Multi Channel Web Audio

Provides a convenient system for the browser-based Web Audio API, for routing sounds to specific speakers in a multi-channel environment. It works for 2 speakers (stereo) but becomes much more useful for environments with more channels.

The idea is to facilitate mono audio sources in multi-channel setups without having to pre/re mix anything for standard "surround sound" systems.

Setup

Install

npm i multi-channel-web-audio

Import the player, specifying the number of channels you intend to output to:

import MultiChannelPlayer from "multi-channel-web-audio";
const player = MultiChannelPlayer.setup(4);

Load a sample so it's ready for playback and control (async):

const mySample = await player.loadSample("/someSampleURL.mp3");

Play samples on specific channel

Call .playOnChannel() for any sample already loaded, e.g:

mysample.playOnChannel(2); // plays out of speaker index 2 (third speaker) ONLY

Optional playback configuration

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

• loop boolean (default: false) - whether to loop the sample or play just once through
• rate: number (default 1.0) - playback speed multiplier (affects pitch)
• volume: number (default 1.0) - target "full" volume, from 0 (silence) to full volume (1.0)
• fadeInDuration: number (default 0) - how long (in ms) to fade in; only applies for play/start operations
• fadeOutDuration: number (default 0) - how long (in ms) to fade out; only applies for stop operations

Example

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

This example uses just 2 channels, to suit most test environments. Two channels obviously doesn't demonstrate the full potential of this library but does show you how to use it.

Development

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

TODO

• Remove all random picking, random variations (outside the scope of this library; should be handled by client library/application)
• Revisit "applyDefaults" mechanism / types
• Create a class for Sample (BufferedSample) which keeps track of its own state
• Check that progress/duration is accurate when rate is not 1.0
• It should be possible to play sample multiple times simultaneously (currently, "exclusive" mode prevents strange issues)
• Should be possible to play sample via multiple channels (same volume)
• Should be possible to play sample with custom "panning" between multiple channels (pseudo-spatialised audio)