How to remove a few seconds from .mp4 file using ffmpeg?

Fast but possibly not accurate

This avoids re-encoding, but you can only cut on key frames, so it may not choose the duration you want.

1. Create segments:

   ffmpeg  -t 00:11:00 -i input.mp4 -map 0 -c copy segment1.mp4
   ffmpeg -ss 00:11:10 -i input.mp4 -map 0 -c copy segment2.mp4
   

2. Create input.txt:

   file 'segment1.mp4'
   file 'segment2.mp4'
   

3. Concatenate with the concat demuxer:

   ffmpeg -f concat -i input.txt -map 0 -c copy output.mp4
   

---

Slow but accurate

You can try to do this without re-encoding, but since you can only cut on keyframes it will possibly not align with your desired cut times, so if you need accuracy you'll need to re-encode:

ffmpeg -i input.mp4 -filter_complex \
  "[0:v]trim=end=660,setpts=N/FRAME_RATE/TB[v0]; \
   [0:a]atrim=end=660,asetpts=N/SR/TB[a0]; \
   [0:v]trim=start=670,setpts=N/FRAME_RATE/TB[v1]; \
   [0:a]atrim=start=670,asetpts=N/SR/TB[a1]; \
   [v0][a0][v1][a1]concat=n=2:v=1:a=1[v][a]" \
  -map "[v]" -map "[a]" output.mp4

• (a)trim will allow you to choose your clips.
• (a)setpts resets timestamps.
• concat concatenates the clips.

See FFmpeg Filter Documentation for details on each filter.

I think u have to cut the video to 2 parts then merge them together. first 'time-value' is starting point, second 'time-value' is length of video u want to cut. In eg below first cut starts at 00:00:00 and length is 11 minutes, second cut starts at 11 mins 10 sec, and length is 10 mins.

cutting:

ffmpeg -i test.mp4 -ss 00:00:00 -t 00:11:00 -acodec copy -vcodec copy test1.mp4

ffmpeg -i test.mp4 -ss 00:11:10 -t 00:10:00 -acodec copy -vcodec copy test2.mp4

merge:

cat test1.mp4 test2.mp4 >> test3.mp4

I haven't tried it, let me know if it works.