The copyFromChannel() method of the AudioBuffer interface copies the audio sample data from the specified channel of the AudioBuffer to a specified Float32Array.


myArrayBuffer.copyFromChannel(destination, channelNumber, startInChannel);


A Float32Array to copy the channel's samples to.
The channel number of the current AudioBuffer to copy the channel data from.
startInChannel Optional
An optional offset into the source channel's buffer from which to begin copying samples. If not specified, a value of 0 (the beginning of the buffer) is assumed by default.

Return value



One of the input parameters has a value that is outside the accepted range:
  • The value of channelNumber specifies a channel number which doesn't exist (that is, it's greater than or equal to the value of numberOfChannels on the channel).
  • The value of startInChannel is outside the current range of samples that already exist in the source buffer; that is, it's greater than its current length.


This example creates a new audio buffer, then copies the samples from another channel into it.

var myArrayBuffer = audioCtx.createBuffer(2, frameCount, audioCtx.sampleRate);  
var anotherArray = new Float32Array(length);
myArrayBuffer.copyFromChannel(anotherArray, 1, 0);


Specification Status Comment
Web Audio API
The definition of 'copyFromChannel' in that specification.
Working Draft  

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
copyFromChannelChrome Full support 43Edge Full support 13Firefox Full support 25IE No support NoOpera Full support 30Safari No support NoWebView Android Full support 43Chrome Android Full support 43Firefox Android Full support 26Opera Android Full support 30Safari iOS No support NoSamsung Internet Android Full support 4.0


Full support  
Full support
No support  
No support

See also