Cheeks spoke about that, maybe he has some informations:
I found:
https://quentin.dufour.io/blog/2019-08-06/le-protocole-shoutcast-au-scalpel/
(in French sorry) and:
But your question is very good; does any standard exist ???
Some examples with different rates:
https://fluxradios.blogspot.com/2014/07/flux-url-france-inter.html
and:
https://community.roonlabs.com/t/live-radio-metadata/84182/25
Thanks