[vlc-devel] Detecting fullscreen under X on linux? (for MMAL vout)

Rémi Denis-Courmont remi at remlab.net
Thu Jul 12 20:31:48 CEST 2018

Le torstaina 12. heinäkuuta 2018, 19.39.19 EEST John Cox a écrit :
> Hi
> >Le torstaina 12. heinäkuuta 2018, 19.01.18 EEST John Cox a écrit :
> >> (...) is there any way in the
> >> vout module to know if the user has requested fullscreen from VLC,
> >> either with the -f flag on the command line or by some other method?
> >
> >Normally, that is passed to the vout window plugin via initial
> >configuration and control request.
> Yes - but it appears to get lost before the vout display module, which
> is what I have here

Uh? If you use X11, the window plugin should ask the window manager to take 
the window fullscreen. If/when that actually happens, the updated window size 
should be passed onto the display plugin.

> - or if that isn't the case please point me in the right direction.

As noted earlier, if you really want to track the fullscreen status, you can 
probably get it from X11 events. I just do not see how that helps, as it is 
not a sufficient criterion to trigger a video overlay.

To use a video overlay in an X11 environment, the X server needs to provide an 
ad-hoc extension. Back in the days when video overlays were a thing, that was 
usually exposed via XVideo.

> >> The mmal vout module bypasses the whole of X and will overlay on top of
> >> whatever X is trying to display (via a separate video plane)
> >> and so is appropriate for use if the user wants fullscreen video, but not
> >> otherwise.
> >
> >The user can select non-windowed vout display plugins with '--window dummy'
> >as Thomas explained.
> Yes and he also correctly reinterpreted my question as: "But this is not
> really what you want. You would like to open/close your module when the
> fullscreen state changes, right ?"
> So far I'm getting the impression that I can't do that.

Display plugin life cycle is essentially the life cycle of the picture buffers 
pool, and is determined by the upstream video decoder.

Windowing events cannot affect that, otherwise you would lose the video until 
the next GOP.


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