpp

@@ -309,6 +309,14 @@ class RemoteVstPlugin : public RemotePluginClient
 	// has to be called as soon as input- or output-count changes
 	int updateInOutCount();
 
+	// called on latency change, returns true on change
+	void updateLatency(bool reply = false);
+
+	inline int cachedLatency() const
+	{
+		return m_latency;
+	}
+
 	inline void lockShm()
 	{
 		m_shmLock.lock();
@@ -481,6 +489,7 @@ class RemoteVstPlugin : public RemotePluginClient
 	bpm_t m_bpm;
 	double m_currentSamplePos;
 	int m_currentProgram;
+	int m_latency;
 
 	// host to plugin synchronisation data structure
 	struct in
@@ -718,6 +727,10 @@ bool RemoteVstPlugin::processMessage( const message & _m )
 			break;
 		}
 #endif
+		case IdVstGetLatency:
+			updateLatency(true);
+			break;
+
 		default:
 			return RemotePluginClient::processMessage( _m );
 	}
@@ -738,6 +751,7 @@ void RemoteVstPlugin::init( const std::string & _plugin_file )
 	updateInOutCount();
 	updateBufferSize();
 	updateSampleRate();
+	updateLatency(true);
 
 	/* set program to zero */
 	/* i comment this out because it breaks dfx Geometer
@@ -1101,6 +1115,7 @@ void RemoteVstPlugin::process( const sampleFrame * _in, sampleFrame * _out )
 #else
 	m_plugin->processReplacing(m_plugin, m_inputs, m_outputs, bufferSize());
 #endif
+	updateLatency();
 
 	unlockShm();
 
@@ -1709,6 +1724,22 @@ int RemoteVstPlugin::updateInOutCount()
 
 
 
+
+void RemoteVstPlugin::updateLatency(bool reply)
+{
+	if (m_latency != m_plugin->initialDelay)
+	{
+		reply = true;
+	}
+	m_latency = m_plugin->initialDelay;
+	if (reply)
+	{
+		sendMessage(message(IdVstLatency).addInt(m_latency));
+	}
+}
+
+
+
 //#define DEBUG_CALLBACKS
 #ifdef DEBUG_CALLBACKS
 #define SHOW_CALLBACK __plugin->debugMessage
@@ -1853,6 +1884,7 @@ intptr_t RemoteVstPlugin::hostCallback( AEffect * _effect, int32_t _opcode,
 		case audioMasterIOChanged:
 			SHOW_CALLBACK( "amc: audioMasterIOChanged\n" );
 			// numInputs, numOutputs, and/or latency has changed
+			__plugin->updateLatency();
 			return __plugin->updateInOutCount();
 
 #ifdef OLD_VST_SDK

plugins/VstBase/VstPlugin.cpp

@@ -128,7 +128,8 @@ VstPlugin::VstPlugin( const QString & _plugin ) :
 			? ConfigManager::inst()->vstEmbedMethod()
 			: "headless" ),
 	m_version( 0 ),
-	m_currentProgram()
+	m_currentProgram(),
+	m_latency(0)
 {
 	setSplittedChannels( true );
 
@@ -488,6 +489,8 @@ bool VstPlugin::processMessage( const message & _m )
 			}
 			break;
 		}
+		case IdVstLatency:
+			setLatency(_m.getInt(0));
 		default:
 			return RemotePlugin::processMessage( _m );
 	}

plugins/VstBase/VstPlugin.h

@@ -123,6 +123,25 @@ class VSTBASE_EXPORT VstPlugin : public RemotePlugin, public JournallingObject
 
 	QString embedMethod() const;
 
+	inline int latency() const
+	{
+		return m_latency;
+	}
+
+	void setLatency(int latency)
+	{
+		if (m_latency != latency)
+		{
+			m_latency = latency;
+			emit latencyChanged();
+		}
+	}
+
+	void updateLatency();
+
+signals:
+	void latencyChanged();
+
 public slots:
 	void setTempo( lmms::bpm_t _bpm );
 	void updateSampleRate();
@@ -171,6 +190,7 @@ public slots:
 
 	QTimer m_idleTimer;
 
+	int m_latency;
 } ;
 
 

plugins/VstBase/communication.h

@@ -71,6 +71,7 @@ enum VstRemoteMessageIDs
 	IdVstIdleUpdate,
 	IdVstParameterDisplays,
 	IdVstParameterLabels,
+	IdVstGetLatency,
 
 	// remoteVstPlugin -> vstPlugin
 	IdVstFailedLoadingPlugin,
@@ -84,7 +85,8 @@ enum VstRemoteMessageIDs
 	IdVstPluginUniqueID,
 	IdVstSetParameter,
 	IdVstParameterCount,
-	IdVstParameterDump
+	IdVstParameterDump,
+	IdVstLatency
 
 } ;
 

plugins/VstEffect/VstEffect.cpp

@@ -142,6 +142,10 @@ void VstEffect::openPlugin( const QString & _plugin )
 		return;
 	}
 
+	connect(m_plugin.data(), &VstPlugin::latencyChanged, [this]() {
+		setLatency(m_plugin->latency());
+	});
+
 	delete tf;
 
 	m_key.attributes["file"] = _plugin;