YCbCr 444 vs YCbCr 422... Why the difference?

Discussion in 'ZIDOO X9S' started by litlgi74, Jan 9, 2018.

  1. litlgi74

    litlgi74 Member

    Why is there such a difference between these two images?

    2160p/24Hz:10bit:YCbCr 422: Limited
    2018-01-08 20.30.35.jpg
    2160p/24Hz:10bit:YCbCr 444:Limited
    2018-01-08 20.30.06.jpg

    Why so much color banding in the 422? shouldn't they be identical?
  2. n_p

    n_p Active Member

    Care to explain the difference you see? ;)

    If its tone mapping, I can measure them both. Afair (from memory - not double checked) there is a slight variation in color mapping between those modes, that usually "shouldnt be there" - but nothing that qualifies as a huge oversight. I'll only doublecheck if needed.. ;)

    If its aspects other than tonemapping you see in the images, the explaination might be different. :)

    4:2:2 vs 4:4:4 refers to chroma subsampling (ie the amount of color information that comes with the image - sometimes also called "color resolution"). For most Bluray titles this is 4:2:2 because of compression benefits. In the PC RGB standard (which is not what Blurays are created on), its 4:4:4. So source most likely is 4:2:2, which then gets converted at some point. So if you are not measuring the output signal - it might also be how "the TV converts it" (which is what I would measure also.).
  3. Sarco

    Sarco Active Member Beta test group

    4K explain.
  4. n_p

    n_p Active Member

    I just now read the "color banding" part. Its not clear from the images posted, as you see screen reflections in there as well.

    It would help to define the source's color bitrate (is it a 10bit source? - most movies are not).

    Some form of color banding could be expected on any content, if its 8bit - and should to a lesser extend at 10bit. If the source is 10 bit, it could be the TVs signal handling. If its 8 bit the results are just strange (would point at a signal handling issue, maybe on Zidoos part). Hard to tell.

    If it is 10bit - it still could be an issue on Zidoos part (not pushing 4:2:2 10bit). Again - hard to tell.

    edit: Its funny - now that I read the color banding part - I myself see it very clearly in the images... :)

    Its this effect:

    (I adjusted gamma to make it more visible.)

    Edit: One more question - does it happen in the Zidoo player, as well as the Kodi player software?
    Last edited: Jan 20, 2018
  5. Sarco

    Sarco Active Member Beta test group

    Color banding could also come from bitrate compression, some h265 10bit files may range from 2GB to 50 and more for same movie, the result may show banding.
  6. litlgi74

    litlgi74 Member

    Thanks for getting back with me guys...

    I've been playing around with a new piece of hardware in order to get my older AVR working with my X9S. Its the HDFury Vertex. In addition to extracting HD audio for my AVR, this device allows me to see most of the details being sent or received from an HDMI signal.

    Anyway... What I've found

    It appears that no matter what bitrate or color space the original file is in... the X9S is converting it to 444 at 12bits. Even if I set the color space to 422 and 10 bit... the tv is getting 444 at 12bit. I tried auto as well... same thing 444 at 12bit. Edit... (I may be wrong about this... I was being rushed by my kids to get off the tv... I'll check again later)

    The interesting thing... If I manually set the color space to 444 (422 or 420) and 10bit, the picture suffers from color banding as in the images I posted earlier. The only non auto mode that looks best is 444 at 12bit... even if the original signal is not...

    The attached picture is of The Revenant ripped from the original UHD. The video info is overlaid on the screen. The X9S in auto color space and bitrate. The info in green on the bottom left corner is the HDMI info the TV is getting...

    I'm no expert... but I think the X9S is doing something to the source, and it's not good.

    Attached Files:

    Last edited: Jan 21, 2018
  7. Gianmaria

    Gianmaria Member

    I set the color space to 420 10bit since that s what you find in an UHD Bluray and i have no artifacts with my LG OLED B7.
  8. litlgi74

    litlgi74 Member

    I agree that is what it should be... but it does not display properly on my E6. What FW are you using?
    I am at 1.5.0.

    Attached is a screenshot in auto colorspace and bitrate... RX1=Source from X9S, TX1=the signal being sent to my AVR and TX0=the untouched source being sent tom my OLEDE6 from the X9S.

