Javascript: How to Export a MIDI File?

Question

I am new to working with MIDI in my javascript code, and I would like to create an application that simply generates a MIDI file based on the user's input. I have looked at using MIDI.js, but I'm not sure if I need any of the library. Ideally, I would like to be able to work with note values rather than hexadecimal MIDI codes... would I need to use the converter within plugin.js?

My current research has indicated that generated soundfonts are the suggested way to go; however, I would like to export/generate a MIDI file for use in a professional DAW.

Thanks for any help.

Answer 1

You can use a library I found called MidiWriterJS.

It is very easy to use:

Step 1: Install

The easiest way to insall is to use npm.

$ npm install midi-writer-js

Then

var MidiWriter = require('midi-writer-js');

Step 2: Create an array of tracks and add notes

var tracks = [];
for(t of <your existing track array>){
    var notes = [];
    for(n of <your existing note array for the track>){
        notes.push(new MidiWriter.NoteEvent({pitch: <array of all notes in the chord>, duration: <how long the chord should last>});
    }
    var newTrack = new MidiWriter.Track();
    newTrack.addEvent(notes, function(event, index){ return {sequential: true}; });
    tracks.push(newTrack);
}

Step 3: Export the MIDI Data

var writer = new MidiWriter.Writer(tracks);
writer.saveMIDI(<filename>);