WaveShaperNode

« WaveShaperNode

The WaveShaperNode interface represents a non-linear distorter. It is an AudioNode that uses a curve to apply a wave shaping distortion to the signal. Beside obvious distortion effects, it is often used to add a warm feeling to the signal.

A WaveShaperNode always has exactly one input and one output.

Number of inputs 1
Number of outputs 1
Channel count mode "max"
Channel count 2 (not used in the default count mode)
Channel interpretation "speakers"

Properties

Inherits properties from its parent, AudioNode.

WaveShaperNode.curve: Is a Float32Array of numbers describing the distortion to apply.
WaveShaperNode.oversample: Is an enumerated value indicating if oversampling must be used. Oversampling is a technique for creating more samples (up-sampling) before applying the distortion effect to the audio signal.

Methods

No specific method; inherits methods from its parent, AudioNode.

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: Distortion curves are not the easiest thing to work out, and you will probably need to look around to find such algorithms. 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 'WaveShaperNode' in that specification.	Working Draft

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari (WebKit)
Basic support	10.0-webkit	25.0 (25.0)	Not supported	15.0-webkit 22 (unprefixed)	6.0-webkit
`oversample`	?	26.0 (26.0)	Not supported	?	?

Feature	Android	Firefox Mobile (Gecko)	Firefox OS	IE Mobile	Opera Mobile	Safari Mobile	Chrome for Android
Basic support	?	26.0 (26.0)	1.2	Not supported	?	?	33.0
`oversample`	?	26.0 (26.0)	1.2	Not supported	?	?	?