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

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

  1. OlivierQC

    OlivierQC Active Member Beta test group

    Hi all,

    Here is a video, the Zidoo switch in the right mode according to the video if it is below or above 30 hz, the zidoo respects the specs of the hdmi 2.0.

    The zidoo chose the YcBcR 4.4.4 10/12Bit because it's the right choice when you watch a movie in 23.976.

    (for information : the 4.2.0 10Bit is used because it does not take much space on blu ray disc)



    The only thing that is present since the FW 1.4.12 is the "problem" with the 12Bit instead of 10Bit.
    (for information the "problem" is also present on the Egreat boxes with the last 2 FW).

    I guess they want to improve image quality by forcing 12Bit (no posterization for example) or in anticipation of Dolby Vision.(they are partner if I can say that)

    I have already reported the problem several times, and we can see the problem when we watch only a UHD HDR demo in 60HZ 4.2.0 10Bit, there is banding, and there is no problem with the UHD demo 4.2.0 10Bit.

    Now it does not bother me, the PQ with the 12Bit gives beautiful gradations of color identical to the 10Bit we had before FW 1.4.12 with my eyes.
    ( i guess the tv does image processing to fit deep color 12Bit on the 10Bit panel of my TV)

    see you
     
    Gianmaria likes this.
  2. klinsmn

    klinsmn New Member

    no matter auto or 444:12b , UHD HDR always shows bandingS !!!FW 1.5
     
  3. Gianmaria

    Gianmaria Member

    Actually with my zidoo X8 and the LG OLED B7 i don't have this issue.
     
  4. klinsmn

    klinsmn New Member

    So what is your image setup for X8 and the FW ver?
     
  5. Gianmaria

    Gianmaria Member

    I followed the Olivier's tips, keeping all in AUTO. FW: 1.5
     
  6. ursiel

    ursiel Active Member

    I'm more confused than ever after reading through this thread. I'm a new x9s owner, and I have no idea what combination of settings to use when viewing various file types (1080p blu-ray, DVD, UHD remuxes and demo discs, etc.). Do I need to change settings back and forth depending on what I watch? That sounds like a mess.

    I'd like to start playing some demo files to see how this player handles stuff, but I don't even know what settings to use. The combination of deep color and color space settings is very confusing, especially when apparently this player also has color space bugs to factor in. No wonder everyone seems so confused.

    Can anybody clear up what settings to use, or at least, what settings to avoid due to player bugs? My LG UHD LCD TV can accept 4:4:4 but only in PC mode so that won't help much for movie viewing. So what are my choices? Auto sounds scary because you never know what it's going to choose. Then again, it sounds like maybe it will send something else out even if you select a certain setting. I have 3 weeks to decide if I will be keeping this player and right now I'm lost trying to figure out what settings to use.
     
  7. klinsmn

    klinsmn New Member

    UHD HDR with any FW and any set is more bandings than 1080p bluray , TV is HDR1000 SAMSUNG 65KS8800.
     
  8. jcetg

    jcetg New Member

    Could someone tell me the correct settings for ziddo X8/X9S and a LG Oled TV (EG910V, which is not 4k)? Everything in Auto will work fine?

    Thanks in advance.
     
    Last edited: Feb 1, 2018
  9. n_p

    n_p Active Member

    Every consumer wanting to play "settings help" without the need to understand what happening here - stay out of it for a while - whe are still trying to understand the issue. If you want to play "in need for customer support", please contact Zidoo directly.

    As for the issue so far, everyone is providing insufficient information.

    - 8bit material (1080p Blurays) always has banding issues to a certain extend. If your TV doesnt show them, it does post processing.
    - 10 bit material (f.e UHD 4K Blurays) shows "better" gradiation, if it was mastered in 10bit, but still hase "some" gradiation issues.

    The original poster in here posted two photos, naming the Zidoo output modes he took them with, naming two color modes as the culprit (YCbCr 4:2:2 and 4:4:4) that at first glance should have nothing to do with the "issue" - but apparently they have. Pointing - at "somewhat".

    Then another user stated, that Zidoo would force a 12 bit output signal, over a 10 bit output signal - in some undefined case, which again - has nothing to do with the origninal Posters question - because clearly he gets two different images on his TV, not two times the same 12bit signal.

    Then a consumer asked for best settings.

    Now you have to decide, either we try to document the issue - by finding sharable source material that shows it, so others can reproduce it as well - or we share smartphone images, and "here is a youtube video, taken with my smartphone of something". Its your choice.

