702 lines
18 KiB
JavaScript
702 lines
18 KiB
JavaScript
var sampleRate = 44100; /* hard-coded in Flash player */
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function AudioPlayer(context, generator, loop) {
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// Uses Webkit Web Audio API if available
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sampleRate = context.sampleRate;
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var channelCount = 2;
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var bufferSize = 4096*4; // Higher for less gitches, lower for less latency
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var node = context.createScriptProcessor(bufferSize, 0, channelCount);
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node.onaudioprocess = function(e) { process(e) };
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function process(e) {
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if (generator.finished) {
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if (loop) {
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generator.reset();
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generator.finished = false;
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}
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else {
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node.disconnect();
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return;
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}
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}
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var dataLeft = e.outputBuffer.getChannelData(0);
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var dataRight = e.outputBuffer.getChannelData(1);
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var generate = generator.generate(bufferSize);
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for (var i = 0; i < bufferSize; ++i) {
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dataLeft[i] = generate[i*2];
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dataRight[i] = generate[i*2+1];
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}
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}
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// start
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// node.connect(context.destination);
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return {
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'play': function () {
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node.connect(context.destination);
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},
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'pause': function() {
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node.disconnect();
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}
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}
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}
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/*
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class to parse the .mid file format
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(depends on stream.js)
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*/
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function MidiFile(data) {
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function readChunk(stream) {
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var id = stream.read(4);
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var length = stream.readInt32();
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return {
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'id': id,
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'length': length,
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'data': stream.read(length)
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};
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}
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var lastEventTypeByte;
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function readEvent(stream) {
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var event = {};
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event.deltaTime = stream.readVarInt();
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var eventTypeByte = stream.readInt8();
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if ((eventTypeByte & 0xf0) == 0xf0) {
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/* system / meta event */
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if (eventTypeByte == 0xff) {
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/* meta event */
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event.type = 'meta';
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var subtypeByte = stream.readInt8();
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var length = stream.readVarInt();
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switch(subtypeByte) {
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case 0x00:
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event.subtype = 'sequenceNumber';
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if (length != 2) throw "Expected length for sequenceNumber event is 2, got " + length;
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event.number = stream.readInt16();
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return event;
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case 0x01:
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event.subtype = 'text';
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event.text = stream.read(length);
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return event;
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case 0x02:
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event.subtype = 'copyrightNotice';
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event.text = stream.read(length);
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return event;
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case 0x03:
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event.subtype = 'trackName';
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event.text = stream.read(length);
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return event;
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case 0x04:
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event.subtype = 'instrumentName';
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event.text = stream.read(length);
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return event;
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case 0x05:
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event.subtype = 'lyrics';
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event.text = stream.read(length);
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return event;
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case 0x06:
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event.subtype = 'marker';
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event.text = stream.read(length);
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return event;
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case 0x07:
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event.subtype = 'cuePoint';
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event.text = stream.read(length);
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return event;
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case 0x20:
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event.subtype = 'midiChannelPrefix';
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if (length != 1) throw "Expected length for midiChannelPrefix event is 1, got " + length;
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event.channel = stream.readInt8();
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return event;
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case 0x2f:
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event.subtype = 'endOfTrack';
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if (length != 0) throw "Expected length for endOfTrack event is 0, got " + length;
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return event;
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case 0x51:
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event.subtype = 'setTempo';
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if (length != 3) throw "Expected length for setTempo event is 3, got " + length;
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event.microsecondsPerBeat = (
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(stream.readInt8() << 16)
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+ (stream.readInt8() << 8)
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+ stream.readInt8()
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)
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return event;
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case 0x54:
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event.subtype = 'smpteOffset';
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if (length != 5) throw "Expected length for smpteOffset event is 5, got " + length;
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var hourByte = stream.readInt8();
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event.frameRate = {
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0x00: 24, 0x20: 25, 0x40: 29, 0x60: 30
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}[hourByte & 0x60];
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event.hour = hourByte & 0x1f;
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event.min = stream.readInt8();
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event.sec = stream.readInt8();
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event.frame = stream.readInt8();
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event.subframe = stream.readInt8();
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return event;
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case 0x58:
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event.subtype = 'timeSignature';
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if (length != 4) throw "Expected length for timeSignature event is 4, got " + length;
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event.numerator = stream.readInt8();
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event.denominator = Math.pow(2, stream.readInt8());
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event.metronome = stream.readInt8();
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event.thirtyseconds = stream.readInt8();
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return event;
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case 0x59:
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event.subtype = 'keySignature';
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if (length != 2) throw "Expected length for keySignature event is 2, got " + length;
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event.key = stream.readInt8(true);
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event.scale = stream.readInt8();
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return event;
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case 0x7f:
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event.subtype = 'sequencerSpecific';
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event.data = stream.read(length);
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return event;
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default:
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// console.log("Unrecognised meta event subtype: " + subtypeByte);
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event.subtype = 'unknown'
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event.data = stream.read(length);
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return event;
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}
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event.data = stream.read(length);
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return event;
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} else if (eventTypeByte == 0xf0) {
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event.type = 'sysEx';
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var length = stream.readVarInt();
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event.data = stream.read(length);
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return event;
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} else if (eventTypeByte == 0xf7) {
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event.type = 'dividedSysEx';
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var length = stream.readVarInt();
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event.data = stream.read(length);
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return event;
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} else {
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throw "Unrecognised MIDI event type byte: " + eventTypeByte;
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}
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} else {
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/* channel event */
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var param1;
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if ((eventTypeByte & 0x80) == 0) {
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/* running status - reuse lastEventTypeByte as the event type.
