[FFmpeg-user] Removing parts of a video using the select filter

Simon van Bernem simon.vanbernem at yahoo.de
Sat Jan 8 21:38:39 EET 2022

I am trying to remove parts of a video (with audio) using the select
filter. I constructed this command to remove seconds 20-25:

(newlines only for readability)

ffmpeg -i input.mkv
  -vf "select='1-between(t,20,25)', setpts=N/FRAME_RATE/TB"
  -af "aselect='1-between(t,20,25)', asetpts=N/SR/TB" output.mkv

This works great, except that when I use multiple "between" clauses
to discard multiple sections, audio and video will start to get out of
sync. After changing the command to:

ffmpeg -i input.mkv
  -vf "select='1-between(t,20,25)'"
  -af "aselect='1-between(t,20,25)'" output.mkv

this doesn't happen anymore, but now the video is glitchy: Parts that
should be gone sort of remain in the video timeline, but are skipped.
Specifically, for the following command executed on a 59 minute long
video, vlc will jump from 6:38 (second 398s) to 9:59 (second 599), but
the video will still be truncated to 25:00 (1500 seconds) correctly: 

ffmpeg -i input.mkv
    -vf "select='1-between(t,20,25)-between(t,100,200)
    -af "aselect='1-between(t,20,25)-between(t,100,200)
    -gt(t,1500)'" output3.mkv

Is there a way to cut up a video into multiple parts using the select
filter without having the video and audio go out of sync or having
glitchy video playback? If not, what is the best alternative?

More information about the ffmpeg-user mailing list