MediaTrackConstraints: deviceId property
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
BCD tables only load in the browser