Requirements for hevc_v4l2m2m?

[alucryd]

Hi there, I recently discovered this fantastic fork which finally fixed my h264_v4l2m2m woes with mpv on the pi 4. However hevc_v4l2m2m still doesn't work for me, what could I be missing?

I'm using https://github.com/jc-kynesim/rpi-ffmpeg/commit/8bba3c74aba3ab00eb4634c25573bad1a3c8b91c right now, and tried a variety of mpv releases from 0.32 to the newly released 0.35. Everything is built using a crosstool toolchain, and tested on official raspbian images, both 32 and 64 bit. Do I need to use a branch based on 5.1.2, if so which one?

Happy to provide more information.