I'm planning to encode some of my blu-ray discs to AV1 with maximum quality in mind. After thinking I had a good set of settings nailed down, I got sensitized to the topic of banding and found that in certain frames, my encodes were suffering from it quite badly.
I also found the biggest magnet for banding in an animated show: the very first episodes of "The Eminence in Shadow" shows a purple blanket that has crazy banding even at 10-bit with high bit rates.
Here's aom-av1-lavish, the "opmox mainline merge" branch as of November, 14th, 2023 with --arnr-strength=0 --enable-dnl-denoising=0 --denoise-noise-level=1

After seeing that another (x265) encode did it much better and even SVT-AV1 with mostly default settings performed well (see further down), I changed to --arnr-strength=1 --enable-dnl-denoising=0 --denoise-noise-level=6
and what a difference:

Finally, this is the result of SVT-AV1-psy as of January, 22nd, 2024. The settings are --film-grain 6 --film-grain-denoise 0
:

So how does one estimate a video's noise / grain level?
Do I just develop a feel for which setting corresponds to what look? That might involve quite a bunch of failed encodes, however.
After reading, the gist of it seems to be:
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In short, just another out of touch entrepreneur who sells snake oil cures to people suffering in the current system, so that they may invite in the boot that stomps them down for good.