Hello. Based from existing posts from the internet, I was able to create a slideshow video in a folder containing numerous files, as in numerous images named in sequential order (eg. 01.png, 02.png, and so on).

ffmpeg.exe
   -reinit_filter 0
   -framerate 1/3
   -start_number 0
   -i "%02d.png"
   "output.mp4"

But, I would really like to add a transition effect between the image files.

There are existing posts out there, but they need to write down the actual files into the command. But what if the folder contains too many image files, like hundreds of them?

Thank you in advance.

UPDATE:

Found a working command from Superuser, the one answered by Michael. Transition effect is crossfade. I don’t understand it myself though, but it indeed works after I tested it with my numerous image files in a folder.

Some commenters back there in Superuser seem to had errors when they used it for themselves. Likely, they didn’t change the values of A, B, and WxH to whatever numerical value they actually needed, and filenames of their images were not 100% sequential. Or there was a gap like a missing numbered image file which would trigger FFmpeg to fully stop when it encountered that gap.

ffmpeg.exe
  -i "%02d.jpg"
  -vf "zoompan=d=(A+B)/B:s=WxH:fps=1/B, framerate=25:interp_start=0:interp_end=255:scene=100"
  "output.mp4"

where A is the duration in seconds how long each picture is shown (without crossfade duration), B is the crossfade duration in seconds, and WxH is the size of the output video.