Avoid the need to implement slice direction detection code, thus
reducing code duplication.
See the thread:
"[FFmpeg-devel] [PATCH] Add a slice_dir parameter to avfilter_start_frame()".
Originally committed as revision 20734 to svn://svn.ffmpeg.org/ffmpeg/trunk
not correctly supported.
See the thread:
"[FFmpeg-devel] [PATCH] Remove not truly supported formats support from the crop filter".
Originally committed as revision 20576 to svn://svn.ffmpeg.org/ffmpeg/trunk