Use Engine frame instead of seconds timestamp for midi::Message.

include/dsp/midi.hpp

@@ -23,7 +23,7 @@ struct MidiGenerator {
 	bool start;
 	bool stop;
 	bool cont;
-	int64_t timestamp = -1;
+	int64_t frame = -1;
 
 	MidiGenerator() {
 		reset();
@@ -56,7 +56,7 @@ struct MidiGenerator {
 			m.setStatus(0x8);
 			m.setNote(note);
 			m.setValue(0);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 	}
@@ -76,7 +76,7 @@ struct MidiGenerator {
 			m.setStatus(0x8);
 			m.setNote(notes[c]);
 			m.setValue(vels[c]);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 		if (changedNote || enabledGate) {
@@ -85,7 +85,7 @@ struct MidiGenerator {
 			m.setStatus(0x9);
 			m.setNote(note);
 			m.setValue(vels[c]);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 		notes[c] = note;
@@ -101,7 +101,7 @@ struct MidiGenerator {
 		m.setStatus(0xa);
 		m.setNote(notes[c]);
 		m.setValue(val);
-		m.timestamp = timestamp;
+		m.frame = frame;
 		onMessage(m);
 	}
 
@@ -114,7 +114,7 @@ struct MidiGenerator {
 		m.setSize(2);
 		m.setStatus(0xd);
 		m.setNote(val);
-		m.timestamp = timestamp;
+		m.frame = frame;
 		onMessage(m);
 	}
 
@@ -127,7 +127,7 @@ struct MidiGenerator {
 		m.setStatus(0xb);
 		m.setNote(id);
 		m.setValue(cc);
-		m.timestamp = timestamp;
+		m.frame = frame;
 		onMessage(m);
 	}
 
@@ -160,7 +160,7 @@ struct MidiGenerator {
 		m.setStatus(0xe);
 		m.setNote(pw & 0x7f);
 		m.setValue((pw >> 7) & 0x7f);
-		m.timestamp = timestamp;
+		m.frame = frame;
 		onMessage(m);
 	}
 
@@ -174,7 +174,7 @@ struct MidiGenerator {
 			m.setSize(1);
 			m.setStatus(0xf);
 			m.setChannel(0x8);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 	}
@@ -189,7 +189,7 @@ struct MidiGenerator {
 			m.setSize(1);
 			m.setStatus(0xf);
 			m.setChannel(0xa);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 	}
@@ -204,7 +204,7 @@ struct MidiGenerator {
 			m.setSize(1);
 			m.setStatus(0xf);
 			m.setChannel(0xb);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 	}
@@ -219,16 +219,16 @@ struct MidiGenerator {
 			m.setSize(1);
 			m.setStatus(0xf);
 			m.setChannel(0xc);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			onMessage(m);
 		}
 	}
 
-	void setTimestamp(int64_t timestamp) {
-		this->timestamp = timestamp;
+	void setFrame(int64_t frame) {
+		this->frame = frame;
 	}
 
-	virtual void onMessage(const midi::Message &message) {}
+	virtual void onMessage(const midi::Message& message) {}
 };
 
 

include/engine/Engine.hpp

@@ -66,10 +66,10 @@ struct Engine {
 	/** Returns the number of audio samples since the Engine was created.
 	*/
 	int64_t getFrame();
-	/** Returns the estimated time corresponding to the current frame, based on the time of when stepBlock() was last called.
-	Calculated by `stepTime + framesSinceStep / sampleRate`.
+	/** Sets the frame of the next stepBlock() call.
+	There is no reason to reset the frame in standalone Rack.
 	*/
-	double getFrameTime();
+	void setFrame(int64_t frame);
 	/** Returns the frame when stepBlock() was last called.
 	*/
 	int64_t getBlockFrame();

include/midi.hpp

@@ -20,8 +20,12 @@ namespace midi {
 struct Message {
 	/** Initialized to 3 empty bytes. */
 	std::vector<uint8_t> bytes;
-	/** Timestamp of MIDI message in nanoseconds. NAN if not set. */
-	double timestamp = NAN;
+	/** The Engine frame timestamp of the Message.
+	For output messages, the frame when the message was generated.
+	For input messages, the frame when it is intended to be processed.
+	-1 for undefined, to be sent or processed immediately.
+	*/
+	int64_t frame = -1;
 
