Confused about HDMI Bandwidth - [email protected] 4:4:4 10 bit + HDR

Discussion in 'General TV Discussions Forum' started by GAmbrose, Oct 24, 2016.

  1. GAmbrose

    GAmbrose
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    Hello all.

    I'm currently researching TV's to upgrade to a bigger 65" UHD screen with HDR.

    I understand that TV's now have to use a minimum 10bit panel to support HDR (And LG OLED's are 12bit?). I will use my TV for Freesat, Netflix/Amazon, Ultra HD Blu-ray, PS4 Pro and PC for 4k gaming.

    Specifically with regard to the PC - I use an Nvidia Titan X SLI (Maxwell 2) GLU

    Would it be possible to set it to:

    [email protected]
    4:4:4
    10 Bit
    And also have HDR?

    Or is it only Displayport that can support that sort of Bandwidth? My 2014 Panasonic 58AX802B actually has a DisplayPort connection but it's an 8 bit panel so it's of no benefit over HDMI 2.0

    Am I to assume Panasonic dropped DisplayPort from their 2016 TV's?

    And Is there a possibility that Samsung's UHD 2016 TV's could let you upgrade/replace the 'one connect' box in future to support HDMI 2.1 or DisplayPort 1.3/1/4?
     
  2. andy1249

    andy1249
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    The Titan X has HDMI 2.0B so should be able to do full bandwidth UHD with HDR however you need to check support for that with Nvidia.
    Some HDMI features are optional and support depends on the manufacturer.

    Displayport tech on TV,s is very rare, TV,s and AV gear are pretty much commited to HDMI only.
    On the few TV sets that do support displayport, the supprted resolutions are still limited to the same as HDMI.

    Displayport is usually dedicated to High End PC monitors only.

    Regarding Samsung upgrading the oneconnect boxes, that was the general idea /promise but it hasnt happened.
    They are more interested in shifting new TV,s rather than oneconnect boxes.
    The promise of the upgradeable boxes seems to have been nothing more than a scam to sell sets prior to the standards being finished, i.e. UHD sets without HDCP 2.2 support.
     
  3. Dodgexander

    Dodgexander
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    Everything should be compatible providing Nvidia follow the HDR 10 standard. I'm not sure how they implement it, perhaps it will be via different means. You'll have to ask them.
    PS 10 bit panels don't really have anything to do with the HDR 10 standard. The main thing to look for in regards to colour is wide colour gamut and as good covered of the rec2020 colour space as possible. Yes 10 bit panels do this better overall but there are also 8 bit panels with wide colour gamuts and 10 bit ones without.
     
  4. GAmbrose

    GAmbrose
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    Thanks for the info.

    I read somewhere that:

    "4:4:4 and Full/Limited RGB or YCbCr are two different things
    4:4:4 is the chroma subsampling, and it's independent from RGB and YCbCr."

    I always assumed that setting my Nvidia settings to Full RGB was giving me 4:4:4 Chroma on the TV.

    Does my current TV tell me what mode it's actually in? It's a 2014 Panasonic 58AX802B
     
  5. andy1249

    andy1249
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    Full or limited RGB has nothing to do with chroma sub sampling, that is correct.

    TVs map pixels within the range 16 -235 (limited).
    Computer monitors within the range 0-255 ( full ).
    They are not the same scale.
    They are both showing the same information , but you must choose the correct scale conversion based on the target screen type.
    For TVs you always choose limited, and despite the name you are not losing any information.
    If you choose full for a TV, you do lose information, most obviously, you get "black crush" i.e. A loss of detail in dark scenes.

    RGB: Full vs. Limited - Reference Home Theater
     
  6. Dodgexander

    Dodgexander
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    You can choose full in the driver resolution settings providing the renderer knows to not expand the range(most will do this correctly). This is how I have it set up so I can have full for games, applications etc but limited for video still.

    However don't ever select full in your media player or render settings and don't in the video section of the driver either as this stretch white and blacks.

    Always have RGB enabled on a PC. If you select YCbCr then your GPU will do an extra conversion stage which you want to avoid. Renderers on PC will send RGB so you don't want your GPU converting that to YCbCr before sending it as that may result in quality loss. The less you alter the signal the better.

