BaseAudioContext: createChannelMerger() method
The createChannelMerger()
method of the BaseAudioContext
interface creates a ChannelMergerNode
,
which combines channels from multiple audio streams into a single audio stream.
Note: The ChannelMergerNode()
constructor is the
recommended way to create a ChannelMergerNode
; see
Creating an AudioNode.
Syntax
createChannelMerger(numberOfInputs)
Parameters
numberOfInputs
-
The number of channels in the input audio streams, which the output stream will contain; the default is 6 if this parameter is not specified.
Return value
Examples
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.
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-createchannelmerger |
Browser compatibility
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