Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rtp-00.txt

On 08/12/2011 03:09 PM, Muthu Arul Mozhi Perumal (mperumal) wrote:
>
> A few comments:
>
> 1) Section 4 has this:
>
> If the responder understands the semantics of the TOGETHER extension,
>
> the parameters of the first section MUST be used to establish the RTP
>
> session, and the parameters for the other sections MUST be ignored.
>
> I think it needs to be:
>
> If the responder understands the semantics of the TOGETHER extension,
>
> the parameters of the first section MUST be used to establish the RTP
>
> and RCP session, and the parameters for the other sections MUST be
>
> ignored.
>
Good point. Will fix. Normally, I think RTCWEB apps will use RTCP port 
multiplexing (RFC 5761), so I did not think of it.
In general, I think we should keep extensions as orthogonal as possible, 
so the normative language here should just say "establish RTCP sessions 
normally for the first section, and don't do it for other sections".
>
> 2) When the RTCP port is not the next higher (odd) port number 
> following the RTP port described in the m-line, the "a=rtcp" attribute 
> (defined in RFC-3605) is used to signal it, as in:
>
> m=audio 49170 RTP/AVP 0
>
> a=rtcp:53020 IN IP4 126.16.64.4
>
> With the grouping semantics described in the draft, it seems this RTCP 
> port should be taken only from the first section. So, this could be 
> could be added to section 4.
>
> 3) RTCP could be multiplexed with RTP on a single port and signaled 
> using the "a=rtcp-mux" attribute (defined in RFC 5761). When it is 
> used together with the grouping semantics described in the draft, it 
> seems all RTCP sessions of that group need to be multiplexed on the 
> RTP port from the first section.
>
There should be only one RTCP session established for all the TOGETHER 
m= lines, yes.
>
> Muthu
>
> *From:*rtcweb-bounces@ietf.org [mailto:rtcweb-bounces@ietf.org] *On 
> Behalf Of *Harald Alvestrand
> *Sent:* Thursday, August 11, 2011 5:02 PM
> *To:* rtcweb@ietf.org
> *Subject:* [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rtp-00.txt
>
> I have taken some of the information I learned from the discussions in 
> Quebec City about the issues of putting video and audio into the same 
> RTP session and created a draft from them outlining a solution to the 
> problem of signalling this configuration using SDP.
>
> Comments welcome, including the recommended context for processing the 
> document; in a few days I'll send the same note to AVTCORE and/or MMUSIC.
>
>                       Harald
>
> -------- Original Message --------
>
> *Subject: *
>
> 	
>
> I-D Action: draft-alvestrand-one-rtp-00.txt
>
> *Date: *
>
> 	
>
> Thu, 11 Aug 2011 04:28:09 -0700
>
> *From: *
>
> 	
>
> internet-drafts@ietf.org <mailto:internet-drafts@ietf.org>
>
> *Reply-To: *
>
> 	
>
> internet-drafts@ietf.org <mailto:internet-drafts@ietf.org>
>
> *To: *
>
> 	
>
> i-d-announce@ietf.org <mailto:i-d-announce@ietf.org>
>
> A New Internet-Draft is available from the on-line Internet-Drafts directories.
>   
>         Title            : SDP Grouping for Single RTP Sessions
>         Author(s)        : Harald Tveit Alvestrand
>         Filename         : draft-alvestrand-one-rtp-00.txt
>         Pages            : 8
>         Date             : 2011-08-11
>   
>     This document describes an extension to the Session Description
>     Protocol (SDP) to describe RTP sessions where media of multiple top
>     level types, for example audio and video, are carried in the same RTP
>     session.
>   
>     This document is presented to the RTCWEB, AVTCORE and MMUSIC WGs for
>     consideration.
>   
>   
>   
> A URL for this Internet-Draft is:
> http://www.ietf.org/internet-drafts/draft-alvestrand-one-rtp-00.txt
>   
> Internet-Drafts are also available by anonymous FTP at:
> ftp://ftp.ietf.org/internet-drafts/
>   
> This Internet-Draft can be retrieved at:
> ftp://ftp.ietf.org/internet-drafts/draft-alvestrand-one-rtp-00.txt
> _______________________________________________
> I-D-Announce mailing list
> I-D-Announce@ietf.org  <mailto:I-D-Announce@ietf.org>
> https://www.ietf.org/mailman/listinfo/i-d-announce
> Internet-Draft directories:http://www.ietf.org/shadow.html
> orftp://ftp.ietf.org/ietf/1shadow-sites.txt
>