FFMPEG Video loop from images files
The "solution" that you gave to your own question confuses me because it seems to be somewhat unrelated to your initial question.

What I understood from your question:


You have a Sequence of Images in 3 directories.
Make a movie from each Image Sequence.
Length is 1s each.
Overlay an image for each 1s movie.
concatenate the movies -> 3s movie
Loop 3 times -> 9s movie


I've added the fllowing to your code in your question:


Add -start_number 1 before every input
Add loop=loop=2:size=30 after concat


Notice loop=2 loops 3 times.

Furthermore it needs a size (the total number of frames to loop over).

This depends on how many images you had.

I had 10 images in the 3 directories. 10 x 3 = 30

ffmpeg \
-start_number 1 -framerate 12 \
-i "imgSequ1/img-%d.png" \
-start_number 1 -framerate 12 \
-i "imgSequ2/img-%d.png" \
-start_number 1 -framerate 12 \
-i "imgSequ3/img-%d.png" \
-i "overlay1.png" \
-i "overlay2.png" \
-i "overlay3.png" \
-filter_complex "\
[0:v]scale=600x900[scaled1];\
[1:v]scale=600x900[scaled2];\
[2:v]scale=600x900[scaled3];\
[scaled1][3:v]overlay[tmp1];\
[scaled2][4:v]overlay[tmp2];\
[scaled3][5:v]overlay[tmp3];\
[tmp1][tmp2][tmp3]concat=n=3,loop=loop=2:size=30[scaled]" \
-map "[scaled]" -r 10 -vcodec libx264 -pix_fmt yuv420p -crf 23 "result.mp4"