FRR bRIB and BGP update dumps are in the well-known MRT format. These are binary files which can be converted to ASCII with the tools below.
zebra-dump-parser is a perl script written by Marco d'Itri. This script is capable of parsing the Route Views files, including the IPV6 RIBS from route-views6. At the top of the script, set the format to 1, and the ignore_v6_routes to 0. The code can be found at:
https://github.com/rfc1036/zebra-dump-parser
bgpscanner is a new/faster tool for parsing MRT files out of the Isolario Project: https://gitlab.com/Isolario/bgpscanner. Note: The Isolario project is no longer operating.
bgpdump is part of the libbgpdump sources maintained by RIPE RIS. It is a fast C program and library for parsing MRT files, and supports all BGP MRT types. The code can be found here:
https://github.com/RIPE-NCC/bgpdump
route_btoa comes with the MRTd package. It does not appear that MRTd is being actively maintained, but the source might be available from:
http://mrt.sourceforge.net/