ffmpeg \
-loop 1 -t 1 -i input0.png \
-loop 1 -t 1 -i input1.png \
-loop 1 -t 1 -i input0.png \
-filter_complex \
"[1:v][0:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b1v]; \
[2:v][1:v]blend=all_expr='A*(if(gte(T,0.5),1,T/0.5))+B*(1-(if(gte(T,0.5),1,T/0.5)))'[b2v]; \
[0:v][b1v][1:v][b2v][2:v]concat=n=5:v=1:a=0,format=yuv420p[v]" -map "[v]" out.mp4