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Old 1st December 2023, 06:06   #21  |  Link
Boulder
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Originally Posted by benwaggoner View Post
Too much PSNR tuning, and to a lesser degree VMAF, can cause the flattening. This can generally be addressed with AQ tuning. It's an encoder limitation, not a codec limitation.

I've done comparisons between encoding AV1 with grain preservation without FGS versus FGS, and while grain preservation requires more bits than with FGS, with proper encoder and parameter tuning the perceptual results are pretty similar, and can match what's possible with x265.
Out of interest, which encoders have you been testing? Are all the current open source encoders based on the same source so they basically work the same way no matter what? At least aomenc and svt-av1 are both smoothing things very heavily, I'd say aomenc less when it is tamed in code and all temporal filtering is switched off in parameters.

Funny thing is that with a very grainy source like "Withnail and I" Blu-ray, the grain is actually preserved quite nicely. I don't know if I should test adding grain before encoding and seeing what comes out
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Old 1st December 2023, 07:13   #22  |  Link
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I'm very interested in transparent encoding. Seems we have different CRF 26, it's not a bluffest for me.
I can assure you CRF 26 destroys fine details and smooths out everything to the point where e.g. sea waves turn into goo.

Again, looks like you're not interested in transparent encoding by a long shot or maybe you have a completely different idea what it is.

Transparent encoding is when your encode matches your source in terms of fine details 100%.

Here, try to encode this clip at CRF 26 and then compare the result to the source. Pay extra attention to the sea and mountains.

Last edited by birdie; 1st December 2023 at 07:19.
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Old 1st December 2023, 07:43   #23  |  Link
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Transparent encoding is when your encode matches your source in terms of fine details 100%.
And svt-av1 will not be able to do that even at CRF 12
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Old 1st December 2023, 13:33   #24  |  Link
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Looking at the 1080p 900kbps samples here: http://download.opencontent.netflix....ix=AV1/Sparks/

Does it make sense to use FGS if the source doesn't have grain ? I am not looking for transparency just a clean result.
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Old 1st December 2023, 17:12   #25  |  Link
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Looking at the 1080p 900kbps samples here: http://download.opencontent.netflix....ix=AV1/Sparks/

Does it make sense to use FGS if the source doesn't have grain ? I am not looking for transparency just a clean result.
FGS won't do much if there isn't grain, but it can help with even light grain. But benefits are proportional to grain levels.
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Old 2nd December 2023, 23:59   #26  |  Link
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I can assure you CRF 26 destroys fine details and smooths out everything to the point where e.g. sea waves turn into goo.

Again, looks like you're not interested in transparent encoding by a long shot or maybe you have a completely different idea what it is.

Transparent encoding is when your encode matches your source in terms of fine details 100%.

Here, try to encode this clip at CRF 26 and then compare the result to the source. Pay extra attention to the sea and mountains.
Thanks for the file. I made an encode with CRF 26 and CRF 0. And yes, you are correct, there are differences with CRF 26 in the waves and the mountain, so it's not transparent. But this differences are so light that I can live with it.
I made a picture of the first frame.
https://www.swisstransfer.com/d/5558...4-9550b636182e
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Old 19th December 2023, 16:51   #27  |  Link
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Thanks for the file. I made an encode with CRF 26 and CRF 0. And yes, you are correct, there are differences with CRF 26 in the waves and the mountain, so it's not transparent. But this differences are so light that I can live with it.
I made a picture of the first frame.
https://www.swisstransfer.com/d/5558...4-9550b636182e
The first frame for most codecs will have higher image quality/detail retention than consecutive frames because it's type I.

Try frames other than I, that's P or B (depending on your compression settings and codec: for offline software codecs it's almost always B frames, hardware codecs are normally only P frames).
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