Imagemagic

Capturing animation

import -delay 20 -snaps 4 snaps.jpeg

Converting multiple static images into one animated image

http://www.imagemagick.org/script/convert.php
  http://www.imagemagick.org/script/command-line-options.php#delay

tps is "ticks per second", the pause between every frame.

tps=30
convert -delay $tps input* output.png