Media Capture and Streams API (Media Stream)

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The Media Capture and Streams API, often called the Media Streams API or MediaStream API, is an API related to WebRTC which provides support for streaming audio and video data.

It provides the interfaces and methods for working with the streams and their constituent tracks, the constraints associated with data formats, the success and error callbacks when using the data asynchronously, and the events that are fired during the process.

Concepts and usage

The API is based on the manipulation of a {{domxref("MediaStream")}}  object representing a flux of audio- or video-related data. See an example in Get the media stream.

A MediaStream consists of zero or more {{domxref("MediaStreamTrack")}}  objects, representing various audio or video tracks. Each MediaStreamTrack may have one or more channels. The channel represents the smallest unit of a media stream, such as an audio signal associated with a given speaker, like left or right in a stereo audio track.

MediaStream objects have a single input and a single output. A MediaStream object generated by {{domxref("MediaDevices.getUserMedia", "getUserMedia()")}}  is called local, and has as its source input one of the user’s cameras or microphones. A non-local MediaStream may be representing a media element, like {{HTMLElement("video")}}  or {{HTMLElement("audio")}} , a stream originating over the network, and obtained via the WebRTC {{domxref("RTCPeerConnection")}}  API, or a stream created using the Web Audio API {{domxref("MediaStreamAudioDestinationNode")}} .

The output of the MediaStream object is linked to a consumer. It can be a media element, like {{HTMLElement("audio")}}  or {{HTMLElement("video")}} , the WebRTC {{domxref("RTCPeerConnection")}}  API or a Web Audio API {{domxref("MediaStreamAudioSourceNode")}} .

Interfaces

In these reference articles, you’ll find the fundamental information you’ll need to know about each of the interfaces that make up the Media Capture and Streams API.

• {{domxref("CanvasCaptureMediaStreamTrack")}} 
• {{domxref("InputDeviceInfo")}} 
• {{domxref("MediaDeviceInfo")}} 
• {{domxref("MediaDevices")}} 
• {{domxref("MediaStream")}} 
• {{domxref("MediaStreamTrack")}} 
• {{domxref("MediaStreamTrackEvent")}} 
• {{domxref("MediaTrackConstraints")}} 
• {{domxref("MediaTrackSettings")}} 
• {{domxref("MediaTrackSupportedConstraints")}} 
• {{domxref("OverconstrainedError")}} 

Events

• {{domxref("MediaStream/addtrack_event", "addtrack")}} 
• {{domxref("MediaStreamTrack/ended_event", "ended")}} 
• {{domxref("MediaStreamTrack/mute_event", "mute")}} 
• {{domxref("MediaStream/removetrack_event", "removetrack")}} 
• {{domxref("MediaStreamTrack/unmute_event", "unmute")}} 

Guides and tutorials

The Capabilities, constraints, and settings article discusses the concepts of constraints and capabilities, as well as media settings, and includes a Constraint Exerciser that lets you experiment with the results of different constraint sets being applied to the audio and video tracks coming from the computer’s A/V input devices (such as its webcam and microphone).

The Taking still photos with getUserMedia() article shows how to use getUserMedia() to access the camera on a computer or mobile phone with getUserMedia() support and take a photo with it.

Browser compatibility

{{Compat}} 

See also

• WebRTC - the introductory page to the API
• Taking still photos with WebRTC: a demonstration and tutorial about using getUserMedia().