[Ekiga-list] Receiving SIP RTP before media description [was ekiga answers with delay ...?]

[Damien Sandras]

Le lundi 27 novembre 2006 à 10:15 +1100, Craig Southeren a écrit :
> Thank you for taking the time to do this, because hopefully we can now
> move on to solving the actual problem rather than continuing the rather
> ridiculous discussion about how to guess the contents of an RTP packet :)

Do you know that in french "ridiculous" is an insult? ;-)

Well, let's forget about that and summarize the results of that
discussion. There are actually right now 2 problems in OPAL :

1: Establishing the media streams after having sent or received the ACK
takes between 1 or 2 seconds during which the media stream is lost.

2: If OPAL sends an INVITE with 3 codecs in a given order, and that
Asterisk supports the 3 same codecs but with a different priority order,
it will send the 200 OK with those 3 codecs in the order it prefers.
OPAL will then choose the codec it prefers and send the media with that
codec. It could happen that Asterisk uses another codec from the list,
ie a codec for which OPAL is not ready to receive a stream.

e.g. :
INVITE PCMU, iLBC, PCMA
200 OK iLBC, PCMA, PCMU

OPAL will send the stream using iLBC.
Asterisk could decide to send the stream using PCMU.
However OPAL expects iLBC...
-- 
 _      Damien Sandras
(o-     
//\   Ekiga Softphone : http://www.ekiga.org/
v_/_ NOVACOM         : http://www.novacom.be/
          FOSDEM          : http://www.fosdem.org/
          SIP Phone       : sip:dsandras at ekiga.net