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SvennoJ on 21 March 2016
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Qwark said:
SvennoJ said:

Uhm, chroma 4:4:4 sampling is essentially the same as RGB in data transfer terms, just different color space on blu-ray. 10 and 12 bit color are already supported on XBox one perhaps ps4 too. I guess it is, it's called HDMI deep color (was already supported on ps3) Sony's 4K mastered blu-rays use XvYCC color space, 1.8x bigger than the standard rec.709, yet still limited by 8 bits encoding. (It's a clever extension on rec.709 that some tvs support)

But true, you need HDMI 2.0 for 10-12 bit 4K at 60fps. HDMI 1.4 tops out at 24fps 8 bit 4K.
However 4K UHD blu-ray movies still use 4:2:0 chroma subsampling and are limited to 10 bit. Still a big step up from blu-ray thanks to 10 bit color Rec.2020 yet not what you get in the cinema.

When you buy a 4K tv, make sure it has a 10 bit panel, otherwise the biggest advantage of 4K blu-ray is lost.

In theory a 4K 4:2:0 blu-ray should be able to be downscaled to 1080p 4:4:4 deep color, but I don't know if anything will do that.
(4K blu-ray has 3840x2160 gray scale, 1920x1080 color info compared to 1920x1080 gray scale, 960x540 color info on regular blu-ray)

Also make sure it's HDR ready since that's also supported on UHD blu ray. As for 4:2:0, the UHD blu ray players themselves are upgrading the footage towards 4:4:4 or at least the samsung and Panasonic are going to do that. Although I must say I am not hapy about the fact that a player needs to do such a thing, oh well software updates might fix that one. As for the theorie, it could work, but why they not make sure it 3840x2160 4:4:4 (colour and luminance/grayscale) is truely beyond me.

True check that too, yet I imagine that a 10 it panel includes HDR processing as that's the main point of having a 10 bit panel.
You already have HDR capable sets with 8 bit panels. Still better than rec.709 yet missing out on finer color detail.

They don't make it 2160p 4:4:4 as that's too much data. 4k UHD discs top out at 100GB 128 mbps, only twice as big as a blu-ray discs with 2.37x the bandwidth. HEVC h.265 is up to twice as efficient as h.264, so at most you can compare it to 4.6x the bandwidth of blu-ray.
2160p 10 bit 4:4:4 is 10x the data of 1080p 8 bit 4:2:0 (as opposed to 2160p 10 bit 4:2:0 being 5x the data) You would need 256 mbps to properly support that and bigger discs to hold a full movie.

But yes, they could in theory. 4K Netflix only runs at 16.7 mbps (not sure if that includes the HDR layer, could be that was for the base layer, Netflix claims it HDR adds 20% at most anway) and people are already amazed by that. Compressing 4:4:4 a bit more heavily than 4:2:0 could still look better in slow scenes. 128mbps is over 6 times of what Netflix 4K is using.