[0:v]split=2[c0v][c1v];[0:a]asplit=2[c0a][c1a];[1:v] scale=1920:1080:force_original_aspect_ratio=1,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:color=white,setsar=1:1,fps=25,settb=AVTB [t0v]; aevalsrc=0:d=3 [t0a]; [c0v] trim=start=0:end=19.17,setpts=PTS-STARTPTS,fps=25,settb=AVTB [t1v]; [c0a] atrim=start=0:end=19.17,asetpts=PTS-STARTPTS [t1a]; [c1v] trim=start=19.409999999999997:end=48.989999999999995,setpts=PTS-STARTPTS,fps=25,settb=AVTB [t2v]; [c1a] atrim=start=19.409999999999997:end=48.489999999999995,asetpts=PTS-STARTPTS [t2a]; [2:v] scale=1920:1080:force_original_aspect_ratio=1,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:color=white,setsar=1:1,fps=25,settb=AVTB [t3v]; aevalsrc=0:d=3 [t3a]; [t0v][t1v]xfade=transition=fade:duration=0.5:offset=3[vfade1];[vfade1][t2v]concat=n=2:v=1:a=0[vfade2]; [vfade2][t3v]xfade=transition=fade:duration=0.5:offset=51.25[outv];[t0a][t1a][t2a][t3a]concat=n=4:v=0:a=1[outa];