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I've been running xbmc for a couple years now on spare hardware, most of this stuffs kinda old so got a cheapish nvidia card out of the supported cards list to keep the more challenging files smooth, everything runs great. Problem is though colors don't really seem as good as I think they should be, especially the blacks, I'm running gotham and have tried switching color space to limited, which results in a very washed out picture, so it's not that.
Panel is the legendary pana vt20, only have ps4 to test against but this looks quite noticeably better. I've played through hundreds of files on this setup, including plenty of bd50. Also I did run many of the same files on a popcorn hour c200 before making the switch and remember colors looking pretty awesome, so I don't think the source media is responsible.
I'm wondering if the GPU could be the culprit? Although I don't really see how since it's over hdmi, bits are bits right? Any suggestions?
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noggin
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2014-07-19, 17:31
(This post was last modified: 2014-07-19, 17:33 by noggin.)
Bits are bits - but unfortunately they get mangled by drivers and processing.
HD and SD video is almost universally in the 16-235 level space (broadcast video, DVD, Blu-ray certainly are) XBMC usually runs 0-255 internally, so 16-235 content is resampled to 0-255. It is also almost universally in the 4:2:0 domain (apart from some feeds which some of us watch) - whereas HDMI is usually 4:2:2 or 4:4:4 so processing is inevitably needed.
Digital video can be output to displays either in 16-235 level space (the norm for YCrCb consumer HDMI) or 0-255 (the norm for RGB PC DVI) Where this 0-255 to16-235 scaling for consumer HDMI (if needed) takes place is often the issue - and sometimes it doesn't... If it happens twice you get washed out blacks, if it happens once BUT you have a display expecting 0-255 you get washed out blacks - and desaturated colours. If it doesn't happen and you have a consumer display then you get crushed blacks and over saturated colours.
Are you running Windows or Linux? OpenElec or a Linux distro + XBMC on top?
I have a C200 too. What colour space was it configured for?
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noggin
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2014-07-19, 20:25
(This post was last modified: 2014-07-19, 20:26 by noggin.)
Ah - if your C200 and display are configured for 0-255 then you may need to do some command line work to get your nvidia drivers into "Full" rather than "Limited" range. If you have grey blacks and washed out colours this could be the cause. You may also find forcing your nvidia drivers to run RGB 4:4:4 might help. (You may not be able to configure 0-255 "Full" range with YCrCb output)
I think many - but not all - PC setups these days default to assuming HDMI 1080i/p and 720p outputs are 16-235 level space - as that is the default standard for HDMI (and avoids the banding that resampling to 0-255 can cause)
Do you still have the C200? If so you might want to check the set-up?
Do you use the same HDMI input with consumer HDMI gear - like Blu-ray players or satellite set-top boxes? Those are almost always 16-235 range. If they look washed out too then that confirms that your display is 0-255 calibrated? (Though there may be some EDID stuff that confuses matters)
It is all such a major pain. Broadcast video used 16-235 level space for very sound engineering reasons - but PC manufacturers have never really properly addressed support for it sensibly... It's always a fudge...
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Unfortunately don't have the c200 to test with still. I do use the same input through to AVR to which both xbmc boxen and ps4 are connected - ps4 colors look just fine. A little further research suggested the panel may accept 0 - 255 colorspace,
I didn't find much though so will have to look into it further - at any rate however, using 16 - 235 in xbmc definitely results in extreme washed out. The washing on 0 - 255 is slight-ish which is why I've been putting up with it for so long, however the ps4 looks better, and I've seen xbmc running on lesser panels with noticeably better reproduction (without even needing to side by side compare), so I'm certain this can be resolved somehow.
I'll conduct some further research and have a tinker with the backend settings. I've also got a few laptops and will prepare an XBMC live disk to see how they perform 'out of the box'
In the mean time, is there any 'ultimate' card xbmc users are finding to work really well? I don't mind tinkering, but I'm also happy to buy a new card if it's known to be good.
