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Old 18th June 2022, 20:44   #201  |  Link
kolak
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UHD uses Rec.2020 when transmitted between devices. There is no such a thing like P3 in HDMI spec. This is why all BD UHD discs use 2020 primaries (and every TV station requires 2020 primaries for UHD) and any connection between 2 UHD devices over HDMI must be done with Rec.2020 (optionally Rec.709 is allowed if I'm correct).
Gamut is one thing and transmission standard another. Atomos is not an exception when it comes to HDMI in/out.

Resolve won't protect you against overshoots by default. FF has/will have some filtering built in (like many other pro tools). Its author meant o publish some technical doc about it.
There are tools which measure actual P3 gamut cover, but those are quite expensive.
Don't trust internet so much.

Last edited by kolak; 19th June 2022 at 00:08.
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Old 18th June 2022, 23:02   #202  |  Link
Balling
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BTW, specifically for you red tulips from BT.2020 mdcv blu-ray of spears and munsil and if limited to P3 in color limiter of Davinci.

https://imgur.com/a/iHcmWdf

And of course AVIF tagged as Bt.2020/bt.2020nc/PQ with all those pixels. Open in chome, not in buggy mozilla. lossless avif with avif samples 420 lossless md5 with original and also not tagged as top left chroma siting, a bug in ffmpeg! Hope will be fixed!

So who is a genious! I am! Hah! (Rename to AVIF, can see it natively here: https://github.com/mpv-player/mpv/issues/10247) https://user-images.githubuserconten...c8c817779.jpeg

>Don't trust internet so much.

Sigh. I do not need to. I generate most of this out of P3 comments on the internet under many different names.

Last edited by Balling; 18th June 2022 at 23:21.
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Old 18th June 2022, 23:47   #203  |  Link
kolak
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Not sure what are you trying to prove?
That this disc has colors out of P3?
Very possible, you already mentioned it.
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Old 19th June 2022, 00:43   #204  |  Link
Balling
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>Not sure what are you trying to prove?

Trying to? I proved it.
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Old 19th June 2022, 01:07   #205  |  Link
wswartzendruber
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I'm not quite sure I'm following the scuffle you two have gotten yourselves into, but HEVC seems to allow a content author to record the "Mastering display color primaries."

Every 4K disc I have reads "Display P3."

In all cases, though, the color primaries signaled are BT.2020.

EDIT: Scratch that! The Matrix trilogy appears to have been graded natively in BT.2020.
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Old 19th June 2022, 01:09   #206  |  Link
Balling
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> Every 4K disc I have reads "Display P3."

Spears and Munsil has BT.2020

Color range : Limited
Color primaries : BT.2020
Transfer characteristics : PQ
Matrix coefficients : BT.2020 non-constant
Mastering display color pri : BT.2020
Mastering display luminance : min: 0.0050 cd/m2, max: 1000 cd/m2
Maximum Content Light Level : 1000 cd/m2
Maximum Frame-Average Light : 400 cd/m2

What it was mastered upon has no impact what can be inside though.
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Old 19th June 2022, 01:10   #207  |  Link
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Yeah, I just caught that. See my edit. All three Matrix movies are BT.2020-graded.
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Old 19th June 2022, 01:16   #208  |  Link
Balling
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Spiderhead on Netflix has a lot of colors outside P3, so Netflix started using BT.2020 masters. Rescued by Ruby also has some scenes, but mostly inside 709. Planet Earth 2 has sometimes all the colors of Bt.2020 uniformely, which is nuts.
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Old 19th June 2022, 02:09   #209  |  Link
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Quote:
Originally Posted by Balling View Post
Planet Earth 2 has sometimes all the colors of Bt.2020 uniformly, which is nuts.
That's the BBC at work.
I look forward to the day they'll upgrade the BBC iPlayer to have HDR on my Google Pixel 6 Pro too!
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Old 19th June 2022, 10:35   #210  |  Link
kolak
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Quote:
Originally Posted by wswartzendruber View Post
I'm not quite sure I'm following the scuffle you two have gotten yourselves into, but HEVC seems to allow a content author to record the "Mastering display color primaries."

Every 4K disc I have reads "Display P3."

In all cases, though, the color primaries signaled are BT.2020.

EDIT: Scratch that! The Matrix trilogy appears to have been graded natively in BT.2020.
Exactly what we said. Most discs are P3 limited or at least P3 graded ( so give correct preview on P3 screen, but have colors outside P3). All use 2020 as primaries as there is no such a thing like P3 transmission format. Single discs may be 2020 graded/tagged, so you are confirming yours and our claims.

