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
.
This replaces the now-obsolete OscillatorNode.setWaveTable()
.
Syntax
OscillatorNode.setPeriodicWave(wave);
Parameters
wave
- A
PeriodicWave
object representing the waveform to use as the shape of the oscillator's output.
Returns
Example
The following example illustrates simple usage of createPeriodicWave()
, recreating a sine wave from a periodic wave.
var real = new Float32Array(2); var imag = new Float32Array(2); var ac = new AudioContext(); var osc = ac.createOscillator(); real[0] = 0; imag[0] = 0; real[1] = 1; imag[1] = 0; var 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 a 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
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'setPeriodicWave' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 14 webkit | (Yes) | 23 | No support | 15 webkit 22 (unprefixed) |
6 webkit |
Feature | Android | Chrome | Edge | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|---|
Basic support | No support | 28 webkit | (Yes) | 25 | 1.2 | No support | No support | 6 webkit |