multi-channel-web-audio

Multi Channel Web Audio

Provides a convenient audio engine that can route sounds to specific speakers in a multi-channel (more than 2 speakers) environment.

Setup

Install

npm i multi-channel-web-audio

Import

import MultiChannelPlayer from "multi-channel-web-audio";

or

const MultiChannelPlayer = require("multi-channel-web-audio");

Usage

Make a player instance

Instantiate with the number of speakers you expect to route. For example, here's a 4 channel setup:

const player = new MultiChannelPlayer(4);

Load a sample bank

Call loadSamples and provide a sample bank object, where each key is a string naming the sample, and the corresponding value is the path to the source file. This happens asynchronously (fetches files and loads array buffers), so the result is a Promise.

For example:

player.loadSamples({
  beep: "/samples/beep.mp3",
  toot: "/samples/toot-toot.mp3"
}).then(() => {
  console.log('yay my samples loaded');
  // now you can play them
}).catch(e => {
  console.error('something went wrong loading samples: ', e);
});

Trigger samples

Specify the sample key (it must exist in your SourceMap, and it must have been loaded already); then specify the channel (speaker) you want it to play from. Example:

player.play("beep", 2); // plays out of speaker index 2 (third speaker)

Optional variations

You can pass a third parameter to play if you like: a PlaybackOptions object, specifying any or all of the following:

{
  loop?: boolean = false;
  rateVariation?: number = 0;
  volumeVariation?: number 0;
  volumeMax?: number = 1.0;
  exclusive?: boolean = false;
}

The rate and volume variations work in similar way. By default, 0 variation will mean that rate is 1.0 or volume is always maximum (1.0 or a value specified in volumeMax).

Specifying another value will allow random variation above or below "normal" up to the range you specify. Example:

player.play("annoyingSound", 0, {
  rateVariation: 0.5
});
// Sound will play in range 0.5x - 1.5x normal speed.

Rate variation will affect the pitch, too.

Pick a sound from a list

You might want to have multiple samples to randomly pick from on a single sound "event". Kind of like an audio "sprite sheet". In that case, supply an array of keys instead of a single key string:

player.play(["beep", "boop", "bahp"], 0);
// You will randomly hear either "beep", "boop" or "bahp" sample each time this is called.

Development

The library is written in TypeScript so compiles with npm run build

You can also run a small browser demo to test again, with npm run example