The sample aspect ratio is a per-frame property, so it makes sense to
define it in AVFrame rather than in the codec/stream context.
Simplify application-level sample aspect ratio information extraction,
and allow further simplifications.
libavcodec to libavcore.
Remove another compile-time dependancy of libavfilter on libavcodec.
Originally committed as revision 25923 to svn://svn.ffmpeg.org/ffmpeg/trunk
Stefano Sabatini
Michael Niedermayer