Recently I discovered ffmpeg-python [1], also a nice Python frontend to FFmpeg. One of its best features is being able to show nice graphs [2] showing where which filters are applied from in to output. And all FFmpeg filters can be used, it is a thin layer over FFmpeg, just much more readable.
[1] https://github.com/kkroening/ffmpeg-python [2] https://github.com/kkroening/ffmpeg-python#complex-filter-gr...