I have no solution to your problem, but one piece of code struck me:

    $filename = "$animdir/frame_00${framenumber}.gif/gif" if ($framenu
+mber<10);
    $filename = "$animdir/frame_0${framenumber}.gif/gif" if (($framenu
+mber>9) and ($f
+ramenumber<100));
    $filename = "$animdir/frame_${framenumber}.gif/gif" if $framenumbe
+r>99;
[download]

There is a much simpler implementation for that:

   $filename = sprintf "%s/frame_%03d.gif/gif", $animdir, $framenumber
+;
[download]