webrtcbin: RFC5576 - early CNAME support
See RFC5576: have CNAME available to the rtpjitterbuffer
before the the first RTCP SR is received, for rapid synchronization. Similar to what was done for RTSP (last 2 commits): !2132 (merged)
gstrtspsrc
sets the attributes form the remote SDP on its src element (e.g. udpsrc
) caps
properties. The SDP contains media attributes such as ssrc-48174845-cname:"user308259505\@host123"
, which are forwarded with the CAPS event from sink to src pads by the rtpbin
elements. rtpjitterbuffer
searches for these attributes to figure out the CNAME before the first RTCP SR is received.