[SR-Users] mediaproxy-ng query

Alex Balashov abalashov at evaristesys.com
Sat Jun 7 18:39:22 CEST 2014


Hello,

I'm invoking mediaproxy-ng with rtpproxy_offer/answer("ow") and am 
getting a scenario where:

INVITE is forwarded to signalling gateway xxx.xxx.xxx.xxx, which returns 
an SDP answer of yyy.yyy.yyy.yyy:51964. rtpproxy is invoked in both 
directions. However, media forwarded from media endpoint A is sent to 
xxx.xxx.xxx.xxx:51964 (the correct port, but to the signalling gateway), 
rather than yyy.yyy.yyy.yyy:51964, which is what's specified in the SDP 
answer in the 200 OK from xxx.xxx.xxx.xxx.

No media is coming back to mediaproxy-ng from yyy.yyy.yyy.yyy:51964. The 
cause of this is a separate and logically unrelated issue. Nevertheless, 
I am curious as to why mediaproxy-ng doesn't send media from the near 
end to yyy.yyy.yyy.yyy:51964--in other words, to the specified SDP 
endpoint on the far end, rather than to the signalling gateway.

I initially imagined that this might be due to the "w" option to 
rtpproxy_offer(), which the documentation says forces symmetric RTP. 
However, this behaviour is not elaborated upon or defined. I tried 
removing the 'w' option but seem to be getting the same result.

Is this a default behaviour of COMEDIA-style source port latching? In 
other words, does mediaproxy-ng need to latch onto incoming RTP from 
yyy.yyy.yyy.yyy:51964 before it will send media there, as opposed to the 
signalling gateway? If so, is there any way this behaviour can be 
disabled, so that mediaproxy-ng simply follows SDP in all cases?

Thanks,

-- 
Alex Balashov - Principal
Evariste Systems LLC
Tel: +1-678-954-0670
Web: http://www.evaristesys.com/, http://www.alexbalashov.com/

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