screenshot
Allows acquiring screenshots of the movie using slave mode com-
mands that can be bound to keypresses. See the slave mode docu-
mentation and the INTERACTIVE CONTROL section for details.
Files named 'shotNNNN.png' will be saved in the working directo-
ry, using the first available number - no files will be over-
written. The filter has no overhead when not used and accepts
an arbitrary colorspace, so it is safe to add it to the configu-
ration file.