> > Stephane van Hardeveld schrieb: >> >> ----- Original Message ----- From: "Klaus Darilion" >> <[email protected]> >> To: "sip-implementors" <[email protected]> >> Sent: Wednesday, February 25, 2009 9:29 AM >> Subject: [Sip-implementors] asymmetric audio codecs >> >> >>> Hi! >>> >>> For a certain application where uplink is low bandwidth and downlink is >>> high bandwidth I want to use the best available codec - ie. up G729, >>> down G.711. >>> >>> How can I setup such an asymmetric session? >>> >>> eg. >>> high down >>> Alice ------------ Bob >>> up low >>> >>> I think if Alice announces G711 and G729, and Bob answers with G.729, >>> Alice must send with G729 and Bob can send with G711 too. Is this >>> correct? >>> >>> Nevertheless, as this requires that Alice's SIP client support this. Is >>> there also a method to explicitly define the asymmetric behavior? >>> >>> Thanks >>> Klaus >> >> You 'should' be able to indicate this with the recvonly and sendonly >> media attributes in the SDP. >> However, not all SIP clients seem currently to support this feature >> correctly. See also: >> rfc 3264, par. 5.1 Unicast streams, or rfc 4566, par. 6 SDP attributes: >> quote: >> 'a=recvonly >> This specifies that the tools should be started in receive-only mode >> where applicable. It can be either a session- or medialevel attribute, >> and it is not dependent on charset. Note that recvonly applies to the >> media only, not to any associated control protocol (e.g., an RTP-based >> system in recvonly mode SHOULD still send RTCP packets). ' > > So I have to setup 2 unidirectional streams (one recvonly and one > sendonly) instead of a single bidirectional stream? That was my solution. Unfortunately, this is (not yet?) supported by the device I tested it against.
> I think this is even less supported :-( > I tend to agree, I have the same issue. However, by discussing it here we might get some support... Good luck! Stephane van Hardeveld _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
