Documentation for writing MIDI files about midifile HOT 4 OPEN

Just a note: if you want to make changes to event.data then you also need to update the length property, otherwise it gets truncated to the old length:

if (event.subtype === 1) {
  event.data = "updated text here!".split("").map(ch => ch.charCodeAt(0));
  event.length = event.data.length;
}

from midifile.

I actually didn't document the MIDIFile write functions since i think it is still experimental. Feel free to document it, i'll accept any PR doing so.

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Here's an example of transforming a MIDI file, simplified from midiflip:

var MIDIFile = require("midifile");
var MIDIEvents = require("midievents");

var midiFile = new MIDIFile(inputArrayBuffer);

for(var track_index = 0; track_index < midiFile.tracks.length; track_index++){
	var events = midiFile.getTrackEvents(track_index);
	for(var i=0; i<events.length; i++){
		var event = events[i];
		if(event.type === MIDIEvents.EVENT_MIDI){
			if(event.subtype === MIDIEvents.EVENT_MIDI_NOTE_OFF || event.subtype === MIDIEvents.EVENT_MIDI_NOTE_ON){
				event.param1 = 127 - event.param1;
			}
		}
	}
	midiFile.setTrackEvents(track_index, events);
}

var outputArrayBuffer = midiFile.getContent();

There should be documentation for individual methods though.

from midifile.

@1j01 i like midiflip, a very good use of midifile ;). I'll try it soon.

On documentation, i know, shame on me but i do not ever use midifile, just wrote it cause i wanted to know if i could.

But the good news is that i merge PRs or even add rights to people wanted to get involved on it ;).

That said, the MIDI standards aren't changing that often and except documentation/tests/refactoring i don't think there is that much work.

I'll probably make an ES6 refactoring sometime and add JSDocs but can't tell when.

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