How to calculate round-trip-time(RTT) in gstreamer

[arpita banerjee]

How I can calculate round trip time in gstreamer?

round-trip-time(RTT) = RR timestamp - LSR - DLSR
Using gst_rtcp_packet_get_rb()  function I am getting LSR, DLSR values
, but how I will get RR timestamp ?
Should I use the current timestamp when Receiver Report(RR) is
received? Which function should I use?

Please reply. Thanks in advance.