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BaseAudioContext: createChannelSplitter() method

The createChannelSplitter() method of the BaseAudioContext Interface is used to create a ChannelSplitterNode, which is used to access the individual channels of an audio stream and process them separately.

Note: The ChannelSplitterNode() constructor is the recommended way to create a ChannelSplitterNode; see Creating an AudioNode.

Syntax

createChannelSplitter(numberOfOutputs)

Parameters

numberOfOutputs: The number of channels in the input audio stream that you want to output separately; the default is 6 if this parameter is not specified.

Return value

A ChannelSplitterNode.

Examples

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.

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

  // Reduce the volume of the left channel only
  const 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);

  const 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
Web Audio API # dom-baseaudiocontext-createchannelsplitter

Browser compatibility