    Also name the player software that you used.

    Zidoo in the past seldomly has reacted proactively or with any comprehensive knowledge of color image processing - so if you dont manage to document the issue in a way that others can look at it, I suggest not to "demand" the same of the chinese Android Box manufacturer you went with.

    To Zidoos defense, when past issues where documented in a way that they could reproduce them, they took action an fixed them.

    edit:

    Here is the current best guess approach: Zidoo does the internal image pocessing in RGB 4:4:4 or YCbCr 4:4:4 and when "downconverting" to 4:2:2 maybe uses an 8bit transformation - thereby rendering both 10bit and 12bit output modes useless in this instance.

    This would put the "blame" squarely on Zidoo, but we cant be sure really - because no one provided all the information we'd even need to make an edicated guess, and everyone was more encouraged about Smartphone picture and video sharing, than to make the issue reproducable.

    There is a reason, why "customers" usually talk to callcenter reps and not to engineers. Guess why...

    "But whats the best setting for me..?"

    Also - never get angry at complexity for complexitys sake. Even if the US president publically explains the cause and the need for the current tax reform exactly along those lines.
     
    Last edited: Feb 1, 2018
  10. wesk05

    wesk05 Member Beta test group

    I'm reluctant to point fingers at Zidoo on this banding issue. From my testings, this banding issue is likely a display related problem. Sony/LG TVs show no banding with 12-bit input. Samsung TVs show banding with 12-bit input, but not with 10-bit. If you capture the HDMI output of Zidoo and compare, you will see minimal difference between the original and 12-bit, 10-bits outputs.

    Here are some frame exports. Original is the export from original bitstream. The other two are exports from 12/10-bit HDMI captures.

    Samsung Wonderland Original
    Samsung Wonderland 12-bit YCbCr 4:4:4
    Samsung Wonderland 10-bit YCbCr 4:4:4

    The Revenant Original
    The Revenant 12-bit YCbCr 4:4:4
    The Revenant 10-bit YCbCr 4:4:4

    The screenshots have an embedded Rec.2020 ICC profile. You may have to use a program that supports ICC profile to see them properly.

    It is however mysterious why I get different result with nVIDIA Shield which also outputs 12-bit YCbCr 4:2:2 at 23.976Hz. I see no banding with the 12-bit output from nVIDIA Shield on my Samsung TV.
     
    Last edited: Feb 1, 2018
  11. n_p

    n_p Active Member

    Thank you very much for looking into this wesk05, also - thank you very much for the laugh.. ;)

    So the culprit likely is 10bit vs 12bit output.

    It shouldnt be triggered by 4:2:2 vs 4:4:4 - but maybe in some way it is.

    The reason why all your TVs do different things to the image signal, without informing you btw - is a cut throat race for differentiation in a space, where in the last year it was actually impossible for me to differentiate the top of the line 1800 USD Samsung QLED TV from a 600 USD TCL - quality wise - and the PR solution to that was basically "we have snapchat filters!".

    The other side of the market is fun as well - where four (might be even more) different vendors sell the same LG OLED panel as their "top of the line TV". Everyone of course is better than the others, in their own special ways, or so they claim.. ;)
     
  12. n_p

    n_p Active Member

    @wesk05: This one is just for you. (And people who want to know what the consumer side of the TV industry is mainly about)



    I laughed tears... Mainly because the "silent film with music overlaid" nature of the clip made the idiosyncrasies stand out that much more.. :)

    Here are my favorite scenes:

    [​IMG]

    !!! ;) (The three TVs on the left are using the same (more or less) LG WOLED panel - the two on the right are not.. ;) )

    [​IMG]

    Also I find the product manager titles of different manufacturers in their Tailand branche - very inspiring... :)

    Sorry for the somewhat offtopic post, but it really gives you an idea what you are up against, as a consumer.. ;)

    edit: This one is great as well... :)
    [​IMG]
    Ah, so many gems... :)

    (I wonder what gamma they used.. ;) )

    One more..., oh - its just so much fun.. ;)

    Great shot of HDR10 in action -
    [​IMG]

    Hey forum users, what do you say to the gradient on that.. ;) (unrelated to post processing, this is the actual HDR10 "standard" in action)
     
    Last edited: Feb 1, 2018
  13. ursiel

    ursiel Active Member

    I posted some info on what I've been experiencing with banding in the current 2.0.5 thread, but I'll post it here too for reference. Note I link to the file I use for testing due it showing a lot of heavy banding at most settings.

