"Half-rate update" like artifacts
I've been seeing seeing these artifacts in videos I've encoded with SVT-AV1 for a while but had't been able to put my finger on what exactly looked off about them.
The way I'd describe this is that they kind of look like the optimization that some video games use of updating some parts of the game at half the framerate or less. If you focus on the part of the image where these artifacts are visible, your first instinct might be that the player is dropping frames.
You can see this in the encoded sample. The evergreen branches on the left half should be swaying in the wind smoothly, but instead parts of them don't change for two or more frames, making the motion appear non-smooth.
This is especially visible in this clip at 480p, but it's also present in lesser quantity at 720p (the included source file is 1080p, so other resolutions can be tested). It's probably related to tune 0, since using tune 1 alleviates the issue. Although with tune 1, the same parts of the image has blurring artifacts, almost as if there's motion interpolation going on.
How to reproduce:
ffmpeg -i hp3test1.mkv -pix_fmt yuv420p10le -vf scale=854:-2 -sn -an -strict -1 -loglevel quiet -f yuv4mpegpipe - |SvtAv1EncApp -i stdin --keyint 240 --preset 8 --crf 33 --tune 0 -b hptest1.480p.tune0.p8.ivf
I'd say this is 1.0 material, so mentioning #1845 (closed).
I'm using the latest git. SvtAv1EncApp build and system info output:
Svt[info]: -------------------------------------------
Svt[info]: SVT [version]: SVT-AV1 Encoder Lib v0.9.1-36-ga9dcf001
Svt[info]: SVT [build] : Ubuntu Clang 12.0.0 64 bit
Svt[info]: LIB Build date: Mar 13 2022 22:17:27
Svt[info]: -------------------------------------------
Svt[warn]: Forced VQ mode to use HierarchicalLevels = 3
Svt[info]: Number of logical cores available: 4
Svt[info]: Number of PPCS 21
Svt[info]: [asm level on system : up to avx]
Svt[info]: [asm level selected : up to avx]
Svt[info]: -------------------------------------------
hptest1.480p.tune0.p8.ivf (SVT-AV1 output that shows the issue, created with the command above)
hptest1.480p.tune1.p8.ivf (SVT-AV1 output created with --tune 1 that doesn't have the issue)
hp3test1.mkv (source file in 1080p)