That is all excellent news.  In the mean time I've done 2 tests.

1) ./testOnDemandRTSPServer <-> ./openRTSP -Q -F test.ts.ts.out 
rtsp://<IPADDRESS:8554/mpeg2TransportStreamTest

And I saw the QoS stats.

2) ./testMPEG2TransportStreamer <-> ./testRTSPClient 
rtsp://<IPADDRESS>:8554/mpeg2TransportStreamTest

And saw there was no '!' after the printouts of the presentation times.  From 
this I understand the client/server are RTCP-synchronized.


I've been told that currently the plan is for "core" -> "UE" data path only.
Server and client will be able to synchronise via NTP  via the control channel.
But there will be no reverse channel at all, so RTSP connection will not happen.
It is not clear to me whether one achieve something similar using the 
TestMPEG2TransportStreamer -> TestMPEG2TransportReceiver.
?


-----Original Message-----
From: live-devel [mailto:live-devel-boun...@ns.live555.com] On Behalf Of Ross 
Finlayson
Sent: April-26-17 1:46 PM
To: LIVE555 Streaming Media - development & use
Subject: Re: [Live-devel] live555 question

> Given that the data flow is across a one-way link (and there is no return 
> path) the sender will not receive Receiver Reports from the receiver.  Off 
> the top of your head, do you know whether this will cause any problems?

No.  (Of course, you’ll need a TCP back channel for the RTSP connection - but 
once RTP/RTCP packets start flowing from the sender, it doesn’t matter if the 
sender doesn’t receive RTCP Reception Report (“RR”) packets back from the 
receiver(s).)

Once a stream has been RTCP-synchronized, then a receiver can compute the 
end-to-end latency *only if* its clock is synchronized with that of the sender 
(e.g., using NTP), and then this is trivial to do: Just look at the 
presentation time of each received media frame, and compare this to the 
(receiver’s) current ‘wall clock’ time (by calling “gettimeofday()”).

(The *sender* can compute the end-to-end latency to each receiver even without 
synchronized clocks, but *only if* it receives RTCP “RR” packets back from the 
receiver.  This is described in RFC 3550.)

Applications that use our library do not need to look at (or care about) ‘RTP 
timestamps’.  Our software automatically converts these to/from ‘presentation 
times’, which is all that you should need to care about.


Ross Finlayson
Live Networks, Inc.
http://www.live555.com/


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