The VideoLAN Forums

What KoenW wanted to do
can be made
converting the still images
into videos
with the same frame repeated
several times
so to last the desired time.

And, in the existing videos,
also,
repeat the last frame to get more time.

That's it !

I unsuccessfully tried many recommendations. I got tired...
I solved the problem this way:

1) Uninstall VLC (make sure to MANUALLY delete all VLC folders in the hard-disk)
2) Reinstall VLC