Dynamic Contrast ??

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aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#148135 15-Jul-2008 15:34

the screen shot for FFDshow looks like lots of options are made available to the user, hopefuly one of them will help...

which one do you use? http://sourceforge.net/project/showfiles.php?group_id=53761
there are two separate dowloads available, one around 350K and the other over 2Mb...

mobo Intel DH55PJ, RAM: 4GB RAM, Nova-T 500 HD + Avermedia Trinity tuner card, Geforce 520 video, 120GB SSD Sandisk + 640 WD + 1000SG, Win7 Home Prem 64-bit, Media Portal 1.15.0; BTC 9019URF Cordless Keyboard, Panasonic 55" (HDMI cable), HTPC Case Silverstone Grandia GD05B.

Masterpiece

247 posts

Master Geek
+1 received by user: 37

#148236 15-Jul-2008 18:54

Codecs are about compression and decoding, not video levels.

Look in the ATI video setup, I don't have access right now to my box, but look for "video levels".
I suspect you are outputing PC levels, not video levels.

To be clear, outputting at video levels(16~235) does not mean you are missing anything.
Currrently all western countries use video levels(16~235), except for Japan who use 1~254(the basis for xvColour).
It is a legacy thing from TV's early days when they had trouble transmitting levels accurately and so created head and foot room to make sure the whole signal was transmited.

It may be dropped one day, for now always use video levels.

xvColour, simply don't bother using it, although mostly acepted by the industry the change is not so easy as the whole industry is entrenched in the current system.

Too round up,
PC = 0~255
Video=16~235
xvcolour= 1~254 (only used by Japan)

You don't mention what display you are using?
High contrast levels, using vivid or so called super bright settings usually clip the top end.

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Me "That sounds like a program with no freewill?"

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richms

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#148237 15-Jul-2008 18:58

coreavc has an option to make it output the full 255 levels, without it the background and encoded letterbox bars are clearly grey when viewed on a PC. I have seen black level options in some other codec installed too.

Richard rich.ms

Masterpiece

247 posts

Master Geek
+1 received by user: 37

#148243 15-Jul-2008 19:16

Viewing 16~235 material expanded to 0~255 only creates artifacts.

You should change the video card to display video levels.

The major one is a banding issue where you can see stages in a grey ramp, which is the basis of video with colour added.

One must be careful not to create a push pull effect by setting up things to expand and contract, you could cause clipping of the signal at either end.

Me:"I'm not a robot!"

ET: "Maybe; you have some freewill, but you chose your path by arrangement"

Me "That sounds like a program with no freewill?"

ET: "We will catch up when you end this cycle"

Me: "Sounds like a 'KPI'!"

ET: "Did you read the terms and conditions?"

Me: .....

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#149748 21-Jul-2008 08:39

Guys!
I think we are on the right track, some of the symptoms described here really apply to my system's behaviour!!

Quote: "Viewing 16~235 material expanded to 0~255 only creates artifacts."
Well, this is one of the issues bothering me the most, I never understood why the 720p signal (or the TV3 1080i) played on a 46" 1366x768 screen has to show sooooo many artifacts, no matter what codec I use !! This might be it! The video levels all of you told me about.

I have ffdshow installed and I looked through it but honestly, there are so many options there that I (nearly) got lost so I did not change anything for the moment.

Do I need to activate ffdshow at every start-up somehow, or you just launch the configuration screen, do the adjustments, close it and from now on, every codec you use will get the settings from there? Do I need a reboot after any adjustment made in ffdshow (does it make changes in the registries)?

Maybe the following will also confirm what you have been saying so far:
- when watching 4:3 signal from aerial or other source connected to the Tv, the black pillars are really black and the "boundaries" where the image starts and stops are very clearly defined (one pixel is on and the next one is completely off, nice perfect vertical lines both sides). No random contrast changes.

- when playing back HD (or not) material on my pc (BUT NOT RECORDED TV !!!)and the image is not exactly 14:9, the black bars (top/bottom or on the sides) are same as before, deep black and very well defined. No random contrast changes. Could be the video levels again, in the right range when playing hd clips from inside Media Portal ??

- LIVE TV: first of all, the contrast change is very annoying, we talked about this (it applies to the whole screen, including the black pillars if they exist). When the image is not "wide screen", the black pillars on the sides are not really black, and they are VERY blocky. The "boundary" betwen image and "pillars" is not very sharp and well defined anymore, looking closely I see the pixels "blending in", approx 2 pixels each side, making the vertical "separation line" more like a strip. Plus all the blocky artifacts inside the black bars and some other vertical lines inside the black bars, fairly light grey, running from top to bottom of the screen. They are visible when watching from fairly close (1-1.5m), I usually watch from 5m away.

I had the tv tuner replaced so far, and phoned Sony several times asking how to turn the dynamic contrast off for the PC inputs but they said they do not know how it can be done as it is not in the Manual !! Thank you for that, Sony, I have the manual myself and I think I read it before asking for help...

I identified an ".inf" file in the nVidia installation directory which contains a line something like "...DynamicContrast = 0x40000000", and I edited that value to 0x00000000 but this did not help (not sure right now about the number of zeroes, all I did was to change the "4" with a "0"). Maybe the file was used to create registry entries during installation and is not used after that. I searched for a registry entry to contain the words/entries/keys "dynamic" or "contrast" but I could not find any... A reboot did not bring any changes to the system. Maybe I should re-install after modifying the ".inf" file...

WHAT I JUST FOUND: http://www.avsforum.com/avs-vb/showthread.php?t=1049346 - DO YOU THINK THIS WILL SORT IT OUT FOR ME???? I WILL SEE LATER TODAY ........ BUT THE FEEDBACK FROM USERS IS REALLY GOOD !!!!!!!!!

aucklander

478 posts

Ultimate Geek
+1 received by user: 11

#156450 12-Aug-2008 22:52

It is all sorted out.
A clean install solves any problem... good old "clean install"... I had no idea my TV set can deliver such nice picture... and there are no artifacts at all on TV1, 2 and 3.

Thank you all for the help and sharing your knowledge.
I will not continue this post.

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