API changes, most recent first:
+2018-01-xx - xxxxxxx - lavf 58.7.100 - avformat.h
+ Deprecate AVFormatContext filename field which had limited length, use the
+ new dynamically allocated url field instead.
+
+2018-01-xx - xxxxxxx - lavf 58.7.100 - avformat.h
+ Add url field to AVFormatContext and add ff_format_set_url helper function.
+
2018-01-xx - xxxxxxx - lavf 58.6.100 - avformat.h
Add AVFMTCTX_UNSEEKABLE (for HLS demuxer).