Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rtp-00.txt
Harald Alvestrand <harald@alvestrand.no> Fri, 12 August 2011 06:45 UTC
Return-Path: <harald@alvestrand.no>
X-Original-To: rtcweb@ietfa.amsl.com
Delivered-To: rtcweb@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 4812521F852E for <rtcweb@ietfa.amsl.com>; Thu, 11 Aug 2011 23:45:12 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -101.399
X-Spam-Level:
X-Spam-Status: No, score=-101.399 tagged_above=-999 required=5 tests=[BAYES_00=-2.599, J_CHICKENPOX_13=0.6, J_CHICKENPOX_15=0.6, USER_IN_WHITELIST=-100]
Received: from mail.ietf.org ([12.22.58.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id HPIa58apDKhG for <rtcweb@ietfa.amsl.com>; Thu, 11 Aug 2011 23:45:11 -0700 (PDT)
Received: from eikenes.alvestrand.no (eikenes.alvestrand.no [158.38.152.233]) by ietfa.amsl.com (Postfix) with ESMTP id 46D6F21F8520 for <rtcweb@ietf.org>; Thu, 11 Aug 2011 23:45:11 -0700 (PDT)
Received: from localhost (localhost [127.0.0.1]) by eikenes.alvestrand.no (Postfix) with ESMTP id 7202439E148; Fri, 12 Aug 2011 08:44:33 +0200 (CEST)
X-Virus-Scanned: Debian amavisd-new at eikenes.alvestrand.no
Received: from eikenes.alvestrand.no ([127.0.0.1]) by localhost (eikenes.alvestrand.no [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BKQwuhkOTwy1; Fri, 12 Aug 2011 08:44:32 +0200 (CEST)
Received: from [10.130.0.56] (4.234.241.83.in-addr.dgcsystems.net [83.241.234.4]) by eikenes.alvestrand.no (Postfix) with ESMTPS id 3BDF939E091; Fri, 12 Aug 2011 08:44:31 +0200 (CEST)
Message-ID: <4E44CC15.3030004@alvestrand.no>
Date: Fri, 12 Aug 2011 08:45:41 +0200
From: Harald Alvestrand <harald@alvestrand.no>
User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.18) Gecko/20110617 Thunderbird/3.1.11
MIME-Version: 1.0
To: Paul Kyzivat <pkyzivat@alum.mit.edu>
References: <4E43BDB3.8000504@alvestrand.no> <4E4423A7.2000501@alum.mit.edu>
In-Reply-To: <4E4423A7.2000501@alum.mit.edu>
Content-Type: text/plain; charset="ISO-8859-1"; format="flowed"
Content-Transfer-Encoding: 7bit
Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rtp-00.txt
X-BeenThere: rtcweb@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Real-Time Communication in WEB-browsers working group list <rtcweb.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/rtcweb>
List-Post: <mailto:rtcweb@ietf.org>
List-Help: <mailto:rtcweb-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/rtcweb>, <mailto:rtcweb-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 12 Aug 2011 06:45:12 -0000
On 08/11/11 20:47, Paul Kyzivat wrote: > On 8/11/11 7:32 AM, Harald Alvestrand wrote: >> 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, > > A few questions/comments: > > 1) If ICE is being used, how do you expect it to be handled on the 2nd > m-line? Since one of the goals of multiplexing on a single rtp session > is to minimize ICE processing, one would hope only to do ICE on the > first of the grouped m-lines. But if the answerer doesn't support this > grouping, then the ICE will be needed on the others. I tried to be explicit that if negotiation is successful, only the ICE parameters from the first section listed in the A=group:TOGETHER would be used: The following parameters are taken from the first section only: o Port number from the m= line o All media-level attributes defined in RFC 5245 section 15.1 - this includes "candidate", "remote-candidates", "ice-mismatch", "ice- ufrag", "ice-pwd" Suggestions for improving this language? > 2) The draft only shows this mechanism being used to combine one audio > and one video. Do you also imagine it being used to represent multiple > audio and/or multiple video streams that might otherwise be handled > independently? (I see no reason why it couldn't be used that way.) > This would allow description of different properties for each one. I certainly think that any number of m= sections could be combined this way, but in other discussions, I've seen people tend towards thinking of sections as "one m= section for all the audio channels, one m= section for all the video channels". Can you give an example of the usage you're thinking of? I'm worried that we may get too many special rules about how parameters from sections are to be combined - multiple codecs with different PT numbers are fine, but other parameters could be confusing, so I'd like to see examples. > > 3) In the example, for an entity that doesn't understand TOGETHER, you > still show the a=mid lines. This is appropriate for an answerer that > *does* understand a=group. However an answerer that doesn't implement > rfc3388 would presumably omit the a=mid lines from the answer. So the > offerer had better be prepared for that as well. Yes, that's a reasonable point. I'll add a third example answer. > > Thanks, > Paul > _______________________________________________ > rtcweb mailing list > rtcweb@ietf.org > https://www.ietf.org/mailman/listinfo/rtcweb >
- [rtcweb] Fwd: I-D Action: draft-alvestrand-one-rt… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Paul Kyzivat
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Ross Finlayson
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Paul Kyzivat
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Paul Kyzivat
- [rtcweb] Combining attributes (Re: Fwd: I-D Actio… Harald Alvestrand
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Paul Kyzivat
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Randell Jesup
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Randell Jesup
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Justin Uberti
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt ICE … Paul Kyzivat
- [rtcweb] draft-alvestrand-one-rtp-00.txt and inte… Christer Holmberg
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Christer Holmberg
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Harald Alvestrand
- Re: [rtcweb] draft-alvestrand-one-rtp-00.txt and … Christer Holmberg
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Randell Jesup
- Re: [rtcweb] I-D Action: draft-alvestrand-one-rtp… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Muthu Arul Mozhi Perumal (mperumal)
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Harald Alvestrand
- Re: [rtcweb] Fwd: I-D Action: draft-alvestrand-on… Colin Perkins