Function same_format 

pub fn same_format(offered: &str, local: &str) -> bool

Whether two a=rtpmap values name the same format, reading both.

The predicate both callers use, so neither has a rule of its own to drift from the other’s.

false when either value names no format at all. A value that identifies nothing matches nothing — including another value that identifies nothing, since PCMU and G729 are not the same format merely because neither carries a clock rate.