Skip to content

Latest commit

 

History

History
160 lines (139 loc) · 5.07 KB

README.md

File metadata and controls

160 lines (139 loc) · 5.07 KB
Raw

♬ MidiWriterJS

npm version Build Status

MidiWriterJS is a JavaScript library providing an API for generating expressive multi-track MIDI files.

Note that the master branch is in active development so if you're looking for a tried and true stable version please use the latest release.

Source Documentation

Install

npm install midi-writer-js

Getting Started

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

// Start with a new track
var track = new MidiWriter.Track();

// Define an instrument (optional):
track.addEvent(new MidiWriter.ProgramChangeEvent({instrument : 1}));

// Add some notes:
var note = new MidiWriter.NoteEvent({pitch:['C4', 'D4', 'E4'], duration: '4'});
track.addEvent(note);

// Generate a data URI
var write = new MidiWriter.Writer([track]);
console.log(write.dataUri());

Documentation

MidiWriter.Track()

  • addEvent({event}, mapFunction)
  • setTempo(tempo)
  • addText(text)
  • addCopyright(text)
  • addTrackName(text)
  • addInstrumentName(text)
  • addMarker(text)
  • addCuePoint(text)
  • addLyric(text)
  • setTimeSignature(numerator, denominator)

MidiWriter.NoteEvent({options})

The NoteEvent supports these options:

Name Type Description
pitch array An array of notes to be triggered. Can be a string or valid MIDI note code. Format for string is C#4. Pro tip: You can use the output from tonal functions to build scales, chords, intervals, etc. in this parameter.
duration string or array How long the note should sound.
  • 1 : whole
  • 2 : half
  • d2 : dotted half
  • 4 : quarter
  • d4 : dotted quarter
  • 8 : eighth
  • 8t : eighth triplet
  • d8 : dotted eighth
  • 16 : sixteenth
  • Tn : where n is an explicit number of ticks
If an array of durations is passed then the sum of the durations will be used.
wait string How long to wait before sounding note (rest). Takes same values as duration.
sequential boolean If true then array of pitches will be played sequentially as opposed to simulatanously. Default: false
velocity number How loud the note should sound, values 1-100. Default: 50
repeat number How many times this event should be repeated. Default: 1
channel number MIDI channel to use. Default: 1

MidiWriter.Writer([tracks])

The Writer class provides a few ways to output the file:

  • buildFile() Uint8Array
  • base64() string
  • dataUri() string
  • stdout() file stream (cli)

Hot Cross Buns

Here's an example of how everyone's favorite song "Hot Cross Buns" could be written. Note use of the mapping function passed as the second argument of addEvent(). This can be used to apply specific properties to all events. With some street smarts you could also use it for programmatic crescendos and other property 'animation'.

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

var track = new MidiWriter.Track();

track.addEvent([
			new MidiWriter.NoteEvent({pitch: ['E4','D4'], duration: '4'}),
			new MidiWriter.NoteEvent({pitch: ['C4'], duration: '2'}),
			new MidiWriter.NoteEvent({pitch: ['E4','D4'], duration: '4'}),
			new MidiWriter.NoteEvent({pitch: ['C4'], duration: '2'}),
			new MidiWriter.NoteEvent({pitch: ['C4', 'C4', 'C4', 'C4', 'D4', 'D4', 'D4', 'D4'], duration: '8'}),
			new MidiWriter.NoteEvent({pitch: ['E4','D4'], duration: '4'}),
			new MidiWriter.NoteEvent({pitch: ['C4'], duration: '2'})
	], function(event, index) {
    return {sequential:true};
  }
);

var write = new MidiWriter.Writer([track]);
console.log(write.dataUri());

VexFlow Integration

MidiWriterJS can export MIDI from VexFlow voices, though this feature is still experimental. Current usage is to use MidiWriter.VexFlow.trackFromVoice(voice) to create a MidiWriterJS Track object:

// ...VexFlow code defining notes
var voice = create_4_4_voice().addTickables(notes);

var track = MidiWriter.VexFlow.trackFromVoice(voice);
var writer = new MidiWriter.Writer([track]);
console.log(writer.dataUri());