Does 4K UHD Blu-ray support 12-bit color depth? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 8 Old 05-24-2019, 03:06 PM - Thread Starter
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Does 4K UHD Blu-ray support 12-bit color depth?

I’m aware that 4K UHD Blu-rays which have HDR10 supports WCG (Wide Color Gamut) which is 10-bit color depth.

However, 4K Blu-ray titles with Dolby Vision enhancement layer is what confuses me.
They say DV supports “up to” 12-bit color depth.

From my searching, it seems that 12-bit color is used at mastering stage in the studio for DV.
However, it looks like they encode into 10-bit HEVC for 4K blu-rays. This part isn’t clear.

Are DV enhanced blu-ray titles encoded in 10-bit or 12-bit color depth?
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post #2 of 8 Old 05-26-2019, 01:36 PM
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When a Dolby Vision encoded disc is played back on a Dolby Vision capable player and DV capable display the player outputs 12 bits indeed.
However it depends on the display's signal processing if the 12 bits will get through all the way to the display.
Does anyone here know if DV capable displays generally also utilize a 12 bits capable panel?

However, DV is beckwards compatible.
My Panasonic ZT60 plasma TV is 1080p/SDR only, but it is 12 bits capable.
So my Oppo UDP-203 outputs 12 bits to it.
I can't tell if there's 12 bits progessing all the way to the plasma panel, but you can clearly see a difference when you compare it to the Oppo set to 8 bits output.

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post #3 of 8 Old 05-26-2019, 04:43 PM - Thread Starter
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Quote:
Originally Posted by SkyCyberguy View Post
When a Dolby Vision encoded disc is played back on a Dolby Vision capable player and DV capable display the player outputs 12 bits indeed.

However it depends on the display's signal processing if the 12 bits will get through all the way to the display.

Does anyone here know if DV capable displays generally also utilize a 12 bits capable panel?



However, DV is beckwards compatible.

My Panasonic ZT60 plasma TV is 1080p/SDR only, but it is 12 bits capable.

So my Oppo UDP-203 outputs 12 bits to it.

I can't tell if there's 12 bits progessing all the way to the plasma panel, but you can clearly see a difference when you compare it to the Oppo set to 8 bits output.
Hi SkyCyberguy,

There is no 12-bit panel. At least not in consumer market.

I kept searching and digging after my post. And found out a few things.

1. H.265 HEVC Main 10 which is the codec used for 4K UHD Blu-rays supports up to 10-bit color depth.
https://en.m.wikipedia.org/wiki/High...y_Video_Coding

2. Dolby Vision titles are encoded in 10-bit color depth. There are no 12-bit DV sources in consumer market.
https://www.dolby.com/us/en/technolo...les-levels.pdf
Table 1 on page 9 has the info.

3. DV may supports up to 12-bit color depth and 10,000 nits of luminance to future proof their tech.

The last but not least, it “seems” that your Oppo is upsampling 10-bit source to 12-bit color. Well, this shouldn’t provide any benefit since it’s padding the extra 2-bits into 12-bit container.
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post #4 of 8 Old 05-26-2019, 11:20 PM
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I thought so that there's no 12-bit consumer panel yet.

However DV UHD Blu-rays most certainly are encoded in 12 bits (the HDR10 base stream is 10 bits, the DV layer is 12 bits for compatible players/displays), at least that's what my Oppo shows (as source!) when playing them back and it's also more or less "common knowledge" about DV.

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post #5 of 8 Old 05-26-2019, 11:50 PM - Thread Starter
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Does 4K UHD Blu-ray support 12-bit color depth?

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Originally Posted by SkyCyberguy View Post
I thought so that there's no 12-bit consumer panel yet.



However DV UHD Blu-rays most certainly are encoded in 12 bits (the HDR10 base stream is 10 bits, the DV layer is 12 bits for compatible players/displays), at least that's what my Oppo shows (as source!) when playing them back and it's also more or less "common knowledge" about DV.
No, it's a common misconception about DV on 4K UHD Blu-ray discs. Did you not check the links I posted?

What your Oppo is doing is just padding 10-bit into 12-bit container.

On 4K UHD Blu-ray discs, both base layer and DV enhancement layer are encoded in H.256 HEVC Main 10.
H.265 HEVC Main 10 only supports up to 10-bit color depth.
And as the paper published by Dolby Lab (the link I posted) has it documented, they are in 10-bit. Period.

Last edited by EC1602; 05-26-2019 at 11:56 PM.
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post #6 of 8 Old 05-27-2019, 12:31 AM - Thread Starter
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Every Dolby Vision demo files straight from Dolby and 4kmedia which I've downloaded and tried are encoded in HEVC and color depth is in 10-bit according to MediaInfo program.

I've just ripped Mortal Engines 4K UHD Blu-ray to check for myself.
According to BDInfo, guess what?


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post #7 of 8 Old 05-27-2019, 11:13 AM
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Interesting.
I'm using BD Info myself, too, but have never payed attention to the video info of the streams.
So the 12 bits, for now, are just kind of a container for the 10 bit signal (just like REC.2020 right now serves just as a container for DCI).
Be interesting to see when (and on what medium) we will start seeing actual real 12 bit content - and what display devices will be able render the advantage visible...
Thanks for the info though!

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post #8 of 8 Old 06-01-2019, 09:34 PM
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Quote:
Does 4K UHD Blu-ray support 12-bit color depth?
Yes.

Quote:
Originally Posted by EC1602 View Post
On 4K UHD Blu-ray discs, both base layer and DV enhancement layer are encoded in H.256 HEVC Main 10.
H.265 HEVC Main 10 only supports up to 10-bit color depth.
That's because the Base Layer and Enhancement Layer are both carried in HEVC Main10 (10-bit streams).
The base layer is the HDR10 backwards compatible part, and the enhancement layer is the delta which contains those final 2 bits.
The player recombines them. Dolby Vision titles done with the Full Enhancement Layer are capable of 12-bits on UHD Blu-ray.

David Mackenzie
Blu-ray Disc (and DVD) Compressionist/Author
US Correspondent & Tech Consultant, HDTVtest
ISF Certified Calibrator (Level 2) / THX Certified Professional (Video Calibration Level 2)
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