Replace FFmpeg with Libav in licence headers
Signed-off-by: Mans Rullgard <firstname.lastname@example.org>
cosmetic changes (indentation, doxygen comments, braces, put structures for API to header, ...)
Originally committed as revision 19773 to svn://svn.ffmpeg.org/ffmpeg/trunk
Support for generic multi-stream key frame finding for new seek API.
Originally committed as revision 19680 to svn://svn.ffmpeg.org/ffmpeg/trunk