[vlc-devel] patches to improve Wayland support

erwan.tulou at gmail.com erwan.tulou at gmail.com
Tue Jun 12 21:40:22 CEST 2018

On 12/06/2018 19:57, Rémi Denis-Courmont wrote:
> Le tiistaina 12. kesäkuuta 2018, 1.02.15 EEST erwan.tulou at gmail.com a écrit :
>> Hello,
>>      Please find attached three patches that improve vlc on Wayland.
>> There were mainly tested with xdg_shell and -V wl on Gnome Mutter, Kwin
>> and Weston.
>>      ( vlc -I qt --no-embedded-video --no-video-deco -V wl)
>>     - patch 1: xdg_shell must not resize while in fullscreen mode
> VLC still needs to track the correct display size even in fullscreen mode.
> Otherwise we will get some small video in the top left. Not to mention the
> corner case that the output resolution changes while playing.
> So this seems very wrong.
Well, this is the other way around. Accepting to change the size of the 
display does give you a truncated fullscreen with the video in the top 
left corner.

>>     - patch 2: preserve the window size when transitioning from one video
>> to the next (reuse of the window)
>> See the rationale in the description within the patch
> I am not sure if this is correct or not. But flagging a core patch for all
> platforms as a Wayland thing is misleading.

Indeed, this patch is platform independent. The thing is that for 
Windows and OS/2 a hack was added, and this was clearly to prevent the 
fullscreen from flickering on and off.
Same cause, same effect. The X platform and Wayland would be better off 
keeping the same size between the transition. And I go a step further, I 
think It would be a very good
thing to also have it for any window transition not just fullscreen. 
Because otherwise, you are bound to see a flickering video that is not 
the size of the existing window before the new one really gets set up.
The patch is really simple (a few line to remove) but the effect is big 
if you trace the sequence of actions (window resize, reporting, vout 
display allocation).

>>      - patch 3: a try at implementing black borders with -V wl.
> This patch disables the scaler. No way.

ok. On a positive note, the patch revealed a few crashes in swscale, and 
some visual artefacts that may be of interest to someone trying to 
enhance these parts of vlc.

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