 	Message() : bytes(3) {}
 

src/core/CV_CC.cpp

@@ -7,7 +7,7 @@ namespace core {
 
 struct CCMidiOutput : midi::Output {
 	int lastValues[128];
-	double timestamp = 0.0;
+	double frame = 0.0;
 
 	CCMidiOutput() {
 		reset();
@@ -29,12 +29,12 @@ struct CCMidiOutput : midi::Output {
 		m.setStatus(0xb);
 		m.setNote(cc);
 		m.setValue(value);
-		m.timestamp = timestamp;
+		m.frame = frame;
 		sendMessage(m);
 	}
 
-	void setTimestamp(double timestamp) {
-		this->timestamp = timestamp;
+	void setFrame(double frame) {
+		this->frame = frame;
 	}
 };
 
@@ -83,7 +83,7 @@ struct CV_CC : Module {
 		else
 			return;
 
-		midiOutput.setTimestamp(APP->engine->getFrameTime());
+		midiOutput.setFrame(args.frame + APP->engine->getBlockFrames());
 
 		for (int i = 0; i < 16; i++) {
 			int value = (int) std::round(inputs[CC_INPUTS + i].getVoltage() / 10.f * 127);

src/core/CV_Gate.cpp

@@ -8,7 +8,7 @@ namespace core {
 struct GateMidiOutput : midi::Output {
 	int vels[128];
 	bool lastGates[128];
-	double timestamp = 0.0;
+	double frame = 0.0;
 
 	GateMidiOutput() {
 		reset();
@@ -30,7 +30,7 @@ struct GateMidiOutput : midi::Output {
 			m.setStatus(0x8);
 			m.setNote(note);
 			m.setValue(0);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			sendMessage(m);
 			lastGates[note] = false;
 		}
@@ -47,7 +47,7 @@ struct GateMidiOutput : midi::Output {
 			m.setStatus(0x9);
 			m.setNote(note);
 			m.setValue(vels[note]);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			sendMessage(m);
 		}
 		else if (!gate && lastGates[note]) {
@@ -56,14 +56,14 @@ struct GateMidiOutput : midi::Output {
 			m.setStatus(0x8);
 			m.setNote(note);
 			m.setValue(vels[note]);
-			m.timestamp = timestamp;
+			m.frame = frame;
 			sendMessage(m);
 		}
 		lastGates[note] = gate;
 	}
 
-	void setTimestamp(double timestamp) {
-		this->timestamp = timestamp;
+	void setFrame(double frame) {
+		this->frame = frame;
 	}
 };
 
@@ -107,7 +107,7 @@ struct CV_Gate : Module {
 	}
 
 	void process(const ProcessArgs& args) override {
-		midiOutput.setTimestamp(APP->engine->getFrameTime());
+		midiOutput.setFrame(args.frame + APP->engine->getBlockFrames());
 
 		for (int i = 0; i < 16; i++) {
 			int note = learnedNotes[i];

src/core/CV_MIDI.cpp

@@ -6,7 +6,7 @@ namespace core {
 
 
 struct MidiOutput : dsp::MidiGenerator<PORT_MAX_CHANNELS>, midi::Output {
-	void onMessage(const midi::Message &message) override {
+	void onMessage(const midi::Message& message) override {
 		Output::sendMessage(message);
 	}
 
@@ -76,7 +76,7 @@ struct CV_MIDI : Module {
 		if (rateLimiterTriggered)
 			rateLimiterTimer.time -= rateLimiterPeriod;
 
-		midiOutput.setTimestamp(APP->engine->getFrameTime());
+		midiOutput.setFrame(args.frame + APP->engine->getBlockFrames());
 
 		for (int c = 0; c < inputs[PITCH_INPUT].getChannels(); c++) {
 			int vel = (int) std::round(inputs[VEL_INPUT].getNormalPolyVoltage(10.f * 100 / 127, c) / 10.f * 127);

