[Live-devel] Live555 presentation times jump when joining multicast streams

[DJM-Avalesta]

Hi,

My video encoder/server streams live video via multicast. It is being 
tested with multiple instances of VLC running under Windows.

At some point, at the moment a new VLC session connects to the multicast 
stream (via an RTSP url), the presentation time can jump forward or back 
by a huge amount and I can't find why. The consequence of this is that 
starting and connecting a second VLC session will cause the first live 
VLC session to freeze. Starting a 3rd VLC session will cause sessions 1 
and 2 to freeze.

My code for presentation time is:-

void StreamSource::setPresentationTime()
{
     if (fPresentationTime.tv_sec == 0 && fPresentationTime.tv_usec == 0)
     {
         gettimeofday(&fPresentationTime, NULL);
         INFO("setPresentationTime: %ld.%06ld\n", 
fPresentationTime.tv_sec, fPresentationTime.tv_usec);
     }
     else
     {
         int iSkip;
         double fMaxFps;
         g_ViewDescriptors[0]->GetFrameSkip(iSkip);
         fMaxFps = CalcTrueFpsfromSkip(iSkip); //eg 25fps, 12.5fps etc, 
the frame rate
         // Increment by the sample time
         unsigned uSeconds = fPresentationTime.tv_usec + 
(unsigned)(1000000.0/fMaxFps);
         fPresentationTime.tv_sec += uSeconds/1000000;
         fPresentationTime.tv_usec = uSeconds%1000000;
     }
}

Via wireshark I can see a huge jump in Presentation time which I don't 
seem to have caused in the code above, ie here, where the time has 
jumped backwards

I need to be able to support multip[le VLC session connecting and 
disconnecting, so what could be causing these seemingly random jumps in 
the frame presentation time when a VLC session connects?

Best regards

David
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