A fast cross-browser riff wave encoder for real-time audio synthesis in HTML5
Switch branches/tags
Nothing to show
Clone or download
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Permalink
Failed to load latest commit information.
README.md
wavencoder.js

README.md

WavEncoder

WavEncoder is a fast cross-browser riff wave encoder for real-time audio synthesis in HTML5. Works in Web Workers and in the main window (in contrast to encoders using window.btoa).

Dual licensed under the MIT or GPL Version 2 licenses.

Examples

To play 1 sec of noise in the main window, we can

<script type='text/javascript' src='wavencoder.js'></script>
<script type='text/javascript'>

  var samples = [];
  for (var t = 0; t < 22050; ++t) {
    samples[t] = 2 * Math.random() - 1;  // in the interval [-1,1]
  }

  var datauri = WavEncoder.encode(samples);
  var audio = new Audio(datauri);

  document.onload(function(){ audio.play(); });

</script>

WavEncoder objects are optimized to create many samples of the same length. A typical use case is to generate a set of tones, say in a web worker

includeScripts('wavencoder.js');

var sampleRateHz = 44100;
var numSamples = 1 * sampleRateHz;                 // 1 sec
var baseFreq = 2 * Math.PI * 27.5 / sampleRateHz;  // A0

var wavEncoder = new WavEncoder(numSamples, {sampleRateHz: sampleRateHz});

var tones = [];
var samples = [];
for (var n = 0; n < 88; ++n) {

  var freq = baseFreq * Math.pow(2, n/12);
  for (var t = 0; t < numSamples; ++t) {
    samples[t] = Math.sin(freq * t);
  }

  tones[n] = wavEncoder.encode(samples);
}

postMessage(tones);