AudioContext

{{APIRef("Web Audio API")}} 

The AudioContext interface represents an audio-processing graph built from audio modules linked together, each represented by an {{domxref("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.

{{InheritanceDiagram}} 

Constructor

• {{domxref("AudioContext.AudioContext", "AudioContext()")}} 
  • : Creates and returns a new AudioContext object.

Instance properties

Also inherits properties from its parent interface, {{domxref("BaseAudioContext")}} .

• {{domxref("AudioContext.baseLatency")}}  {{ReadOnlyInline}} 
  • : Returns the number of seconds of processing latency incurred by the AudioContext passing the audio from the {{domxref("AudioDestinationNode")}}  to the audio subsystem.
• {{domxref("AudioContext.outputLatency")}}  {{ReadOnlyInline}} 
  • : Returns an estimation of the output latency of the current audio context.
• {{domxref("AudioContext.sinkId")}}  {{ReadOnlyInline}}  {{Experimental_Inline}}  {{SecureContext_Inline}} 
  • : Returns the sink ID of the current output audio device.

Instance methods

Also inherits methods from its parent interface, {{domxref("BaseAudioContext")}} .

• {{domxref("AudioContext.close()")}} 
  • : Closes the audio context, releasing any system audio resources that it uses.
• {{domxref("AudioContext.createMediaElementSource()")}} 
  • : Creates a {{domxref("MediaElementAudioSourceNode")}}  associated with an {{domxref("HTMLMediaElement")}} . This can be used to play and manipulate audio from {{HTMLElement("video")}}  or {{HTMLElement("audio")}}  elements.
• {{domxref("AudioContext.createMediaStreamSource()")}} 
  • : Creates a {{domxref("MediaStreamAudioSourceNode")}}  associated with a {{domxref("MediaStream")}}  representing an audio stream which may come from the local computer microphone or other sources.
• {{domxref("AudioContext.createMediaStreamDestination()")}} 
  • : Creates a {{domxref("MediaStreamAudioDestinationNode")}}  associated with a {{domxref("MediaStream")}}  representing an audio stream which may be stored in a local file or sent to another computer.
• {{domxref("AudioContext.createMediaStreamTrackSource()")}} 
  • : Creates a {{domxref("MediaStreamTrackAudioSourceNode")}}  associated with a {{domxref("MediaStream")}}  representing an media stream track.
• {{domxref("AudioContext.getOutputTimestamp()")}} 
  • : Returns a new AudioTimestamp object containing two audio timestamp values relating to the current audio context.
• {{domxref("AudioContext.resume()")}} 
  • : Resumes the progression of time in an audio context that has previously been suspended/paused.
• {{domxref("AudioContext.setSinkId()")}}  {{Experimental_Inline}}  {{SecureContext_Inline}} 
  • : Sets the output audio device for the AudioContext.
• {{domxref("AudioContext.suspend()")}} 
  • : Suspends the progression of time in the audio context, temporarily halting audio hardware access and reducing CPU/battery usage in the process.

Events

• {{domxref("AudioContext/sinkchange_event", "sinkchange")}}  {{Experimental_Inline}} 
  • : Fired when the output audio device (and therefore, the {{domxref("AudioContext.sinkId")}} ) has changed.

Examples

Basic audio context declaration:

const audioCtx = new AudioContext();

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

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Using the Web Audio API
• {{domxref("OfflineAudioContext")}}