Jeremya wrote:
Stefan Sayer wrote:
Hello Jayesh,
Jayesh Nambiar wrote:
Hi,
I intend to test SEMS 1.2 starting with the b2b_connect application.
It works well but the only issue is that in the second leg, it sends
out only the enabled codec plugins.
Is it possible somehow to make sems work in transparent codec mode,
where it just forwards the codec value as it is and does not try to
transcode?? The aim is to send G729 in pass-through mode !!
in SEMS 1.2 there is only applications with signaling only B2BUA
(call_timer, auh_b2b, sw_prepaid_sip etc) and applications with full
media decode/encode, there is no pass-through mode in SEMS yet.
What do you want to use the B2B for? You could use one of the
signaling only B2B applications in SEMS in combination with one of the
RTP relay solutions for SER-based proxies
(kamailio/sip-router+iptrtpproxy, opensips+mediaproxy2,
k/sip-router/os + rtpproxy/mediaproxy), if you need to force RTP
through that server.
I have been thinking about an RTP forwarding mode for the B2B for a
while, but haven't had the actual need for it. If there is interest, I
think it would not be particularly large implementation task, as all
the necessary components are already there.
I read the original post and I assumed the OP wanted pass-through so
proprietary codecs could work. SEMS does not support G729, so a
pass-through option is the only choice.
I realise SEMS is a media server but I think a design goal should be
that it does the minimum with the media stream - simply for efficiency.
In the B2B mode pass-through should be default unless there is a
transcoding requirement. I realise this is relatively difficult as the
B2B code must determine if there are compatible codecs or if it is
required to do a transcode.
The use of external RTP proxies requires SEMS to figure out the
requirements and then somehow instruct the RTP proxy to do the correct
transcode. I'm not sure this works easily at present.
i was thinking about the possibility to have the call go through a
proxy which just engages RTP relay for every call.
The simplest solution is for different SEMS applications - or different
parameters for SEMS applications - to allow pass-through as an option.
e.g. "transcode=no"
right (or: relay_rtp=yes).
I was asking what the B2B is used for, because I would usually like to
see it at another level of "optimizing for efficiency": If it is
possible, the RTP should be flowing end to end and the B2B should not
need to touch it (e.g. for topology hiding, identity change, call
timer etc; or after pre-call announcements or similar applications).
The RTP should flow through the B2B only if needed, for example
something will be played into the stream (like, a tone shortly before
the prepaid card is empty), and in that case it needs to
decode/encode, or at least it needs to support the codecs.
The only other use of RTP pass through where it would make sense for
me is to catch RTP time out and for NAT handling, and on the border of
the network. For catching RTP time out, that feature definitely would
make sense. On the border of the network, I would usually recommend a
proxy anyway, possibly behind a SEMS working as topo hiding B2B; as
SEMS currently does not support multi homing, you would need a proxy
in that situation anyway.
So, in conclusion, there is interest?
Regards
Stefan
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Stefan Sayer
VoIP Services Consulting and Development
Warschauer Str. 24
10243 Berlin
tel:+491621366449
sip:[email protected]
email/xmpp:[email protected]
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