Feedback Color issue thread - Discussion 2

Discussion in 'ZIDOO X9S' started by n_p, Jun 30, 2017.

  1. wesk05

    wesk05 Member Beta test group

    I checked the new firmware for the X9S and these are my findings:

    Source: test pattern video (YCbCr with Super Blacks/Whites)
    [​IMG]

    Source: Spectracal MobileForge RGB test pattern (This simulates browser, game etc.)
    [​IMG]
    [​IMG]
    (RGB/YCbCr Output indicates the color space mode selected on X9S; RGB Limited/Full indicates the range of the source content)

    To summarize:
    1) If you have a TV that doesn't report quantization range (e.g. Samsung SUHD TVs), for video playback the best options are YCbCr (Range:Auto or Limited) and RGB (Range:Limited). RGB (Range:Full) is also OK but keep in mind that this is an expanded/rescaled output.

    2) If you have a TV that does report quantization range (e.g. LG OLEDs), for video playback the best options are YCbCr (Range:Limited) or RGB (Range:Limited). The Auto mode defaults to Full Range which has expanded/rescaled output.

    3) Super Blacks (0-15) and Super Whites (236-255) are clipped in all modes. So, you can't use a video test pattern to set the brightness/contrast.

    4) For RGB sources, the best option is to use RGB (Range: Full) whether the TV reports quantization range or not.

    5) There is no difference between ZDMC and native Kodi 17.x playback.

    Edit 9/6/17
    I rechecked YCbCr Full range output on a different analyzer. I have updated the tables with the new results.
     
    Last edited: Sep 6, 2017
    videobruce and Cyclion like this.
  2. wesk05

    wesk05 Member Beta test group

    What is the native player? I don't see this working with external player in ZDMC. Does it parse the video bitstream or just the VUI/SEI?

    Your TV's black level setting is not the one that determines X9S output. X9S sets the default output based on your TV's EDID. LG OLED, Sony TVs etc. declare support for RGB/YCC quantization ranges. Based on that, X9S sets the quantization range bits in the AVI InfoFrame to "Full" by default. These bits override the display's auto mode. Very few source devices actually set this "overriding" bit.
     
    neo2017 likes this.
  3. Cyclion

    Cyclion New Member

    I would like to thank @wesk05 much for these detailed findings, which brings much more light in the extensive possibilities of HDMI settings! :)
    Now i know, that the EDID of my LG UHD TV (LG 65UF8609) doesn't report quantization range. I was a little bit confused, because my findings doesn't fit with from the findings of @n_p with the LG OLED TV, because with an YCbCr output my auto setting for the HDMI range was the same as the limited setting... But in my case the super blacks (0-15) and super whites (236 - 255) were not clipped with the limited setting and i have no chance to set the brightness/contrast setting to clip until 15 and respectively 236... With the full HDMI range setting i can see and have a chance to set the clipping...?
    I have found another strange thing with the setting of the brightness and contrast of my TV. For a fast setting of my TV without calibration equipment i normally use the following test picture for the clipping (http://www.burosch.de/ladies-testbild-v-2.html) and the following picture (http://www.burosch.de/testbilder-uebersicht/869-full-hd-testbild-ladies-2.html) for a quick setting of the colors. The strange thing with the second test image was, that i can see smooth grey steps with no discoloration of the different grey levels when i display them with ZDMC or KODI, but i got some strange green discoloration in some of the grey steps, when i display the same test image with the Zidoo Explorer...???
     
  4. wesk05

    wesk05 Member Beta test group

    It is interesting that you mention that super blacks/whites are not clipped in your setup. I cannot detect anything below 16 or above 235 (from the source) in the analyzer in any mode. You cannot use a picture to set the brightness/contrast for video. Picture is handled as RGB source. If you know that your TV doesn't report quantization range, table 2 (RGB Full) will be the one that applies to picture. 0-255 will be contracted to 16-235 in auto and limited modes.
     
    Last edited: Aug 28, 2017
  5. n_p

    n_p Active Member

    I've had (superwhite and superblack) clipping in YCbCr limited mode. (somewhat expectedly.. ;) could test other modes if needed).

    Its a pitty, that superwhite and superblack arent supported in any mode - Thats something Zidoo could look into.

    Question concerning the quantization override. At what level does this take place? Just video playback, or system/ui as well? (I guess just video playback.)

    My experience on the LG 2016 OLED was, that although the X9S outputs full by default (auto), the TV would never auto switch to full on its own, so there always was a blacklevel mismatch. With some devices I would see an Auto option in the TVs black level settings "populate" (that presumably does its job), but never with the X9S connected. (I never double checked that Auto option appearing with other devices. But I know for sure, that I never saw the X9S autoswitch my TV.)

