Bug#540723: Subject: vlc: video brightness/contrast/gamma is really off

Reinhard Tartler siretart at tauware.de
Mon Aug 10 16:11:39 UTC 2009

Gary Dale <garydale at rogers.com> writes:

> Reinhard Tartler wrote:
>> This really sounds like video driver issues here. I'm reassigning this
>> bug to both packages for now. However, since fglrx is developed by
>> AMD/ATI, I persume they would be in the best position to actually do
>> something about that.
> I might agree except that:
> 1) my desktop display is fine. I didn't have to do anything with gimp,
> gwenview or any of my other desktop applications. It was just the video
> applications that were messed up.

gimp and other 'normal' applications do not require hardware assistance
in the same way as a media player needs it. Xv is useful to lower CPU
consumption in media players. X11 backends makes media players to behave
like other 'normal' applications, at the expense of wasting CPU time.

> 2) the Kafeine fix was a simple setting that was off while mPlayer
> needed a different output to be selected. It appears that the fglrx GL
> implementation is faulty, since I can't get good output from
> it. However both Kaffeine and mPlayer have no problem with normal x11
> video. Kaffeine picks x11 automatically while mPlayer needed to be
> told to use it.

Video drivers sometimes offer only limited xv ports, which limits the
number of applications that can simultaneously use the xv extension.

> Unfortunately vlc's x11 video output, which works fine for the other two
> players, produces bad output. And there doesn't appear to be a way to
> reduce the extreme contrast like there was in Kaffeine.

The application could indeed influence this. However, I see little point
in working around bugs in proprietary display drivers like this in open
source applications.

Reinhard Tartler, KeyID 945348A4

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