midifile

Read/write standard MIDI files.

MIDIFile uses the MIDIEvents project and is part of the MIDIPlayer one. You can also check this Karaoke Player built on top of those libraries.

What it does

• Read MIDI files
• Check MIDI file structure (using strictMode)
• Write MIDI files (still experimental)

What it doesn't do

• Playing MIDI files. It's the role of the MIDIPlayer project.

Usage

// Your variable with your MIDI file as an ArrayBuffer or UInt8Array instance
var anyBuffer;
 
// Creating the MIDIFile instance
var midiFile = new MIDIFile(anyBuffer);
 
// Reading headers
midiFile.header.getFormat(); // 0, 1 or 2
midiFile.header.getTracksCount(); // n
// Time division
if(midiFile.header.getTimeDivision() === MIDIFile.Header.TICKS_PER_BEAT) {
    midiFile.header.getTicksPerBeat();
} else {
    midiFile.header.getSMPTEFrames();
    midiFile.header.getTicksPerFrame();
}
 
// MIDI events retriever
var events = midiFile.getMidiEvents();
events[0].subtype; // type of [MIDI event](https://github.com/nfroidure/MIDIFile/blob/master/src/MIDIFile.js#L34)
events[0].playTime; // time in ms at wich the event must be played
events[0].param1; // first parameter
events[0].param2; // second one
 
// Lyrics retriever
var lyrics = midiFile.getLyrics();
if ( lyrics.length ) {
    lyrics[0].playTime; // Time at wich the text must be displayed
    lyrics[0].text; // The text content to be displayed
}
 
// Reading whole track events and filtering them yourself
var events = midiFile.getTrackEvents(0);
 
events.forEach(console.log.bind(console));
 
// Or for a single track
var trackEventsChunk = midiFile.tracks[0].getTrackContent();
var events = MIDIEvents.createParser(trackEventsChunk);
 
var event;
while(event = events.next()) {
    // Printing meta events containing text only
    if(event.type === MIDIEvents.EVENT_META && event.text) {
        console.log('Text meta: '+event.text);
    }
}

Testing

Unit tests are using mocha and NodeJS. Install them and run the following command:

mocha tests/*.mocha.js

Why ArrayBuffers ?

ArrayBuffer instances are the best way to manage binary data like MIDI files.

Why not streams ?

The Standard MIDI files format isn't streamable by nature. If you want to stream MIDI file contents, you should consider transforming your files in another format (plain linearized MIDI events should do the job).

Requirements

• ArrayBuffer, DataView or their polyfills

Contributing

• Feel free to PR
• If you find a MIDI File the library can't read an if it's under a free, PR the file in the sounds folder and add tests for him. I'll work on it asap.

License

MIT