Thanks for the reply. I actually made that change about a year ago; I was aware that the code was already calculating presentation time for the purpose of synchronization, but for some reason I thought it was just a relative presentation time, not an absolute one that accurately reflected the time of frame capture. Looking at the code now though I'm not sure why I came to that conclusion as it definitely looks like it's doing the right thing.
In which case please disregard my patch. From: [email protected] [mailto:[email protected]] On Behalf Of Ross Finlayson Sent: Monday, April 01, 2013 4:52 PM To: LIVE555 Streaming Media - development & use Subject: Re: [Live-devel] [PATCH] Provide access to the full time mapping inthe last received sender report The attached patch allows access to the last received sender report RTP timestamp, making it possible to get the full NTP/RTP time mapping currently in effect (since it was already possible to get the last received NTP timestamp). This information can be used to calculate the wallclock timestamp of each sample in a live stream sent by an IP camera, according to the camera's clock. I think you may not realize that our software already does this automatically! Whenever each frame of data is received (from a "RTPSource" subclass), then the "presentationTime" value will automatically get set to the value calculated from RTCP's 'RTP timestamp-to-NTP' mapping, as long as it has received at least one RTCP "SR" packet. In other words, receiving application software should never need to look at RTP timestamps (or RTCP-reported NTP times) directly. Instead, it just needs to look at the "presentation time" values for each received frame. For more information see http://www.live555.com/liveMedia/faq.html#separate-rtp-streams and http://www.live555.com/liveMedia/faq.html#rtcp-synchronization-issue (Therefore, I won't be applying your patch, unless you can demonstrate a clear need for it.) Ross Finlayson Live Networks, Inc. http://www.live555.com/
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