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 8x8 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.