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eventTypeByte is actually the first parameter
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*/
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param1 = eventTypeByte;
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eventTypeByte = lastEventTypeByte;
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} else {
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param1 = stream.readInt8();
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lastEventTypeByte = eventTypeByte;
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}
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var eventType = eventTypeByte >> 4;
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event.channel = eventTypeByte & 0x0f;
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event.type = 'channel';
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switch (eventType) {
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case 0x08:
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event.subtype = 'noteOff';
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event.noteNumber = param1;
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event.velocity = stream.readInt8();
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return event;
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case 0x09:
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event.noteNumber = param1;
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event.velocity = stream.readInt8();
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if (event.velocity == 0) {
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event.subtype = 'noteOff';
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} else {
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event.subtype = 'noteOn';
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}
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return event;
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case 0x0a:
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event.subtype = 'noteAftertouch';
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event.noteNumber = param1;
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event.amount = stream.readInt8();
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return event;
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case 0x0b:
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event.subtype = 'controller';
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event.controllerType = param1;
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event.value = stream.readInt8();
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return event;
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case 0x0c:
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event.subtype = 'programChange';
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event.programNumber = param1;
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return event;
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case 0x0d:
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event.subtype = 'channelAftertouch';
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event.amount = param1;
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return event;
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case 0x0e:
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event.subtype = 'pitchBend';
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event.value = param1 + (stream.readInt8() << 7);
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return event;
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default:
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throw "Unrecognised MIDI event type: " + eventType
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}
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}
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}
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stream = Stream(data);
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var headerChunk = readChunk(stream);
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if (headerChunk.id != 'MThd' || headerChunk.length != 6) {
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throw "Bad .mid file - header not found";
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}
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var headerStream = Stream(headerChunk.data);
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var formatType = headerStream.readInt16();
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var trackCount = headerStream.readInt16();
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var timeDivision = headerStream.readInt16();
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if (timeDivision & 0x8000) {
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throw "Expressing time division in SMTPE frames is not supported yet"
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} else {
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ticksPerBeat = timeDivision;
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}
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var header = {
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'formatType': formatType,
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'trackCount': trackCount,
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'ticksPerBeat': ticksPerBeat
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}
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var tracks = [];
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for (var i = 0; i < header.trackCount; i++) {
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tracks[i] = [];
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var trackChunk = readChunk(stream);
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if (trackChunk.id != 'MTrk') {
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throw "Unexpected chunk - expected MTrk, got "+ trackChunk.id;
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}
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var trackStream = Stream(trackChunk.data);
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while (!trackStream.eof()) {
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var event = readEvent(trackStream);
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tracks[i].push(event);
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//console.log(event);
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}
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}
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return {
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'header': header,
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'tracks': tracks
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}
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}
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function Replayer(midiFile, synth) {
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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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var channelCount = 16;
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var channels = [];
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var nextEventInfo;
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var samplesToNextEvent;
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function Channel() {
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var generatorsByNote = {};
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var currentProgram = PianoProgram;
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function noteOn(note, velocity) {
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if (generatorsByNote[note] && !generatorsByNote[note].released) {
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/* playing same note before releasing the last one. BOO */
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generatorsByNote[note].noteOff(); /* TODO: check whether we ought to be passing a velocity in */
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}
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generator = currentProgram.createNote(note, velocity);
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synth.addGenerator(generator);
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generatorsByNote[note] = generator;
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}
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function noteOff(note, velocity) {
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if (generatorsByNote[note] && !generatorsByNote[note].released) {
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generatorsByNote[note].noteOff(velocity);
