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 simply ignore any constraints they're unfamiliar with.
Syntax
var constraintsObject = { deviceId: constraint }; constraintsObject.deviceId = constraint;
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()
.
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.
Example
See "Example: Constraint exerciser" in Capabilities, constraints, and settings for an example.
Specifications
Specification | Status | Comment |
---|---|---|
Media Capture and Streams The definition of 'deviceId' in that specification. |
Editor's Draft | Initial specification. |
Browser compatibility
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | (Yes) | 50 (50) | No support | (Yes) | ? |
Feature | Android | Android Webview | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile | Chrome for Android |
---|---|---|---|---|---|---|---|
Basic support | ? | (Yes) | 50.0 (50) | No support | ? | ? | (Yes) |