ffmpeg exited 1: Stream specifier ':v' in filtergraph description [0:v]settb=AVTB,fps=30,setsar=1[v0];[1:v]settb=AVTB,fps=30,setsar=1[v1];[2:v]settb=AVTB,fps=30,setsar=1[v2];[3:v]settb=AVTB,fps=30,setsar=1[v3];[v0][v1]xfade=transition=fade:duration=0.800:offset=4.400[x1];[x1][v2]xfade=transition=fade:duration=0.800:offset=13.600[x2];[x2][v3]xfade=transition=fade:duration=0.800:offset=38.230[vout] matches no streams.