node-libao

Node.js libao bindings, output PCM data to the speakers.

A Writable stream instance that accepts PCM audio data and outputs it to the speakers. The output is backed by libao, which supports a ton of audio backends.

This module is very much based on the awesome node-speaker.

Installation

You need libao installed on your system before installig node-libao.

• Debian

$ apt-get install libao-dev

• OSX:

$ brew install libao

Now, simply compile and install node-libao using npm:

$ npm install libao

A few examples

var libao = require('libao');

// Create the libao instance
var ao = new libao({
  channels: 2,          // 2 channels
  bitDepth: 16,         // 16-bit samples
  sampleRate: 44100     // 44,100 Hz sample rate
});

// PCM data from stdin gets piped into the speaker
process.stdin.pipe(ao);

var fs = require('fs');
var wav = require('wav');
var libao = require('libao');

var file = fs.createReadStream(filepath);

var reader = new wav.Reader();
reader.on('format', function (format) {
  reader.pipe(new libao(fmt));
});

file.pipe(reader);

API

require('libao') directly returns the libao constructor. It is the only interface exported by the module.

new libao([ format ]) -> libao instance;

Creates a new libao instance, which is a writable stream that you can pipe PCM audio data to. The optional format object may contain any of the Writable base class options, as well as any of these PCM formatting options:

• channels - The number of audio channels. PCM data must be interleaved. Defaults to 2.
• bitDepth - The number of bits per sample. Defaults to 16 (16-bit).
• sampleRate - The number of samples per second per channel. Defaults to 44100.

"open" event

Fired when the backend open() call has completed. This happens once the first write() call happens on the ao instance.

"close" event

Fired after the "flush" event, after the backend close() call has completed. This ao instance is essentially finished after this point.