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).

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

See also

• Using the Web Audio API