OscillatorNode

The OscillatorNode interface represents a periodic waveform, like a sine wave. It is an AudioNode audio-processing module that causes a given frequency of sine wave to be created — in effect, a constant tone.

An OscillatorNode is created using the AudioContext.createOscillator method. It always has exactly one output and no inputs, both with the same amount of channels. Its basic property defaults (see AudioNode for definitions) are:

Properties

Inherits properties from its parent, AudioNode.

OscillatorNode.frequency

An a-rate AudioParam representing the frequency of oscillation in hertz (though the AudioParam returned is read-only, the value it represents is not.)

OscillatorNode.detune

An a-rate AudioParam representing detuning of oscillation in cents (though the AudioParam returned is read-only, the value it represents is not.)

OscillatorNode.type

Represents the shape of the oscillator wave generated. Different waves will produce different tones.

Methods

Inherits methods from its parent, AudioNode.

OscillatorNode.start()

This method specifies the exact time to start playing the tone.

OscillatorNode.stop()

This method specifies the exact time to stop playing the tone.

OscillatorNode.setPeriodicWave()

Used to point to a PeriodicWave defining a periodic waveform that can be used to shape the oscillator's output, when type = "custom" is used. This replaces the now-obsolete OscillatorNode.setWaveTable.

Event handlers

OscillatorNode.onended

Used to set the event handler for the ended event, which fires when the tone has stopped playing.

Examples

The following example shows basic usage of an AudioContext to create an oscillator node. For an applied example, check out our Violent Theremin demo (see app.js for relevant code).

// create web audio api context
var audioCtx = new (window.AudioContext || window.webkitAudioContext)();

// create Oscillator node
var oscillator = audioCtx.createOscillator();

oscillator.type = 'square';
oscillator.frequency.value = 440; // value in hertz
oscillator.connect(audioCtx.destination);
oscillator.start();

Specifications

Browser compatibility

See also

• Using the Web Audio API