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
Originally committed as revision 763 to svn://svn.ffmpeg.org/ffmpeg/trunk
* generic optimization:
- enable ALT and ALIGNED stream
- move "if(const)" out from loops
- supress duplicated computing
* first attempt to fix problem with strides
Originally committed as revision 734 to svn://svn.ffmpeg.org/ffmpeg/trunk