3.0 KiB
3.0 KiB
DEMO
MidiConvert makes it straightforward to work with MIDI files in Javascript. It uses midi-file-parser to decode MIDI files and jsmidgen to encode MIDI files.
//load a midi file
MidiConvert.load("path/to/midi.mid", function(midi){
console.log(midi)
})
Format
The data parsed from the midi file looks like this:
{
// the transport and timing data
header : {
bpm : Number, // the tempo, e.g. 120
timeSignature : [Number, Number], // the time signature, e.g. [4, 4],
PPQ : Number // the Pulses Per Quarter of the midi file
},
// an array of midi tracks
tracks : [
{
name : String, // the track name if one was given
notes : [
{
midi : Number, // midi number, e.g. 60
time : Number, // time in seconds
note : String, // note name, e.g. "C4"
velocity : Number, // normalized 0-1 velocity
duration : String // duration between noteOn and noteOff
}
],
//midi control changes
controlChanges : {
//if there are control changes in the midi file
'91' : [
{
number : Number // the cc number
time : Number, // time in seconds
value : Number // normalized 0-1
}
],
},
instrument : String //the instrument if one is given
}
]
}
Raw Midi Parsing
If you are using Node.js or have the raw binary string from the midi file, just use the parse method:
fs.readFile("test.mid", "binary", function(err, midiBlob){
if (!err){
var midi = MidiConvert.parse(midiBlob)
}
})
Encoding Midi
You can also create midi files from scratch of by modifying an existing file.
//create a new midi file
var midi = MidiConvert.create()
//add a track
midi.track()
//chain note events: note, time, duration
.note(60, 0, 2)
.note(63, 1, 2)
.note(60, 2, 2)
//write the output
fs.writeFileSync("output.mid", midi.encode(), "binary")
Tone.Part
The note data can be easily passed into Tone.Part
var synth = new Tone.PolySynth(8).toMaster()
MidiConvert.load("path/to/midi.mid", function(midi){
//make sure you set the tempo before you schedule the events
Tone.Transport.bpm.value = midi.bpm
//pass in the note events from one of the tracks as the second argument to Tone.Part
var midiPart = new Tone.Part(function(time, note){
//use the events to play the synth
synth.triggerAttackRelease(note.name, note.duration, time, note.velocity)
}, midi.tracks[0].notes).start()
//start the transport to hear the events
Tone.Transport.start()
})
Acknowledgment
MidiConvert uses midi-file-parser which is ported from jasmid for decoding MIDI data and and jsmidgen for encoding MIDI data.