Dolby Vision now possible through MP4 Mux.

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So I'm no longer watching 2.9 retail movies. CMv4.0 for everything!

I apologize if I have missed some developments, but, are we now able to convert retail CMv2.9 to CMv4.0? If so how involved is that process?

You can restore cmv4.0 on a P7 rip with the metadata from web streaming. If no cmv4.0 source is available, then I will just generate it.

https://www.youtube.com/watch?v=RI_e-MPIPlw

[bbeny123]

You can restore cmv4.0 on a P7 rip with the metadata from web streaming. If no cmv4.0 source is available, then I will just generate it.

But wouldn’t generating CMv4.0 metadata mean losing the original manual L2 trims? In that case, wouldn’t it be better to just stick with CMv2.9 if those trims were carefully tuned?

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But wouldn’t generating CMv4.0 metadata mean losing the original manual L2 trims? In that case, wouldn’t it be better to just stick with CMv2.9 if those trims were carefully tuned?

My 2500nits G5 rarely needs tone mapping, so this doesn't really affect me, and all the 1000nits MDL trims are already ignored anyway on this TV.
For 4000nits MDL RPU, even in movies that have a lot of modification in the cmv2.9 trims like Mad Max, DV still dims a lot of 200-500nits shots on my G5.

[daffie]

But wouldn’t generating CMv4.0 metadata mean losing the original manual L2 trims? In that case, wouldn’t it be better to just stick with CMv2.9 if those trims were carefully tuned?

My 2500nits G5 rarely needs tone mapping, so this doesn't really affect me, and all the 1000nits MDL trims are already ignored anyway on this TV.
For 4000nits MDL RPU, even in movies that have a lot of modification in the cmv2.9 trims like Mad Max, DV still dims a lot of 200-500nits shots on my G5.

And for us people with G1/G2 for example?

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And for us people with G1/G2 for example?

I would generate cmv4.0 for movies made in the old/original cmv2.9 algo (the ones with no automatic trims, no cmv4.0 to 2.9 conversion).
For the cmv2.9 rpu with automatic L2 trims from the cmv4.0 workflow master, I guess it's fine(minus black crush).


PS: Dolby knows that cmv2.9 is not very good, see their QC recommendations:
https://www.youtube.com/watch?v=t7mlzQNSdOw&t=3718s

[bbeny123]

I would generate cmv4.0 for movies made in the old/original cmv2.9 algo (the ones with no automatic trims, no cmv4.0 to 2.9 conversion).
For the cmv2.9 rpu with automatic L2 trims from the cmv4.0 workflow master, I guess it's fine(minus black crush).

I ran some tests on my Sony A95L, and it seems tone mapping starts at:

• avg_pq 600, MDL 1000, CM v2.9: 1150 nits
• avg_pq 600, MDL 1000, CM v4.0: 1150 nits
• avg_pq 600, MDL 4000, CM v2.9: 150 nits!
• avg_pq 600, MDL 4000, CM v4.0: 1150 nits

How can one be sure that the old algorithm is being used?
Does having empty L2 trims guarantee the use of the legacy algorithm, or is there another way to confirm it?

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I ran some tests on my Sony A95L, and it seems tone mapping starts at:

• avg_pq 600, MDL 1000, CM v2.9: 1150 nits
• avg_pq 600, MDL 1000, CM v4.0: 1150 nits
• avg_pq 600, MDL 4000, CM v2.9: 150 nits!
• avg_pq 600, MDL 4000, CM v4.0: 1150 nits

How can one be sure that the old algorithm is being used?
Does having empty L2 trims guarantee the use of the legacy algorithm, or is there another way to confirm it?

thanks, I will add your TV to the chart. hard clipping point 1100nits?

Any cmv2.9 rpu made from a cmv4.0 workflow will always have an avg_pq floor of 10nits with L2 trims at 100,600,1000nits.
see this comparison, I've compared all the Dolby algo version: https://slow.pics/c/OA0pupEN

[bbeny123]

thanks, I will add your TV to the chart. hard clipping point 1100nits?

yep, 1100nits.

