API changes, most recent first:
+2015-xx-xx - xxxxxxx - lavc 57.7.0 - avcodec.h
+ Deprecate av_free_packet(). Use av_packet_unref() as replacement,
+ it resets the packet in a more consistent way.
+
2015-xx-xx - xxxxxxx - lavc 57.5.0 - avcodec.h
Add data and linesize array to AVSubtitleRect, to be used instead of
the ones from the embedded AVPicture.