Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recycling m-lines
Harald Alvestrand <harald@alvestrand.no> Wed, 06 November 2013 20:59 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 49DDE21E805F for <rtcweb@ietfa.amsl.com>; Wed, 6 Nov 2013 12:59:24 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -110.492
X-Spam-Level:
X-Spam-Status: No, score=-110.492 tagged_above=-999 required=5 tests=[AWL=0.107, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8, 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 O0iAfu8nr9bO for <rtcweb@ietfa.amsl.com>; Wed, 6 Nov 2013 12:59:19 -0800 (PST)
Received: from eikenes.alvestrand.no (eikenes.alvestrand.no [158.38.152.233]) by ietfa.amsl.com (Postfix) with ESMTP id 0E88F11E80E2 for <rtcweb@ietf.org>; Wed, 6 Nov 2013 12:59:19 -0800 (PST)
Received: from localhost (localhost [127.0.0.1]) by eikenes.alvestrand.no (Postfix) with ESMTP id 84B4739E230 for <rtcweb@ietf.org>; Wed, 6 Nov 2013 21:59:17 +0100 (CET)
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 Sn5yFwnF5pIP for <rtcweb@ietf.org>; Wed, 6 Nov 2013 21:59:16 +0100 (CET)
Received: from [IPv6:2001:67c:370:160:6056:eeee:f72d:1d19] (unknown [IPv6:2001:67c:370:160:6056:eeee:f72d:1d19]) by eikenes.alvestrand.no (Postfix) with ESMTPSA id 5DEB639E09F for <rtcweb@ietf.org>; Wed, 6 Nov 2013 21:59:16 +0100 (CET)
Message-ID: <527AADA1.7060304@alvestrand.no>
Date: Wed, 06 Nov 2013 21:59:13 +0100
From: Harald Alvestrand <harald@alvestrand.no>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0
MIME-Version: 1.0
To: rtcweb@ietf.org
References: <527420FF.2@alum.mit.edu> <CAOJ7v-2OjY0UYgDPk2WRLodKUYLytKGtV8HL84NujKfy64q7RQ@mail.gmail.com> <527AA850.3050807@alum.mit.edu>
In-Reply-To: <527AA850.3050807@alum.mit.edu>
X-Enigmail-Version: 1.5.2
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7bit
Subject: Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recycling m-lines
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: Wed, 06 Nov 2013 20:59:24 -0000
On 11/06/2013 09:36 PM, Paul Kyzivat wrote: > On 11/3/13 11:09 PM, Justin Uberti wrote: >> >> On Fri, Nov 1, 2013 at 2:45 PM, Paul Kyzivat <pkyzivat@alum.mit.edu >> <mailto:pkyzivat@alum.mit.edu>> wrote: > ... >> Later in 5.2.2: >> >> o If a m= section exists in the current local description, >> but has >> its state set to inactive or recvonly, and a new >> MediaStreamTrack >> is added, the previously existing m= section MUST be recycled >> instead of creating a new m= section. [OPEN ISSUE: Nail down >> exactly what this means. Should the codecs remain the same? >> (No.) Should ICE restart? (No.) Can the "a=mid" >> attribute be >> changed? (Yes?)] >> >> This seems to assume that there is no existing MediaStreamTrack for >> these m-lines. >> >> Yes. The text should state that more clearly. >> >> If there is, then >> - the m-line shouldn't be recycled. >> If there isn't, then >> - where do its address and port come from? >> - what is managing the RTCP? >> >> >> The m= section will still have completed ICE negotiation, despite being >> marked as inactive. So the address/port information should already be >> present. > > *Why* would you do this if there is no MediaStreamTrack and hence no > possibility of using the port? > > IOW, why not use port zero in these cases? > >> I don't follow your question about who is managing RTCP. > > It may be a misunderstanding on my part. > > My thinking is that the MediaStreamTrack is a surrogate for the > resource that manages the RTP/RTCP for that track. If so, then no > track -> no RTCP. > > Of course, with bundling, that resource gets spread across multiple > MediaStreamTracks. That's why thinking of it in the way you suggest is likely to lead to misunderstandings and confusion all around. I've had greater success thinking of a MediaStreamTrack as an SSRC; the resource that manages the RTP/RTCP is then a container that contains MSTs.
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Paul Kyzivat
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Justin Uberti
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Paul Kyzivat
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Harald Alvestrand
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Paul Kyzivat
- Re: [rtcweb] draft-ietf-rtcweb-jsep-05 - Recyclin… Harald Alvestrand