[Live-devel] Is it possible to enable RFC 6051 extended headers for rapid stream synchronization

[David Gessel]

Dear Live555 list,

I am trying to sync multiple mobotix IP cameras, which use Live555 as the RTSP server.  I'm having a little trouble getting multiple streams to sync at all and exploring with wireshark, it seems that while the RTCP sender report packets have expected Timestamps as:

Real-time Transport Control Protocol (Sender Report)
     [Stream setup by RTSP (frame 12)]
         [Setup frame: 12]
         [Setup Method: RTSP]
     10.. .... = Version: RFC 1889 Version (2)
     ..0. .... = Padding: False
     ...0 0000 = Reception report count: 0
     Packet type: Sender Report (200)
     Length: 6 (28 bytes)
     Sender SSRC: 0xcead8bcd (3467480013)
     Timestamp, MSW: 3819973440 (0xe3b02b40)
     Timestamp, LSW: 2861491896 (0xaa8ee6b8)
     [MSW and LSW as NTP timestamp: Jan 18, 2021 15:44:00.666242999 UTC]
     RTP timestamp: 3443889037
     Sender's packet count: 953
     Sender's octet count: 1342235

The RTP packets have the RFC 3550 5.1 structure:

Real-Time Transport Protocol
     [Stream setup by RTSP (frame 12)]
         [Setup frame: 12]
         [Setup Method: RTSP]
     10.. .... = Version: RFC 1889 Version (2)
     ..0. .... = Padding: False
     ...0 .... = Extension: False
     .... 0000 = Contributing source identifiers count: 0
     1... .... = Marker: True
     Payload type: JPEG-compressed video (26)
     Sequence number: 13228
     [Extended sequence number: 78764]
     Timestamp: 3443877091
     Synchronization Source identifier: 0xcead8bcd (3467480013)

(payload description)

Is there any way to enable insertion of the RFC 6051 extended header into the RTP header structure to enable rapid synchronization?

I found the 2013 thread on the topic at https://live-devel.live.narkive.com/WgLSYFbC/synchronize-the-rtcp-time-using-rtsp-range which seems to conclude that such headers weren't on the roadmap 8 years ago, but 8 years... has anything changed?

Thank you,

-David