Devices > Video Cards, Monitors, Televisions, and Projectors

4K / HDMI 2.0 : What Colour Space & Bit Depth to use?

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Hendrik:
Use what looks best to you. Different people are more susceptible to different parts of the image. Consider that YCbCr starts out as 4:2:0 on generally all consumer content anyway and consumer devices are likely going to send 4:2:0 or 4:2:2 to the TV as well, and some TV features don't always work with 4:4:4. But on the other hand properly dithered 8-bit content is not easily distinguished from real 10-bit content either.

I'm just waiting for HDMI 2.1 to allow all the combinations, don't even have a 4K TV yet because of still maturing technology. Don't want to be an early adopter with a device that costs several thousands of dollars. Hopefully devices in 2018 will have it, but i'm not 100% sure yet they'll manage.

PS:
RGB 4:4:4 @ 4K 60Hz works over HDMI 2.0, as long as you stick to 8-bit. Its *probably* what I would use, but without owning a 4K TV its hard to compare. The higher DPI of 4K makes translating experience with the relatively low DPI of a 1080p TV not really any good.

Daydream:
The HDR aspect of 4k Blu-Rays is touted as the most significant improvement, even above increased resolution, vs old 1080p media. Therefore I think it should be "darn obvious" and not a "maybe you can see it" type of experience. It is obvious come to think of it, the orange palette in the outside scenes in The Martian looked so intense that it painted my entire living room with a new hue.

The most talked of approach (so not scientific) seems to be 'get all color, forget precision'. So 4:4:4 8 bit and it can be pushed at 60Hz. But that's just not enough.

Because HDR10 is 10 bits and Dolby Vision is 12 bits. So staying with the numbers I'd say go 4:4:4 10 or 12 bits (if the panel/projector allows it) and stay stuck at 24Hz. Most content one would want to watch is 24p anyways (talking about only 4K stuff); demo files with other specs are only for 4k geeks. Any other files (1080p) at 60Hz - throw hands in the air. Or I don't know, use a second port on the device (and things get complicated).

My problem is that a lot of 4K TVs have been released with only ONE HDMI 2.0 port that allows HDR and stuff (and normal AVRs have only one HDMI out, unless one jumps above $500). So how the heck can the tv be calibrated for two different color specs on the same port? It detects HDR metadata and pushes the backlight to 10 but there's no logic to swap calibrated profiles depending on the feed. This is dumb.

And BTW, don't know about Europe but in US a decent 4K TV can be had for under $1000 now. Not the best, but not the worst either. I got mine around Thanksgiving 2015 without braking the bank. Only an OLED 65" costs $3000 (no comment on jmone's projector that ca be traded for a car :) ). TVs are affordable. Too bad true 4K content is way behind expectation (new movies coming out from 2K masters, what the heck?!), and the transporting spec is a mess.

jmone:
At present I've set it up for RGB 8 Bit and that works for most of my existing content (and stop my PJ from freaking out,....it hangs if you change between too many formats too quickly but I hope the new firmware I'll apply this weekend will fix that).  From what I've seen so far:
- If I set 10 or 12 Bit then the PJ goes into HDR mode (not good with std BD)
- If I set 8-Bit I can't use HDR
- There is even a UHD BD release encoded at 4K/10Bit/60fps (Billy Lynn's Long Halftime Walk) which would only work with 4:2:2

So I'm "thinking" 4:2:2 @ 12 Bit as it is supported at all 4K Refresh rates but then I need to work out how to toggle HDR on and off.  I also need to see what happens with MC's Auto Display rate changer to see what profiles get picked once the firmware fixes the freezing.  Who knows, maybe we need the ability in MC's Auto Display Rate changing the abililty to also specify Bit Depth and Colour Format as well as Resolution and Frame Rate....

Hendrik:
Of course the decision also depends on what your TV or projector actually accepts in which mode. Some TVs can do HDR in 8-bit, and if its properly dithered it can contain a similar amount of information as a 10-bit image, so even HDR10 would work just fine. Dithering is magic and can increase the perceived bitdepth far over the actual transport bitdepth.

My main problem with a 4:2:2 transport over HDMI is that a PC is always RGB, and a 4:2:2 transport is YCbCr, so when you play something on a PC the player converts the YCbCr file to RGB, then the graphics card converts it to 4:2:2 YCbCr for HDMI, and the TV again converts it to RGB, its two extra conversions that may (and do) incur extra loss on the image, and has the potential for mis-matching conversion matrices even throwing off your colors entirely.


--- Quote from: Daydream on June 06, 2017, 08:24:51 pm ---And BTW, don't know about Europe but in US a decent 4K TV can be had for under $1000 now. Not the best, but not the worst either. I got mine around Thanksgiving 2015 without braking the bank. Only an OLED 65" costs $3000 (no comment on jmone's projector that ca be traded for a car :) ). TVs are affordable. Too bad true 4K content is way behind expectation (new movies coming out from 2K masters, what the heck?!), and the transporting spec is a mess.

--- End quote ---

Not going to replace my high-end 1080p TV with some mediocre 4K TV when we don't even have any content available yet, its just not worth it, especially with all the limitations the current gen of TVs still have. HDR is still developing, and a 2015 TV will likely be lacking support for new HDR tech in a year or two, so I prefer to let it settle first.

jmone:
Got my PJ's firmware updated so it no longer crashes and I can test a bit more.  The good news is if I set the nVidia Control panel to 4K / 4:2:2 / 10-Bit, ROHQ is working correctly in passing SDR and HDR to the PJ so that both BD and UHD content is using the correct colour profile at all frame rates.... and it looks great.  The only downside is that the Desktop look blurry as it is not in RGB but as this is a dedicated HTPC that is a small issue.

I also found that my 1070 drops frames if using NGU for Chroma on 4K HDR material (I have to use Jinc for Chroma).  What ever conversion madVR is doing really must need some punch for this material.

All I really need now is for some cleaver crow to beat AACS2 so I can rip my UHD BD to the file server so I can play them in MC (else I'm stuck with just some 4K HDR trailers to play with).

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