index.html

---
title: AudioBuffer.numberOfChannels
slug: Web/API/AudioBuffer/numberOfChannels
tags:
- API
- AudioBuffer
- Property
- Reference
- Web Audio API
- numberOfChannels
browser-compat: api.AudioBuffer.numberOfChannels
---
<p>{{ APIRef("Web Audio API") }}</p>

<div>
  <p>The <code>numberOfChannels</code> property of the {{ domxref("AudioBuffer") }}
    interface returns an integer representing the number of discrete audio channels
    described by the PCM data stored in the buffer.</p>
</div>

<h2 id="Syntax">Syntax</h2>

<pre class="brush: js">var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);
myArrayBuffer.numberOfChannels;</pre>

<h3 id="Value">Value</h3>

<p>An integer.</p>

<h2 id="Example">Example</h2>

<pre class="brush: js;">// 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 &lt; channels; channel++) {
    // This gives us the actual ArrayBuffer that contains the data
    var nowBuffering = myArrayBuffer.getChannelData(channel);
    for (var i = 0; i &lt; 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);
}</pre>

<h2 id="Specifications">Specifications</h2>

{{Specifications}}

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>{{Compat}}</p>

<h2 id="See_also">See also</h2>

<ul>
  <li><a href="/en-US/docs/Web/API/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio
      API</a></li>
</ul>