npm install @tonejs/midi
Midi makes it straightforward to read and write MIDI files with Javascript. It uses midi-file for parsing and writing.
Node.js:
const { Midi } = require('@tonejs/midi')Typescript / ES6
import { Midi } from '@tonejs/midi'Browser
<script src="https://unpkg.com/@tonejs/midi"></script>const midi = new Midi()// load a midi file in the browser
const midi = await Midi.fromUrl("path/to/midi.mid")
//the file name decoded from the first track
const name = midi.name
//get the tracks
midi.tracks.forEach(track => {
//tracks have notes and controlChanges
//notes are an array
const notes = track.notes
notes.forEach(note => {
//note.midi, note.time, note.duration, note.name
})
//the control changes are an object
//the keys are the CC number
track.controlChanges[64]
//they are also aliased to the CC number's common name (if it has one)
track.controlChanges.sustain.forEach(cc => {
// cc.ticks, cc.value, cc.time
})
//the track also has a channel and instrument
//track.instrument.name
})The data parsed from the midi file looks like this:
{
// the transport and timing data
header: {
name: String, // the name of the first empty track,
// which is usually the song name
tempos: TempoEvent[], // the tempo, e.g. 120
timeSignatures: TimeSignatureEvent[], // the time signature, e.g. [4, 4],
PPQ: Number // the Pulses Per Quarter of the midi file
// this is read only
},
duration: Number, // the time until the last note finishes
// an array of midi tracks
tracks: [
{
name: String, // the track name if one was given
channel: Number, // channel
// the ID for this channel; 9 and 10 are
// reserved for percussion
notes: [
{
midi: Number, // midi number, e.g. 60
time: Number, // time in seconds
ticks: Number, // time in ticks
name: String, // note name, e.g. "C4",
pitch: String, // the pitch class, e.g. "C",
octave : Number, // the octave, e.g. 4
velocity: Number, // normalized 0-1 velocity
duration: Number, // duration in seconds between noteOn and noteOff
}
],
// midi control changes
controlChanges: {
// if there are control changes in the midi file
'91': [
{
number: Number, // the cc number
ticks: Number, // time in ticks
time: Number, // time in seconds
value: Number, // normalized 0-1
}
],
},
instrument: { // and object representing the program change events
number : Number, // the instrument number 0-127
family: String, // the family of instruments, read only.
name : String, // the name of the instrument
percussion: Boolean, // if the instrument is a percussion instrument
},
}
]
}If you are using Node.js or have the raw binary string from the midi file, just use the parse method:
const midiData = fs.readFileSync("test.mid")
const midi = new Midi(midiData)You can also create midi files from scratch or by modifying an existing file.
// create a new midi file
var midi = new Midi()
// add a track
const track = midi.addTrack()
track.addNote({
midi : 60,
time : 0,
duration: 0.2
})
.addNote({
name : 'C5',
time : 0.3,
duration: 0.1
})
.addCC({
number : 64,
value : 127,
time : 0.2
})
// write the output
fs.writeFileSync("output.mid", new Buffer(midi.toArray()))Thank you midi-file!
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