Create a video from a landscape image with ffmpeg
You can just use the crop filter.

ffmpeg -loop 1 -t 10 -i img.png
       -vf "crop=w=W:h=ih:x='(iw-W)*t/10':y=0"
       -r 25 -pix_fmt yuv420p out.mp4


The crop filter crops the image to Wxih pixels where ih is the original height. You should substitute W with your target width in pixels. The position of the top-left corner of the crop window is set by the x and y expressions.

Since you only want to move left-to-right, y is set to a fixed 0. For x, the expression (iw-W)*t/10 governs the horizontal position of the crop window. t is the processed frame's timestamp in fractional seconds. W is substituted with the target width. iw is the input width. The crop will start from the left edge and end at the right edge at t = 10 seconds.



For an image sequence of 10 seconds, use

ffmpeg -i img%d.png
       -vf "crop=w=W:h=ih:x='(iw-W)*t/10':y=0"
       -r 25 -pix_fmt yuv420p out.mp4