src/core/MIDI_CC.cpp

@@ -72,8 +72,8 @@ struct MIDI_CC : Module {
 	void process(const ProcessArgs& args) override {
 		while (!midiInput.queue.empty()) {
 			midi::Message& msg = midiInput.queue.front();
-			// Don't process MIDI message until its timestamp corresponds with the audio frame time when played back in the next block.
-			if (msg.timestamp + APP->engine->getBlockDuration() > APP->engine->getFrameTime())
+			// Don't process MIDI message until we've reached its frame.
+			if (msg.frame > args.frame)
 				break;
 			processMessage(msg);
 			midiInput.queue.pop();

src/core/MIDI_CV.cpp

@@ -123,8 +123,8 @@ struct MIDI_CV : Module {
 	void process(const ProcessArgs& args) override {
 		while (!midiInput.queue.empty()) {
 			midi::Message& msg = midiInput.queue.front();
-			// Don't process MIDI message until its timestamp corresponds with the audio frame time when played back in the next block.
-			if (msg.timestamp + APP->engine->getBlockDuration() > APP->engine->getFrameTime())
+			// Don't process MIDI message until we've reached its frame.
+			if (msg.frame > args.frame)
 				break;
 			processMessage(msg);
 			midiInput.queue.pop();

src/core/MIDI_Gate.cpp

@@ -66,8 +66,8 @@ struct MIDI_Gate : Module {
 	void process(const ProcessArgs& args) override {
 		while (!midiInput.queue.empty()) {
 			midi::Message& msg = midiInput.queue.front();
-			// Don't process MIDI message until its timestamp corresponds with the audio frame time when played back in the next block.
-			if (msg.timestamp + APP->engine->getBlockDuration() > APP->engine->getFrameTime())
+			// Don't process MIDI message until we've reached its frame.
+			if (msg.frame > args.frame)
 				break;
 			processMessage(msg);
 			midiInput.queue.pop();

src/core/MIDI_Map.cpp

@@ -84,8 +84,8 @@ struct MIDI_Map : Module {
 
 		while (!midiInput.queue.empty()) {
 			midi::Message& msg = midiInput.queue.front();
-			// Don't process MIDI message until its timestamp corresponds with the audio frame time when played back in the next block.
-			if (msg.timestamp + APP->engine->getBlockDuration() > APP->engine->getFrameTime())
+			// Don't process MIDI message until we've reached its frame.
+			if (msg.frame > args.frame)
 				break;
 			processMessage(msg);
 			midiInput.queue.pop();

src/engine/Engine.cpp

@@ -618,9 +618,8 @@ int64_t Engine::getFrame() {
 }
 
 
-double Engine::getFrameTime() {
-	double timeSinceBlock = (internal->frame - internal->blockFrame) * internal->sampleTime;
-	return internal->blockTime + timeSinceBlock;
+void Engine::setFrame(int64_t frame) {
+	internal->frame = frame;
 }
 
 

src/midi.cpp

@@ -4,6 +4,8 @@
 #include <midi.hpp>
 #include <string.hpp>
 #include <system.hpp>
+#include <context.hpp>
+#include <engine/Engine.hpp>
 
 
 namespace rack {
@@ -44,15 +46,24 @@ void InputDevice::unsubscribe(Input* input) {
 		subscribed.erase(it);
 }
 
-void InputDevice::onMessage(const Message &message) {
-	// Set timestamp to now if unset
+void InputDevice::onMessage(const Message& message) {
 	Message msg = message;
-	if (msg.timestamp == 0.0)
-		msg.timestamp = system::getTime();
 
 	for (Input* input : subscribed) {
 		// We're probably in the MIDI driver's thread, so set the Rack context.
 		contextSet(input->context);
+
+		// Set timestamp to now if unset
+		if (message.frame < 0) {
+			double deltaTime = system::getTime() - APP->engine->getBlockTime();
+			int deltaFrames = std::floor(deltaTime * APP->engine->getSampleRate());
+			int64_t nextBlockFrame = APP->engine->getBlockFrame() + APP->engine->getBlockFrames();
+			msg.frame = nextBlockFrame + deltaFrames;
+		}
+		else {
+			msg.frame = message.frame;
+		}
+
 		// Filter channel if message is not a system MIDI message
 		if (msg.getStatus() != 0xf && input->channel >= 0 && msg.getChannel() != input->channel)
 			continue;
@@ -245,7 +256,7 @@ std::vector<int> Input::getChannels() {
 	return channels;
 }
 
