seq-emitter

EventEmitter for Web Audio API sequencer

Installation

$ npm install seq-emitter

API

SeqEmitter

• constructor(tracks: Iterator[], config = {})
  • configuration for WebAudioScheduler
    • config.context: AudioContext
    • config.interval: number
    • config.aheadTime: number
    • config.timerAPI: global

Instance attribute

• scheduler: WebAudioScheduler
• state: string
  • "suspended"
  • "running"
  • "closed"

Instance methods

Also implements methods from the interface EventEmitter.

• start([ t0: number ]): void
• stop([ t0: number ]): void

Events

• * / Emitted when a scheduled item.
  • type: string
  • playbackTime: number
  • trackNumber: number
  • assign properties that defined on an iterator
• end:all / Emitted when all iterators will be no more data to read.
  • type: "end:all"
  • playbackTime: number
• statechange / Emitted when state changed.
  • type: "statechange"
  • playbackTime: number
  • state: string

Examples

import SeqEmitter from "seq-emitter";

let musicIterator = [
  { type: "note", time: 0.00, noteNumber:  88 },
  { type: "note", time: 0.15, noteNumber:  91 },
  { type: "note", time: 0.30, noteNumber: 100 },
  { type: "note", time: 0.45, noteNumber:  96 },
  { type: "note", time: 0.60, noteNumber:  98 },
  { type: "note", time: 0.75, noteNumber: 103 },
  { type: "end", time: 0.9 },
][Symbol.iterator]();

let audioContext = new AudioContext();
let sequencer = new SeqEmitter([ musicIterator ], { context: audioContext });

sequencer.on("note", (e) => {
  console.log(JSON.stringify(e, null, 2));
});

sequencer.start(audioContext.currentTime);

License

MIT