xen-midi

Free-pitch polyphonic MIDI I/O based on webmidi.js using multi-channel pitch-bend.

Installation

Install the package from npm:

npm install xen-midi

Documentation

API docs are generated with TypeDoc from the source comments in src/index.ts and published at the project GitHub Pages site:

• https://xenharmonic-devs.github.io/xen-midi

To regenerate TypeDoc locally:

npm run doc

This command writes documentation output to docs/.

Example

import {WebMidi} from 'webmidi';
import {MidiOut} from 'xen-midi';

async function play() {
  await WebMidi.enable();

  // Set maximum microtonal polyphony to 4 (the number of channels reserved).
  const channels = new Set([1, 2, 3, 4]);
  const midiOut = new MidiOut(WebMidi.outputs[0], channels);

  // Play a just intonation 4:5:6 major chord.
  midiOut.playNotes([
    {
      frequency: 440,
      rawAttack: 80,
      rawRelease: 80,
      time: '+0',
      duration: 500,
    },
    // Attack and release default to 64.
    {
      frequency: 550,
      time: '+100',
      duration: 500,
    },
    {
      frequency: 660,
      time: '+200',
      duration: 500,
    },
  ]);
}

play();

Note fields used in playNotes

• frequency: frequency in Hertz (Hz)
• rawAttack: attack velocity from 0 to 127 (optional, defaults to 64)
• rawRelease: release velocity from 0 to 127 (optional, defaults to 64)
• time: note-on time in milliseconds; use '+N' for a delay of N ms from now
• duration: note length in milliseconds (ms)

API overview

The library exports:

• BEND_RANGE_IN_SEMITONES
• MidiOut
• MidiIn
• midiKeyInfo
• Type aliases: Voice, Note, NoteOff, NoteOnCallback, MidiKeyInfo