ScriptProcessorNode: audioprocess event

The audioprocess event of the ScriptProcessorNode interface is fired when an input buffer of a script processor is ready to be processed.

[!NOTE] This feature was replaced by AudioWorklets and the AudioWorkletNode interface.

This event is not cancelable and does not bubble.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("audioprocess", (event) => { })

onaudioprocess = (event) => { }

Event type

An AudioProcessingEvent. Inherits from Event.

Examples

scriptNode.addEventListener("audioprocess", (audioProcessingEvent) => {
  // The input buffer is a song we loaded earlier
  const inputBuffer = audioProcessingEvent.inputBuffer;

  // The output buffer contains the samples that will be modified and played
  const outputBuffer = audioProcessingEvent.outputBuffer;

  // Loop through the output channels (in this case there is only one)
  for (let channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
    const inputData = inputBuffer.getChannelData(channel);
    const outputData = outputBuffer.getChannelData(channel);

    // Loop through the 4096 samples
    for (let sample = 0; sample < inputBuffer.length; sample++) {
      // make output equal to the same as the input
      outputData[sample] = inputData[sample];

      // add noise to each output sample
      outputData[sample] += (Math.random() * 2 - 1) * 0.2;
    }
  }
});

You could also set up the event handler using the onaudioprocess property:

scriptNode.onaudioprocess = (audioProcessingEvent) => {
  // …
};

Specifications

Browser compatibility

See also

• Web Audio API