[Jingle] 1.1 XEPs (166, 167, 177)

Paul Witty paulrw at codian.com
Tue Dec 1 05:50:22 CST 2009

Justin Karneges wrote:
> I'm not 100% sure, but I believe each component is assigned a profile.  So 
> component 1 would always be "RTP/AVP" and component 2 would always 
> be "RTP/AVPF" (which I think is more or less synonymous with RTCP).
> This as opposed to the entire session being assigned a single profile.
> But probably an RTP guru should confirm this.
> -Justin
That's not right: looking from the SDP world, the two streams together 
(RTP and RTCP) would be given a single profile e.g. RTP/AVP or 
RTP/AVPF.  For example a line m=video 23300 RTP/AVP 34 would imply RTP 
on port 23300, with RTCP on 23301 (RFC 4566 actually specifies m=video 
23300/2 to explicitly state that there are two ports in use, but in 
practice this is almost never seen).  RTP/AVPF (as defined in RFC 4586) 
just extends the RTCP to provide better feedback, but again applies to 
both the RTP and RTCP channels.

Within a call, different RTP profiles could be used for different media 
streams e.g. m=video 23300 RTP/AVPF and m=audio 23302 RTP/AVP.


Paul Witty

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