ffmpeg -re -i input-1.jpg -re -i input-2.jpg -re -i input-3.jpg -re -i input-4.jpg\
-filter_complex “nullsrc=size=660×500 [base];\
[0:v] setpts=PTS-STARTPTS,scale=320×240 [upperleft]; \
[1:v] setpts=PTS-STARTPTS,scale=320×240 [upperright]; \
[2:v] setpts=PTS-STARTPTS,scale=320×240 [lowerleft];\
[3:v] setpts=PTS-STARTPTS,scale=320×240 [lowerright]; \
[base][upperleft] overlay=shortest=1[tmp1];\
[tmp1][upperright] overlay=shortest=1:x=325 [tmp2]; \
[tmp2][lowerleft]overlay=shortest=1:y=245 [tmp3];\
[tmp3][lowerright] overlay=shortest=1:x=325:y=245” \
-c:v libx264 -t 00:00:30 -f mp4 input-0-4.mp4 -y