hardware accelerated encoding on mac

https://codetv.dev/blog/hardware-acceleration-ffmpeg-apple-silicon

-c:v h264_videotoolbox \ # use Apple Silicon hardware acceleration

Just like

ffmpeg -h encoder=hevc_nvenc

(Trying on Linux running on a PC, 

Codec 'h264_videotoolbox' is not recognized by FFmpeg - will work only on Mac.)

libx265 itself went at 20+fps.

hevc_videotoolbox with warping went at 33 fps.