MediaTrackConstraints: deviceId property

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2017.

The MediaTrackConstraints dictionary's deviceId property is a ConstrainDOMString describing the requested or mandatory constraints placed upon the value of the deviceId constrainable property.

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.deviceId as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.

Because RTP doesn't include this information, tracks associated with a WebRTC RTCPeerConnection will never include this property.

Value

An object based on ConstrainDOMString specifying one or more acceptable, ideal, and/or exact (mandatory) device IDs which are acceptable as the source of media content.

Device IDs are unique for a given origin, and are guaranteed to be the same across browsing sessions on the same origin. However, the value of the deviceId is determined by the source of the track's content, and there's no particular format mandated by the specification (although some kind of GUID is recommended). That means that a given track will only return one value for the deviceId when you call getCapabilities().

Because of this, there's no use for the device ID when calling MediaStreamTrack.applyConstraints(), since there is only one possible value; however, you can record a deviceId and use it to ensure that you get the same source for multiple calls to getUserMedia().

Note: An exception to the rule that device IDs are the same across browsing sessions: private browsing mode will use a different ID, and will change it each browsing session.

Examples

See the Constraint exerciser example.

Specifications

Specification
Media Capture and Streams
# dom-mediatrackconstraintset-deviceid

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
deviceId constraint

Legend

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Full support
Full support
See implementation notes.

See also