ChannelMergerNode

The ChannelMergerNode interface, often used in conjunction with its opposite, ChannelSplitterNode, reunites different mono inputs into a single output. Each input is used to fill a channel of the output. This is useful for accessing each channels separately, e.g. for performing channel mixing where gain must be separately controlled on each channel.

If ChannelMergerNode has one single output, but as many inputs as there are channels to merge; the number of inputs is defined as a parameter of its constructor and the call to AudioContext.createChannelMerger. In the case that no value is given, it will default to 6.

Using a ChannelMergerNode, it is possible to create outputs with more channels than the rendering hardware is able to process. In that case, when the signal is sent to the AudioContext.listener object, supernumerary channels will be ignored.

Number of inputs variable; default to 6.
Number of outputs 1
Channel count mode "max"
Channel count 2 (not used in the default count mode)
Channel interpretation "speakers"

Constructor

ChannelMergerNode()
Creates a new ChannelMergerNode object instance.

Properties

No specific property; inherits properties from its parent, AudioNode.

Methods

No specific method; inherits methods from its parent, AudioNode.

Example

The following example shows how you could separate a stereo track (say, a piece of music), and process the left and right channel differently. To use them, you need to use the second and third parameters of the AudioNode.connect(AudioNode) method, which allow you to specify both the index of the channel to connect from and the index of the channel to connect to.

var ac = new AudioContext();
ac.decodeAudioData(someStereoBuffer, function(data) {
 var source = ac.createBufferSource();
 source.buffer = data;
 var splitter = ac.createChannelSplitter(2);
 source.connect(splitter);
 var merger = ac.createChannelMerger(2);

 // Reduce the volume of the left channel only
 var gainNode = ac.createGain();
 gainNode.gain.setValueAtTime(0.5, ac.currentTime);
 splitter.connect(gainNode, 0);

 // Connect the splitter back to the second input of the merger: we
 // effectively swap the channels, here, reversing the stereo image.
 gainNode.connect(merger, 0, 1);
 splitter.connect(merger, 1, 0);

 var dest = ac.createMediaStreamDestination();

 // Because we have used a ChannelMergerNode, we now have a stereo
 // MediaStream we can use to pipe the Web Audio graph to WebRTC,
 // MediaRecorder, etc.
 merger.connect(dest);
});

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 14Edge Full support YesFirefox Full support 25IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes
ChannelMergerNode() constructorChrome Full support 55Edge ? Firefox Full support 53IE No support NoOpera Full support 42Safari ? WebView Android Full support 55Chrome Android Full support 55Edge Mobile ? Firefox Android Full support 53Opera Android Full support 42Safari iOS ? Samsung Internet Android Full support 6.0

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown

See also

Document Tags and Contributors

Last updated by: sideshowbarker,