OscillatorNode
The OscillatorNode
interface represents a periodic waveform, such as a sine wave. It is an AudioScheduledSourceNode
audio-processing module that causes a specified frequency of a given wave to be created—in effect, a constant tone.
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 |
Constructor
OscillatorNode()
-
Creates a new instance of an
OscillatorNode
object, optionally providing an object specifying default values for the node's properties. As an alternative, you can use theBaseAudioContext.createOscillator()
factory method; see Creating an AudioNode.
Instance properties
Inherits properties from its parent, AudioScheduledSourceNode
, and adds the following properties:
OscillatorNode.frequency
-
An a-rate
AudioParam
representing the frequency of oscillation in hertz (though theAudioParam
returned is read-only, the value it represents is not). The default value is 440 Hz (a standard middle-A note). OscillatorNode.detune
-
An a-rate
AudioParam
representing detuning of oscillation in cents (though theAudioParam
returned is read-only, the value it represents is not). The default value is 0. OscillatorNode.type
-
A string which specifies the shape of waveform to play; this can be one of a number of standard values, or
custom
to use aPeriodicWave
to describe a custom waveform. Different waves will produce different tones. Standard values are"sine"
,"square"
,"sawtooth"
,"triangle"
and"custom"
. The default is"sine"
.
Event handlers
OscillatorNode.onended
-
Sets the event handler for the
ended
event, which fires when the tone has stopped playing.
Instance methods
Inherits methods from its parent, AudioScheduledSourceNode
, and adds the following:
OscillatorNode.setPeriodicWave()
-
Sets a
PeriodicWave
which describes a periodic waveform to be used instead of one of the standard waveforms; calling this sets thetype
tocustom
. OscillatorNode.start()
-
Specifies the exact time to start playing the tone.
OscillatorNode.stop()
-
Specifies the time to stop playing the tone.
Examples
The following example shows basic usage of an AudioContext
to create an oscillator node and to start playing a tone on it. For an applied example, check out our Violent Theremin demo (see app.js for relevant code).
js
// create web audio api context
const audioCtx = new (window.AudioContext || window.webkitAudioContext)();
// create Oscillator node
const oscillator = audioCtx.createOscillator();
oscillator.type = "square";
oscillator.frequency.setValueAtTime(440, audioCtx.currentTime); // value in hertz
oscillator.connect(audioCtx.destination);
oscillator.start();
Specifications
Specification |
---|
Web Audio API # OscillatorNode |
Browser compatibility
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