[SR-Users] question about rtpproxy "r" flag

[Juha Heinanen]

rtpproxy_offer and answer functions have "r" flag described as follows:

  r - flags that IP address in SDP should be trusted. Without this flag,
  rtpproxy ignores address in the SDP and uses source address of the SIP
  message as media address which is passed to the RTP proxy.

how does rtpproxy "use" this ip address?

if sip message comes from behind nat, ip address in sdp is local
address, not the address where rtp packets come from.  and if this
request has passed another (e.g. outbound) proxy before hitting the
current one, also source address of sip message is not the address where
rtp packets come from.  either address thus seems to be useless for
rtpproxy.

-- juha