frames that will be skipped, mencoded tells vf_softskip (if present)
that it should drop the next frame. this allows filters that need to
see every input frame (inverse telecine, denoise3d, ...) to see
skipped frames before they get dropped.
in principle, a smarter softskip filter could be written that would
buffer frames and choose to drop the one with least change, rather
than strictly dropping the next one.
git-svn-id: svn://svn.mplayerhq.hu/mplayer/trunk@12338 b3059339-0415-0410-9bf9-f77b7e298cf2