[Cin]hevc qsv alpha encoding patchest from 2024

https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2024-September/333791.html I think it should be applicable to ffmpeg from around that time, but we mostly interested in first patch (for testing) Idea is to patch ffmpeg checkout from ~sept 2024 with first path named libavcodec/qsvenc: enable Alpha Encode for HEVC and try provided command line: ffmpeg.exe -v verbose -hwaccel qsv -hwaccel_output_format qsv -f rawvideo \ -pix_fmt bgra -s:v 1920x1080 -r:v 25 -i input.argb -vf \ 'format=bgra,hwupload=extra_hw_frames=120' -an -c:v hevc_qsv \ -alpha_encode 1 -y out.mp4 I guess developer was on Windows ....