If frame-rate <= 2, video from images is a black screen

Question

I made a video from 40 images using first Matlab and then "A4 video converter" just to compare results. I found something happening that I don't understad and maybe somebody can explain to me.

When I set frame-rate at 2 frames per second and I play the video I can only see a black screen.

If I set frame rate more than 2 frames per senconds then I can see the video perfectly. This happens with both programs, so I guess it is not a bug, but maybe some physics or signal processing issue.

Why is this happening?

Answer 1

I don't know why it is happening, but a workaround could be to show each pic twice. This would allow you to play it at 4 frames per second without speeding up the video.