97 lines
2.7 KiB
JavaScript
97 lines
2.7 KiB
JavaScript
var clone = function (o) {
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if (typeof o != 'object') return (o);
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if (o == null) return (o);
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var ret = (typeof o.length == 'number') ? [] : {};
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for (var key in o) ret[key] = clone(o[key]);
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return ret;
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};
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function Replayer(midiFile, timeWarp, eventProcessor) {
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var trackStates = [];
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var beatsPerMinute = 120;
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var ticksPerBeat = midiFile.header.ticksPerBeat;
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for (var i = 0; i < midiFile.tracks.length; i++) {
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trackStates[i] = {
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'nextEventIndex': 0,
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'ticksToNextEvent': (
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midiFile.tracks[i].length ?
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midiFile.tracks[i][0].deltaTime :
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null
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)
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};
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}
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var nextEventInfo;
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var samplesToNextEvent = 0;
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function getNextEvent() {
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var ticksToNextEvent = null;
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var nextEventTrack = null;
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var nextEventIndex = null;
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for (var i = 0; i < trackStates.length; i++) {
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if (
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trackStates[i].ticksToNextEvent != null
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&& (ticksToNextEvent == null || trackStates[i].ticksToNextEvent < ticksToNextEvent)
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) {
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ticksToNextEvent = trackStates[i].ticksToNextEvent;
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nextEventTrack = i;
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nextEventIndex = trackStates[i].nextEventIndex;
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}
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}
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if (nextEventTrack != null) {
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/* consume event from that track */
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var nextEvent = midiFile.tracks[nextEventTrack][nextEventIndex];
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if (midiFile.tracks[nextEventTrack][nextEventIndex + 1]) {
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trackStates[nextEventTrack].ticksToNextEvent += midiFile.tracks[nextEventTrack][nextEventIndex + 1].deltaTime;
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} else {
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trackStates[nextEventTrack].ticksToNextEvent = null;
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}
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trackStates[nextEventTrack].nextEventIndex += 1;
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/* advance timings on all tracks by ticksToNextEvent */
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for (var i = 0; i < trackStates.length; i++) {
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if (trackStates[i].ticksToNextEvent != null) {
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trackStates[i].ticksToNextEvent -= ticksToNextEvent
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}
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}
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return {
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"ticksToEvent": ticksToNextEvent,
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"event": nextEvent,
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"track": nextEventTrack
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}
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} else {
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return null;
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}
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};
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//
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var midiEvent;
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var temporal = [];
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//
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function processEvents() {
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function processNext() {
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if ( midiEvent.event.type == "meta" && midiEvent.event.subtype == "setTempo" ) {
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// tempo change events can occur anywhere in the middle and affect events that follow
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beatsPerMinute = 60000000 / midiEvent.event.microsecondsPerBeat;
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}
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if (midiEvent.ticksToEvent > 0) {
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var beatsToGenerate = midiEvent.ticksToEvent / ticksPerBeat;
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var secondsToGenerate = beatsToGenerate / (beatsPerMinute / 60);
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}
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var time = (secondsToGenerate * 1000 * timeWarp) || 0;
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temporal.push([ midiEvent, time]);
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midiEvent = getNextEvent();
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};
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//
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if (midiEvent = getNextEvent()) {
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while(midiEvent) processNext(true);
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}
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};
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processEvents();
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return {
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"getData": function() {
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return clone(temporal);
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}
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};
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};
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