[Live-devel] Calculating rtptime for RTSP/PLAY-Response "RTP-Info" header

[Ross Finlayson]

First, let's make sure that we're talking about the same thing.  I 
assume that you're referring to the way that our RTSP *server* 
implementation fills in the "RTP-Info:" header that it includes in 
the response to each RTSP "PLAY" request.  If you're instead 
referring to something else, then please correct me.

>The crux of my question concerns the *delta* that a reference 
>implementation (Helix USM) applies to one of the rtptime=X values 
>that is reported in the RTP-Info header. All of our testing (with 
>~30 different brand/model combinations) has shown that this is 
>critical for many mobile phones to correctly apply A/V sync.

What exactly is this 'delta', and which RFC (or Internet-Draft) 
document defines it?

>The live555 code (the 2008.07.25 release) does not adjust (calculate 
>a delta) the RTP-Info header in this way. It simply reports the 
>seqNum & rtptime of the first packet on each stream.

I believe that the information that we put in the "RTP-Info:" header 
is correct.  It is the information defined in section 12.33 of RFC 
2326 (the RTSP specification).
-- 

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