    I still not comprehend the function of the quantization bit and override fully. One is the capability of both limited/full being signaled, the other one is the connected device actually "switching" it? (Only when video is played?)
    --

    Also lets say someone owns an old PC monitor thats only capable of RGB full - is the scaling math for video playback on that device correct at this point ("as good as it can be" (excluding superwhite))? Do you know?
    --

    Ok I think I've parsed your tables correctly.. ;) When you are talking about

    RGB Limited
    RGB Full

    in the second sets of tables, this refers to the input signal (displayed RGB pattern either limited or full), correct?
    -

    So the quick summation is:

    - stay away from YCbCr FULL - its mapped incorrectly
    - therefore stay away from YCbCr auto, as it has a chance to end up at YCbCr FULL. ;)
    - if you need a FULL (0-255) signal output out of the X9s, stick to RGB Full
    - if you need an RGB signal, but can switch between FULL and LIMITED, both are fine.

    - sticking to either YCbCr LIMITED, or RGB LIMITED, has the usual benefits with limited signal (as in almost all video content) sources, because there is no forced color conversion from limited to full.
    - sticking to either YCbCr LIMITED or RGB LIMITED, has the usual detrements, when dealing with RGB full sources (UI stuff, apps, games, ...) in that the signal space has to be compressed to limited, but its at least done correctly.

    Please correct me if I have got any of this wrong. :)
     
    Last edited: Aug 29, 2017
  6. wesk05

    wesk05 Member Beta test group

    @n_p: Quantization bits are part of the AVI InfoFrame data carried in HDMI signal. Qunatization bits (Q0, Q1, YQ0, YQ1) are used only when the sink (TV) declares selectable quantization. When Q1,Q0/YQ1,YQ0 = 0, the defaults are used which is "Limited" for CE Video formats and "Full" for IT formats (also includes 640x480 video). Ideally, these bits are set to Limited or Full based on the content range. @mirror had mentioned that the native player can do this, but I haven't seen it working. As it is now, the bits are set to "Full" for TVs that declare selectable quantization and "Limited" for those that do not, irrespective of the content range.

    TVs are supposed to switch to the correct level based on these bits. I can't say why it is not happening on your LG OLED. Have you tried RGB color space? The use of full range YCbCr for video is questionable. Based on the standards, full range YCbCr is to be used for sYCC601/AdobeYCC601 and xvYCC. I am not even sure of the conversion matrix coefficients that Zidoo is using for full range YCbCr Rec. 709. There are values that are invalid/out of gamut for Rec. 709.

    For video, YCbCr output is bit accurate on X9S. There are some insignificant rounding errors for RGB output.

    Yes, you are correct in your interpretation of the tables. RGB Limited/Full refers to the input signal.
     
  7. n_p

    n_p Active Member

  8. Theeraphon

    Theeraphon Member

    How can I find out that my TV reports or doesn't report quantization range?
    I use 3 years old LG Plasma TV.
     
  9. mirror

    mirror Well-Known Member SUPER Administrator Zidoo TECH Supporter

    Attachment
     

    Attached Files:

  10. Clint74

    Clint74 New Member

    Hello, firstly thanks to wesk05 and all the others for figuring this out.

    I have an LG oled C6 and with the color range set to limited the "dark image" issue is fixed with H264 1080p movies.

    One question: For 4K HDR movies should this be set back to full? If not will the expanded color range be lost or I'm getting this wrong?

    Thanks.
     
  11. PacoRabanne

    PacoRabanne Well-Known Member Beta test group

    With my LG OLED D6 I (temporarily) solved mantaining TV HDMI input to full range and setting X96 HDMI output to RGB 4.4.4 and range full.
    Anyway I don't think is a perfect solution. Watching some calibration grayscale video files with TV internal native player I see all blacks and white steps distinguishable but with X9S some are not.
    I'm sorry, I'm not an expert as n_p or wesk05, so I don't understand (yet) some of their explanation and advices.
     
  12. Clint74

    Clint74 New Member

    Thanks anyway for the input.
     
  13. wesk05

    wesk05 Member Beta test group

    I rechecked YCbCr Full range output on a different analyzer (Astro Design VA-1842) and am glad to report that I got the same results as Realtek has reported. I had used DVDO AVLab TPG for the earlier testing and it looks like that device goes "crazy" with YCbCr Full range signal. Accordingly, I have updated post #101.

    I have issues with some of the statements that Realtek has made in the Power Point presentation.

    1) output range is based on display EDID. default is limited range.
    Doesn’t make sense because of statement 2 below.

