MIDI: In spite of the useless documentation on the Apple Developer website, add support for Roland GS master volume control, and since MIDI reset does not actually DO anything, spam the stupid software synth to shut up on MIDI reset to minimize how many leftover notes were there before reset. Sorry Apple, useless lists of constants with no reference on what you do with them or what they mean or even any kind of useful mention about them is not documentation, it is a dumb grep of headers. Maybe you should ask Microsoft how they document their APIs because you can at least work from their documentation to implement something.

src/gui/midi_coreaudio.h

@@ -57,7 +57,8 @@ class MidiHandler_coreaudio : public MidiHandler {
 private:
 	AUGraph m_auGraph;
 	AudioUnit m_synth;
-        const char *soundfont;
+	const char *soundfont;
+	bool resetVolume = true;
 public:
 	MidiHandler_coreaudio() : m_auGraph(0), m_synth(0) {}
 	const char * GetName(void) { return "coreaudio"; }
@@ -67,6 +68,8 @@ public:
 		if (m_auGraph)
 			return false;
 
+		resetVolume = true;
+
 		// Open the Music Device.
 		RequireNoErr(NewAUGraph(&m_auGraph));
 
@@ -183,12 +186,73 @@ public:
 	}
 
 	void PlayMsg(uint8_t * msg) {
-		MusicDeviceMIDIEvent(m_synth, msg[0], msg[1], msg[2], 0);
+		if (msg[0] == 0xff) {
+			// This is what it takes to stop all notes!
+			MusicDeviceMIDIEvent(m_synth, 0xFF, 0, 0, 0); // MIDI reset
+			for (unsigned int i=0;i < 16;i++) {
+				MusicDeviceMIDIEvent(m_synth, 0xB0+i, 120, 0, 0); // All notes off
+				MusicDeviceMIDIEvent(m_synth, 0xB0+i, 121, 0, 0); // Reset the controllers
+				MusicDeviceMIDIEvent(m_synth, 0xB0+i, 123, 0, 0); // All notes off
+				MusicDeviceMIDIEvent(m_synth, 0xB0+i, 124, 0, 0); // All notes off
+				MusicDeviceMIDIEvent(m_synth, 0xB0+i, 127, 0, 0); // All notes off
+			}
+			MusicDeviceMIDIEvent(m_synth, 0xFF, 0, 0, 0); // MIDI reset
+														  // Also resets volume
+			resetVolume = true;
+		}
+		else {
+			MusicDeviceMIDIEvent(m_synth, msg[0], msg[1], msg[2], 0);
+			if (resetVolume) {
+				resetVolume = false;
+				if (roland_gs_sysex) {
+					SetVolume(127);
+				}
+			}
+		}
 	}	
 
 	void PlaySysex(uint8_t * sysex, Bitu len) {
+		if (roland_gs_sysex) {
+			if (sysex[1] == 0x41/*Roland*/ && sysex[3] == 0x42/*GS*/ && sysex[4] == 0x12/*Send*/ && len >= 9) {
+				const uint32_t addr =
+					((uint32_t)sysex[5] << 16) +
+					((uint32_t)sysex[6] <<  8) +
+					(uint32_t)sysex[7];
+
+				if (addr == 0x400004) { /* MASTER VOLUME */
+					/* Fluidsynth doesn't appear to support this message, so we have to handle it ourself. */
+					SetVolume(sysex[8]);
+					resetVolume = false;
+					return;
+				}
+			}
+		}
+
 		MusicDeviceSysEx(m_synth, sysex, len);
 	}
+
+	void SetVolume(uint8_t vol) {
+		/* Despite the Apple Developer site and their TERRIBLE DOCUMENTATION, I was able to figure out
+		   these magic incantations that make setting the MIDI synthesizer volume possible.
+
+		   If you're going to document kMusicDeviceParam_Volume, document what it means, how you use it,
+		   and even if you figure out that it has something to do with AudioUnitSetParameters, document
+		   what the float value is supposed to mean. For fucks sake, even Microsoft who is traditionally
+		   terrible at documentation has figured out how to document an API! I had to figure out through
+		   trial and error that the float value was a decibel value! */
+		if (vol > 127) vol = 127;
+		Float32 fvol = vol > 0 ? (((Float32)vol - 127.0) / 2.0) : -999999.0; /* The volume value is decibels? Thanks for NOT documenting this Apple! */
+		OSErr err = 0;
+
+		err = AudioUnitSetParameter(
+				m_synth,
+				kMusicDeviceParam_Volume,
+				kAudioUnitScope_Global,
+				0,
+				fvol,
+				0
+				);
+	}
 };
 
 #undef RequireNoErr