rav1e VS obs-amd-encoder

Sure. You'll see it very often in codec implementations. From rav1e, a fast AV1 encoder mostly written in Rust: https://github.com/xiph/rav1e/tree/master/src/x86

Large portions of the algorithm have been translated into assembly for ARM and x86. Shaving even a couple percent off something like motion compensation search will add up to meaningful gains.

Or the current reference implementation of JPEG: https://github.com/libjpeg-turbo/libjpeg-turbo/tree/main/sim...

You can speed up the sampling process with --vmaf n_subsample=5, which in my experience works more accurately than either 2 or 4, possibly due to this bug/feature present in multiple encoders. You might also need to manually set the number of threads used for VMAF calculation with --vmaf n_threads=16, but YMMV.

That remember me of https://github.com/xiph/rav1e which is an AV1 encoder

It's getting there.. Initial steps for FFmepg: https://patchwork.ffmpeg.org/project/ffmpeg/list/?series=8444 rav1e: https://github.com/xiph/rav1e/pull/3000

I doubt much will be done on such an exotic feature any time soon. Progress has been slow on rav1e, it's missing a lot of features, and only supports tile threading.

rav1e is quite well maintained, the fix for the lint was merged days after the ilog PR merged. But the 0.5.1 release of rav1e was one year ago, in December 2021, while the ilog rename was end of August 2022. There hadn't been a release though of rav1e until end of November 2022, which was also a semver incompatible one. Users had only 2-ish months of time to get to the new rav1e version without experiencing breakage.

The rav1e encoder for AV1 has more assembly in it than Rust, which also doesn't bode well for memory-safe video codec implementations. But this might change once Rust provides portable and memory-safe explicit SIMD.

I wouldn't be so sure, OBS doesn't have popular support for radeon development, iirc the last update for AMD cards was in 2019 and the single dev who used to do AMF work on their spare unpaid time quit.