Quote:
Originally Posted by Boulder
Ben Waggoner was doing some tests with --aq-mode 4, I don't think he got them finished though. He's probably the only one (apart from the devs) who has some kind of an insight to how it looks with real life examples.
For what it's worth, lately I've found --aq-mode 3 being troublesome. With normal sources originating from film, like the older seasons of X-Files which contain quite a lot of grain and noise, it works well at around ~0.6 for strength. Then there's something like Suits, or The Killing, which look terrible. The sources are terrible in quality -- lots of macroblocking which appears when the encoder starts removing the grain hiding some of that -- and aq-mode 3 produces a substantially lower average bitrate at the same CRF than aq-mode 1. I don't know why the rate control works this way, The Killing does contain quite a lot of dark scenes but I was unable to get a good result without switching to --aq-mode 1 at the default strength. I also raised psy-rd to 3.0 and deblock to 0:0 to try to keep the higher frequencies and avoid banding where the encoder removes too much from the original image.
I really scratched my head at the issue the whole weekend. Yes, I did test x264 at --preset veryslow, but it wasn't any better 
Sometimes I have used a dirty trick and added a light amount of fake grain with GrainFactory3 before feeding the video to the encoder. I may need to test that too  |
I did my own testing, both with AQ mode 2 and 3. It did not make things beter here and I was hoping AQ mode 3 would work well on dark scenes, but it didn't. All I saw is increased bitrate for 2 and 3 with no meaningful improvements... so I went back and stick to my good ol' AQ mode 1
As for psy-rd/psy-rdoq, they are meant to keep the original energy of the source as much as possible at higher strength. So if you have a (very) noisy sample, the bitrate will shoot up in order to preserve the noise/grain. These two settings are set to high values when using --tune grain (psy-rd is set to 4 and psy-rdoq is set to 10). I personally now use psy-rd of 3.2 and psy-rdoq of 15. I do not mind the increase of bitrate as I aim to preserver the input as much as possible. These two especially have an effect on dark scenes and look better than using AQ mode 2 or 3. I haven't tested AQ mode 4, though