Media Capture and Streams API (Media Stream)
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 MediaStream
object representing a flux of audio- or video-related data. See an example in Get the video.
A MediaStream
consists of zero or more 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 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 <video>
or <audio>
, a stream originating over the network, and obtained via the WebRTC RTCPeerConnection
API, or a stream created using the Web Audio API MediaStreamAudioDestinationNode
.
The output of the MediaStream
object is linked to a consumer. It can be a media elements, like <audio>
or <video>
, the WebRTC RTCPeerConnection
API or a Web Audio API 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.
BlobEvent
CanvasCaptureMediaStreamTrack
InputDeviceInfo
MediaDeviceKind
MediaDeviceInfo
MediaDevices
MediaStream
MediaStreamEvent
MediaStreamTrack
MediaStreamTrackEvent
MediaTrackCapabilities
MediaTrackConstraints
MediaTrackSettings
MediaTrackSupportedConstraints
NavigatorUserMedia
NavigatorUserMediaError
OverconstrainedError
URL
Early versions of the Media Capture and Streams API specification included separate AudioStreamTrack
and VideoStreamTrack
interfaces—each based upon MediaStreamTrack
—which represented streams of those types. These no longer exist, and you should update any existing code to instead use MediaStreamTrack
directly.
Events
Guides and tutorials
The articles below provide additional guidance and how-to information that will help you learn to use the API, and how to perform specific tasks that you may wish to handle.
- Capabilities, constraints, and settings
- This article discusses the twin concepts of constraints and capabilities, as well as media settings, and includes an example we call the Constraint Exerciser. The Constraint Exerciser 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).
Browser compatibility
BCD tables only load in the browser
See also
- WebRTC - the introductory page to the API
mediaDevices.getUserMedia()
- Taking still photos with WebRTC: a demonstration and tutorial about using
getUserMedia()
.