The RTCP SR NTP timestamp is only valid in direct comparison with a NTP timestamp from another stream of the same reference clock. So you can use it to synchronize the presentation times of multiple streams in the same session. You're not supposed to use it to directly generate a presentation time since you have no guarantee that you and the sender share a reference clock.<br>
<br><br>The fSyncTime/fPresentationTime members are both being overloaded to be both the multi-stream synchronization time and the presentation time. It works great when the sync time and pts have the same reference clock. I tried to preserve this behavior with my diff.<br>
<br><br>In an ideal world multiple RTP/RTCP streams would be grouped together. You would compare their NTP timestamps and use the results to shift their RTP timestamps. Thus synchronizing them between each other.<br><br>Otherwise the use() member should probably be passed both a presentation time based off the RTP timestamp and a synchronization time (which is actually the currently named fPresentationTime). The callback could then synchronize multiple RTP streams itself if it so chooses.<br>
<br>.mike<br><br><br><div class="gmail_quote">On Tue, Jun 24, 2008 at 2:53 PM, Ross Finlayson <<a href="mailto:finlayson@live555.com">finlayson@live555.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Sorry, but I won't be making any such change to the code. Once RTCP-generated presentation times become available, they should *always* be used. Note that the function "RTPSource:: hasBeenSynchronizedUsingRTCP()" can be used by a client to distinguish between 'guessed' initial presentation times, and accurate RTCP-generated presentation times.<br>
<br>
If VLC - as a RTSP client - is having trouble handling the transition between these two different kinds of presentation times, then please report this on a VLC mailing list.<br>
-- <br><font color="#888888">
<br>
Ross Finlayson<br>
Live Networks, Inc.<br>
<a href="http://www.live555.com/" target="_blank">http://www.live555.com/</a><br>
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