SMFDriver now flushes / discards all the MidiSession buffers

when seeking / pausing / stopping playback as appropriate.
Also, the buffers are purged when closing the SynthRoute.

mt32emu_qt/src/QMidiBuffer.cpp

@@ -163,7 +163,13 @@ bool QMidiBuffer::nextEvent() {
 	return retieveEvents();
 }
 
+void QMidiBuffer::discardEvents() {
+	bytesRead += bytesToRead;
+	popEvents();
+}
+
 void QMidiBuffer::popEvents() {
+	if (readPointer == NULL) return;
 	ringBuffer.advanceReadPointer(bytesRead);
 	readPointer = NULL;
 	bytesRead = 0;

mt32emu_qt/src/QMidiBuffer.h

@@ -23,6 +23,7 @@ public:
 	quint64 getEventTimestamp() const;
 	quint32 getEventData(const uchar *&sysexData) const;
 	bool nextEvent();
+	void discardEvents();
 	void popEvents();
 
 private:

mt32emu_qt/src/SynthRoute.cpp

@@ -24,6 +24,8 @@
  * - Merging MIDI streams coming from several MIDI sessions
  */
 
+#include <climits>
+
 #include "SynthRoute.h"
 #include "MidiSession.h"
 #include "QMidiBuffer.h"
@@ -118,6 +120,7 @@ bool SynthRoute::close() {
 	audioStream = NULL;
 	qSynth.close();
 	disableExclusiveMidiMode();
+	discardMidiBuffers();
 	return true;
 }
 
@@ -269,11 +272,33 @@ bool SynthRoute::playMIDISysex(MidiSession &midiSession, const Bit8u *sysex, Bit
 	}
 }
 
-void SynthRoute::mergeMidiStreams(uint renderingPassFrameLength) {
-	if (audioStream == NULL) return; // May happen during startup, occasionally.
+void SynthRoute::discardMidiBuffers() {
+	if (!multiMidiMode) return;
 	QMutexLocker midiSessionsLocker(&midiSessionsMutex);
 	QVarLengthArray<QMidiBuffer *, 16> streamBuffers;
-	const quint64 renderingPassEndTimestamp = audioStream->computeMIDITimestamp(renderingPassFrameLength);
+
+	for (int i = 0; i < midiSessions.size(); i++) {
+		QMidiBuffer *midiBuffer = midiSessions[i]->getQMidiBuffer();
+		while (midiBuffer->retieveEvents()) {
+			midiBuffer->discardEvents();
+		}
+	}
+
+	qSynth.flushMIDIQueue();
+}
+
+void SynthRoute::flushMIDIQueue() {
+	if (multiMidiMode) mergeMidiStreams(0);
+	qSynth.flushMIDIQueue();
+}
+
+// When renderingPassFrameLength == 0, all pending messages are merged.
+void SynthRoute::mergeMidiStreams(uint renderingPassFrameLength) {
+	QMutexLocker midiSessionsLocker(&midiSessionsMutex);
+	QVarLengthArray<QMidiBuffer *, 16> streamBuffers;
+	const quint64 renderingPassEndTimestamp = renderingPassFrameLength == 0
+		? std::numeric_limits<quint64>::max()
+		: audioStream->computeMIDITimestamp(renderingPassFrameLength);
 
 	for (int i = 0; i < midiSessions.size(); i++) {
 		QMidiBuffer *midiBuffer = midiSessions[i]->getQMidiBuffer();
@@ -317,12 +342,14 @@ void SynthRoute::mergeMidiStreams(uint renderingPassFrameLength) {
 }
 
 void SynthRoute::render(MT32Emu::Bit16s *buffer, uint length) {
-	if (multiMidiMode) mergeMidiStreams(length);
+	// Occasionally, audioStream may appear NULL during startup.
+	if (multiMidiMode && audioStream != NULL) mergeMidiStreams(length);
 	qSynth.render(buffer, length);
 }
 
 void SynthRoute::render(float *buffer, uint length) {
-	if (multiMidiMode) mergeMidiStreams(length);
+	// Occasionally, audioStream may appear NULL during startup.
+	if (multiMidiMode && audioStream != NULL) mergeMidiStreams(length);
 	qSynth.render(buffer, length);
 }
 
@@ -336,10 +363,6 @@ void SynthRoute::enableRealtimeMode() {
 	qSynth.enableRealtime();
 }
 
-void SynthRoute::flushMIDIQueue() {
-	qSynth.flushMIDIQueue();
-}
-
 void SynthRoute::playMIDIShortMessageNow(Bit32u msg) {
 	qSynth.playMIDIShortMessageNow(msg);
 }

mt32emu_qt/src/SynthRoute.h

@@ -41,6 +41,7 @@ private:
 
 	void setState(SynthRouteState newState);
 	void disableExclusiveMidiMode();
+	void mergeMidiStreams(uint renderingPassFrameLength);
 
 public:
 	SynthRoute(QObject *parent = NULL);
@@ -65,7 +66,7 @@ public:
 	bool playMIDISysex(MidiSession &midiSession, const MT32Emu::Bit8u *sysex, MT32Emu::Bit32u sysexLen, quint64 timestamp);
 	bool pushMIDIShortMessage(MidiSession &midiSession, MT32Emu::Bit32u msg, MasterClockNanos midiNanos);
 	bool pushMIDISysex(MidiSession &midiSession, const MT32Emu::Bit8u *sysex, unsigned int sysexLen, MasterClockNanos midiNanos);
-	void mergeMidiStreams(uint renderingPassFrameLength);
+	void discardMidiBuffers();
 	void render(MT32Emu::Bit16s *buffer, uint length);
 	void render(float *buffer, uint length);
 	void audioStreamFailed();

mt32emu_qt/src/mididrv/SMFDriver.cpp

@@ -26,7 +26,11 @@ static const MasterClockNanos MAX_SLEEP_TIME = 200 * MasterClock::NANOS_PER_MILL
 
 static void sendAllSoundOff(SynthRoute *synthRoute, bool resetAllControllers) {
 	if (synthRoute->getState() != SynthRouteState_OPEN) return;
-	synthRoute->flushMIDIQueue();
+	if (resetAllControllers) {
+		synthRoute->discardMidiBuffers();
+	} else {
+		synthRoute->flushMIDIQueue();
+	}
 	for (quint8 i = 0; i < 16; i++) {
 		// All notes off
 		quint32 msg = 0x7FB0 | i;