    2) if EDID is read as full range, output is the same as full range mode.
    This is incorrect interpretation of the use of EDID quantization bits. Just because a sink declares selectable RGB/YCbCr quantization range it doesn’t mean that the sink’s default mode is full range. It only means that the source can override the default quantization ranges for the video formats and the sink will interpret and use Qo/1, YQ0/1 bits in the AVI InfoFrame.

    3) And if a video is labeled as “full range”, it won’t be clipped in all modes under full range display.
    This doesn’t seem to work with the “Media Center” app or ZDMC with external player.

    4) To the best of my knowledge, YCbCr Full range applies to JPG (and xvYCC). This is what is stated in HDMI 2.0 spec for YCC quantization:
    5) I don't understand the rationale for clipping super black/white based on the VUI. Almost all Blu-ray players passthrough super black/white in YCbCr mode and all popular AV calibration discs have test patterns with limited range in the VUI.
     
    Last edited: Sep 6, 2017
  14. wesk05

    wesk05 Member Beta test group

    No, you can leave it at Limited. You will not lose anything.
     
  15. Clint74

    Clint74 New Member

    Thanks.

    Anyway i noticed that apparently to my eyes with my setup (LG oled c6) choosing between auto, RGB or YCbCr doens't affect this problem, only the limited or full range setting does. Even setting to auto doesn't seem to revert to the full range.
    I haven't done any proper test and only checked a few movies, there still might be differences which are not so apparent for the casual viewer like me.
    Anyway I'll leave it on RGB for safety.

    Is there a preference between RGB and YCbCr?

    Thanks again.
     
  16. Carsten Busch

    Carsten Busch Member

    I have the same problem with my LG oled 4k. I need to manually switch between full and limited to match with the source. For some h.265 1080p movies I have to switch to full to get the right level of black.

    Is there any solution planned?
     
  17. Gianmaria

    Gianmaria Member

    I ve installed the firmware 1.5 and testing some specifics chapters of Transformers i can see artifacts during the Daily scenes looking at the Sky. This happens only with RGB whereas with YCBCR all works correctly. I own a OLED LG B7.

    Watching hdr 4k movies, the brightness is proper but with bluray 1080p i need to raise It of 6 notches.
     
  18. vadergr

    vadergr Member

    What video settings are you using ?
     
  19. Gianmaria

    Gianmaria Member

    YCBCR 4.4.4, 10bit , limited range
     
  20. ursiel

    ursiel Active Member

    To n_p or anyone else who can answer this for me.

    I have yet to purchase this player, but I'm doing research, and after reading this thread, I'm left confused. My TV is an LG UHD LED 60Hz US TV set. I need some advice on what to expect if I buy this player.

    For starters, I read in this thread:

    "Super Blacks (0-15) and Super Whites (236-255) are clipped in all modes. So, you can't use a video test pattern to set the brightness/contrast."


    - Does this mean I can't use test patterns like the AVS test patterns on the Zidoo to set or check my TV's brightness, contrast, color clipping, etc? If so, that's definitely an issue, because I do use those patterns on occasion to check my TV settings. If I can't rely on this player for that, it makes me wonder if I can trust the image it's putting out to be accurate. Is this still an issue?

    You also said earlier in this thread:

    - stay away from YCbCr FULL - its mapped incorrectly
    - therefore stay away from YCbCr auto, as it has a chance to end up at YCbCr FULL. ;)
    - if you need a FULL (0-255) signal output out of the X9s, stick to RGB Full


    Is this all still accurate, or has this changed? My TV has been adjusted with basic AVS patterns, but not professionally, so I imagine it's using the limited (16-235) color space for blu-rays and other media I feed it. Would I just set this player to output YCbCr limited for all video (DVD/blu-ray/UHD/HDR)? It sounds like YCbCr auto is bad because there's a chance it may choose full which is mapped incorrectly, right?

    - What about when viewing images/jpegs with the Zidoo? Would I need to change the color space on the Zidoo or the TV for accurate color? If so, to what?

    - How about when gaming/web surfing? Sometimes when gaming with my PC on my TV I set my TV to PC mode, which reduces input lag, and allows YCbCr 4:4:4 chroma. But you say to avoid YCbCr full altogether, as it's mapped incorrectly. Is that correct? If I need to use RGB full due to the YCbCr full being incorrectly mapped, wouldn't that mean it's not sending out 4:4:4 chroma? Therefore, when using the Zidoo for gaming, would it be better to use Game mode on my TV instead of PC mode, and set the Zidoo to RGB full?

    Sorry for the questions but you seem to be one of the only people around here that could answer these questions, and I feel this is important stuff I would like to know to get the most accurate output from the Zidoo.
     

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