I am creating video clips from images with a resolution of 800px X 8000px like this:
ffmpeg -y -loop 1 -i image_800x8000.png -vf "scroll=vertical=0.002,crop=800:450:0:0, format=yuv420p" -t 10 image_video.mp4
The result looks like somebody is slowly scrolling downwards on that very long image.
Would that be possible with the Shotstack API?
Yes, this would be possible. I just put together this example for you: Vertical scrolling skyscraper video template — Shotstack
The image might not be as long as yours and the speed direction might be different but I think this is the effect you are aiming for.
The key thing to look at is using clip motion
slideDown. There is also
slideUp and speed variants: