MpegEncContext->opaque MUST NOT be used by the codec, its for the parent program
 using standart values for pict_type
 using (uv)linesize
 handling dropable p-frames like b-frames


git-svn-id: file:///var/local/repositories/ffmpeg/trunk@763 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b