Juha Heinanen writes:
it thus looks like that when ICE=force_relay is given,
also adding of
a=rtcp:<port> need to be prevented.
if a=rtcp:<port> did not exist in incoming sdp, there is no need for
rtpengine to add it, because then, by default, rtcp port is one larger
than rtp port.
if a=rtcp:<port> did exist in incoming sdp, then rtpengine needs to
change <port> value, if it changed m line port value.
so this issue is not really related to ICE=force_relay except that when
ICE=force_relay exists in incoming sdp, then m line port is not changed.
-- juha