    You can use test patterns to work out of full chroma/full range is being sent to your display. You also need to make sure your TV is set right to receive 4:4:4 by enabling pure direct in the settings. Your TV btw displays both full range and 4:4:4 chroma correctly, I'm sure.
     
    Last edited: Oct 26, 2016
  7. GAmbrose

    GAmbrose
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    Yes I have 4k pure direct enabled for 4:4:4 chroma.

    Unfortunately I have all my devices going in to a Denon A/V receiver and then all in to HDMI 4 on the TV.

    If a device doesn't support 4:4:4 chroma for whatever reason will it cause issues if the TV is in that mode? Shame I didn't get a receiver with 2x HDMI outputs.
     
  8. Dodgexander

    Dodgexander
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    If you aren't getting 4:4:4 through your receiver that's exactly the same with my Onkyo. In my case I found out disabling the OSD of the Onkyo let it pass through truly untouched. I know some newer receivers support full chroma being passed with the OSD so I'm not sure if it applies in your situation or not. You can test using this pattern. Open the picture with a media player. (I use mpc hc with madVR renderer) if it shows 4:4:4 embedded then it's passing it fine. If it doesn't your receiver is likely clipping it. Test directly connected to be sure to see the difference in case too.
    [​IMG]

    Make sure to download the image and that your display is set to its correct native resolution when displaying it.

    No it won't cause any issue. The pure direct mode is only for displaying higher chroma it has nothing to do with full or limited range. That's automatic. Chroma is different to full or limited range. The TV can expect 4:4:4 and receive 4:2:0 and it will still display correctly.
     
  9. GAmbrose

    GAmbrose
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    My Denon X3200W does full 4:4:4 passthrough. I know 4:4:4 is working because I tested it last night with the Red and Magenta 'fuzzy text' test.

    Thanks, I'll leave the TV with 4:4:4 Chroma enabled then.

    Why don't TV's just come with it enabled by default?
     
  10. Dodgexander

    Dodgexander
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    No idea, maybe it uses less power or something. Connecting a PCs gaming/editing or browsing are the only reason you need 4:4:4 so it's probably an option just because it's rarely used. In fact if you only watch movies and TV via the PC you may as well leave it disabled. You'll only see a difference outside of movies/TV.
     
  11. ricky121

    ricky121
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    I had a similar question, my TV had the UHD HDMI colour option which is required for 4:4:4 - i was actually thinking of getting a UHD blu ray player and Sky Q which presumably means that i need to turn on UHD colour for 4k?

    my problem is my current set up everything feeds into my receiver which then goes into the TV HDMI 4 (ARC). If i turn on UHD colour on HDMI 4 when watching a blu ray, would i then need to turn off when watching non UHD content? if so seems a bit of hassel constantly switching on / off depending what you watch?

    Thanks
     
  12. Dodgexander

    Dodgexander
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    No you can keep it on. Btw you don't need 4:4:4 for UHD colour. It's exclusively only for PC use.

    UHD Blu-ray even those with wide colour gamuts and HDR still use 4:2:0 chroma. Sky Q will too.

    No need for 4:4:4 unless you're connecting a PC and play games or editing. Even then you can still play in 4:2:0 but text/games won't look as good.
     
  13. ricky121

    ricky121
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    thanks for clearing that up! I was under the impression UHD blu ray players and Sky Q would use 4:4:4.....didnt relaise it was just for PC. Think i will just leave it off then :)

    Thanks
     
  14. Dodgexander

    Dodgexander
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    Yeah it's strange. Even some UHD Blu-ray players like the Panasonic's on here have a setting to output 4:4:4 but it's pointless because no discs use it.
     
  15. ricky121

    ricky121
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    what about streaming devices such as nvidia shirld netflix 4k? do they use it?
     
  16. Dodgexander

    Dodgexander
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    No, I believe the reason UHD Blu-ray doesn't use it is because of bandwidth limitations so definitely streaming services will not either.

    Chroma subsampling is the first thing they hit to reduce bandwidth because it's the least noticeable.

    But actually it doesn't matter what you have everything set. You can set your Blu-ray player 4:4:4 and TV 4:2:0 and it won't make a difference. Unlike full/limited range there's no clipping with chroma or anything.

    However it's always best to keep everything the same so ideally unless you have a PC connected don't use 4:4:4.

    Also. Some settings may not be available when using these pure direct/UHD colour for example, most commonly it disables the use of motion control.
     

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