[Bug 725835] v4l2sink: Use GstVideoCropMeta to set overlay window if available

[GStreamer (bugzilla.gnome.org)]

https://bugzilla.gnome.org/show_bug.cgi?id=725835
  GStreamer | gst-plugins-good | git

--- Comment #5 from Aurélien Zanelli <aurelien.zanelli at parrot.com> 2014-03-31 08:19:20 UTC ---
(In reply to comment #4)
> Well, if you place your video at a negative location and make the window larger
> then display, what you get is a crop (assuming the HW can scale).

I think it could work but it depends of the drivers. For instance my v4l2
output doesn't support negative coordinates.


> I'd love to know, specially, how to userspace know that the driver is doing it
> right.
Well in fact it doesn't know and we shouldn't assume that it does. This work
should be done by the application according with the pixelaspect given by
CROPCAP ioctl.
I wrote a draft of a solution but it may be better to submit it in another
issue, no ?

> > Moreover, since all this behavior with output device seems to be an abuse of
> > the V4L2 cropping/overlay API, it could be interesting to rely on the
> > experimental selection API. Drawback is device compatibilty issue.
> 
> Heard about this one, obviously not yet implemented in GStreamer, but I'd like
> to know more at some point.

Just for reference :
http://linuxtv.org/downloads/v4l-dvb-apis/selection-api.html

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