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.


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.

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.


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 Example 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