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}
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}
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function setProgram(programNumber) {
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currentProgram = PROGRAMS[programNumber] || PianoProgram;
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}
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return {
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'noteOn': noteOn,
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'noteOff': noteOff,
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'setProgram': setProgram
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}
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}
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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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nextEventInfo = {
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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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var beatsToNextEvent = ticksToNextEvent / ticksPerBeat;
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var secondsToNextEvent = beatsToNextEvent / (beatsPerMinute / 60);
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samplesToNextEvent += secondsToNextEvent * synth.sampleRate;
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} else {
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nextEventInfo = null;
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samplesToNextEvent = null;
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self.finished = true;
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}
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}
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function generate(samples) {
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var data = new Array(samples*2);
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var samplesRemaining = samples;
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var dataOffset = 0;
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while (true) {
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if (samplesToNextEvent != null && samplesToNextEvent <= samplesRemaining) {
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/* generate samplesToNextEvent samples, process event and repeat */
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var samplesToGenerate = Math.ceil(samplesToNextEvent);
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if (samplesToGenerate > 0) {
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synth.generateIntoBuffer(samplesToGenerate, data, dataOffset);
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dataOffset += samplesToGenerate * 2;
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samplesRemaining -= samplesToGenerate;
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samplesToNextEvent -= samplesToGenerate;
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}
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handleEvent();
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getNextEvent();
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} else {
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/* generate samples to end of buffer */
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if (samplesRemaining > 0) {
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synth.generateIntoBuffer(samplesRemaining, data, dataOffset);
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samplesToNextEvent -= samplesRemaining;
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}
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break;
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}
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}
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return data;
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}
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function handleEvent() {
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var event = nextEventInfo.event;
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switch (event.type) {
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case 'meta':
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switch (event.subtype) {
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case 'setTempo':
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beatsPerMinute = 60000000 / event.microsecondsPerBeat
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}
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break;
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case 'channel':
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switch (event.subtype) {
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case 'noteOn':
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channels[event.channel].noteOn(event.noteNumber, event.velocity);
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break;
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case 'noteOff':
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channels[event.channel].noteOff(event.noteNumber, event.velocity);
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break;
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case 'programChange':
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//console.log('program change to ' + event.programNumber);
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channels[event.channel].setProgram(event.programNumber);
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break;
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}
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break;
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}
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}
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function reset() {
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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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for (var i = 0; i < channelCount; i++) {
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channels[i] = Channel();
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}
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samplesToNextEvent = 0;
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getNextEvent();
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}
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reset();
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var self = {
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'reset': reset,
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'generate': generate,
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'finished': false
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}
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return self;
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}
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/* Wrapper for accessing strings through sequential reads */
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function Stream(str) {
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var position = 0;
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function read(length) {
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var result = str.substr(position, length);
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position += length;
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return result;
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}
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/* read a big-endian 32-bit integer */
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function readInt32() {
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var result = (
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(str.charCodeAt(position) << 24)
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+ (str.charCodeAt(position + 1) << 16)
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+ (str.charCodeAt(position + 2) << 8)
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+ str.charCodeAt(position + 3));
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position += 4;
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return result;
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}
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/* read a big-endian 16-bit integer */
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function readInt16() {
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var result = (
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(str.charCodeAt(position) << 8)
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+ str.charCodeAt(position + 1));
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position += 2;
