AudioNode

The AudioNode interface is a generic interface for representing an audio processing module like an audio source (e.g. an HTML <audio> or <video> element, an OscillatorNode, etc.), the audio destination, intermediate processing module (e.g. a filter like BiquadFilterNode or ConvolverNode), or volume control (like GainNode).

An AudioNode has inputs and outputs, each with a given amount of channels. An AudioNode with zero inputs and one or multiple outputs is called a source node. The exact processing done varies from one AudioNode to another but, in general, a node reads its inputs, does some audio-related processing, and generates new values for its outputs, or simply lets the audio pass through (for example in the AnalyserNode, where the result of the processing is accessed separately).

Different nodes can be linked together to build a processing graph. Such a graph is contained in an AudioContext. Each AudioNode participates in exactly one such context. In general, processing nodes inherit the properties and methods of AudioNode, but also define their own functionality on top. See the individual node pages for more details, as listed on the Web Audio API homepage.

Properties

AudioNode.context Read only

Returns the associated AudioContext, that is the object representing the processing graph the node is participating in.

AudioNode.numberOfInputs Read only

Returns the number of inputs feeding the node. Source nodes are defined as nodes having a numberOfInputs property with a value of 0.

AudioNode.numberOfOutputs Read only

Returns the number of outputs coming out of the node. Destination nodes — like AudioDestinationNode — have a value of 0 for this attribute.

AudioNode.channelCount

Represents an integer used to determine how many channels are used when up-mixing and down-mixing connections to any inputs to the node. Its usage and precise definition depend on the value of AudioNode.channelCountMode.

AudioNode.channelCountMode

Represents an enumerated value describing the way channels must be matched between the node's inputs and outputs.

AudioNode.channelInterpretation

Represents an enumerated value describing the meaning of the channels. This interpretation will define how audio up-mixing and down-mixing will happen.
The possible values are "speakers" or "discrete".

Methods

Also implements methods from the interface EventTarget.

AudioNode.connect(AudioNode)

Allows us to connect one output of this node to one input of another node.

AudioNode.connect(AudioParam)

Allows us to connect one output of this node to one input of an audio parameter.

AudioNode.disconnect()

Allows us to disconnect the current node from another one it is already connected to.

Example

This simple snippet of code shows the creation of some audio nodes, and how the AudioNode properties and methods can be used. You can find examples of such usage on any of the examples linked to on the Web Audio API landing page (for example Violent Theremin.)

var AudioContext = window.AudioContext || window.webkitAudioContext;

var audioCtx = new AudioContext();

var oscillator = audioCtx.createOscillator();
var gainNode = audioCtx.createGain();

oscillator.connect(gainNode);
gainNode.connect(audioCtx.destination);

oscillator.context;
oscillator.numberOfInputs;
oscillator.numberOfOutputs;
oscillator.channelCount;

Specifications

Browser compatibility

See also

• Using the Web Audio API