[mythtv-users] VDPAU Brightness or Gamma Settings

Andre Newman mythtv-list at dinkum.org.uk
Wed Feb 17 18:35:21 UTC 2010


On 17 Feb 2010, at 18:20, Kirk Bocek wrote:

> 
> 
> Andre Newman wrote:
>> 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.
> 
> Well, this is pretty obvious to me too. Playback is too dark on my plasma.

No detail in the blacks and everyone looks like they just got a part in a vampire movie?
Colour is usually a little too saturated in darker parts of scenes, plasmas don't often render full range video levels that's usually LCDs, with plasma's reduced colour depth it's even more important that everything is right going in. They do render proper motion very well, unlike LCDs.


> 
> I'm running the most current ATrpms packages described as:
> 
> * Sun Jan 31 2010 Axel Thimm <email address here> - 0.22-227
> - Update to latest svn fixes (23323).
> - Fix bugs #1544, #1527.
> 
> I'll try adding your filters string and see what happens. Is that the only way
> to change anything akin to gamma or brightness?

The only one I know, give it a go, if it's working you'll know straight away. I heard comments on here about deleting the profile and re-creating but I'd try creating a new one from scratch first, seems safest.

I switched to Debian & Ubuntu a long long time ago so ATrpms isn't a strong point, I understand that Axel's rpms are to ones to have though.

Hopefully someone with more detailed knowledge will be along shortly but I think I'm right about this being added in trunk and JYA's 0.22fixes.

Andre


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