Re: [mediacapture-image] Add pan and tilt constraints

> Looking at the UVC 1.5 Spec I don't see much definition for these issues, so we might simply need to explicit that the way "coordinates" in the pantilt space are reached is UA specific.

Well, more than that, the UVC 1.5 Spec defines the PanTilt as a single control, you set both in one USB command. While you could use the relative version to enforce an order, setting 0 for the relative movement of the non-target control, the ImageCapture spec here is using absolute values, and there's no way in the UVC 1.5 Spec to set the absolute pan and tilt values separately. You have to define them at the same time, so the order in which they are applied is entirely undefined in the spec. The implementation could perform the pan and tilt in any order when it has been set both at the same time.

> Personally I haven't found any webcams with roll, so we might also need some evidence of implementations in the wild.

You can find some [if you search it](https://www.google.com/search?q="bmControls"+roll) particularly on the second page but it seems like they're less common than webcams with pan tilt.

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Received on Wednesday, 21 June 2017 06:49:29 UTC