ffmpeg failed to drawbox and set volume

Question

I don't know what is wrong in my command with ffmpeg. Lets say I have a video and I want to make a black screen with muted audio between 20-30 seconds. So what I wrote is:

ffmpeg -i input.mp4 -filter_complex "[0:v]trim=0:20[0v];[0:a]atrim=0:20[0a];[0:v]trim=20:30,drawbox=color=black:t=fill[1v];[0:a]atrim=20:30,volume=0[1a];[0:v]trim=30:60[2v];[0:a]atrim=30:60[2a];[0v][1v][2v]concat=n=3:v=1:a=0[outv];[0a][1a][2a]concat=n=3:v=0:a=1[outa]" -map [outv] -map [outa] output.mp4

Now, I expect to have a video with 1 min length where the seconds between 20 & 30 are muted with black screen, but what I got is:

20 sec correct
20 sec freezing video with no audio
40 sec black video with no audio
30 sec correct

Can anyone help and tell me what is wrong in the command line?

question from:https://stackoverflow.com/questions/65914491/ffmpeg-failed-to-drawbox-and-set-volume

Answer 1

add setpts:

ffmpeg -i "input 2.mp4" -filter_complex "
[0:v] trim=0:20[0v];
[0:a]atrim=0:20[0a];
[0:v] trim=20:30, setpts=PTS-STARTPTS,drawbox=color=black:t=fill[1v];
[0:a]atrim=20:30,asetpts=PTS-STARTPTS,volume=0[1a];
[0:v] trim=30:60, setpts=PTS-STARTPTS[2v];
[0:a]atrim=30:60,asetpts=PTS-STARTPTS[2a];
[0v][0a][1v][1a][2v][2a]concat=n=3:v=1:a=1[outv][outa]
" -map [outv] -map [outa] output.mp4