Session Description Protocol

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Session Description Protocol (SDP)

The following is an example of an actual SDP message:

v=0
o=root 702294668 702294668 IN IP4 192.168.0.158
s=Asterisk PBX 1.8.32.6
c=IN IP4 192.168.0.158
t=0 0
m=audio 10288 RTP/AVP 8 0 4 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:4 G723/8000
a=fmtp:4 annexa=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv

Explanation

  • v= (protocol version number, currently only 0)
  • o= (originator and session identifier : username, id, version number, network address)
  • s= (session name : mandatory with at least one UTF-8-encoded character)
  • i= (session title or short information)
  • u= (URI of description)
  • e= (zero or more email address with optional name of contacts)
  • p= (zero or more phone number with optional name of contacts)
  • c= (connection information. This will tell the IP address where the media will come from and where it should be sent to)
  • t= (time the session is active)
  • m= (media name and transport address)
  • b= (zero or more bandwidth information lines)
  • z= (time zone adjustments)
  • k= (encryption key)
  • a= (zero or more session attribute lines. There will be an attribute line for each codec advertised in the media line)

See also

Sources for more information and examples: