I would like to make a movie showing a volume gradually cropped along one axis .e.g. volume #1 region 0,0,0,410,375,336 (start) volume #3 region 0,0,0,410,375,31 (end). Could you please tell me how to provide the range in “perframe” command to perform this operation? Ie as trying something like this 

perframe "volume #1 region $1" 0,0,0,410,375,200 0,0,0,410,375,336 frames 10 without success though.

Many thanks in advance,

Edoardo