feature idea: only reencode audio on already-h265 files

[mjc]

I have a lot of existing h265 that I would like to use normalized opus audio for instead of just skipping the file entirely. I might implement this and submit a PR if it'll be accepted but it'll be a few months before I am sure I have time

[Kazz3r24]

Any news on this? I'd love to have more audio options in h265ize. Kinda a pain to run h265ize then independently run ffmpeg just to change audio from DCA to AC3 or similar, especially when we just need the ability to pass more arguments to ffmpeg.