CV to MIDI: Generate Note Off message for active notes when number of channels is decreased.

include/dsp/midi.hpp

@@ -16,6 +16,7 @@ CHANNELS is the number of polyphony channels. Use 1 for monophonic.
 */
 template <int CHANNELS>
 struct MidiGenerator {
+	uint8_t channels;
 	int8_t vels[CHANNELS];
 	int8_t notes[CHANNELS];
 	bool gates[CHANNELS];
@@ -34,6 +35,7 @@ struct MidiGenerator {
 	}
 
 	void reset() {
+		channels = CHANNELS;
 		for (int c = 0; c < CHANNELS; c++) {
 			vels[c] = 100;
 			notes[c] = 60;
@@ -65,6 +67,16 @@ struct MidiGenerator {
 		}
 	}
 
+	void setChannels(uint8_t channels) {
+		if (this->channels == channels)
+			return;
+		// Disable notes when channels decreases
+		for (uint8_t c = channels; c < this->channels; c++) {
+			setNoteGate(notes[c], false, c);
+		}
+		this->channels = channels;
+	}
+
 	/** Must be called before setNoteGate(). */
 	void setVelocity(int8_t vel, int c) {
 		vels[c] = vel;

src/core/CV_MIDI.cpp

@@ -7,6 +7,7 @@ namespace core {
 
 struct MidiOutput : dsp::MidiGenerator<PORT_MAX_CHANNELS>, midi::Output {
 	void onMessage(const midi::Message& message) override {
+		// DEBUG("MIDI: %ld %s", message.getFrame(), message.toString().c_str());
 		Output::sendMessage(message);
 	}
 
@@ -78,7 +79,10 @@ struct CV_MIDI : Module {
 
 		midiOutput.setFrame(args.frame);
 
-		for (int c = 0; c < inputs[PITCH_INPUT].getChannels(); c++) {
+		uint8_t channels = inputs[PITCH_INPUT].getChannels();
+		midiOutput.setChannels(channels);
+
+		for (int c = 0; c < channels; c++) {
 			int vel = (int) std::round(inputs[VEL_INPUT].getNormalPolyVoltage(10.f * 100 / 127, c) / 10.f * 127);
 			vel = clamp(vel, 0, 127);
 			midiOutput.setVelocity(vel, c);