Web/API/AudioBuffer/numberOfChannels

The numberOfChannels property of the AudioBuffer interface returns an integer representing the number of discrete audio channels described by the PCM data stored in the buffer.

Syntax

var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
myArrayBuffer.numberOfChannels;

Value

An integer.

Example

// Stereo
var channels = 2;

// Create an empty two second stereo buffer at the
// sample rate of the AudioContext
var frameCount = audioCtx.sampleRate * 2.0;
var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);

button.onclick = function() {
  // Fill the buffer with white noise;
  // just random values between -1.0 and 1.0
  for (var channel = 0; channel < channels; channel++) {
    // This gives us the actual ArrayBuffer that contains the data
    var nowBuffering = myArrayBuffer.getChannelData(channel);
    for (var i = 0; i < frameCount; i++) {
      // Math.random() is in [0; 1.0]
      // audio needs to be in [-1.0; 1.0]
      nowBuffering[i] = Math.random() * 2 - 1;
    }
  }

  console.log(myArrayBuffer.numberOfChannels);
}

Specification

Specification	Status	Comment
Web Audio APIThe definition of 'numberOfChannels' in that specification.	Working Draft

Browser compatibility

The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
numberOfChannels	Chrome Full support 14	Edge Full support 12	Firefox Full support 25	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support 6	Samsung Internet Android Full support 1.0

Legend

Full support  

Full support

No support  

No support

See also

• Using the Web Audio API

AudioBuffer.numberOfChannels by Mozilla Contributors is licensed under CC-BY-SA 2.5.