Limit internal GM synth to stereo output to prevent glitches

Author: timothyschoen

Source/Standalone/InternalSynth.cpp

@@ -45,7 +45,7 @@ void InternalSynth::run()
     unprepareLock.lock();
 
     // Fluidlite does not like setups with <2 channels
-    internalBuffer.setSize(std::max(2, lastNumChannels.load()), lastBlockSize);
+    internalBuffer.setSize(2, lastBlockSize);
     internalBuffer.clear();
 
     // Check if soundfont exists to prevent crashing
@@ -57,7 +57,7 @@ void InternalSynth::run()
         fluid_settings_setint(settings, "synth.ladspa.active", 0);
         fluid_settings_setint(settings, "synth.midi-channels", 16);
         fluid_settings_setnum(settings, "synth.gain", 0.9f);
-        fluid_settings_setnum(settings, "synth.audio-channels", lastNumChannels);
+        fluid_settings_setnum(settings, "synth.audio-channels", 2);
         fluid_settings_setnum(settings, "synth.sample-rate", lastSampleRate);
         synth = new_fluid_synth(settings); // Create fluidsynth instance:
 
@@ -90,7 +90,6 @@ void InternalSynth::unprepare()
 
         lastSampleRate = 0;
         lastBlockSize = 0;
-        lastNumChannels = 0;
 
         ready = false;
 
@@ -106,15 +105,13 @@ void InternalSynth::unprepare()
 void InternalSynth::prepare(int sampleRate, int blockSize, int numChannels)
 {
 #ifdef PLUGDATA_STANDALONE
-    if (ready && !isThreadRunning() && sampleRate == lastSampleRate && blockSize == lastBlockSize && numChannels == lastNumChannels) {
+    if (ready && !isThreadRunning() && sampleRate == lastSampleRate && blockSize == lastBlockSize) {
         return;
     } else {
         waitForThreadToExit(-1);
 
         lastSampleRate = sampleRate;
         lastBlockSize = blockSize;
-        lastNumChannels = numChannels;
-
         startThread();
     }
 
@@ -125,7 +122,7 @@ void InternalSynth::process(AudioBuffer<float>& buffer, MidiBuffer& midiMessages
 {
 #ifdef PLUGDATA_STANDALONE
 
-    if (buffer.getNumChannels() != lastNumChannels || buffer.getNumSamples() > lastBlockSize) {
+    if (buffer.getNumSamples() > lastBlockSize) {
         unprepare();
         return;
     }
@@ -169,7 +166,7 @@ void InternalSynth::process(AudioBuffer<float>& buffer, MidiBuffer& midiMessages
     // Run audio through fluidsynth
     fluid_synth_process(synth, internalBuffer.getNumSamples(), internalBuffer.getNumChannels(), const_cast<float**>(internalBuffer.getArrayOfReadPointers()), internalBuffer.getNumChannels(), const_cast<float**>(internalBuffer.getArrayOfWritePointers()));
 
-    int numChannelsToProcess = std::min(buffer.getNumChannels(), internalBuffer.getNumChannels());
+    int numChannelsToProcess = std::min(buffer.getNumChannels(), 2);
     for (int ch = 0; ch < numChannelsToProcess; ch++) {
         buffer.addFrom(ch, 0, internalBuffer, ch, 0, buffer.getNumSamples());
     }