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 Voice-change-O-matic 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 API
The definition of 'oversample' in that specification.
Working Draft  

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support 14Edge Full support 12Firefox Full support 26IE No support NoOpera Full support 15Safari Full support 6WebView Android Full support YesChrome Android Full support 18Edge Mobile Full support YesFirefox Android Full support 26Opera Android Full support 15Safari iOS ? Samsung Internet Android Full support Yes

Legend

Full support  
Full support
No support  
No support
Compatibility unknown  
Compatibility unknown

See also

Document Tags and Contributors

Contributors to this page: fscholz, erikadoyle, teoli, chrisdavidmills
Last updated by: fscholz,