    Banding

    I did some extensive testing to try and pinpoint what modes were causing banding for me. I'll post the results here. The test file I used (due to it displaying heavy banding) was:

    The World In HDR 4K Demo.mkv
    http://4kmedia.org/the-world-in-hdr-uhd-4k-demo/

    This is with "Switch frame rate and resolution" selected.
    I used the native "Media Center" player, not ZDMC.

    HDMI mode: AUTO
    Color Space: AUTO / YCbCr 444 / YCbCr 420
    Deep Color Mode:
    - OFF - severe banding
    - 10bit - much less banding
    - 12bit - minimal/no banding
    - AUTO - minimal/no banding


    HDMI mode: Auto
    Color Space: YCbCr 422 / RGB 444
    Deep Color Mode:
    - OFF - severe banding
    - 10bit - severe banding
    - 12bit - severe banding
    - AUTO - severe banding


    What this tells me is for me, deep color "Auto" is selecting 12-bit, as the results are the same between the two when using color space AUTO / YCbCr 444 / YCbCr 420.

    YCbCr 422 / RGB 444 both have severe banding with the above demo and other videos prone to banding, regardless of deep color mode. The only configuration I can use to reduce the banding to an absolute minimum is 12bit deep color in AUTO / YCbCr 444 / YCbCr 420.

    10-bit should offer the same improvement as 12-bit, but 12-bit shows less banding for some reason. Currently, 12-bit is the only option to offer an image that matches what my TV displays when playing the file directly, and then only when using certain Color Space modes.

    Unfortunately, because of the issue I posted yesterday with 23.976 files outputting at the wrong frame rate when in 2160p 4:4:4 mode with 10-bit or 12-bit color, this means I cannot use the YCbCr 444 configuration above to reduce/eliminate the banding, because it would introduce the 23.976 stuttering bug.

    Is this how the player should be handling banding or is something not right with what the player is sending out? Why do I need to select 12-bit to get the best results, when the TV is 10-bit and the files are processed as 10-bit? Also, I can play that demo above directly from my TV's native media player via USB 3 thumb drive, and it plays with minimal banding - it looks the same through the TV's media player as it does when setting the x9s to 12-bit color in AUTO / YCbCr 444 / YCbCr 420.

    Another big drawback of all this is, as I posted in the 2.0.5 thread, is I have an issue with the screen flashing back, which I narrowed down to deep color being enabled in AUTO, YCbCr 444 and YCbCr 420 - the very settings I need to eliminate banding. So I have a choice of the screen flashing black (which is unwatchable) or having heavy banding issues on some videos. That's the choice I need to make right now with my configuration.
     
  14. n_p

    n_p Active Member

    Thank you for the testing and the comprehensive writeup.

    Now that we have a video source, we can look into reproducing your results, then take it from there.

    "Is this how banding should be handled" is a funny question.. ;)

    Banding is not "supposed to be handled" it is "supposed to be there" (if it is there in the source material).

    Why do you get better results selecting 12 bit over 10 bit? Either the Zidoo, or the Sony applies a debanding algorithm to the source material, when either 12bit is selected in the Zidoo, or the Sony recognizes a 12 bit signal. Sony is known for advertising its post processing capabilities, especially in regards to debanding, so this might be a hint.. ;)


    Severe banding in
    YCbCr 422 / RGB 444
    always -

    but not in
    YCbCr 444 / YCbCr 420
    is interesting.

    With RGB 444 - the color range gets "upconverted" (expended) - maybe the Sony debanding algorithm cant handle debanding in 0-255 range (it would have to recognize, that the video content originally was a 16-235 source (those numbers are 8bit, but its easier to explain the underlying concept with them :) )), maybe Zidoos conversion to RGB is done in 8 bit.

    YCbCr 422 showing more banding than 420 is harder to wrap ones head around.. ;)
    -


    Two more things - if you know how to play the example video in Kodis/ZDMCs native player (DVD Player) (use the settings button on the remote, when the file is highlighted in ZDMC), can you do a comparison between two of the extreme cases, and look at if the difference is still the same?

    Second - can you provide a timecode in the video, so we can compare the native frame (one single image) as well?
     
    Last edited: Feb 3, 2018
    ursiel likes this.
  15. n_p

    n_p Active Member

    I can confirm the issue.

