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SDP media alignment in SIP. draft-camarillo-sip-sdp-00.txt. Gonzalo Camarillo. Gonzalo.Camarillo@ericsson.com. Outline. What is needed? Scenarios Cellular access 3rd party developed RTP libraries Transcoding point Proposal: Flow identification. What is needed?.
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SDP media alignment in SIP draft-camarillo-sip-sdp-00.txt Gonzalo Camarillo Gonzalo.Camarillo@ericsson.com
Outline • What is needed? • Scenarios • Cellular access • 3rd party developed RTP libraries • Transcoding point • Proposal: Flow identification
What is needed? • Systems have to be able to receive media from a single media stream, encoded in different formats during the session, in different ports and host interfaces. • Better method to perform SDP media alignment in SIP than matching the nth lines.
Cellular Access RAB 1 RAB 2 Packet filter (TFT) RAB 3 INVITE contains different port numbers for different codecs
3rd party developed RTP libraries SIP User Agent Interface Interface RTP library supporting PCM and GSM RTP library supporting AMR UDP 20000 UDP 20010 INVITE contains different port numbers for different codecs
Transcoding point Cellular Wired infrastructure Wired infrastructure Transcoding point Wired infrastructure INVITE contains different IP addresses for different codecs
Proposal • SDP session parameter: Flow Identifier (fid) • Example: v=0 o=Laura 289083124 289083124 IN IP4 second.example.com t=0 0 c=IN IP4 222.222.222.222 m=audio 30000 RTP/AVP 0 a=fid:1 m=audio 30002 RTP/AVP 8 c=IN IP4 123.123.123.123 a=fid:1 m=audio 30004 RTP/AVP 0 a=fid:2 m=audio 30006 RTP/AVP 8 c=IN IP4 123.123.123.123 a=fid:2