midifile

Read/write standard MIDI files.

MIDIFile

MIDIFile is a project intended to read/write standard MIDI files with JavaScript. MIDIFile is fully tested with the 3 existing MIDI formats.

MIDIFile can be used either in modern browsers (pick the last bundle) or with NodeJS by installing the following NPM module :

npm install midifile

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.

You can also find a Karaoke MIDI player based on MIDIFile and a very trivial MIDI player in the test folder.

Browser support

Usage

// Your variable with a ArrayBuffer instance containing your MIDI file 
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()===MIDIFileHeader.TICKS_PER_BEAT) {
    midiFile.header.getTicksPerBit();
} 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();
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 trackEventsChunk=midiFile.tracks[0].getTrackEvents(),
    events=new MIDIFile.createParser(trackEventsChunk),
    event;
while(event=events.next()) {
    // Printing meta events containing text only 
    if(event.type===MIDIFile.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 ar the best way to manage binary datas like MIDI files.

Why not streams ?

The Standard MIDI files format isn't streamable by nature. If you want to stream midifile 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

Copyright Nicolas Froidure 2013. MIT licence.