On Mon, Jan 10, 2011 at 1:57 PM, Douglas Hubler <[email protected]> wrote:
> On Mon, Jan 10, 2011 at 1:12 PM, W. E. W. Russell <[email protected]> 
> wrote:
>> All,
>> I tried to get this answer a months ago, but I'll try again.
>> I'm trying to make a video call from one sipXecs to another. After months of
>> work on this, I've narrowed down the issue:
>> It seems as though the sipXbridge/relay will only process one
>> media attribute, not two. The comments in the code seem to imply that you
>> would need a SECOND bridge for the second (video) media.
>> Again, there is no issues with the calls. I have walked through the call
>> flows (Wireshark packet captures) and found no issue except one: the RTP
>> media streams sent from our Polycom VVX1500 phones to the PBX are rejected
>> on sight.
>> This clearly means that the PBX/bridge is not listening on those ports.
>> Simple issue, or so I thought. I could just open up that range of ports and
>> the problem would go away - still no dice.
>> I looked into the code of how the SDP is parsed (SIPUtilities.java,
>> RTPSessionUtilities.java, etc) and kept find references to "one media
>> stream" or "just the first media attribute".
>> So, I ask a very simple question: can the sipXbridge/relay handle BOTH audio
>> & video streams?
>> Just to clarify, the only problem I have with my call is no video - audio is
>> amazing and call control and signalling are responsive. Just one missing
>> piece and I need to know how involved it will be to "create a second bridge"
>> that functions EXACTLY the same way, but handles the video.
>> Please do not ask for configs and packet captures - not because I don't have
>> them, but because I'm asking a development question, not a call
>> troubleshooting question.
>> Thank you very much for your time and patience.
>
> i suspect only the original author of this code knows the answer for
> sure, and that is Ranga.  I did a pass thru the code and it wasn't
> obvious to me either way whether it supports it.  Maybe Ranga will
> reply...


Hello!

A happy new year to all!

SipXbridge will only allocate a single RTP bridge for a call and will
only relay a single stream. It will only look at (and modify) the
"audio" or "fax" portions of the session description. It will only
relay a single stream (either audio or fax). Video is entirely
ignored.

The reason for this is quite simple - ITSPs do not support video calls
and hence there is no need for the additional complexity. SipXbridge
was designed to be a ITSP gateway. ITSPs are usually meant for
bridging to the PSTN. Other uses for sipxbridge were not envisioned at
the time it was put together. SipXbridge has obviously gone a bit
beyond its original intent and is in need of enhancement.

I hope that helps clarify the motivation for the design choices and limitations.


Regards

Ranga



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-- 
M. Ranganathan
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