> -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of > Peter Howard > Sent: 14 November 2006 00:38 > To: Asterisk Users Mailing List - Non-Commercial Discussion > Subject: Problem found Re: [asterisk-users] Headaches with > Video over SIP
> Found the problem. Some other people on the list might be > interested in the problem. > > Looking at the initial INVITE call from station 1 to asterisk > and from asterisk to station 2, you see the following discrepancy: > > >From Polycom to asterisk: > a=rtpmap:109 H264/90000 > a=rtpmap:96 H263-1998/90000 > > >From asterisk to other Polycom: > a=rtpmap:103 h263-1998/90000 > a=rtpmap:99 H264/90000 > > The latter numbers match the numbers in rtp.c, which clearly > don't agree with the Polycom's opinion on life. However the > other Polycom seems to accept asterisk's version, while the > first Polycom is still working on it's version. > > I modified the initialisation of static_RTP_PT in rtp.c to > match the Polycom values and, hey presto! I have video > working between the two stations. > > However, this doesn't look like a "proper" solution, if there > are multiple opinions out there of what h263p and h264 (at > least) should be mapped to. There's also the array > current_RTP_PT in rtp.c What is that used for? I would have > thought that either: > 1) Asterisk should tell _both_ ends what mapping to use, > 2) Asterisk should update it's own mapping based on what it's > told (though this would have to be on a call-by-call basis) #2 is true (at least for audio, so I guess for video as well). Codec identifiers >= 96 refer to dynamic payload types. They have to be negotiated on each SDP offer/answer exchange. So for the Polycom->Asterisk traffic, Asterisk should parse the SDP and say to itself "Hey, the caller wants me to send it H264 marked with payload type 109, and/or H263-1998 marked with payload type 96." and adapt it's outgoing payload type marking accordingly. _______________________________________________ --Bandwidth and Colocation provided by Easynews.com -- asterisk-users mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
