OscillatorNode: setPeriodicWave() method

Syntax

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.

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

See also

• Using the Web Audio API
• AudioContext.createPeriodicWave