[vlc-devel] [PATCH v2 12/18] video_output: render the picture immediately if filters changed

[Rémi Denis-Courmont]

Le torstaina 17. syyskuuta 2020, 8.42.14 EEST Steve Lhomme a écrit :
> On 2020-09-16 20:56, Rémi Denis-Courmont wrote:
> > Le keskiviikkona 16. syyskuuta 2020, 14.14.38 EEST Steve Lhomme a écrit :
> >> It doesn't matter if we are displaying a new picture or an old picture.
> >> If
> >> the user changed the filter it should be displayed ASAP.
> > 
> > I don't really agree. Sure, in many cases, the picture would look
> > different
> > with or without the filter. But the same could be said of changing window
> > size, display settings or filter settings. So doing it when changing the
> > filter string seems rather arbitrary.
> 
> Without this, in pause, you have to wait for VOUT_REDISPLAY_DELAY (80ms)
> before it's applied. It's less responsive. But I agree it's not a
> meaningful optimization.

Then again, VOUT_REDISPLAY_DELAY is a well-known bug of its own (#541).

> I disagree on the window size change. It would be a lot nicer to have
> less lag when resizing the window (again, more visible in pause).
> On the
> other hand it would put a lot of stress on the display module which
> might not always be able to cope with it. That's less true if we wait
> 80ms (typically the time to display 2 frames).

No, you don't disagree. Of course, ideally, the window resize would 
immediately update the video scale and position. And of course, that may cause 
processing stress. And neither you nor I have a solution to fix this or even a 
discriminant to determine the right trade-off.

I have only two very imperfect options to suggest:
1) Put a warning comment with XXX and FIXME in it, that will hopefully be 
noticed when #541 is properly taken upon, or
2) Skip this patch and limit the patchset to cleaning up and simplifying the 
code.

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