Hi, I'm trying to find here a common base for the negotiation regarding the different codecs on the video media side.
It seems that when you advertise fmtp, you declare what you are willing to receive (decoder capabilities) and implicitly what you prefer to send (except for some H264 exceptions). The thumb rule is that when receiving an offer, and there is intersection between the offerer and offeree capabilities, then video channels can be opened in both directions. Is my observation correct? Example: Alice supports QCIF(MPI=2) Maximum-Bit=Rate=256Kbps Bob supports CIF(MPI=1) QCIF(MPI=1) Maximum-Bit=Rate=128Kbps Scenario 1: Alice offers: QCIF(MPI=2) Maximum-Bit=Rate=256Kbps Bob answers: QCIF(MPI=2) Maximum-Bit=Rate=128Kbps (or CIF(MPI=1) QCIF(MPI=1) Maximum-Bit=Rate=128Kbps). Is that a correct negotiation? Scenario 2: Bob offers CIF(MPI=1) QCIF(MPI=1) Maximum-Bit=Rate=128Kbps. Alice answers: QCIF(MPI=2) Maximum-Bit=Rate=128Kbps (or QCIF(MPI=2) Maximum-Bit=Rate=256Kbps). Is that a correct negotiation? In both scenarios, both incoming and outgoing channels should be opened correctly with QCIF(MPI=2) Maximum-Bit=Rate=128Kbps. BTW The drafts/RFCs I'm using are: H.261: draft-ietf-avt-rfc2032-bis-13.txt H.263: draft-koskelainen-sdp263-01.txt (I'm not sure about that one, does the H.263+ draft overrides it?) H.263+: draft-ietf-avt-rfc2429-bis-09.txt H.264: RFC 3984 Thanks, Erez _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
