API changes, most recent first:
+2018-xx-xx - xxxxxxx - lavc 7.13.100 - avcodec.h
+ Deprecate use of avfilter_register(), avfilter_register_all(),
+ avfilter_next(). Add av_filter_iterate().
+
2018-03-xx - xxxxxxx - lavc 58.16.100 - avcodec.h
Add FF_SUB_CHARENC_MODE_IGNORE.