W3cubDocs

/Web APIs

OscillatorNode: setPeriodicWave() method

The setPeriodicWave() method of the OscillatorNode interface is used to point to a PeriodicWave defining a periodic waveform that can be used to shape the oscillator's output, when type is custom.

Syntax

js

setPeriodicWave(wave)

Parameters

wave

A PeriodicWave object representing the waveform to use as the shape of the oscillator's output.

Return value

None (undefined).

Examples

The following example illustrates simple usage of createPeriodicWave(), recreating a sine wave from a periodic wave.

js

const real = new Float32Array(2);
const imag = new Float32Array(2);
const ac = new AudioContext();
const osc = ac.createOscillator();

real[0] = 0;
imag[0] = 0;
real[1] = 1;
imag[1] = 0;

const wave = ac.createPeriodicWave(real, imag);

osc.setPeriodicWave(wave);

osc.connect(ac.destination);

osc.start();
osc.stop(2);

This works because a sound that contains only a fundamental tone is by definition a sine wave.

Here, we create a PeriodicWave with two values. The first value is the DC offset, which is the value at which the oscillator starts. 0 is good here, because we want to start the curve at the middle of the [-1.0; 1.0] range.

The second and subsequent values are sine and cosine components. You can think of it as the result of a Fourier transform, where you get frequency domain values from time domain value. Here, with createPeriodicWave(), you specify the frequencies, and the browser performs an inverse Fourier transform to get a time domain buffer for the frequency of the oscillator. Here, we only set one component at full volume (1.0) on the fundamental tone, so we get a sine wave.

Specifications

Browser compatibility

Desktop Mobile
Chrome Edge Firefox Internet Explorer Opera Safari WebView Android Chrome Android Firefox for Android Opera Android Safari on IOS Samsung Internet
setPeriodicWave 30 12 25 No 17 8 ≤37 30 25 18 8 2.0

See also

© 2005–2023 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/OscillatorNode/setPeriodicWave