Cut multiple parts of a video with ffmpeg

In what I'm trying to do, I need to remove some parts of a video file, and create a new one from that.

For example, from a video file like this:

===================

I make two cuts

======||=====||||==

and generate a new smaller video file:

=============

And when I say 2, I mean an arbitrary number of separate cuts, depending on the video file.

If I wanted to cut just one part I would do:

ffmpeg -i video.mp4 -ss 00:00:03.500 -to 00:00:08.500 -async 1 cut.mp4 -y

Which works perfectly. I could perhaps do this many times and then join all the cuts together... But this is very inefficient for larger video files.

To make two cuts I was looking at filter_complex. I've been trying to get it right for hours but I can't seem to get this working :/

If I do something like this I get a video with no audio:

command  = 'ffmpeg -i video.mp4 \
    -filter_complex "\
        [0]trim=start_frame=10:end_frame=20[v0];\
        [0]trim=start_frame=30:end_frame=40[v1];\
        [v0][v1]concat=n=2[v5]"\
     -map [v5]  -async 1 output.mp4'

If I try to do this, things get all messed up:

ffmpeg -y -i video.mp4 \
    -filter_complex "\
        [0:v]trim=start_frame=10:end_frame=20[v0];\
        [0:a]atrim=start=10:end=20[a0];\
        [0:v]trim=start_frame=30:end_frame=40[v1];\
        [0:a]atrim=start=30:end=40[a1];\
        [v0][a0][v1][a1]concat=2:v=1:a=1[v5][a]"\
     -map [v5] -map [a] -async 1 output.mp4

I even trying to to this in Python with ffmpeg-python https://github.com/kkroening/ffmpeg-python but I also can't get audio to work.

Can anyone give me some help on this? Thank you very much!!

The select filter is better for this.

ffmpeg -i video -vf "select='between(t,4,6.5)+between(t,17,26)+between(t,74,91)',setpts=N/FRAME_RATE/TB" -af "aselect='between(t,4,6.5)+between(t,17,26)+between(t,74,91)',asetpts=N/SR/TB" out.mp4

select and its counterpart filter is applied to the video and audio respectively. Segments selected are times 4 to 6.5 seconds, 17 to 26 seconds and finally 74 to 91 seconds. The timestamps are made continuous with the setpts and its counterpart filter..