Mediaportal EVR renderer output 16-235? (1 Viewer)

rohnfe

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Thats exactly what i thought: that my TV or AVR does not clip levels.Still the only way to i figured out to see all the levels is to set GPU to Full RGB
or limited RGB and set lav to RGB32 and untouched.
But somehow i think it must be clipping somewhere else because my ambilight shows no more correct black using 16-235 but it does when switching back to 0-255 within LAV... which i wanted to prevent

Meanwhile i guess EVR expands the video levels somehow when RGB32 is not ticked while VMR9 does not.

PS: just made another test without using the TV connected via Teamviewer:

I went to MPHC EVR and chose load standard settings for renderer...now output of the renderer shows up as 0-255 instead of 16-235 it was before and guess what it shows BTB and WTW without having RGB32 ticked. So completely different as it was before - now its working as you told it should right ?
Anyhow i went to MePo LAV settings and unticked RGB32 too..and did the same test same result it shows up without the option set. So somehow changing/loading optimzed settings and standard settings again within MPHC seemed to have the same effect in MePo...

Unfortunately i am not at home right now --> just need to figure out if my Ambilight still works correctly using the settings now.
 

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kiwijunglist

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    earlier you stated that with GPU: RGB Full 0-255 you can see 0-255 desktop levels.
    if evr expands video levels they should still be visible bc your desktop levels are visible.

    you are sure that you can see 0-255 in the following image in windows explorer with RGB set to Full in the GPU.
     

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    rohnfe

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    Hi kiwijunglist,

    i just updated my previous post :)
    I will test that when i am at home again this afternoon!

    Using Teamviewer i can see all the steps .. i know thats not a test that makes sense but at least i can check the chain right before the GPU :)
     

    rohnfe

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    (y) right just updated my previous post again..

    too fast .. somehow i made another change before that and forgot that i made it:whistle:

    I changed a setting in NVidia control panel additionaly that seems to be the reason..
    I have changed video color control to 16-235 instead of player controlled..

    GPU is still set to FULL RGB btw.

    Anyhow now i can see the full range without anything ticked within LAV...

    As said still need to confirm without using teamviewer!!
     
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    rohnfe

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    The level and ramp are 16-235 color space too right?

    I found a setup where the ramp and level show up exactly what they should like described some posts earlier (clipping 0-16 and 236-255)... the flashing bars pattern behave the same way clipping. But can you please tell why clipping BTB and WTW should be correct ?
    If i change Nvidia video color control to 16-235 all of these patterns do not clip.... what i thought would be correct?!
    Normal output setting of the GPU is still at Full RGB like before...

    Then I use the attached 'levels.wmv' to check/set the video levels (16-235 should be the visible grey range, 0-15 and 236-255 should be clipped).

    ramp.mpg should also play correctly (the white dotted lines mark the 16 and 235 levels).

    Or is this meant to look like that after calibration (setting contrast and brightness)? which would obviously make sense :)
     
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    Owlsroost

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    The level and ramp are 16-235 color space too right?

    They are special test patterns that are encoded with the full 0-255 possible range (to get BTB and WTW areas), but the 'legal' video content is between 16 and 235 - the BTB and WTW areas should be clipped so you can't see it on the display.

    Normal video files should not have any BTB or WTW content - it's effectively 'illegal', out-of-spec content.

    But can you please tell why clipping BTB and WTW should be correct ?

    Anything below 16 and above 235 is not 'legal' video as per the digital video specifications.

    Because PCs have traditionally worked with displays using RGB in a 0-255 range (black to peak white), digital video content has to be expanded in this situation from 16-235 to 0-255, otherwise video black looks dark grey and video white looks pale grey on the display.

    All this 0-255 versus 16-235 situation is because of history - computer display standards and digital video standards evolved independently many years ago - they didn't 'converge' until years after the standards were established. (Working as a hardware designer, I've watched the situation develop over the last 35 years :))

    The reason video black and peak white levels are 16 and 235 is to allow for a small amount of BTB and WTW capture when filming if required - it's very difficult to keep exposure levels in a camera precise enough all the time to keep within 16-235. The BTB and WTW content is then removed when the video is edited, colour graded and encoded, but it's useful to have it at the editing stage.
     
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    rohnfe

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    Your patterns as i saw are YUV right ? (so video levels 8 bit) the patterns from almost every calibration disc i know is 16-235 8 bit video levels (limited color range) so it should be the "same" as to my understanding.

    Sure i know what you mean but nevertheless BTB and WTW exists and there some movies showing Details in WTW otherwise i guess no one would ever try to prevent BTB and WTW to be clipped as far as i know this is why you want prevent to expand video levels to 0-255 cause BTB and WTW is clipped that way. as 16 is the new 0 and 235 is the new 255....
    Both is still 8 bits (0-255) but 0-16 is never used in video levels other than to hide certain things on purpose but WTW is used sometimes .... at least this is what i have read and discussed about. I guess if you want to have the "best possible" picture you want to try to preserve BTB and WTW (as you will have it using a stand alone BD Player for example). And this is what seems to be difficult when using a HTPC and calibrating for video levels afterwards. I know that BTB will/should never be visible on a calibrated TV but still its there (for example if i turn up brightness to max)...other than WTW what might be visible sometimes.

    Please correct me if what i said is totally nonsense ;)

    Please don`t get me wrong i just try to learn more about this stuff and try to get the best possible setup... ( i am not a hardware designer but still i am in IT business too :) )
     

    kiwijunglist

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    My pattern shows 0-255 levels for desktop. It is only relevant for testing if your gpu is set to full rgb. Then you can see if your display is showing 0-16 and 235-255. It is not useful for anything else.

    Yes you can preserve btb and wtw from the yuv video in the rendered video signal *if* you want to, however you should still calibrate your display so it is NOT "visible".

    If you make btb visible then you will not have nice black levels.

    Calibration discs are yuv so by definition they contain 0-255 levels. Whether or not they contain btb or wtw is up to whoever made the disc. You only want to see the yuv:16-235 part.
     

    rohnfe

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    Yes you can preserve btb and wtw from the yuv video in the rendered video signal *if* you want to, however you should still calibrate your display so it is NOT "visible".

    If you make btb visible then you will not have nice black levels.

    Thats for sure ... i was never talking about something else :)
     

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