[Feature Request] Container/Codec support?

[konafly]

Thank you for your work, even if you say it's not the most efficient implementation on a gpu, it speeds calculating ssimu2 scores up so very much and gives me more room to do stuff with the cpu.

I'd love to see support for eg. MP4 container, just for simplicity of use (not having to mux non-ivf videos into an mkv-container) and most interesting would be the ability to support X265/HEVC, so this tool could be used for eg. HDR content, or just not having to re-encode before using turbo-metrics.

Right now I'm very happy using it for H264/AV1 video and working around things by creating mkv files. It was quite a struggle to build it (agreeing to #12 ) but worth it all the way.