-void InputQueue::onMessage(const Message &message) {
+void InputQueue::onMessage(const Message& message) {
 	if ((int) queue.size() >= queueMaxSize)
 		return;
 	// Push to queue
@@ -326,7 +337,7 @@ std::vector<int> Output::getChannels() {
 	return channels;
 }
 
-void Output::sendMessage(const Message &message) {
+void Output::sendMessage(const Message& message) {
 	if (!outputDevice)
 		return;
 

src/rtmidi.cpp

@@ -16,6 +16,8 @@
 #include <midi.hpp>
 #include <string.hpp>
 #include <system.hpp>
+#include <context.hpp>
+#include <engine/Engine.hpp>
 
 
 namespace rack {
@@ -78,29 +80,32 @@ struct RtMidiInputDevice : midi::InputDevice {
 
 		midi::Message msg;
 		msg.bytes = std::vector<uint8_t>(message->begin(), message->end());
+		// Don't set msg.frame from timeStamp here, because it's set in onMessage().
 		midiInputDevice->onMessage(msg);
 	}
 };
 
 
-/** Makes priority_queue prioritize by the earliest MIDI message. */
-static auto messageEarlier = [](const midi::Message& a, const midi::Message& b) {
-	return a.timestamp > b.timestamp;
-};
-
-
 struct RtMidiOutputDevice : midi::OutputDevice {
 	RtMidiOut* rtMidiOut;
 	std::string name;
 
-	std::priority_queue<midi::Message, std::vector<midi::Message>, decltype(messageEarlier)> messageQueue;
+	struct MessageSchedule {
+		midi::Message message;
+		double timestamp;
+
+		bool operator<(const MessageSchedule& other) const {
+			return timestamp > other.timestamp;
+		}
+	};
+	std::priority_queue<MessageSchedule, std::vector<MessageSchedule>> messageQueue;
 
 	std::thread thread;
 	std::mutex mutex;
 	std::condition_variable cv;
 	bool stopped = false;
 
-	RtMidiOutputDevice(int driverId, int deviceId) : messageQueue(messageEarlier) {
+	RtMidiOutputDevice(int driverId, int deviceId) {
 		try {
 			rtMidiOut = new RtMidiOut((RtMidi::Api) driverId, "VCV Rack");
 		}
@@ -137,10 +142,21 @@ struct RtMidiOutputDevice : midi::OutputDevice {
 		return name;
 	}
 
-	void sendMessage(const midi::Message &message) override {
-		// sendMessageNow(message);
+	void sendMessage(const midi::Message& message) override {
+		// If frame is undefined, send message immediately
+		if (message.frame < 0) {
+			sendMessageNow(message);
+			return;
+		}
+		// Schedule message to be sent by worker thread
+		MessageSchedule ms;
+		ms.message = message;
+		// Compute time in next Engine block to send message
+		double deltaTime = (message.frame - APP->engine->getBlockFrame()) * APP->engine->getSampleTime();
+		ms.timestamp = APP->engine->getBlockTime() + deltaTime;
+
 		std::lock_guard<decltype(mutex)> lock(mutex);
-		messageQueue.push(message);
+		messageQueue.push(ms);
 		cv.notify_one();
 	}
 
@@ -159,8 +175,8 @@ struct RtMidiOutputDevice : midi::OutputDevice {
 			}
 			else {
 				// Get earliest message
-				const midi::Message& message = messageQueue.top();
-				double duration = message.timestamp - system::getTime();
+				const MessageSchedule& ms = messageQueue.top();
+				double duration = ms.timestamp - system::getTime();
 
 				// If we need to wait, release the lock and wait for the timeout, or if the CV is notified.
 				// This correctly handles MIDI messages with no timestamp, because duration will be NAN.
@@ -170,13 +186,13 @@ struct RtMidiOutputDevice : midi::OutputDevice {
 				}
 
 				// Send and remove from queue
-				sendMessageNow(message);
+				sendMessageNow(ms.message);
 				messageQueue.pop();
 			}
 		}
 	}
 
-	void sendMessageNow(const midi::Message &message) {
+	void sendMessageNow(const midi::Message& message) {
 		try {
 			rtMidiOut->sendMessage(message.bytes.data(), message.bytes.size());
 		}