node-sdl-mixer-multi-channels-player

The purpose of node-sdl-mixer-multi-channels-player is to allow mono sound routing through any channel (left or right only) of any audio devices, in order to create audio automation devices.

node-sdl-mixer-multi-channels-player contains a NodeJS C++ addon to drive SDL2_Mixer.

Due to SDL2_Mixer limitations, you can only play WAV files but more formats could be supported through libraries like node-lame wich can convert MP3 to WAV.

Installation

yarn add node-sdl-mixer-multi-channels-player

or

npm install --save node-sdl-mixer-multi-channels-player

Usage

Create a player

Create a multi-channel player :

const MultiChannelsPlayer = require('sdl-mixer-multi-channels-player')

const channels = new MultiChannelsPlayer({
  channels: [
    {channel: MultiChannelsPlayer.LEFT},
    {channel: MultiChannelsPlayer.RIGHT}  // Right
  ]
})

This player can dispatch sound to the system default audio device left or right channels.

Dispatch sound

To dispatch sound to a specific sound device, put deviceName in channels :

const player = new MultiChannelsPlayer({
  channels: [
    {deviceName: 'Built-in Output', channel: MultiChannelsPlayer.LEFT},
    {deviceName: 'Built-in Output', channel: MultiChannelsPlayer.RIGHT},
    {deviceName: 'USB audio CODEC', channel: MultiChannelsPlayer.LEFT},
    {deviceName: 'USB audio CODEC', channel: MultiChannelsPlayer.RIGHT}
  ]
})

List sound devices

You may want to list your available sound devices names:

console.log(MultiChannelsPlayer.availableDevices())

Play a sound from file

The player can play WAV sound files only !

const file = 'test.wav'
player.playFile(0, file)

0 here means that you want to play test.wav through the first channel which is LEFT channel of Built-in Output.

If you play a file through a busy channel, the sound playing will be stopped and the new one will be play.

Stopping sound

To stop, just call stop(channel_id)

player.playFile(0, file)
// Stop after 1s
setTimeout(() => { player.stop(0) }, 1000)

Check if channel is playing sound (busy)

// Check if channel 0 is playing sound
console.log(player.playing(0) ? 'Playing' : 'Not playing')

Log events for debug

If you want to log the channels states:

const player = new MultiChannelsPlayer({
  channels: [
    {
      deviceName: 'Built-in Output',
      channel: MultiChannelsPlayer.LEFT,
      debug: true
    }
  ]
})

Every actions executed by the channel will be log to STDOUT. If you want to use a custom logger :

const player = new MultiChannelsPlayer({
  channels: [
    {
      deviceName: 'Built-in Output',
      channel: MultiChannelsPlayer.LEFT,
      debug: true,
      logger: (...args) => {
        console.log('[Defaut::Ch.1]', ...args)
      }
    }
  ]
})

Play sound from buffer

The player can play WAV sound buffer.

const fs = require('fs')
const buffer = Buffer.from(fs.readFileSync(file))
player.playBuffer(1, buffer)

We've created a buffer from a WAV file. It's not very useful here. But you could use node-lame to create a WAV buffer from a MP3 file !!!

const Lame = require('node-lame').Lame
const decoder = new Lame({
  'output': 'buffer'
}).setFile('my-sound.mp3')

decoder.decode()
  .then(() => {
    player.playBuffer(0, decoder.getBuffer())
  })

Author

René BIGOT

License

MIT : http://opensource.org/licenses/MIT