API changes, most recent first:
+2014-06-xx - xxxxxxx - lavc 55.55.0 - avcodec.h
+ Add av_packet_rescale_ts() to simplify timestamp conversion.
+
2014-xx-xx - xxxxxxx - lavf 55.20.0 - avformat.h
The proper way for providing a hint about the desired timebase to the muxers
is now setting AVStream.time_base, instead of AVStream.codec.time_base as was