BaseAudioContext: createScriptProcessor() method
================================================

**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 `createScriptProcessor()` method of the `BaseAudioContext` interface
 creates a `ScriptProcessorNode` used for direct audio processing.

**Note:** This feature was replaced by AudioWorklets and the `AudioWorkletNode` interface.

Syntax
------


```js
createScriptProcessor(bufferSize, numberOfInputChannels, numberOfOutputChannels)
```

### Parameters

`bufferSize`

 The buffer size in units of sample-frames. If specified, the bufferSize must be one
 of the following values: 256, 512, 1024, 2048, 4096, 8192, 16384. If it's not passed
 in, or if the value is 0, then the implementation will choose the best buffer size for
 the given environment, which will be a constant power of 2 throughout the lifetime of
 the node.


 This value controls how frequently the `audioprocess` event is dispatched
 and how many sample-frames need to be processed each call. Lower values for
 `bufferSize` will result in a lower (better) latency. Higher values will be
 necessary to avoid audio breakup and glitches. It is recommended for authors to not
 specify this buffer size and allow the implementation to pick a good buffer size to
 balance between latency and audio quality.


`numberOfInputChannels`

 Integer specifying the number of channels for this node's input, defaults to 2.
 Values of up to 32 are supported.


`numberOfOutputChannels`

 Integer specifying the number of channels for this node's output, defaults to 2.
 Values of up to 32 are supported.




**Warning:** Webkit currently (version 31) requires that a valid
 `bufferSize` be passed when calling this method.



**Note:** It is invalid for both `numberOfInputChannels` and
 `numberOfOutputChannels` to be zero.


### Return value

A `ScriptProcessorNode`.

Examples
--------

### Adding white noise using a script processor

The following example shows how to use a `ScriptProcessorNode` to take a track loaded via `AudioContext.decodeAudioData()`, process it, adding a bit of white noise to each audio sample of the input track, and play it through the `AudioDestinationNode`.

For each channel and each sample frame, the script node's `audioprocess` event handler uses the associated `audioProcessingEvent` to loop through each channel of the input buffer, and each sample in each channel, and add a small amount of white noise, before setting that result to be the output sample in each case.

**Note:** You can run the full example live, or view the source.


```js
const myScript = document.querySelector("script");
const myPre = document.querySelector("pre");
const playButton = document.querySelector("button");

// Create AudioContext and buffer source
let audioCtx;

async function init() {
  audioCtx = new AudioContext();
  const source = audioCtx.createBufferSource();

  // Create a ScriptProcessorNode with a bufferSize of 4096 and
  // a single input and output channel
  const scriptNode = audioCtx.createScriptProcessor(4096, 1, 1);

  // Load in an audio track using fetch() and decodeAudioData()
  try {
    const response = await fetch("viper.ogg");
    const arrayBuffer = await response.arrayBuffer();
    source.buffer = await audioCtx.decodeAudioData(arrayBuffer);
  } catch (err) {
    console.error(
      `Unable to fetch the audio file: ${name} Error: ${err.message}`,
    );
  }

  // Give the node a function to process audio events
  scriptNode.addEventListener("audioprocess", (audioProcessingEvent) => {
    // The input buffer is the song we loaded earlier
    let inputBuffer = audioProcessingEvent.inputBuffer;

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

    // Loop through the output channels (in this case there is only one)
    for (let channel = 0; channel < outputBuffer.numberOfChannels; channel++) {
      let inputData = inputBuffer.getChannelData(channel);
      let 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) \* 0.1;
      }
    }
  });

  source.connect(scriptNode);
  scriptNode.connect(audioCtx.destination);
  source.start();

  // When the buffer source stops playing, disconnect everything
  source.addEventListener("ended", () => {
    source.disconnect(scriptNode);
    scriptNode.disconnect(audioCtx.destination);
  });
}

// wire up play button
playButton.addEventListener("click", () => {
  if (!audioCtx) {
    init();
  }
});
```

Specifications
--------------

Since the August 29 2014 Web Audio API specification publication, this feature has been deprecated. It is no longer on track to become a standard.

It was replaced by AudioWorklets and the `AudioWorkletNode` interface.

Browser compatibility
---------------------

BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.

See also
--------

* Using the Web Audio API