Why WMC video quality is/was/will always be poor (unless this is fixed)

Discussion of getting WMC to work on Windows 10 (unsupported)
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incog

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Why WMC video quality is/was/will always be poor (unless this is fixed)

#1

Post by incog » Sun Jan 03, 2021 9:08 pm

It's always bothered me that video output on WMC looks somewhat blurry and lacking in dynamics.

Well, for some reason, WMC does not display the rightmost column of pixels (even with display type TV, overscan off, TV set to 1:1 fit) AND no matter the video decoder (MF, LAV, ffdshow...)

Just about the only refence I can find to this on the web is here, all the way back to 2013 :-)
viewtopic.php?t=6213

Who cares you say? Well, it means 1:1 pixel mapping is simply impossible in WMC and always has been - I see 1:1 mentioned a lot in posts and in the ModernMedia tweak program. Well folks, 1:1 just ain't happening for you I'm afraid.

This is important because it completely messes up clarity. It's easy to see by running any overscan test video (e.g. AVS HD 709 Basic Settings/5 as I've used here).

I've attached screenshots here comparing WMP (which, curiously does not have the issue!) and WMC. It you want to evaluate the effects simply run them fullscreen in Paint or Photos on a 1080 panel (or in your browser - just make sue to zoom to 100%) and flick between them with ctrl-tab. You'll see the WMC output is more blurry in general, but also you lose dynamic range of colour due to the unnecessary interpolation across the entire frame (zoom into the white single pixel pattern and you'll see why this is).

Why WMC ended up with this it anybody's guess, though interestingly, several people have had issues with flickering in the rightmost column of pixels, apparently fixed by a hotfix a number of years ago - did MS simply cut of the pixels to fix this?! Were they using the last column as a data channel or something for DRM?

I guess since WMC was born in the days of CRTs and severe overscan and TVs that couldn't do 1:1 pixel mapping it was considered moot.

I'd hazard a guess this is one of the main reasons people end up preferring other media players for video quality.

Is there any hope of this ever being resolved by hacking the DLLs, reg edits or the like? Which component of ehome causes it? Given WMP is fine it has to be something peculiar to the WMC renderer.
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WMP.png
WMC.png

jachin99

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#2

Post by jachin99 » Wed Jan 06, 2021 7:33 pm

Maybe it is the difference between 32 vs. 64 bit players. If you enable the 64 bit version of WMP, do you get the same missing pixels? https://www.mydigitallife.net/how-to-se ... lt-player/

incog

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#3

Post by incog » Thu Jan 07, 2021 10:06 pm

Unfortunately it's not. Both WMP x64 and x86 playback flawlessly by themselves. Forcing one or the other as the backend player makes no difference to what's displayed in WMC.

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#4

Post by jachin99 » Fri Jan 08, 2021 3:48 pm

I think if I wanted to know more about this I would grab a tool like graphedit and look at the codec chains. They might be exactly the same but that would at least eliminate one potential point of failure. I know others have said they have the issue with both lavv and microsofts decoder but I would still peek at it to see what I come up with.

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#5

Post by incog » Sat Jan 09, 2021 5:09 pm

I tried it with lav, with MF and with FDSHOW - same behaviour and WMP player directly is always perfect. Active codecs verified with graphedit and equivalent tools, relevant sys tray icons appearing as well.

This appears to be connected to the WMC rendering engine (which is presumably buried on the code for the OSD) and is almost certainly in the compiled program.

I mentioned it on the off chance someone's managed to hack the dlls but literally, since this issue got an airing in 2013, the people bothered by it appear to have abandoned WMC and user investigations got no further forward.

As I said, anyone can easily verify it by running the AVS HD 709 Basic Settings/5 test available free from here: https://www.avsforum.com/threads/avs-hd ... on.948496/

I tried some obvious things with logical and physical dimensions with the well-known reg hack (HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Media Center\Settings\DisplayService).

The best you can do is get the far right line to appear again by mucking with the horizontal settings. Unfortunately all this does is that (for FHD) instead of:
- clean 1920 video -> WMC removes line 1920 to give 1919 then re-stretch to 1920 -> grotty image (without final line of pixels)
you get something like this (probably not precisely this, but it can't be far off given the end result):
- clean 1920 video -> image badly re-dimensioned by reg hack to 1919 -> WMC removes (now non-existent) line 1920 then badly stretches 1919 back to 1920 -> grotty image, albeit last line of pixels is now visible.

I got excited for about two seconds when I managed to get the line to appear with the reg settings, only to realise the pixel grid, moire patterns, general dullness, distortions and anti-aliasing artefacts were still there (if not worse) proving 1:1 pixel mapping still wasn't happening.

I fear the only way to fix this is if some clever person was able to fix it in the (unavailable) source code and recompile it, but that may bring back an issue that MS were hiding with this horrible workaround!

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#6

Post by jachin99 » Sat Jan 09, 2021 5:51 pm

Thinking about this a little more... If it isn't codec related, one difference between WMC and wmp is the now playing viewport, whose existance documented in the WMC sdk. This is the container in WMC that holds the playing video, and it gets manipulated throughout various views in WMC. For instance when your watching TV and press the green button to make the home screen appear, the viewport moves to the background to show the menu. If someone were to investigate the issue maybe that would be another avenue. Also you might be able to look at the viewport sizing properties in the mcml code which can be changed via a resource editor.

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