Web/API/WaveShaperNode/oversample

The oversample property of the WaveShaperNode interface is an enumerated value indicating if oversampling must be used. Oversampling is a technique for creating more samples (up-sampling) before applying a distortion effect to the audio signal.

Once applied, the number of samples is reduced to its initial numbers. This leads to better results by avoiding some aliasing, but comes at the expense of a lower precision shaping curve.

The possible oversample values are:

Value	Effect
`'none'`	Do not perform any oversampling.
`'2x'`	Double the amount of samples before applying the shaping curve.
`'4x'`	Multiply by 4 the amount of samples before applying the shaping curve.

Syntax

distortion.oversample = enumeratedValue;

Values

distortion is a WaveShaperNode.
enumeratedValue is one of 'none', '2x', or '4x'.

Example

The following example shows basic usage of an AudioContext to create a wave shaper node. For applied examples/information, check out our [[../../../../../../../mdn.github.io/voice-change-o-matic/index|Voice-change-O-matic]] [[../../../../../../../mdn.github.io/voice-change-o-matic/index|demo]] (see app.js for relevant code).

Note: Sigmoid functions are commonly used for distortion curves because of their natural properties. Their S-shape, for instance, helps create a smoother sounding result. We found the below distortion curve code on Stack Overflow.

var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var distortion = audioCtx.createWaveShaper();

  ...

function makeDistortionCurve(amount) {
  var k = typeof amount === 'number' ? amount : 50,
    n_samples = 44100,
    curve = new Float32Array(n_samples),
    deg = Math.PI / 180,
    i = 0,
    x;
  for ( ; i < n_samples; ++i ) {
    x = i * 2 / n_samples - 1;
    curve[i] = ( 3 + k ) * x * 20 * deg / ( Math.PI + k * Math.abs(x) );
  }
  return curve;
};

  ...

distortion.curve = makeDistortionCurve(400);
distortion.oversample = '4x';

Specifications

Specification	Status	Comment
Web Audio APIThe definition of 'oversample' in that specification.	Working Draft

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`oversample`	Chrome Full support 14	Edge Full support 12	Firefox Full support 26	IE No support No	Opera Full support 15	Safari Full support 6	WebView Android Full support Yes	Chrome Android Full support 18	Firefox Android Full support 26	Opera Android Full support 14	Safari iOS Full support Yes	Samsung Internet Android Full support 1.0

Legend

Full support: Full support
No support: No support