Gonzalo Camarillo

Gonzalo Camarillo Advanced Signalling Research Lab48th IETFMMUSIC WG

Gonzalo Camarillo

[email protected]

draft-camarillo-sip-sdp-00.txt

SDP media alignment in SIP


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.


Packetfilter (TFT)

Cellular Access

INVITE contains different port numbers for different codecs

RAB 1

RAB 2

RAB 3


3rd party developed RTP libraries

INVITE contains different port numbers for different codecs

SIP User Agent

RTP library supporting

PCM and GSM

RTP library supporting

AMR

UDP 20000 UDP 20010

InterfaceInterface


Transcoding point

Cellular

Wired infrastructure

Wired infrastructureWired infrastructure

Transcoding point

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

Gonzalo Camarillo

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