A MIDI file parser/writer using ArrayBuffers
JavaScript HTML
Latest commit 6bbd238 Feb 5, 2017 @nfroidure RIP Testling



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

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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.

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

npm install midifile --save

What it does

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

What it doesn't do

You can also find a very trivial MIDI player in the test folder.


// 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) {
} else {

// 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);


// 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);


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).


  • ArrayBuffer, DataView or their polyfills


  • 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.


Copyright Nicolas Froidure. MIT licence.