Tile several successive frames together.

It accepts as argument the tile size (i.e. the number of lines and columns) in the form "wxh".

For example, produce 8×8 PNG tiles of all keyframes (-skip_frame nokey) in a movie:

ffmpeg -skip_frame nokey -i file.avi -vf 'scale=128:72,tile=8x8' -an -vsync 0 keyframes%03d.png

The -vsync 0 is necessary to prevent ffmpeg from duplicating each output frame to accomodate the originally detected frame rate.