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
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
setPeriodicWave | Chrome Full support 14 | Edge Full support 12 | Firefox Full support 25 | IE No support No | Opera Full support 15 | Safari Full support 6 | WebView Android Full support Yes | Chrome Android Full support 18 | Firefox Android Full support 26 | Opera Android Full support 14 | Safari iOS Full support Yes | Samsung Internet Android Full support 1.0 |
Legend
- Full support
- Full support
- No support
- No support