    Attached Files:

    Last edited: Jan 21, 2018
  9. Gianmaria

    Gianmaria Member

    Same here. Just watched the Dark Tower and It was properly shown. Before you talked about 422 vs 444 not 420.
  10. OlivierQC

    OlivierQC Well-Known Member

    since fw 1.4.12 there is a banding problem with the 4.4.4 10Bit, you have to go back to fw 1.4.6 or choose AUTO and the zidoo will switch to 4.4.4 12Bit, the banding will disappear.

    my settings : http://forum.zidoo.tv/index.php?threads/zidoo-x10-review-updated-to-1-5-0.5596/

    there is only 4.2.2 8Bit with the Zidoo, that explains the banding on your images.

    4.2.0 10Bit works only with videos above 30Hz (HDMI 2.0 standard), the zidoo switches in 4.4.4 10Bit when the videos are below 30Hz like 99% of the movies.
  11. Gianmaria

    Gianmaria Member

    Like you wrote i Watch UHD below 30hz but i don t see differences between 10bit or 12bit (with 420 and 444) . And i use to stop the movies in the same moment to do a comparison.
  12. litlgi74

    litlgi74 Member

    Very interesting... I just did some more tests...

    It took me a bit to find 420... I could only find it under 60Hz resolutions.

    So i set the color space to 420 and the bit rate to 10... The photo show the results.

    Check out the green text at the bottom left of the screen... That is the signal the display is getting.



    Select the file to play...

    Blamo... Zidoo changes it!!!!

    So what you think you set to 420 @ 10bit... Is being played at 444 @ 10bit
  13. litlgi74

    litlgi74 Member

    I think that is because you haven't tried auto Colorspace or bitrate yet.... No mater if you choose 444 or 420... the player is changing it to 444. If you choose 10 bit... it shows up at the display as 10 bit, but something strange has happened to the signal.... hence the color banding.

    Even though the source is 420 at 10 bit... In auto mode, the player changes it to 444 at 12 bit, which IMO (even though its wrong... has very little (if any) color banding and looks best.

    Something is most certainly wrong with the color management of the player!
  14. litlgi74

    litlgi74 Member

    Very little (if any) color banding... but the player is sending the wrong signal to the display...

    Like OlivierQC said... choose AUTO and the zidoo will switch to 4.4.4 12Bit, the banding will disappear.
  15. Gianmaria

    Gianmaria Member

    So the best solution is to set auto For Deep color and color space?
  16. litlgi74

    litlgi74 Member

    At FW 1.5.0... No matter what you set the colorspace or the bitrate to... The player is changing them... And usually giving an inferior result.

    So I think auto works best.
    Last edited: Jan 21, 2018
    Gianmaria likes this.
  17. OlivierQC

    OlivierQC Well-Known Member

    hi all,

    if the frequency of the video is not above 30 HZ, the zidoo will switch for 4.4.4 10/12Bit and it is normal.

    the zidoo will keep the 4.2.0 10bit with the videos above 30HZ like the demos uhd hdr for example or the only movie I know in 59.940hz (Billy Lynn)

    in my last tests, the zidoo switches correctly to the good deep color and space color according to the frequency of the video, but I'll check tonight with fw 1.5.0.

    see you
    Gianmaria likes this.
  18. litlgi74

    litlgi74 Member

    Here is a video of what is happening...
    What FW are you using...

    If the video is encoded at 420 at 10bit (most UHD BDs)... how can your above statement be true?
  19. Sarco

    Sarco Active Member Beta test group

    Depending on your TV the signal will be output to the max your tv accept. If you read the article I post all signal at the end will be upsample to 4.4.4 then RGB. If TV only accept 4.2.2 input this will be upsample to 4.4.4 by your TV then RGB. But if your TV accept 4.4.4 on 10 or 12bit Zidoo will output to 4.4.4. The situation will go to 4.2.0 or 4.2.2 if use HDR 4K 4.4.4 60hz since HDMI 2.0 is limite to 18Gb. All parameter are set in HDMI handshake where tv send to zidoo the max it accept.
    Gianmaria likes this.
  20. Gianmaria

    Gianmaria Member

    Hi Olivier, i'm waiting for your test so i ll choose my final setup

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