A.7 SDP examples with "3gpp_sync_info" attribute
26.1143GPPIP Multimedia Subsystem (IMS)Media handling and interactionMultimedia telephonyRelease 18TS
A.7.1 Synchronized streams
In the example given below in table A.7.1, streams identified with "mid" attribute 1 and 2 are to be synchronized (default operation if the "3gpp_sync_info" attribute is absent).
Table A.7.1: SDP example with requirement on synchronization
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SDP offer |
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v=0 o=Laura 289083124 289083124 IN IP4 one.example.com s=Demo c=IN IP4 224.2.17.12/127 t=0 0 a=group:LS 1 2 a=3gpp_sync_info:Sync a=tcap:1 RTP/AVPF m=audio 30000 RTP/AVP 0 a=pcfg:1 t=1 a=rtcp-fb:* trr-int 5000 a=rtcp-fb:* nack a=rtcp-fb:* nack pli a=rtcp-fb:* ccm fir a=rtcp-fb:* ccm tmmbr a=mid:1 m=video 30002 RTP/AVP 31 a=pcfg:1 t=1 a=mid:2 m=audio 30004 RTP/AVP 2 a=pcfg:1 t=1 i=This media stream contains the Spanish translation a=mid:3 |
A.7.2 Nonsynchronized streams
The SDP in table A.7.2 gives an example of the usage of "3gpp_sync_info" attribute at media level. In this example, there are two H.264 video streams where the first video stream, using port number 6000, should not be synchronized with any other media stream in the session.
Table A.7.2: SDP example with no requirement on synchronization
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SDP offer |
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v=0 o=Laura 289084412 2890841235 IN IP4 123.124.125.1 s=Demo c=IN IP4 123.124.125.1 t=0 0 a=tcap:1 RTP/AVPF m=video 6000 RTP/AVP 98 a=pcfg:1 t=1 a=rtpmap:98 H264/90000 a=fmtp:98 packetization-mode=0; profile-level-id=42e00c; \ sprop-parameter-sets=J0LgDJWgUH6Af1A=,KM46gA== a=rtcp-fb:* trr-int 5000 a=rtcp-fb:* nack a=rtcp-fb:* nack pli a=rtcp-fb:* ccm fir a=rtcp-fb:* ccm tmmbr a=3gpp_sync_info:No Sync a=extmap:4 urn:3gpp:video-orientation m=video 5000 RTP/AVP 99 a=pcfg:1 t=1 a=rtpmap 99 H264/90000 a=fmtp:99 packetization-mode=0; profile-level-id=42e00c; \ sprop-parameter-sets=J0LgDJWgUH6Af1A=,KM46gA== a=rtcp-fb:* trr-int 5000 a=rtcp-fb:* nack a=rtcp-fb:* nack pli a=rtcp-fb:* ccm fir a=rtcp-fb:* ccm tmmbr a=extmap:4 urn:3gpp:video-orientation m=audio 7000 RTP/AVP 100 a=pcfg:1 t=1 a=rtpmap:100 AMR/8000/1 a=fmtp:97 mode-change-capability=2; max-red=220 a=rtpmap:98 AMR/8000/1 a=fmtp:98 mode-change-capability=2; max-red=220; octet-align=1 a=ptime:20 a=maxptime:240 |