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Old 26th July 2022, 11:09   #321  |  Link
ErazorTT
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Originally Posted by wswartzendruber View Post
Can Dolby Vision be used to determine reference white adjustment?
Not that I know of.
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Old 26th July 2022, 11:13   #322  |  Link
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This is Dolby secret I assume. Nothing public. Every tool does it using Dolby SDK.
On the creation side yes, I would assume that anything uses the SDK. But on the presentation side, like Software players, these must somehow implement that. I looked into the source codes of VLC / FFMPEG and mpv but have not found anything. So my current assumption is that these also don't actually apply any of the processes of the dynamic tonemapping.
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Old 26th July 2022, 11:28   #323  |  Link
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It's all licensed and proprietary. So they may know it, but it's protected by licensing agreement. Dolby is always done same way and that's the whole idea of it.
Look at mpv - they may have it:
https://emby.media/community/index.p...vision-in-mpv/

Actually this may only work if your display is DV capable and certified. Idea is simple- someone has to pay Dolby licensing fees

Last edited by kolak; 26th July 2022 at 11:39.
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Old 26th July 2022, 15:00   #324  |  Link
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mpv doesn't do the whole dynamic tone map processing, only the initial colourspace (polynomial and chroma MMR mapping).
It's based on some RE efforts and "ETSI GS CCM 001", nothing related to Dolby licensing.

The first step would be to parse the display management metadata in FFmpeg, to make the shot-by-shot tone map metadata available.
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Old 26th July 2022, 16:19   #325  |  Link
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I'm sure it's nothing to do with licensing
Point is - there is no official Dolby processing without licensing.
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Old 26th July 2022, 22:28   #326  |  Link
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Quote:
Originally Posted by kolak View Post
It's all licensed and proprietary. So they may know it, but it's protected by licensing agreement. Dolby is always done same way and that's the whole idea of it.
Dolby stuff have always been a pain to handle and after creating proprietary stuff with audio, now they're fiddling with video too. (T_T)

It took ages for the open source community to decode proprietary audio codecs like DolbyE (and the current ffmpeg implementation is far from ideal and only works with the u8 workaround which made me write several lines of code cross-checking with mediainfo given that ffprobe cannot even recognize DolbyE in an mxf container) and now they're back with DolbyED2 Atmos (currently impossible to decode) and DolbyVision profiles (also currently impossible to decode).
Best case scenario, they're just using the 12bit dual layer profile so that it's H.265 10bit PQ + metadata layer to create the 12bit and we can still watch the content by ignoring the proprietary Dolby Vision metadata layer. Worse case scenario: they're using the Dolby Vision Proprietary colorspace like dvhe0509 and we won't be able to see the content correctly (although there's been a recent attempt with libplacebo in VLC, MPV and Avisynth to tackle it).

Last edited by FranceBB; 26th July 2022 at 22:30.
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Old 27th July 2022, 06:36   #327  |  Link
wswartzendruber
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I'm just going to continue to appreciate HLG for its abundant simplicity.
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Old 29th July 2022, 15:22   #328  |  Link
ErazorTT
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There is something wrong with v1.0.1 and v1.0.0 which was ok for 0.4.1. Using a perfect 16bits grayscale (this is just a 8bits jpeg of it) and applying the luts with a lum-scaling factor of more than 1 I'm getting the following picture:


While with v0.4.1 I was getting this:


Please look at the enlarged picture and not at the thumbnail. In the area where it should have been perfect white there is a wave structure. Lum-scale factor was 3.0 in this case, but other factors above 1 will produce the same structures. I used a 65x65x65 lut.

This is the script how I generated that:
Code:
ImageReader("GreyRamp16bits.png",use_devil=true,pixel_type="RGB48").ConvertToPlanarRGB()
Cube("z:\lut_3.0_1000.cube",fullrange=true)

Last edited by ErazorTT; 29th July 2022 at 15:33.
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Old 29th July 2022, 16:33   #329  |  Link
wswartzendruber
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I also need to know what you're passing for MaxCLL.
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Old 31st July 2022, 21:17   #330  |  Link
ErazorTT
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Originally Posted by wswartzendruber View Post
I also need to know what you're passing for MaxCLL.
I was using 1000 nits, thus the filename lut_3.0_1000.cube.

But that issue is independent of the maxcll. I just tested it also with 4000 and 10000.

Last edited by ErazorTT; 31st July 2022 at 21:21.
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Old 31st July 2022, 22:44   #331  |  Link
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If --max-cll * --lum-scale <= 1,000...no tone mapping will be performed.

That is why I wanted to know.
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Old 3rd August 2022, 04:17   #332  |  Link
wswartzendruber
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I'm not getting this at all. Can you send over the LUT that's been generated with your 1.0.1 binary?
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Old 4th August 2022, 19:37   #333  |  Link
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There's nothing wrong with your build of pq2hlg, is there? You did some kind of image processing (scaling?) on the output that put that banding in, didn't you?

