Forcing 422 10bit for UHD - is it possible? (422/12 and 444/8/10/12 discussion, inc. pixel peeping))

Hi All,

Would anybody know if there is a way to force Zidoo boxes to output 422 10bit for UHD rips (instead of default 444 10bit)?

Many thanks

 

No - 4:2:2 10-bit is not a legal HDMI mode.

 

Thanks Mark.

And is it possible to force Zidoo to send 422 12bit (which is allowable by HDMI if I am correct)?

I am asking as I have Lumagen in the chain and it does its internal processing in 422 (I assume 12bit). So I would like it not to downsample chroma from 444 sent by Zidoo especially that Zidoos chroma upsampling (at least for UHD 3000 gen) is proven not to be the greatest around (and even if it would be top notch it would be still lossy processing to go from 420 to 444 and then back to 422 at Luma level).

Hopefully it makes sense and thank you.

 

Yes, you can set 12-bit 4:2:2.



Oddly, the Zidoo settings also list 8-bit 4:2:2 and 10-bit 4:2:2 despite neither being legal modes - I've pulled them up about this several times, but it's still there, albeit useless by definition.

Obviously content is generally encoded at 4:2:0 10-bit or 8-bit so the only way you get native colour subsampling and bit depth out of HDMI is at 50~60Hz where you should choose 10-bit 4:2:0 for 4K and 8-bit 4:2:0 for 2K (unless of course you have true 10-bit 2K material).

As far as 23~30Hz goes, I'd still recommend 10-bit 4:4:4 since you are outputting native bit depth (even though at 12-bits there is no interpolation, only padding) and the 4:2:0 signal sits the same in 4:4:4 as is does in 4:2:2 - there's no upsampling, that's to say video processing, involved, so the output is like this:

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Instead of this:

​

 

Wow, that is great info Mark (as always). I don't know how I missed 4k 23-30hz. I mean I have seen it before but I only registered 30hz part and thought it does not apply while skipping the fact it is a range or refresh rates!

That leads me to another question (which I will be able to check myself). Since Zidoo allows for "not supported" and in this case pointless HDMI modes for 4k resolutions. Does it maybe also allows for 420 8bit for 1080p for untouched signal? And if it does in the menu does it really send it as 420?

More importantly you wrote:

Is it some specific function of Zidoo that it does not do any processing when going from 420 to 444 10bit? Does not do chroma upsampling? DMDreviws on YT showed not that great chroma upsampling of Relatek chipset.

I am slightly confused about that part of your reply.

 

No, 2K options are only 4:2:2 12-bit, 4:4:4/RGB 8-bit, 10-bit & 12-bit.

(Again, 4:2:2 8 & 10-bit are listed but obviously don't do anything)

Sorry - should have been clearer - so technically yes it does do chroma upsampling - it has to to get from 4:2:0 to 4:2:2/4:4:4/RGB but there is no video processing involved - no interpolation - this is a slightly inaccurate metaphor, but think of it as 4:2:0 in a 4:2:2/4:4:4 wrapper - as far as I know it just uses Nearest Neighbour.

Not sure what VS10 does though - that's a black box presumably uses bicubic or similar but I presume you don't want to use that if you're sticking it though a Lumagen?

Have you got a link to that review? - be interesting to see that.

 

I am pretty sure that you are correct on both counts (it was a while ago when I watched videos confirming it). If I remember correctly there is problem with gradation when using pure Relatek capabilities and some additional problems as well but I might be mistaken - and in general upsampling including chroma upsampling.

I think this vid should be a good start. I cannot remember which contains which tests but if you look at their channel there is plenty of great info about how these boxes process image (and the flaws that come with it) across number of videos.



In this video around 5min mark, I believe, he finds and discusses problem with range output leading to him recommending using Full range on (at last Dune boxes but based on the same chipset) and Limited on the display to mitigate it. I have to rewatch that one to remind myself his findings.



EDIT: Ok so i just watched piece of 2nd vid I linked starting from around 4:55 mark. And he says that some of the native chipset problems were (retrospectively) accounted for and addresses by Zidoo team leading to usable 422 12bit and no need to set it to 444 10bti full range like it is most likely still the case with Dune (as I have not seen it being mentioned as fixed in FW release notes) and now defunct Zap players (based on Dune HW).

But he also claims that 422 12bit is a better output mode due to no need to do upscaling and downscaling of chroma. In that statement he has no problem with colour depth manipulation. I am pretty sure that this is backed up by his pixel peeping in other videos. So basically if you would watch quite few of their videos (in chronological order) you would get the whole picture. I did it when they were released and cannot remember most of it but I intend to refresh my memory.

I have both Dune and Zidoo players and looking for best options between them and also to see which I will keep as a mainstay in my HT room.

 

I added an edit to previous post.

 

Cool - interesting... I always assumed 4:2:2 gave essentially the same output as 4:4:4 - but then again, I tend to use VS10 and output everything as LLDV to my projector, which is native at 4:2:2 anyway.

 

That is correct that I am not using VS10 as I have no use for it with Lumagen in the chain. But VS10 solves some of PQ processing problems of native Realtek processing.

 

Be interesting to stick VS10 LLDV through it though... Might need an HDFury to produce an HDR SEI but it'd be an interesting, if expensive, experiment...

 

I have one of HDFury boxes. What would be the aim of it tough? I mean I could test but would need to understand what to test and what would be the goal of it.

 

Well, firstly you could push Dolby Vision through the Lumagen without it realising it.

You take an LLDV EDID with MaxPQ set at a nominal, say, 500nits, with colour primaries set to BT.2020 so now your Zidoo outputs LLDV but in BT.2020 (essentially HDR10!) and modulates the output according to the Dolby RPU.

You set the HDFury to output an HDR10 SEI in BT.2020 with MaxCLL (and probably Max MDL) to 500nits and that fools the Lumagen into believing it's receiving HDR10.

And see what happens...

It kind of makes your head hurt to work out all the permutations and which would be worth investigating, but it's an interesting idea.

Another one is that VS10 will produce HDR10 from a DV input and use the RPU to modulate the HDR10 output - again, fed in the LRP - interesting!

 

It will be some weeks before I get to it as am working on finishing the room but I will test it.

I will get back to you in this thread with some questions about the setup of the test when I get to it (or probably I will create a dedicated thread for it as it would be more appropriate). I bought HDFury box before I got Lumagen to try LLDV but never used it as I got Lumagen shortly after. So don't know how to configure it - I will do my research when time comes for it but will probably bother you with some details beyond basic research.

Interestingly enough - I found at least one Lumagen user who uses VS10 with Lumagen and prefers it to native Realtek playback. He says that VS10 produces cleaner image. Which maybe could be explained with error free gradation of colours and better chroma scaling plus whatever VS10 does on top of it.

 

Looking forward to it

If you create a new thread, @ me on it.

 

Will do.

 

I am also interested in any tips on setting up a Zidoo optimally with a Lumagen as I am looking to do the same thing.

If you dont mind please also let me know of any tests/results you find.