2015-xx-xx - xxxxxxx - lavc 57.11.0 - avcodec.h
xxxxxxx - Add av_packet_add_side_data().
xxxxxxx - Add AVCodecContext.coded_side_data.
+ xxxxxxx - Add AVCPBProperties API.
2015-xx-xx - xxxxxxx - lavc 57.9.1 - avcodec.h
Deprecate rtp_callback without replacement, i.e. it won't be possible to