How to get RTCP sender report from rtspsrc element?

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Hi.
I’m new on gstreamer, and I have some problem with this issue for many days.. 

I need to get absolute timestamp from multiple rtsp camera.
And with some effort, I got to know that I can get absolute timestamp from "RTCP SR(sender report)” in RTSP packets
But I can not find the proper way to get RTCP SR from rtspsrc element or rtpbin in gstreamer document..
And actually I can not understand well about rtpbin’s role
So my questions are

1. How to get RTCP SR with rtspsrc element or rtpbin element

2. If I connect devices into rtpbin element, then does rtpbin sync sources from multiple device automatically?
I mean, suppose If there are two rtsp camera CAM_1 CAM_2, and if I send PLAY request in same time on my client
And if there have network delay, so client get packets of PLAY request of CAM_1 10 seconds more later than CAM_2
Then does rtpbin element sync that 10 seconds automatically?

Thanks for reading.