:-)
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Old 4th August 2022, 21:58   #334  |  Link
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Its more prominent with smaller LUTs, try size 33. Here is an archive containing anything, even a cmd to create the LUT: hlg_test.7z
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Old 4th August 2022, 23:31   #335  |  Link
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https://wswartzendruber.net/uploads/..._converted.png

When sampling pixels, the brightness always increases as I progress rightward. I cannot find any row of pixels that's brighter on the left side than the right.

ffmpeg -i GreyRamp16bits.png -vf lut3d=lut_4000_3.0.cube -pix_fmt rgb48be GreyRamp16bits_converted.png

I did recompress with The GIMP. It has preserved the 16-bit sampling precision.

EDIT: This is with the same LUT you provided.
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Old 7th August 2022, 19:12   #336  |  Link
ErazorTT
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So you are not using avisyth and the Cube function from here: http://rationalqm.us/hdr/avscube_1.3.zip?

Thus I guess, this means that there is a bug in the avscube library.

Last edited by ErazorTT; 7th August 2022 at 19:14.
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Old 8th August 2022, 00:40   #337  |  Link
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Originally Posted by kolak View Post
It's not just about brightness itself. It's about color volume, which makes huge impact on your brain.
I'm not going to argue with you as I don't have enough expertise. I can only pass what Dolby people said. They done a lot of study including many tests on random people (not just engineers). 4K nits is apparently not "burning" your eyes at all.
Atm. color volume is an issue even for 1K content as OLEDs due to technology limitations makes signal pure what above some nits (if I remember well they fall apart already at 200 or so), which is not how it should be.
Sony reference OLED monitor was RGB based and it behaved much better. There is video on YT (from Vincent) where it can be seen compared to Apple HDR screen.
They do not fall apart, you are talking about this dumb display that was just a bug in power adapter (more accurately USB-C plug, LOL). LG C9 does not have such problems, in fact they can be calibrated to reference (even if Sony is slighly better it does not really matter, since both are under JND, though slightly bigger than a JND if Delta IPT is used). Some colors can be 0.0001 Delta E 2000 (not that 2000 standard is that accurate for HDR). Asus monitor though: https://youtu.be/vYWDsJGVYWY?t=565

Last edited by Balling; 8th August 2022 at 00:51.
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Old 8th August 2022, 00:50   #338  |  Link
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Quote:
Originally Posted by wswartzendruber View Post
EDIT: Redid the whole post.

@FranceBB

I punched in the HLG EOTF into Groovy and ran it.

https://pastebin.com/uBSvprpG

That produced these results, measured in nits:

https://wswartzendruber.net/uploads/hlg-values.txt

So for a 1,000 nits reference display, those are the values of the 64-940 range (as my script calculates them).

Here's an except from the 64-96 range:

64: 0
65: 0.00002319768460764913344820080387531646692877984605729579925537109375
66: 0.0001224381134056305307951373340102918518823571503162384033203125

Those are all below 1/10 of a nit. Can the human eye even perceive more than that?
Are you kidding me? Human vision can persieve (LG C9 is 0.00006 nits, PQ is minimal 0.0001) 0.000003 (after some adaptation, I personally tried, I can see after 68 (not 65, 66, (64 is black, it does not flicker)) in PQ after 10 minutes of dark room). https://www.mkrgeo-blog.com/the-role...-human-vision/
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Old 8th August 2022, 01:17   #339  |  Link
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Originally Posted by ErazorTT View Post
I just know the bin files, and I have only used theses until now.



Well, I wished I knew how to perform the trim pass based on the signaled values, but I have not found any source which describes this technically. Does anybody have any idea how I could put my hands on that?

Trims as in for different displays should be described in the standards of SMPTE. Artistic meta maybe too. https://libgen.li/index.php?req=+Dyn...lume+Transform

Or artistic meta can be reverse ingeenered by getting root on Android OS of LG C9 or Movies & TV plugins. In fact I pasted SDR screenshots in russian ixbt of the sample where the metadata changes but the base layer is same encoded image. Oh, Nvidia's windows driver also support their NVAPI for this, it is very buggy though (and I think it is TV led only, so no support for Low Latency player led DV). https://forums.developer.nvidia.com/...ision/199530/2

Last edited by Balling; 8th August 2022 at 01:21.
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Old 8th August 2022, 01:23   #340  |  Link
Balling
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Originally Posted by wswartzendruber View Post
Can Dolby Vision be used to determine reference white adjustment?
You are talking about true RAW (not partially debayered like in BRAW), like N-RAW? Well, Red is suing Nikon for it, LOL, Nikon Z9 can lose pretty quick, after all it is hilariuous every thing above 24 fps debayered is patented by Red (and Canon, but those are just sublicensing it).

Last edited by Balling; 8th August 2022 at 01:36.
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