MediaTrackSupportedConstraints
The MediaTrackSupportedConstraints
dictionary establishes the list of constrainable properties recognized by the user agent or browser in its implementation of the MediaStreamTrack
object. An object conforming to MediaTrackSupportedConstraints
is returned by MediaDevices.getSupportedConstraints()
.
Because of the way interface definitions in WebIDL work, if a constraint is requested but not supported, no error will occur. Instead, the specified constraints will be applied, with any unrecognized constraints stripped from the request.That can lead to confusing and hard to debug errors, so be sure to use getSupportedConstraints()
to retrieve this information before attempting to establish constraints so you know the difference between silently ignoring a constraint and a constraint being accepted.
To learn more about how constraints work, see "Capabilities and constraints" in MediaStream API.
Properties
Some combination—but not necessarily all—of the following properties will exist on the object.
width
- A Boolean value whose value is
true
if thewidth
constraint is supported in the current environment. height
- A Boolean value whose value is
true
if theheight
constraint is supported in the current environment. aspectRatio
- A Boolean value whose value is
true
if theaspectRatio
constraint is supported in the current environment. frameRate
- A Boolean value whose value is
true
if theframeRate
constraint is supported in the current environment. facingMode
- A Boolean value whose value is
true
if thefacingMode
constraint is supported in the current environment. volume
- A Boolean value whose value is
true
if thevolume
constraint is supported in the current environment. sampleRate
- A Boolean value whose value is
true
if thesampleRate
constraint is supported in the current environment. sampleSize
- A Boolean value whose value is
true
if thesampleSize
constraint is supported in the current environment. echoCancellation
- A Boolean value whose value is
true
if theechoCancellation
constraint is supported in the current environment. latency
- A Boolean value whose value is
true
if thelatency
constraint is supported in the current environment. channelCount
- A Boolean value whose value is
true
if thechannelCount
constraint is supported in the current environment. deviceId
- A Boolean value whose value is
true
if thedeviceId
constraint is supported in the current environment. groupId
- A Boolean value whose value is
true
if thegroupId
constraint is supported in the current environment.
See also
MediaDevices.getUserMedia()
MediaStreamTrack.getConstraints()
MediaStreamTrack.applyConstraints()
MediaStreamTrack.getSettings()
License
© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-us/docs/web/api/mediatracksupportedconstraints