diff options
Diffstat (limited to 'Processing-js/libs/inc/jasmid/midifile.js')
| -rw-r--r-- | Processing-js/libs/inc/jasmid/midifile.js | 238 |
1 files changed, 238 insertions, 0 deletions
diff --git a/Processing-js/libs/inc/jasmid/midifile.js b/Processing-js/libs/inc/jasmid/midifile.js new file mode 100644 index 0000000..5e60e79 --- /dev/null +++ b/Processing-js/libs/inc/jasmid/midifile.js @@ -0,0 +1,238 @@ +/* +class to parse the .mid file format +(depends on stream.js) +*/ +function MidiFile(data) { + function readChunk(stream) { + var id = stream.read(4); + var length = stream.readInt32(); + return { + 'id': id, + 'length': length, + 'data': stream.read(length) + }; + } + + var lastEventTypeByte; + + function readEvent(stream) { + var event = {}; + event.deltaTime = stream.readVarInt(); + var eventTypeByte = stream.readInt8(); + if ((eventTypeByte & 0xf0) == 0xf0) { + /* system / meta event */ + if (eventTypeByte == 0xff) { + /* meta event */ + event.type = 'meta'; + var subtypeByte = stream.readInt8(); + var length = stream.readVarInt(); + switch(subtypeByte) { + case 0x00: + event.subtype = 'sequenceNumber'; + if (length != 2) throw "Expected length for sequenceNumber event is 2, got " + length; + event.number = stream.readInt16(); + return event; + case 0x01: + event.subtype = 'text'; + event.text = stream.read(length); + return event; + case 0x02: + event.subtype = 'copyrightNotice'; + event.text = stream.read(length); + return event; + case 0x03: + event.subtype = 'trackName'; + event.text = stream.read(length); + return event; + case 0x04: + event.subtype = 'instrumentName'; + event.text = stream.read(length); + return event; + case 0x05: + event.subtype = 'lyrics'; + event.text = stream.read(length); + return event; + case 0x06: + event.subtype = 'marker'; + event.text = stream.read(length); + return event; + case 0x07: + event.subtype = 'cuePoint'; + event.text = stream.read(length); + return event; + case 0x20: + event.subtype = 'midiChannelPrefix'; + if (length != 1) throw "Expected length for midiChannelPrefix event is 1, got " + length; + event.channel = stream.readInt8(); + return event; + case 0x2f: + event.subtype = 'endOfTrack'; + if (length != 0) throw "Expected length for endOfTrack event is 0, got " + length; + return event; + case 0x51: + event.subtype = 'setTempo'; + if (length != 3) throw "Expected length for setTempo event is 3, got " + length; + event.microsecondsPerBeat = ( + (stream.readInt8() << 16) + + (stream.readInt8() << 8) + + stream.readInt8() + ) + return event; + case 0x54: + event.subtype = 'smpteOffset'; + if (length != 5) throw "Expected length for smpteOffset event is 5, got " + length; + var hourByte = stream.readInt8(); + event.frameRate = { + 0x00: 24, 0x20: 25, 0x40: 29, 0x60: 30 + }[hourByte & 0x60]; + event.hour = hourByte & 0x1f; + event.min = stream.readInt8(); + event.sec = stream.readInt8(); + event.frame = stream.readInt8(); + event.subframe = stream.readInt8(); + return event; + case 0x58: + event.subtype = 'timeSignature'; + if (length != 4) throw "Expected length for timeSignature event is 4, got " + length; + event.numerator = stream.readInt8(); + event.denominator = Math.pow(2, stream.readInt8()); + event.metronome = stream.readInt8(); + event.thirtyseconds = stream.readInt8(); + return event; + case 0x59: + event.subtype = 'keySignature'; + if (length != 2) throw "Expected length for keySignature event is 2, got " + length; + event.key = stream.readInt8(true); + event.scale = stream.readInt8(); + return event; + case 0x7f: + event.subtype = 'sequencerSpecific'; + event.data = stream.read(length); + return event; + default: + // console.log("Unrecognised meta event subtype: " + subtypeByte); + event.subtype = 'unknown' + event.data = stream.read(length); + return event; + } + event.data = stream.read(length); + return event; + } else if (eventTypeByte == 0xf0) { + event.type = 'sysEx'; + var length = stream.readVarInt(); + event.data = stream.read(length); + return event; + } else if (eventTypeByte == 0xf7) { + event.type = 'dividedSysEx'; + var length = stream.readVarInt(); + event.data = stream.read(length); + return event; + } else { + throw "Unrecognised MIDI event type byte: " + eventTypeByte; + } + } else { + /* channel event */ + var param1; + if ((eventTypeByte & 0x80) == 0) { + /* running status - reuse lastEventTypeByte as the event type. + eventTypeByte is actually the first parameter + */ + param1 = eventTypeByte; + eventTypeByte = lastEventTypeByte; + } else { + param1 = stream.readInt8(); + lastEventTypeByte = eventTypeByte; + } + var eventType = eventTypeByte >> 4; + event.channel = eventTypeByte & 0x0f; + event.type = 'channel'; + switch (eventType) { + case 0x08: + event.subtype = 'noteOff'; + event.noteNumber = param1; + event.velocity = stream.readInt8(); + return event; + case 0x09: + event.noteNumber = param1; + event.velocity = stream.readInt8(); + if (event.velocity == 0) { + event.subtype = 'noteOff'; + } else { + event.subtype = 'noteOn'; + } + return event; + case 0x0a: + event.subtype = 'noteAftertouch'; + event.noteNumber = param1; + event.amount = stream.readInt8(); + return event; + case 0x0b: + event.subtype = 'controller'; + event.controllerType = param1; + event.value = stream.readInt8(); + return event; + case 0x0c: + event.subtype = 'programChange'; + event.programNumber = param1; + return event; + case 0x0d: + event.subtype = 'channelAftertouch'; + event.amount = param1; + return event; + case 0x0e: + event.subtype = 'pitchBend'; + event.value = param1 + (stream.readInt8() << 7); + return event; + default: + throw "Unrecognised MIDI event type: " + eventType + /* + console.log("Unrecognised MIDI event type: " + eventType); + stream.readInt8(); + event.subtype = 'unknown'; + return event; + */ + } + } + } + + stream = Stream(data); + var headerChunk = readChunk(stream); + if (headerChunk.id != 'MThd' || headerChunk.length != 6) { + throw "Bad .mid file - header not found"; + } + var headerStream = Stream(headerChunk.data); + var formatType = headerStream.readInt16(); + var trackCount = headerStream.readInt16(); + var timeDivision = headerStream.readInt16(); + + if (timeDivision & 0x8000) { + throw "Expressing time division in SMTPE frames is not supported yet" + } else { + ticksPerBeat = timeDivision; + } + + var header = { + 'formatType': formatType, + 'trackCount': trackCount, + 'ticksPerBeat': ticksPerBeat + } + var tracks = []; + for (var i = 0; i < header.trackCount; i++) { + tracks[i] = []; + var trackChunk = readChunk(stream); + if (trackChunk.id != 'MTrk') { + throw "Unexpected chunk - expected MTrk, got "+ trackChunk.id; + } + var trackStream = Stream(trackChunk.data); + while (!trackStream.eof()) { + var event = readEvent(trackStream); + tracks[i].push(event); + //console.log(event); + } + } + + return { + 'header': header, + 'tracks': tracks + } +}
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