SDP Learning Notes

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First, the SDP specification of the format of the reply description, generally combined with the session protocol work together.

Common session transfer protocols include: SAP (sessionannouncement Protocol Session Announcement Protocol), Sip,rtsp,http, and e-mail using MIME.

(PS: Only one session description can be included for SAP, and the SDP for other session protocols can contain multiple session descriptions)

The SDP includes some of the following information:

1) name and purpose of the session

2) Session Survival time

3) The media information contained in the session, including:

1 Media type (video, audio,application,etc)

2 Transmission Protocol (RTP/UDP/IP, H.320,ETC)

3 Media Format (H-video, MPEGVideo, etc)

4 Multicast or remote (unicast) addresses and ports

4) information required to receive the media (address, port, encoding format, etc.)

5) bandwidth information on this side

6) Trusted Engagement information (contact information)

Third, the case analysis

1. v=0

1 Definition: Version information of the Protocol

2 format:v=< version > current only version 0

3 Select: Required

2. o=-14661305181466130518 in IP4 192.168.8.76

1 Definitions: Owner/creator and session information

2 format:o=< User name > < session id> < version > < network type > < address type > < address >

3 Select: Required

3. s=mrd=mremrc-v=1.0.0

1 Definition: Session name

2 format:s=< name >

3 Select: Required

4. C=in IP4192.168.8.76

1 Definition: Connection information

2 format:c=< Network type > < address type > < address >

3 Select: Optional

5. b=as:1920

1 Definition: Bandwidth information at the local end

2 format:b=< type >:< bandwidth >

3 Select: Optional

6. t=0 0

1 Definition: Start time

2 format:t=< start time > < end time >

3 Select: Required

7. A=sendrecv

1 Definition: Media properties

2 Format:a=< Properties >

3 Select: Optional

8. M=audio 3230RTP/AVP 118 115 114 113 102 101 103 99 98 97 9 18 15 0 8 104 119

1 Definition: media information

2 format:m=< Media type > < media port > < transport protocol > < encoded information >

3 Select: Required

9. A=RTPMAP:118SIRENLPR/48000/1

1 Definition: Media properties

2 format:a=< Properties >:< values >

3 Select: Optional

Ten. a=fmtp:115bitrate=48000

1 with 9

M=video 3232RTP/AVP 109 110 96 34 31 106 105 116

1 with 8

12. More Video Attribute Information

A=label:1

a=rtcp-fb:* Nackpli

a=rtcp-fb:* Ccmfir

a=rtcp-fb:* CCMTMMBR

A=vnd.polycom.forcevideomode:9

a=rtpmap:109h264/90000

a=fmtp:109profile-level-id=42801f; max-br=20010; Sar=13

a=rtpmap:110h264/90000

a=fmtp:110profile-level-id=42801f; packetization-mode=1; max-br=20010; Sar=13

a=rtpmap:96h263-1998/90000

A=fmtp:96cif4=1; cif=1; qcif=1; sqcif=1; custom=352,240,1; custom=704,480,1; custom=1024,768,1; custom=800,600,1; custom=640,480,1; T

a=rtpmap:34h263/90000

A=fmtp:34cif4=1; cif=1; qcif=1; Sqcif=1

a=rtpmap:31h261/90000

a=fmtp:31cif=1; Qcif=1

a=rtpmap:106h264-svc/90000

a=fmtp:106profile-level-id=56001f; packetization-mode=1; max-br=20010; Sar=13

a=rtpmap:105h264-svc/90000

a=fmtp:105profile-level-id=53e01f; packetization-mode=1; max-br=20010; Sar=13

a=rtpmap:116vnd.polycom.lpr/9000

A=fmtp:116v=1;minpp=0; pp=150; rs=52; rp=10;ps=1400

m=application3238 UDP/BFCP *

1 with 8

A=setup:actpass

A=connection:new

A=floorctrl:c-s

m=application3236 RTP/AVP 100

1 with 8

a=rtpmap:100h224/4800

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