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OscillatorNode

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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:

  • Number of inputs: 0
  • Number of outputs: 1
  • Channel count mode: max
  • Channel count: 2 (not used in the default count mode)
  • Channel interpretation: speakers

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 = 3000; // value in hertz
oscillator.start();

Specifications

Specification Status Comment
Web Audio API
The definition of 'OscillatorNode' in that specification.
Working Draft  

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 14 webkit 23 Not supported 15 webkit
22 (unprefixed)
6 webkit
Feature Android Chrome Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support Not supported 28 webkit 25 1.2 Not supported Not supported webkit

See also

 

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Contributors to this page: teoli, chrisdavidmills, bradleymeck, kscarfone
最終更新者: teoli,