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

NPM version Build status Dependency Status devDependency Status Coverage Status

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.

Browser support

Build Status


// 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]( 
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.getTrackEvents(0);
var events = new MIDIFile.createParser(trackEventsChunk);
var event;
while( {
    // Printing meta events containing text only 
    if(event.type === MIDIFile.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.