ScriptProcessorNode: audioprocess event

Deprecated: This feature is no longer recommended. Though some browsers might still support it, it may have already been removed from the relevant web standards, may be in the process of being dropped, or may only be kept for compatibility purposes. Avoid using it, and update existing code if possible; see the compatibility table at the bottom of this page to guide your decision. Be aware that this feature may cease to work at any time.

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.

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

onaudioprocess = (event) => { }

Event type

An AudioProcessingEvent. Inherits from Event.

Event AudioProcessingEvent

Examples

js
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:

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

Specifications

Specification
Web Audio API
# eventdef-scriptprocessornode-audioprocess

Browser compatibility

See also