Poor black levels and picture too bright (media portal)

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aarond

33 posts

Geek

#29855 21-Jan-2009 15:34

Hi all,

After years of very happily living with XBMC on my xbox, I recently decided to put together a PC based HTPC. I recently got it working with XMBC Windows version, but my goal was always to get the Live TV side of things working. I have now installed Mediaportal, however I am really disappointed with the picture quality. Specifically, the picture in mediaportal looks really bright, with blacks showing up as grays and therefore blockiness in my 720p sample video showing up. Can anyone help with this?

Some other details - I am running MediaPortal 1.0 on Windows Vista SP1. I don't have any codec packs installed, just running ffdshow tryout. The really strange thing is that the same video looks picture perfect in Windows Media Player and XBMC with good blacks and other picture quality, which has me stumped since I would have thought Windows Media Player would also be using ffdshow tryout. Can anyone shed any light on this? Any setting in MP that could help?

Hardware specs: Asus P5K SE mobo, Asus GeForce 8500GT graphics board, 4GB RAM, Sony KLV40V300A 40" LCD running at native resolution 1366 x 768 over VGA.

All other settings on MediaPortal have been left as default.

Thanks
Aaron

Loftus

140 posts

Master Geek
+1 received by user: 2

#191096 21-Jan-2009 16:39

I had a similar issue with MediaPortal and my 8500GT. This forum thread is very helpful, although I am not sure how effective the registry fix is with Vista (my HTPC is on XP SP3):
http://forum.inmatrix.com/lofiversion/index.php?t5661.html

richms

29098 posts

Uber Geek
+1 received by user: 10207

Trusted

Lifetime subscriber

#191125 21-Jan-2009 19:13

Easiest way is to right click the ffdshow icon in the tray, and go into there and tick levels, I cant see now but there is something in there about full range or similar - it needs to stretch the 16-135 range used in component video to the 0-255 that PC uses. Otherwise there is sometimes an option on displays to force it to use 16-235 on the VGA input, but then you will lose the darks and bright areas from non video content out of the PC.

Richard rich.ms

aarond

33 posts

Geek

#191132 21-Jan-2009 20:15

Hi,

Thanks for the responses. Hmmm... I have done some other research and read a number of posts advising similar things. But I have to admit, I am confused by all of the different suggestions to address the same fundamental issue but yet I don't have the same problem with the Windows Media Player which also uses ffdshow filter.

I will give the ffdshow levels suggestion a go - however from what I have read there is a down side. As I understand it, this means that you then lose the hardware acceleration, which puts more load on the CPU. If I am using TVServer on the same box as the frontend, will this cause a problem from excess CPU load?

Given the number of peope using MediaPortal, I am amazed I am having this issue.

Cheers
Aaron

Masterpiece

247 posts

Master Geek
+1 received by user: 37

#191694 23-Jan-2009 23:31

The first step in video balance is setting the brightness and contrast to optimum.
Get these right and you generally have solved half your imagery issues, get them wrong and you highlight a whole pile of issues.

Part of the problem is that you are used to devices that send the correct signals(or somewhat close), aka DVD players etc, however HTPC's are a whole different beast as you have to to battle a whole list of independent hardware devices then overcome software trying to do things that donot conform to SMPTE standards.

To clear something up from a slightly off previous post.

All video(Movies/DTV) is based upon 16~235, and in NZ upon PAL and Rec709(HD) colour gamut.

The reason 16~235 exists is due to legacy and although wider gamuts and deeper ranges exist in the form of 1~254 and PC outputs 0~255 the 16~235 range is going to be around for some time yet. xvColor,Deepcolor are pretty much unused and unlikely to be used in the mainstream for some time yet. Dispite this you never lose anything by setting outputs to 16~235, infact you gain by the fact that the ouput range is maximised to your display which doesnt care if it is video 16~235 or PC 0~255.

The trick is to not overdrive, clip,crush the black point or white levels.

The way to set them is to use reference signals, ie video generators, or calibration DVD or otherwise to optimise the signals.

Mediaportal doesnt really do anything as far as I can see, but the software to run the video can be set wrong, FFDshow, PowerDVD etc.

Always to set to 16~235 output for video.

Then ofcourse the list of other problems can start once the black and white poits are set being, Whitebalance, gamuts and Gamma issues can be evident.

Me:"I'm not a robot!"

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

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

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

Me: .....