[0:v] scale=1920:1080:force_original_aspect_ratio=1,pad=1920:1080:(ow-iw)/2:(oh-ih)/2:color=white,setsar=1:1,fps=30[i_video];color=c=black:s=1920x1080:r=30:d=0.5[i_black];[i_video][i_black]concat=n=2:v=1:a=0,settb=AVTB [t0v]; aevalsrc=0|0:d=2 [t0a]; [1:v]split=1[c0v];[1:a]asplit=1[c0a];[c0v] trim=start=0:end=48.279,setpts=PTS-STARTPTS,setsar=1:1,fps=30,settb=AVTB [t1v]; [c0a] atrim=start=0:end=47.779,asetpts=PTS-STARTPTS [t1a]; [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=30,settb=AVTB [t2v]; aevalsrc=0:d=2 [t2a]; [t0v][t1v]xfade=transition=fade:duration=0.5:offset=2[vfade1];[vfade1][t2v]xfade=transition=fade:duration=0.5:offset=49.779[outv];[t0a][t1a][t2a]concat=n=3:v=0:a=1[outa];