[Live-devel] Presentation time, multicast and multiple client connections

[DJM-Avalesta]

Hi Ross,

> OK, so we've established (again!) that your problem is that your 
> server's presentation times are not properly aligned with 'wall clock' 
> time
> (the time that you'd get by calling "gettimeofday()").  This is 
> necessary because the periodic RTCP "SR" ("Sender Report") packets -
> sent by the server - are used, by receivers, to properly synchronize 
> the stream, and the timestamps in these RTCP "SR" packets are set by 
> calling
> "gettimeofday()".
> (Note, BTW, that these RTCP "SR" packets are sent frequently, and do 
> *not* necessarily coincide with the connection of new RTSP clients.)

So, this RTCP SR logic is calling gettimeofday() and changing 
fPresentationTime outside of my control?

> If - using your current scheme - you cannot keep your presentation 
> times aligned with wall clock time, then I suggest computing your 
> presentation
> times by calling "gettimeofday()" each time - not just at the start of 
> the stream.  Or, if you feel that that's too expensive,
> then compute it using "gettimeofday()" something like every 100 frames.

I've come full circle now, I started with calling gettimeofday() every 
single frame, but the users complained that vlc was way too jumpy and 
they
insisted that other encoders showed exactly 40ms between the 
presentation times of every frame.

However, it sounds promising to re-align with wall-clock time every 100 
frames, which is every 4 seconds in my application.

- D

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