Re: [mediacapture-screen-share] Constraints for Captured Display Surfaces should move to MediaTrackSettings (#66)

@jan-ivar 

> Well, because they are "supported", but yes. The current definition of [getSupportedConstraints](https://w3c.github.io/mediacapture-main/getusermedia.html#dom-mediadevices-getsupportedconstraints) does not explicitly guarantee that they do something when set, only that the browser implements those constrainable properties (not that they're effectively actually constrainable).

That is apparently the case for Firefox, where `getSupportedConstraints()` includes `viewportOffsetX` and `viewportOffsetY`, though setting those properties and values at a `MediaStreamTrack` of `kind` `"video"` following executing `getDisplayMedia()` when trying to resolve https://github.com/w3c/mediacapture-screen-share/issues/105 has no effect, and the set properties are not set at the object returned by `getSettings()`. Essentially making the call to `applyConstraints()` null and void.

Can the various stream and media capture API specifications clarify what constraints are and are not actually applicable and capable of being set relevant to the respective media stream and capture APIs?

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Received on Saturday, 4 May 2019 17:54:33 UTC