[AVT] Re: draft-ietf-avt-rtp-howto-01.txt
Magnus Westerlund <magnus.westerlund@ericsson.com> Mon, 18 December 2006 10:35 UTC
Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1GwFq6-0001El-4F; Mon, 18 Dec 2006 05:35:22 -0500
Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1GwFq5-0001Eg-GM for avt@ietf.org; Mon, 18 Dec 2006 05:35:21 -0500
Received: from mailgw3.ericsson.se ([193.180.251.60]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1GwFq1-0007VP-TZ for avt@ietf.org; Mon, 18 Dec 2006 05:35:21 -0500
Received: from esealmw128.eemea.ericsson.se (unknown [153.88.254.121]) by mailgw3.ericsson.se (Symantec Mail Security) with ESMTP id 0E8111AD; Mon, 18 Dec 2006 11:35:05 +0100 (CET)
Received: from esealmw126.eemea.ericsson.se ([153.88.254.170]) by esealmw128.eemea.ericsson.se with Microsoft SMTPSVC(6.0.3790.1830); Mon, 18 Dec 2006 11:35:04 +0100
Received: from [147.214.30.247] ([147.214.30.247]) by esealmw126.eemea.ericsson.se with Microsoft SMTPSVC(6.0.3790.1830); Mon, 18 Dec 2006 11:35:04 +0100
Message-ID: <45866ED8.3060803@ericsson.com>
Date: Mon, 18 Dec 2006 11:35:04 +0100
From: Magnus Westerlund <magnus.westerlund@ericsson.com>
User-Agent: Thunderbird 1.5.0.8 (Windows/20061025)
MIME-Version: 1.0
To: lazzaro <lazzaro@eecs.berkeley.edu>, IETF AVT WG <avt@ietf.org>
References: <0CADE989-5A47-4B44-B072-F70AC5F98684@eecs.berkeley.edu>
In-Reply-To: <0CADE989-5A47-4B44-B072-F70AC5F98684@eecs.berkeley.edu>
Content-Type: text/plain; charset="ISO-8859-1"; format="flowed"
Content-Transfer-Encoding: 7bit
X-OriginalArrivalTime: 18 Dec 2006 10:35:04.0225 (UTC) FILETIME=[2DCAD110:01C72290]
X-Brightmail-Tracker: AAAAAA==
X-Spam-Score: 0.0 (/)
X-Scan-Signature: d8ae4fd88fcaf47c1a71c804d04f413d
Cc:
Subject: [AVT] Re: draft-ietf-avt-rtp-howto-01.txt
X-BeenThere: avt@ietf.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Audio/Video Transport Working Group <avt.ietf.org>
List-Unsubscribe: <https://www1.ietf.org/mailman/listinfo/avt>, <mailto:avt-request@ietf.org?subject=unsubscribe>
List-Post: <mailto:avt@ietf.org>
List-Help: <mailto:avt-request@ietf.org?subject=help>
List-Subscribe: <https://www1.ietf.org/mailman/listinfo/avt>, <mailto:avt-request@ietf.org?subject=subscribe>
Errors-To: avt-bounces@ietf.org
Hi John, (CC AVT) Thanks for the comments. I have incorporated the typos in my working copy. I do have some comments regarding a few of the items. lazzaro skrev: > Hi Magnus, > > Comments on draft-ietf-avt-rtp-howto-01.txt below. > > --- > In 3.1.1, mention RFC Errata as a pragmatic way of > disseminating small fixes. Well, maybe. It is something that is worth checking. However in general it is a mechanism that hasn't be working. The RFC-editor hadn't until a month or so published more than a handful erratas in the last 1.5 years. Thus without a working Errata publication mechanism it isn't worth mentioning as something that works. Also despite its pragmatism too few people know about it. Thus even minor errors can be worth republishing an RFC for. > > In 3.1.2, mention framing RTP over TCP as another > robustness solution (with its own pros and cons). Yes, for completeness I guess it should be mentioned. However it is not something that one should design towards, unless really, really necessary. In fact I think using HTTP or some other protocol on top of TCP may be a better way to handle data that can't handle losses at all then using RTP in between. > > Somewhere in 3, mention UDP-lite and how certain > payload formats may benefit by organizing its > bitfields to be compatible with it. Uneven FEC > protection could also be fit in here. Yes, however I think the verdict is still not in for this mechanism. So far I don't think anyone is really using it. The big issue is that you don't know if you have 10E-5 bit errors or if you have 100% error in the unprotected bits. Thus it makes designing for it very difficult. Despite being on the spearhead of this development with the AMR payload I today are very skeptic on its usefulness. Here the ULP may be slightly better. At least you have a known design target, which is 100% loss of unprotected bits. > 6.1 Consider mentioning RTP MIDI's use of the > recovery journal concept to drive payload-format > specific resiliency for payload formats that > carry time-stamped symbolic media representations. > Also mention how it uses the Extended Highest > Sequence Number Received in RTCP, and how > other forms of resiliency might also want to use > this field. > I don't think we want to promote payload specific resilience to much due to the complexity it incurs. Only when absolutely necessary should it be used. But I guess one can't avoid these things in all cases. Cheers Magnus Westerlund IETF Transport Area Director & TSVWG Chair ---------------------------------------------------------------------- Multimedia Technologies, Ericsson Research EAB/TVA/A ---------------------------------------------------------------------- Ericsson AB | Phone +46 8 4048287 Torshamsgatan 23 | Fax +46 8 7575550 S-164 80 Stockholm, Sweden | mailto: magnus.westerlund@ericsson.com ---------------------------------------------------------------------- _______________________________________________ Audio/Video Transport Working Group avt@ietf.org https://www1.ietf.org/mailman/listinfo/avt
- [AVT] Re: draft-ietf-avt-rtp-howto-01.txt Magnus Westerlund
- [AVT] Re: draft-ietf-avt-rtp-howto-01.txt lazzaro