Kkroening's wrapper has been inactive for some time. I suggest using https://github.com/jonghwanhyeon/python-ffmpeg instead. It has proper async support and a better API.

Scratch that I thought it was a different version. The one you linked has no support for filtergraphs so isn't even comparable to the old one.

Thing is, if you want to use LLMs for mockups you got to use the old one.