ffmpeg leaves audio gap when concatening videos

Question

I am trying to cut a video in 2 parts then reassembling with ffmpeg but the final output has a small audio glitch right where the segments meet. I am using the following command to split the video 1.mp4 in 2 parts:

ffmpeg -i 1.mp4 -ss 00:00:00 -t 00:00:02 -async 1 1-1.mp4

and

ffmpeg -i 1.mp4 -ss 00:00:02 -t 00:00:02 -async 1 1-2.mp4

Once I have the 2 parts I am concatening them back together with:

ffmpeg -f concat -i files.txt -c copy output.mp4

files.txt is correctly listing both files. Can anyone point me to where the problem might be?

Thanks

Gyan Gyan · Accepted Answer · 2016-07-06T20:14:43

The glitch is likely due to the audio priming sample showing up in between.

Since you're re-encoding the segments, you can do this in one command:

ffmpeg -i 1.mp4 -filter_complex 
                "[0]trim=duration=2[v1];[0]trim=2:4,setpts=PTS-STARTPTS[v2];
                 [0]atrim=duration=2[a1];[0]atrim=2:4,asetpts=PTS-STARTPTS[a2];
                 [v1][a1][v2][a2]concat=n=2:v=1:a=1[v][a]"
       -map "[v]" -map "[a]" output.mp4

ffmpeg leaves audio gap when concatening videos

2 Answers