ChannelSplitterNode

The ChannelSplitterNode interface, often used in conjunction with its opposite, ChannelMergerNode, separates the different channels of an audio source into a set of mono outputs. This is useful for accessing each channel separately, e.g. for performing channel mixing where gain must be separately controlled on each channel.

If your ChannelSplitterNode always has one single input, the amount of outputs is defined by a parameter on its constructor and the call to AudioContext.createChannelSplitter(). In the case that no value is given, it will default to 6. If there are fewer channels in the input than there are outputs, supernumerary outputs are silent.

Constructor

ChannelSplitterNode()

Creates a new ChannelSplitterNode 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 simple 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 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

Browser compatibility

See also

• Using the Web Audio API