Damn, now I’m really torn about whether to generate DV for The Return of the King...
The original DV was already created using the new algorithm, with an MDL of 4000 nits, and it actually has really rich L2 trims.
Unfortunately, it seems the original CM v4.0 version isn’t available anywhere online.

L1_plot.png (227.42 KiB) Viewed 407 times

L2_plot-100.png (270.99 KiB) Viewed 407 times

L2_plot-600.png (255.4 KiB) Viewed 407 times

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I would generate cmv4.0. The whole movie L1 is under your TV tone mapping target nits.
It doesn't matter how much editing they did in the trims... Unless they deliver a trim, the HDR10 layer always has the original HDR master brightness/grade and should be the reference, the intended representation.

[daffie]

I ran some tests on my Sony A95L, and it seems tone mapping starts at:

• avg_pq 600, MDL 1000, CM v2.9: 1150 nits
• avg_pq 600, MDL 1000, CM v4.0: 1150 nits
• avg_pq 600, MDL 4000, CM v2.9: 150 nits!
• avg_pq 600, MDL 4000, CM v4.0: 1150 nits

How can one be sure that the old algorithm is being used?
Does having empty L2 trims guarantee the use of the legacy algorithm, or is there another way to confirm it?

Any cmv2.9 rpu made from a cmv4.0 workflow will always have an avg_pq floor of 10nits with L2 trims at 100,600,1000nits.
see this comparison, I've compared all the Dolby algo version: https://slow.pics/c/OA0pupEN

What is the easiest way to check this ?

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What is the easiest way to check this ?

Check the L1 plot for the 10nits avg_pq floor

[daffie]

Is there some list of movies in old/original cmv2.9 algo (the ones with no automatic trims, no cmv4.0 to 2.9 conversion)?

I read some pages back that this is only about 10% of the movies anyway. Is that correct?

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Probably all the bluray released before 2020.

Just look at the plot here, it has practically all the movies plotted:
https://drive.google.com/drive/u/1/fold ... KFJwFxnDt-

[bbeny123]

I would generate cmv4.0. The whole movie L1 is under your TV tone mapping target nits.
It doesn't matter how much editing they did in the trims... Unless they deliver a trim, the HDR10 layer always has the original HDR master brightness/grade and should be the reference, the intended representation.

So the artistic impact of those L2 trims would be minimal?
In your opinion, is it better to go for higher brightness by eliminating the too early tone mapping issue in CM v2.9, rather than keeping the version with manually tuned L2 trims?

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So the artistic impact of those L2 trims would be minimal?
In your opinion, is it better to go for higher brightness by eliminating the too early tone mapping issue in CM v2.9, rather than keeping the version with manually tuned L2 trims?

It depends on how strongly the colorist adjusted them. I’ve seen many 100 nits trim passes that make the image brighter than the master (HDR10 encode). It seems some colorists are not aware and/or are not monitoring the interpolation to the 600–1000 nits target when they do the SDR trim. The trim’s purpose is to adjust Dolby’s default tone mapping (L1) when it deviates from the artistic intent, which is the 12-bit master.
Making the trims different/brighter from the master doesn’t make much sense and is not recommended in Dolby best practice because this trim will affect more displays with lower targets, and higher-nits displays won’t even see that trim’s effect.

There is a way for the colorist to be more aggressive on the 100 nits trim without affecting the other targets. When you see an RPU with a blank 600 and/or 1000 nits trim, this is exactly what the colorist did.
When I create trims for my own work, I always start by making the 600 nits trim blank, and then I go through all the shots and adjust my 100 nits trim. This way, I know that whatever I do in 100 nits will not affect my other targets. When I’m working on a shot that exceeds 600 nits in the scopes, then I can either unblank the 600 nits trim and let the 100 nits interpolation do its work, or better, adjust the 600 nits trim.

FYI, you can use my script workflow 7-4 to make L1 vs L1-L2 comparison of any frame: I already did many here:
https://drive.google.com/drive/folders/ ... dMiy2ka0mf