Re: [AVT] Synchronization question abt RFC 2250

[Ross Finlayson <finlayson at live555.com>]

Title: Re: [AVT] Synchronization question abt RFC 2250

> According to RFC 3550,
> RTP timestamp is defined as sample time of each unit. It also
> reflacts the presentation time. 
> But for some of
> payload type (e.g. mpeg1/mpeg2 vedio, RFC2250 ),  RTP
> timestamp is not the presentation timestamp any more.
> > RFC 2250, Page 4:
> > The RTP timestamp will not be passed to
> > the MPEG
> >    decoder.  This use of the timestamp is somewhat
> > different than
> >    normally is the case in RTP, in that it is not considered
> > to be the
> >    media display or presentation timestamp. The primary
> > purposes of the
> >    RTP timestamp will be to estimate and reduce any
> > network-induced
> >    jitter and to synchronize relative time drift between the
> > transmitter
> >    and
> > receiver.

That paragraph refers only to the encapsulation of MPEG System and Transport Streams - *not* Elementary Streams - over RTP.  For MPEG-1 or 2 Audio or Video Elementary Streams - described later in RFC 2250 - the RTP timestamp *does* correspond to presentation time, as usual.

-- 

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

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