12.8.1. SEI method

Some SRT encoders like new JVC-cams , Haivision-encoder and software encoder LarixBroadcaster (iPhone/Android) can do this:

synchronize internal clock by time-server (usually by NTP protocol).

It means all encoders have one clock:if one camera has time 11:59:59 then other cameras have same time.
send this time inside encoded feed (SEI metainfo)

More info see here