[mythtv-users] VDPAU Brightness or Gamma Settings

Andre Newman mythtv-list at dinkum.org.uk
Wed Feb 17 18:12:09 UTC 2010


On 17 Feb 2010, at 17:57, Kirk Bocek wrote:

> 
> 
> Andre Newman wrote:
>> Have you checked for the vdpaustudio setting in custom filters in the vdpau profile?
>> 
>> If your display can only do TV (studio) video levels then blacks will look crushed, maybe that why you think you need to adjust brightness & contrast or gamma?
>> If your display can do full range maybe you will get a better result with vdpaustudio removed.
>> 
>> With digital signals all the way from the tv station or movie studio to your display (HDMI or DVI) adjusting brightness or contrast in the video card will only degrade the picture quality, the display should be calibrated to the correct settings. Of course it's important that the software is processing the signals correctly. The default is now vdpaucolorspace=auto,vdpaustudio for the vdpau filters in the profile, this should give correct settings for a TV standard display, removing vdpaustudio may work better with some computer displays but it isn't the correct levels.  
>> 
>> Andre
> 
> I am unfamiliar with these filters. Are they documented somewhere? A search on
> the wiki for vdpaustudio didn't return anything.
> 
> The custom filters field in the VDPAU setup screen was empty. Should it
> contain something?

Mine has vdpaucolorspace=auto,vdpaustudio which is the new default but I just realised this is a feature only in trunk and back ported to JY Avenard's 0.22 fixes, oops sorry.

Before I switched to this I wasn't happy with vdpau because the levels were wrong and my projector doesn't work with full range so that made it look even worse. I don't know which colour space vdpau uses without the auto setting but broadcast HDTV, SDTV, bluray and dvd potentially use different colour spaces, this could mean the gamma might be wrong for your source, amongst many other things.  

I work in TV so these things are very obvious to me when they are wrong.

Andre


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