Those HDR tags always been there and some TVs use them some not. Regardless, they should be accurate, not some random or max values as you will find on some discs ( like 10K MaxCCL). Early disc are not done 100% properly as industry was struggling with tools. It’s way better now, but exceptions still happen.
Btw. when you see 1000/400 for MaxCLL/MaxFALL then it's likely to be a false value as this is some default used by Resolve.

Last edited by kolak; 19th June 2022 at 11:28.
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Old 19th June 2022, 10:48   #211  |  Link
kolak
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>Not sure what are you trying to prove?

Trying to? I proved it.
I already believed you that some discs may have colors outside P3 ( where some may be just falsely reported as such). I said that standard practice is to limit gamut to P3 (for broadcast it’s in many cases a hard rule, not just a recommendation).
It’s down to studio practice- if they turn on P3 limiter or not.
Content which is graded to full Rec.2020 on Rec.2020 capable device is very rare.
As I said- disc which is graded on P3 screen but kept as 2020 may actually be "problematic" when watched on 2020 capable display. You may find that some lights etc. are annoyingly saturated etc. as they were not seen by anyone to judge.
You can't just assume that that portion of the colors which you don't see during grading with P3 display will look perfectly (without seen it).
It's like if you were grading to P3 on Rec.709 display. I'm not a colorist, but I know no one does it.

Last edited by kolak; 19th June 2022 at 14:29.
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Old 19th June 2022, 16:25   #212  |  Link
rwill
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I have seen my fair share of content and almost never have encountered content that was graded in P3D65 and delivered in BT.2020 that had problems. One just has to be somewhat careful.

I have seen problems with P3D65 being clipped to BT.2020 though.
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Old 19th June 2022, 19:07   #213  |  Link
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I have seen problems with P3D65 being clipped to BT.2020 though.
What?
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Old 19th June 2022, 19:37   #214  |  Link
rwill
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What?
P3D65 does not completely fit into the BT.2020 gamut. Its somewhat academical though.

If I remember correctly I only ever investigated things flagged by automated QC tools and nothing found by actual human guided QC.
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Old 20th June 2022, 06:56   #215  |  Link
huhn
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well just compare them p3d65 just have a very tiny be of red that bt 2020 can't do.
compared to bt 2020 that red is more green.
it is so little it is kinda irrelevant.
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Old 21st June 2022, 18:37   #216  |  Link
Balling
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well just compare them p3d65 just have a very tiny be of red that bt 2020 can't do.
compared to bt 2020 that red is more green.
it is so little it is kinda irrelevant.
I checked with 3D, it does not appear to be the case (in-gamut, liminance is not HDR) https://www.colour-science.org:8020/

(select as primary colorspace BT.2020 and as secondary P3-D65).
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Old 21st June 2022, 20:53   #217  |  Link
kolak
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Originally Posted by wswartzendruber View Post
I found where the two SMPTE snippets above come from:

https://www.murideo.com/uploads/5/2/...-ecosystem.pdf

This includes the algorithm for calculating MaxCLL. It demonstrates that MaxCLL is not necessarily the Y value of the brightest pixel in the stream as many sites suggest. Instead, MaxCLL tells the display what magnitude each color channel can reach, but all three don't have to reach this level, only one does. In practice, though, if the brightest pixel is truly white, then all color channels will reach this level.

EDIT: Working on hlg-tools-0.2.0 now... Version 0.1.0 is not even remotely correct.
Looks like industry is changing.
In one of the reference tools used in post MaxCLL is now calculated for compressed formats based on luminance (ITU-R BT.2020-2 Table 4). This is opposite to the max R, G or B component.
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Old 21st June 2022, 22:04   #218  |  Link
huhn
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Originally Posted by Balling View Post
I checked with 3D, it does not appear to be the case (in-gamut, liminance is not HDR) https://www.colour-science.org:8020/

(select as primary colorspace BT.2020 and as secondary P3-D65).
please just move on it's very easy to prove.
https://abload.de/img/dcip3redisnotpartofbt6nku5.png
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Old 21st June 2022, 23:37   #219  |  Link
wswartzendruber
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Quote:
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Looks like industry is changing.
In one of the reference tools used in post MaxCLL is now calculated for compressed formats based on luminance (ITU-R BT.2020-2 Table 4). This is opposite to the max R, G or B component.
Using Y for MaxCLL is outright irrational. Let's say the value is signaled at 593 nits. That can mean anything from 6% equal intensity across all three channels to 100% intensity on just blue.
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Old 22nd June 2022, 04:56   #220  |  Link
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Since I don't have a BT.2020 display at my house, I'll have to ask everyone (subjectively) how good Yavin IV looks here:

https://www.youtube.com/watch?v=oMHK7IbpI_I
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