[Live-devel] track synchronization with live555

[David Betrand]

Ross,

> No, I think you're confused here.  RTCP SR packets are *always* used
> to generate synchronized presentation times.  This is not - and never
> will be - optional functionality.  
I agree that's the only way to synchronize if rtp-info is not available. 

> Note that "presentation time" is
> not the same as NPT ("normal play time").  
I shouldn't have talk about NPT, it introduced confusion. My idea was to show you that there is probably something incorrect in the way you process timestamps in noteIncomingSR(). You can't simply say something like :
fSyncTime = ntpTimestamp; //wall clock time received in SR
fSyncTimestamp = rtpTimestamp; //timestamp received in the SR

You should instead do something like :

ts= timevalToTimestamp(ntpTimestamp)-timestampBase; // express in timestamps the synchronization time difference between us and the sender 
fSyncTimestamp = rtpTimestamp + ts; // update our reference timestamp, taking into account this difference 


Furtheremore, I really would like to use the rtp-info if it is available. This allows to have live555 library handle synchronization perfectly in case of RTSP (in this kind of applications -not real-time- where it is the most important)

Anyway, let me a couple of days and I will send a complete proposal for this. I hope we will be able to continue this thread at that time ...

Cheers,
David


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