ffmpeg \
-i v0.mp4 \
-i v2.mp4 \
-i v3.mp4 \
-i v4.mp4 \
-i v5.mp4 \
-filter_complex \
"[0][1]xfade=transition=fade:duration=0.5:offset=3.500000[V01]; \
 [V01][2]xfade=transition=fade:duration=0.5:offset=6.366667[V02]; \
 [V02][3]xfade=transition=fade:duration=0.5:offset=13.800000[V03]; \
 [V03][4]xfade=transition=fade:duration=0.5:offset=20.433333,format=yuv420p[video]; \
 [0:a]aresample=async=1:first_pts=0,apad,atrim=0:4[A0]; \
 [1:a]aresample=async=1:first_pts=0,apad,atrim=0:3.366667[A1]; \
 [2:a]aresample=async=1:first_pts=0,apad,atrim=0:7.933333[A2]; \
 [3:a]aresample=async=1:first_pts=0,apad,atrim=0:7.133333[A3]; \
 [4:a]aresample=async=1:first_pts=0,apad,atrim=0:6.566667[A4]; \
 [A0][A1]acrossfade=d=0.5:c1=tri:c2=tri[A01]; \
 [A01][A2]acrossfade=d=0.5:c1=tri:c2=tri[A02]; \
 [A02][A3]acrossfade=d=0.5:c1=tri:c2=tri[A03]; \
 [A03][A4]acrossfade=d=0.5:c1=tri:c2=tri[audio]" \
-map "[video]" -map "[audio]" -movflags +faststart out4.mp4