Subject: In band signalling of PT

From: Stephan Wenger <[email-masked]>
Date: Tue, 12 Sep 2000 23:07:13 +0200

Folks,

the recent discussion about the MPEG-4 ES payload brought up an
issue that, IMHO, may be a shortcoming of current RTP and could
easily be fixed.  This shortcoming is RTP's need for the out-of-band
announcement/negotiation of parameters, including the PT.

I wonder whether it may make sense to signal such information in-band
as well, e.g. through sender reports or through special media packets.
That would allow receivers to "tune" to RTP broadcasts with only
IP/Port information (which could, for example, be owned by a TV station).

Questions:

a) Did I miss something in the current spec?  Is this already specified?
b) Does such a scenario make sense?  Specifically, how do people think
   to include session announcements in the media packetstream (or in
   RTCP)?  I recall that some time ago there was some discussion
   about architectural cleanness (it does / doesn't make sense to include
   session info in the media stream).  What is the status of that?
c) Would such an enhancement have any impact on the current MPEG
   discussion? (IMHO not, but I may have missed something)

Stephan

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From: Colin Perkins <[email-masked]>
Date: Wed, 13 Sep 2000 16:39:10 -0400

>   session info in the media stream).  What is the status of that?

Does it help? Since you need out of band information to know where to find
the media stream, you may as well include information about the format of
the media.

Colin