There are tons of Python FFmpeg wrappers out there but they seem to lack complex filter support - useless for anything but trivial examples. ffmpeg-python works well for simple as well as complicated signal graphs.

Quickstart

import ffmpeg
ffmpeg \
    .file_input('input.mp4') \
    .file_output('output.mp4') \
    .run()

Or if you prefer a non-fluent interface:

import ffmpeg
in = ffmpeg.file_input('input.mp4')
out = ffmpeg.file_output(in)
ffmpeg.run(out)

Complex filter graphs

FFmpeg is extremely powerful, but it's command-line interface gets really complicated really quickly - especially when working with signal graphs and doing anything more than trivial.

Take for example a signal graph that looks like this:

The corresponding command-line arguments are pretty gnarly:

ffmpeg -i input.mp4 \
    -filter_complex "\
        [0]trim=start_frame=10:end_frame=20,setpts=PTS-STARTPTS[v0];\
        [0]trim=start_frame=30:end_frame=40,setpts=PTS-STARTPTS[v1];\
        [0]trim=start_frame=50:end_frame=60,setpts=PTS-STARTPTS[v2];\
        [v0][v1][v2]concat=n=3[v3]"\
     -map [v3] output.mp4

Maybe this looks great to you, but if you haven't worked with FFmpeg before, this probably looks pretty alien.

If you're like me and find Python to be powerful and readable, it's easy with ffmpeg-python:

import ffmpeg

in_file = ffmpeg.file_input('input.mp4')
joined = ffmpeg.concat(
    ffmpeg.trim(in_file, start_frame=10, end_frame=20),
    ffmpeg.trim(in_file, start_frame=30, end_frame=40),
    ffmpeg.trim(in_file, start_frame=50, end_frame=60)
)
out = ffmpeg.file_output(joined, 'output.mp4')
out.run()

ffmpeg-python takes care of running ffmpeg with the command-line arguments that correspond to the above filter diagram, and it's easy to what's going on and make changes as needed.

Real-world signal graphs can get a heck of a lot more complex, and ffmpeg-python doesn't care.