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return result;
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}
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/* read an 8-bit integer */
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function readInt8(signed) {
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var result = str.charCodeAt(position);
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if (signed && result > 127) result -= 256;
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position += 1;
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return result;
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}
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function eof() {
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return position >= str.length;
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}
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/* read a MIDI-style variable-length integer
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(big-endian value in groups of 7 bits,
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with top bit set to signify that another byte follows)
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*/
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function readVarInt() {
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var result = 0;
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while (true) {
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var b = readInt8();
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if (b & 0x80) {
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result += (b & 0x7f);
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result <<= 7;
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} else {
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/* b is the last byte */
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return result + b;
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}
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}
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}
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return {
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'eof': eof,
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'read': read,
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'readInt32': readInt32,
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'readInt16': readInt16,
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'readInt8': readInt8,
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'readVarInt': readVarInt
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}
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}
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function SineGenerator(freq) {
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var self = {'alive': true};
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var period = sampleRate / freq;
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var t = 0;
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self.generate = function(buf, offset, count) {
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for (; count; count--) {
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var phase = t / period;
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var result = Math.sin(phase * 2 * Math.PI);
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buf[offset++] += result;
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buf[offset++] += result;
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t++;
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}
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}
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return self;
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}
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function SquareGenerator(freq, phase) {
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var self = {'alive': true};
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var period = sampleRate / freq;
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var t = 0;
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self.generate = function(buf, offset, count) {
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for (; count; count--) {
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var result = ( (t / period) % 1 > phase ? 1 : -1);
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buf[offset++] += result;
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buf[offset++] += result;
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t++;
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}
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}
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return self;
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}
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function ADSRGenerator(child, attackAmplitude, sustainAmplitude, attackTimeS, decayTimeS, releaseTimeS) {
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var self = {'alive': true}
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var attackTime = sampleRate * attackTimeS;
|
|
var decayTime = sampleRate * (attackTimeS + decayTimeS);
|
|
var decayRate = (attackAmplitude - sustainAmplitude) / (decayTime - attackTime);
|
|
var releaseTime = null; /* not known yet */
|
|
var endTime = null; /* not known yet */
|
|
var releaseRate = sustainAmplitude / (sampleRate * releaseTimeS);
|
|
var t = 0;
|
|
|
|
self.noteOff = function() {
|
|
if (self.released) return;
|
|
releaseTime = t;
|
|
self.released = true;
|
|
endTime = releaseTime + sampleRate * releaseTimeS;
|
|
}
|
|
|
|
self.generate = function(buf, offset, count) {
|
|
if (!self.alive) return;
|
|
var input = new Array(count * 2);
|
|
for (var i = 0; i < count*2; i++) {
|
|
input[i] = 0;
|
|
}
|
|
child.generate(input, 0, count);
|
|
|
|
childOffset = 0;
|
|
while(count) {
|
|
if (releaseTime != null) {
|
|
if (t < endTime) {
|
|
/* release */
|
|
while(count && t < endTime) {
|
|
var ampl = sustainAmplitude - releaseRate * (t - releaseTime);
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
t++;
|
|
count--;
|
|
}
|
|
} else {
|
|
/* dead */
|
|
self.alive = false;
|
|
return;
|
|
}
|
|
} else if (t < attackTime) {
|
|
/* attack */
|
|
while(count && t < attackTime) {
|
|
var ampl = attackAmplitude * t / attackTime;
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
t++;
|
|
count--;
|
|
}
|
|
} else if (t < decayTime) {
|
|
/* decay */
|
|
while(count && t < decayTime) {
|
|
var ampl = attackAmplitude - decayRate * (t - attackTime);
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
buf[offset++] += input[childOffset++] * ampl;
|
|
t++;
|
|
count--;
|
|
}
|
|
} else {
|
|
/* sustain */
|
|
while(count) {
|
|
buf[offset++] += input[childOffset++] * sustainAmplitude;
|
|
buf[offset++] += input[childOffset++] * sustainAmplitude;
|
|
t++;
|
|
count--;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
return self;
|
|
}
|
|
|
|
function midiToFrequency(note) {
|
|
return 440 * Math.pow(2, (note-69)/12);
|
|
}
|
|
|
|
PianoProgram = {
|
|
'attackAmplitude': 0.2,
|
|
'sustainAmplitude': 0.1,
|
|
'attackTime': 0.02,
|
|
'decayTime': 0.3,
|
|
'releaseTime': 0.02,
|
|
'createNote': function(note, velocity) {
|
|
var frequency = midiToFrequency(note);
|
|
return ADSRGenerator(
|
|
SineGenerator(frequency),
|
|
this.attackAmplitude * (velocity / 128), this.sustainAmplitude * (velocity / 128),
|
|
this.attackTime, this.decayTime, this.releaseTime
|
|
);
|
|
}
|
|
}
|
|
|
|
StringProgram = {
|
|
'createNote': function(note, velocity) {
|
|
var frequency = midiToFrequency(note);
|
|
return ADSRGenerator(
|
|
SineGenerator(frequency),
|
|
0.5 * (velocity / 128), 0.2 * (velocity / 128),
|
|
0.4, 0.8, 0.4
|
|
);
|
|
}
|
|
}
|
|
|
|
PROGRAMS = {
|
|
41: StringProgram,
|
|
42: StringProgram,
|
|
43: StringProgram,
|
|
44: StringProgram,
|
|
45: StringProgram,
|
|
46: StringProgram,
|
|
47: StringProgram,
|
|
49: StringProgram,
|
|
50: StringProgram
|
|
};
|
|
|
|
function Synth(sampleRate) {
|
|
|
|
var generators = [];
|
|
|
|
function addGenerator(generator) {
|
|
generators.push(generator);
|
|
}
|
|
|
|
function generate(samples) {
|
|
var data = new Array(samples*2);
|
|
generateIntoBuffer(samples, data, 0);
|
|
return data;
|
|
}
|
|
|
|
function generateIntoBuffer(samplesToGenerate, buffer, offset) {
|
|
for (var i = offset; i < offset + samplesToGenerate * 2; i++) {
|
|
buffer[i] = 0;
|
|
}
|
|
for (var i = generators.length - 1; i >= 0; i--) {
|
|
generators[i].generate(buffer, offset, samplesToGenerate);
|
|
if (!generators[i].alive) generators.splice(i, 1);
|
|
}
|
|
}
|
|
|
|
return {
|
|
'sampleRate': sampleRate,
|
|
'addGenerator': addGenerator,
|
|
'generate': generate,
|
|
'generateIntoBuffer': generateIntoBuffer
|
|
}
|
|
}
|