Use ffmpeg to create a video from a few images I trying to create a video using FFmpeg from a few images. I tried several ffmpeg commands but I can't repeat each image for several frames, instead, each image is one frame size and the video result is too short.

The idea, in general, is to obtain a video like:
Firs_image during X seconds, Second_image during X seconds, Third_image during x seconds...

There is any command to accomplish this?
Use

ffmpeg -framerate 1/X -i img%d.png -r 25 -pix_fmt yuv420p out.mp4


e.g. for each image to show for 2.5 seconds,

ffmpeg -framerate 1/2.5 -i img%d.png -r 25 -pix_fmt yuv420p out.mp4