ffmpeg -i in.mp4 -i main.mp4 -i out.mp4 -filter_complex "[0:v]fade=type=out:duration=2:start_time=28,setpts=PTS-STARTPTS[v0];[1:v]fade=type=in:duration=2,fade=type=out:duration=2:start_time=28,setpts=PTS-STARTPTS[v1];[2:v]fade=type=in:duration=2,setpts=PTS-STARTPTS[v2];[v0][0:a][v1][1:a][v2][2:a]concat=n=3:v=1:a=1[v][a]" -map "[v]" -map "[a]" output.mp4
- duration : durée de la transition en secondes
- fade=type : sens du fading
