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Old 17th August 2020, 22:08   #41  |  Link
FranceBB
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Originally Posted by wswartzendruber View Post
I've noticed that VLC tone maps HLG differently depending on OS, which is strange.

Anyway, I also remember the release notes for 3.0.0 saying that they corrected HLG tone mapping.
Since you have the latest version of VLC, can you try to compare its HLG tonemapping to the one done by MPV? It would be interesting to see how they look like and whether the VLC guys actually really improved it compared to years ago.
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Old 17th August 2020, 23:59   #42  |  Link
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VLC uses different video output APIs vs OS.
Default on Win10 is Dx11. If you check the changelog you will see there have been a number of HDR updates for this mode in the last year.

there is also an OpenGL for windows mode.

Dx9 doesn't do tonemapping without using a shader.
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Old 18th August 2020, 02:35   #43  |  Link
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Quote:
Originally Posted by FranceBB View Post
Since you have the latest version of VLC, can you try to compare its HLG tonemapping to the one done by MPV? It would be interesting to see how they look like and whether the VLC guys actually really improved it compared to years ago.
Here you go; VLC is on the top in each one while MPV is on the bottom: https://imgur.com/a/2JeNJvT

I was blown away by this at first. MPV seems to handle 2020->709 conversion with dramatic superiority along with having much more pleasing gamma. In fact with MPV, I can't even tell it wasn't graded natively in 709.

Last edited by wswartzendruber; 18th August 2020 at 02:37.
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Old 18th August 2020, 09:57   #44  |  Link
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Here you go; VLC is on the top in each one while MPV is on the bottom: https://imgur.com/a/2JeNJvT
Thanks.

Quote:
Originally Posted by wswartzendruber View Post
I was blown away by this at first. MPV seems to handle 2020->709 conversion with dramatic superiority along with having much more pleasing gamma. In fact with MPV, I can't even tell it wasn't graded natively in 709.
Yeah, that's exactly what I was talking about when I said that I switched to MPV years ago. Looks like VLC did improve, but it still lacks behind MPV when it comes to tone-mapping HDR contents.
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Old 28th August 2020, 05:59   #45  |  Link
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Two things:

1. MPV on Linux is using luminance mapping. Bright specular areas will dim over a couple of seconds, and it's not part of the movie.

2. VLC on Windows doesn't exhibit this and looks much better than VLC on Linux.
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Old 11th September 2020, 07:18   #46  |  Link
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I finally got to watch my encodes on a HLG display, a Samsung from either this year or last. It was absolutely abysmal. The TV correctly detected the gamma curve as HLG, and I disabled the TV's enhancements for everything, but it just looked bland and washed out.

Luminance

I could see the TV continually adjusting the brightness level depending on the average luminance of the frame being shown. I'm not understanding why it wouldn't just apply tone mapping similar to VLC and MPV, although much less aggressively. The tone mapping used would depend on what the TV's brightness is set to. The higher the brightness setting, the more quickly specular detail gets compressed. This...shouldn't be hard.

Color

I don't know how to describe this other than "underwhelming."

HEVC Decode

On my PC, the HEVC decoding is exceptional. For movies where I instructed x265 to preserve grain, that comes through nicely. Whereas with this television, each frame seemed more like a matte painting. I wasn't quite sure what I was even looking at or how messed up the decode filtering would have to be to produce this result.

This isn't the result I was looking for. My converter only does linear brightness adjustment followed by gamma conversion. That's it.

Last edited by wswartzendruber; 11th September 2020 at 07:21.
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Old 13th October 2020, 00:31   #47  |  Link
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I did The Matrix.

https://imgur.com/gallery/SL3NYCe

What surprises me is how overly bright and washed out the 2018 Blu-ray release is.
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Old 13th October 2020, 11:25   #48  |  Link
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For me, the worst thing about Matrix is the green-ish tint they spread everywhere on the SDR BD.
I mean, I know it's an artistic choice, but still...
Thankfully, the HDR BD isn't affected, as your MPV preview shows.
Your version looks good too, by the way.
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Old 24th October 2020, 23:02   #49  |  Link
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Is there a defacto standard tonemapping algorithm for compressing +1,000 nit brightness levels down to within 1,000 nits?

HDR TVs are doing something to apply metadata...

Right now, pq2hlg is just hard-clipping.
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Old 24th October 2020, 23:56   #50  |  Link
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Oh no, you don't want to hard-clip it!
As you're working with curves, just knee it down to the desired level.
I think that applying a knee is a far better approach than brutally clipping values above 1000 nits
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Old 25th October 2020, 19:08   #51  |  Link
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Quote:
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Oh no, you don't want to hard-clip it!
As you're working with curves, just knee it down to the desired level.
I think that applying a knee is a far better approach than brutally clipping values above 1000 nits
It looks like I need to apply the Rec.2020 coefficients to the RGB tuple to get that pixel's luminosity, map that to a lower luminosity, get the adjustment ratio, and then adjust each of the RGB channels by that ratio...
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