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+--- Thread: Dolby Vision to SDR converting problem (/thread-3729.html)
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Dolby Vision to SDR converting problem - shurikello - 05.06.2024
When encoding DoVi to SDR using Vapoursynth, I ran into the following problem: in some cases, the algorithm highlights some scenes in the video too much (in preview mode, numerous flickering frames are visible in the direction of increasing brightness a ~1 second before this scene). No matter what settings I adjusted, I couldn't turn off this flickering and floating brightness and force/fix it on some specific scale.
My settings in attach.
RE: Dolby Vision to SDR converting problem - Selur - 05.06.2024
I have 0 real world experience with DOV -> SDR, iirc the 'smooth period' setting is what you should try to adjust to get rid of this flickering.
Cu Selur
RE: Dolby Vision to SDR converting problem - shurikello - 05.06.2024
This is the first thing I tried. None of the settings change the behavior and the encoding algorithm DoVi to SDR.
To make it clear, here is a small video with an example. There are scenes with Patrick Swayze in front of a bright window, the brightness is automatically turned up. Why - is not very clear, it is absolutely unnecessary. I need to turn it off:
https://youtu.be/eEh2wpSfNhA
P.S. HDR to SDR conversion works perfectly at the same time.
RE: Dolby Vision to SDR converting problem - Selur - 05.06.2024
Okay, I would have increased the 'smooth period' not lowered it to 0.
With 0 I would expect such flickering to occur.
As an 'ugly workaround' one could try whether adding Frame->Stabilize->ReduceFlicker or SmallDeflicker helps.
Cu Selur
RE: Dolby Vision to SDR converting problem - shurikello - 05.06.2024
I just did it all. Smooth Period (1000, 10000), all kinds of settings with ReduceFlicker and SmallDeflicker - no changes, at all, the algorithm continues to turn up the brightness on already bright scenes.
if you are interested, here is this piece of 4K video with DoVi: https://drive.google.com/file/d/1CSczL6YN2nIdhOmeNFx6SizRSWFzKNU4/view
RE: Dolby Vision to SDR converting problem - Selur - 05.06.2024
I checked, Hybrid does use the latest vs-placebo release.
Might be a bug in libplacebo or vs-placebo, sadly there is nothing I can do.
If you can share a small sample of your source with me, I can look at it more after work today.
Cu Selur
RE: Dolby Vision to SDR converting problem - shurikello - 05.06.2024
I changed the message above by adding a link to part of the this video DoVi.
RE: Dolby Vision to SDR converting problem - Selur - 05.06.2024
I downloaded the file and will look at it after work and report back.
RE: Dolby Vision to SDR converting problem - Selur - 05.06.2024
I can reproduce the problem, but no clue why this happens with vs-placebo.
To me, this looks like a bug in vs-placebo, since otherwise I would have expected for it to happen in MPC-HC too
=> your best bet is to report this to the vs-placebo developers, maybe they can fix it.
Cu Selur
Ps.: Maybe something can be done with https://github.com/quietvoid/dovi_tool
PPs.: there is an updated vs-placebo fork: https://github.com/sgt0/vs-placebo/releases/tag/v3.0.0, but from my first test updating the dll doesn't help.
RE: Dolby Vision to SDR converting problem - shurikello - 05.06.2024
Can you tell me, studying vs-placebo github link, I found several commands that are not presented in Hybrid's Tonemap (Placebo) settings section, these are:
metadata: Data source to use when tone-mapping. Setting this to a specific value allows overriding the default metadata preference logic. Defaults to 0 (automatic selection).
0 Automatic selection
1 None (disabled)
2 HDR10 (static)
3 HDR10+ (MaxRGB)
4 Luminance (CIE Y)
visualize_lut: Display a (PQ-PQ) graph of the active tone-mapping LUT. See mpv docs.
show_clipping: Highlight hard-clipped pixels during tone-mapping.
contrast_recovery: HDR contrast recovery strength. If set to a value above 0.0, the source image will be divided into high-frequency and low-frequency components, and a portion of the high-frequency image is added back onto the tone-mapped output. May cause excessive ringing artifacts for some HDR sources, but can improve the subjective sharpness and detail left over in the image after tone-mapping. Defaults to 0.0.
Can the default settings of these commands (one of them) give the autobrightness effect that we were talking about?