let there be midi

js/lib/jasmid/replayer.js

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+var clone = function (o) {
+	if (typeof o != 'object') return (o);
+	if (o == null) return (o);
+	var ret = (typeof o.length == 'number') ? [] : {};
+	for (var key in o) ret[key] = clone(o[key]);
+	return ret;
+};
+
+function Replayer(midiFile, timeWarp, eventProcessor) {
+//console.log(midiFile)
+	var trackStates = [];
+	var beatsPerMinute = 120;
+	var ticksPerBeat = midiFile.header.ticksPerBeat;
+	for (var i = 0; i < midiFile.tracks.length; i++) {
+		trackStates[i] = {
+			"nextEventIndex": 0,
+			"ticksToNextEvent": (
+				midiFile.tracks[i].length ? midiFile.tracks[i][0].deltaTime : null
+			)
+		};
+	}
+	function getNextEvent() {
+		var ticksToNextEvent = null;
+		var nextEventTrack = null;
+		var nextEventIndex = null;
+		for (var i = 0; i < trackStates.length; i++) {
+			if (trackStates[i].ticksToNextEvent != null && (ticksToNextEvent == null || trackStates[i].ticksToNextEvent < ticksToNextEvent)) {
+				ticksToNextEvent = trackStates[i].ticksToNextEvent;
+				nextEventTrack = i;
+				nextEventIndex = trackStates[i].nextEventIndex;
+			}
+		}
+		if (nextEventTrack != null) {
+			/// consume event from that track
+			var nextEvent = midiFile.tracks[nextEventTrack][nextEventIndex];
+			if (midiFile.tracks[nextEventTrack][nextEventIndex + 1]) {
+				trackStates[nextEventTrack].ticksToNextEvent += midiFile.tracks[nextEventTrack][nextEventIndex + 1].deltaTime;
+			} else {
+				trackStates[nextEventTrack].ticksToNextEvent = null;
+			}
+			trackStates[nextEventTrack].nextEventIndex += 1;
+			/// advance timings on all tracks by ticksToNextEvent
+			for (var i = 0; i < trackStates.length; i++) {
+				if (trackStates[i].ticksToNextEvent != null) {
+					trackStates[i].ticksToNextEvent -= ticksToNextEvent
+				}
+			}
+			return {
+				"ticksToEvent": ticksToNextEvent,
+				"event": nextEvent,
+				"track": nextEventTrack
+			}
+		} else {
+			return null;
+		}
+	};
+	//
+	var midiEvent;
+	var temporal = [];
+	//
+	function processEvents() {
+		function processNext() {
+			if (midiEvent.ticksToEvent > 0) {
+				var beatsToGenerate = midiEvent.ticksToEvent / ticksPerBeat;
+				var secondsToGenerate = beatsToGenerate / (beatsPerMinute / 60);
+			}
+			var time = secondsToGenerate * 1000 * timeWarp || 0;
+			temporal.push([ midiEvent, time]);
+			midiEvent = getNextEvent();
+		};
+		//
+		if (midiEvent = getNextEvent()) {
+			while(midiEvent) processNext(true);
+		}
+	};
+	processEvents();
+	return {
+		"getData": function() {
+//		console.log(temporal)
+			return clone(temporal);
+		}
+	};
+};