AudioContext

The AudioContext interface represents an audio-processing graph built from audio modules linked together, each represented by an AudioNode.

An audio context controls both the creation of the nodes it contains and the execution of the audio processing, or decoding. You need to create an AudioContext before you do anything else, as everything happens inside a context. It's recommended to create one AudioContext and reuse it instead of initializing a new one each time, and it's OK to use a single AudioContext for several different audio sources and pipeline concurrently.

Constructor

AudioContext()

Creates and returns a new AudioContext object.

Properties

Also inherits properties from its parent interface, BaseAudioContext.

AudioContext.baseLatency Read only

Returns the number of seconds of processing latency incurred by the AudioContext passing the audio from the AudioDestinationNode to the audio subsystem.

AudioContext.outputLatency Read only

Returns an estimation of the output latency of the current audio context.

Methods

Also inherits methods from its parent interface, BaseAudioContext.

AudioContext.close()

Closes the audio context, releasing any system audio resources that it uses.

AudioContext.createMediaElementSource()

Creates a MediaElementAudioSourceNode associated with an HTMLMediaElement. This can be used to play and manipulate audio from <video> or <audio> elements.

AudioContext.createMediaStreamSource()

Creates a MediaStreamAudioSourceNode associated with a MediaStream representing an audio stream which may come from the local computer microphone or other sources.

AudioContext.createMediaStreamDestination()

Creates a MediaStreamAudioDestinationNode associated with a MediaStream representing an audio stream which may be stored in a local file or sent to another computer.

AudioContext.createMediaStreamTrackSource()

Creates a MediaStreamTrackAudioSourceNode associated with a MediaStream representing an media stream track.

AudioContext.getOutputTimestamp()

Returns a new AudioTimestamp object containing two audio timestamp values relating to the current audio context.

AudioContext.resume()

Resumes the progression of time in an audio context that has previously been suspended/paused.

AudioContext.suspend()

Suspends the progression of time in the audio context, temporarily halting audio hardware access and reducing CPU/battery usage in the process.

Examples

Basic audio context declaration:

var audioCtx = new AudioContext();

Cross browser variant:

var AudioContext = window.AudioContext || window.webkitAudioContext;
var audioCtx = new AudioContext();

var oscillatorNode = audioCtx.createOscillator();
var gainNode = audioCtx.createGain();
var finish = audioCtx.destination;
// etc.

Specifications

Browser compatibility

See also

• Using the Web Audio API
• OfflineAudioContext