    I'm still on the second to last firmware version on the Zidoo, where I dont have a YCbCr 4:2:0 option in the settings, but I did compare YCbCr 4:2:2 and YCbCr 4:4:4 - as well as the Auto, OFF, 10bit and 12bit modes on YCbCr 4:4:4.

    The issue description ursiel provided is correct.

    I used an eecolor 3D Lut box between the LG TV (B6) and the Zidoo. The Lut Box accepts up to a 12bit signal, but then converts it to a 10bit signal internally and forwards it to the TV. Also - the Lut Box is a 1080p device, so the Zidoos output in my case was 1080p.

    This is especially useful - as I can say for certain, that this is not an issue of 4K deep color (10, or 12 bit) handling - which some TVs might show. This also is an issue in 1080p with 10bit content.

    The scene in the provided video this should be tested with is the sideshot of the Taj Mahal, close to the end of the video (after a red firework display) - it is most obvious there.
    -

    I've also tested this with Zidoos Player (Filemanager, or default ZDMC), and with Kodi 16's default player (DVDPlayer) and it is reproducible on both - so it is an internal signal handling issue - not a player issue.

    Neither the LG B6, nor the eecolor Box, nor Kodi 16's native player do any form of "debanding", so this is not a post processing issue. Also the eecolor 3D Lut Box always outputs a 10 bit signal, and the resulting images on the TV still show banding in one case, and no banding in the other - so the Zidoo is the culprit.

    --

    This is symptomatic of an HDMI bandwidth issue.

    I've experienced, and solved the same issue on an older HTPC with a GTx 970. The issue was solved by using Amazon Basic 4K "high speed" HDMI cables (dont ask about the standard there.. ;) ) AND by switching the HDMI input on my TV. The last part sounds especially silly - but with the HDMI ports on the side of the TV the signal would flicker/drop out, but with the HDMI ports on the back of the TV (HDMI 3 and 4) it would not. In your case - make sure you know which of your HDMI ports support 4K deep color - if all of them do, experiment with different ones, and different cables.

    That said - this still could be a limitation on the chipset side, in which case you are screwed.. ;)

    Now - lets all have fun bringing this to Zidoos attention.. ;)

    The issue is, that the internal signal conversion to YCbCr 422 and RGB 444 is done in 8bit (very likely) - regardless of what "deep color mode" you select in the menu (Auto, 10 bit, 12 bit).

    There also might be an issue with 10bit output showing banding that should not be there, because of internal signal processing at 12 bit, and then downconverting the signal.

    Please keep in mind that this is still a chinese Android Box though... ;)
     
    Last edited: Feb 3, 2018
    ursiel likes this.
  16. litlgi74

    litlgi74 Member

    If you mean FW 1.5.. you should be able to access 4:2:0... but there's a trick to it.:D

    In quick settings, choose one of below (others don't seem to work) resolution options, click home then go back to Display>Color Space Mode, and 4:2:0 should be available
    Auto
    1080p 30Hz
    3840x2160p 60Hz
    4096x2160p 25Hz
    4096x2160p 30Hz
    4096x2160p 60Hz

    But it doesn't really matter... as soon as you play a video... it switches back to 444.

    What I find interesting is the fact that other than playing movies... the X9s defaults to 420.
     
    Last edited: Feb 3, 2018
  17. ursiel

    ursiel Active Member

    Thank you very much for looking deeper into this and confirming what I have posted. I hope Zidoo is willing to take this seriously now and are able to get all of this fixed soon. This could be an amazing box but sadly it has some serious issues that need to be ironed out, and soon. I'm willing to keep this player if we can hear from the Zidoo team on this. But as it stands I don't want to keep this player if things aren't going to improve. I'll hold onto it for a while longer and continue testing as best as I can.

    Let me know if I can help in any way.

    I bought a premium certified 18Gbps HDMI cable from WalMart today so I'll see if that solves my black flashing issue at least. I'll post later how I make out.
     
  18. wesk05

    wesk05 Member Beta test group

    Thanks!
     
  19. Gianmaria

    Gianmaria Member

    I noticed that setting Auto in HDMI range mode, It s equivalent to full range. So i suppose is better to change it in limited range
     
  20. ursiel

    ursiel Active Member

    I wouldn't trust AUTO mode for any setting in this player right now. This player has problems putting out what it's supposed to. Auto imo just makes it even more confusing as you have to try and figure out what it's sending out. You would be better to force limited.
     

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