[vlc-devel] Re: lip sych problem

Ross Finlayson finlayson at live555.com
Mon Nov 28 00:14:18 CET 2005

>Should add here - RTP streams are actually 2 (at least) different streams
>with different payloads

This is correct.

>that are not syncronised well (look at live555
>mailing list). I.e - system will "sync on average bitrate", not on each
>video packet. It means, that LiveMedia free library do not contain
>mechanisms to make A/V sync/resync.

But this is all completely false.  See 

Once again: If your original data source (at the server end) has (i) 
proper presentation times (corresponding to the 'wall clock' time 
generated by calling "gettimeofday()"), and (ii) it properly 
implements RTCP, then RTSP/RTP clients that use the "LIVE555 
Streaming Media" software - including VLC - *will* get correct, 
time-synchronized presentation times.

If, however, your server does not implement RTCP, and/or does not use 
properly synchronized presentation times to begin with, then you're 
SOL.  End of story.

I spent a lot of time making sure that the LIVE555 RTP/RTCP 
implementation works properly - to generate correct, 
time-synchronized presentation times at the client end.  I wish 
people would stop claiming that this doesn't work.

	Ross Finlayson
	Live Networks, Inc. (LIVE555.COM)

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