Re: [rtcweb] Making progress on the signaling discussion (NB: Action items enclosed!)

Tim Panton <tim@phonefromhere.com> Wed, 12 October 2011 14:58 UTC

Return-Path: <tim@phonefromhere.com>
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 AB0D221F8BC4 for <rtcweb@ietfa.amsl.com>; Wed, 12 Oct 2011 07:58:18 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -2.599
X-Spam-Level:
X-Spam-Status: No, score=-2.599 tagged_above=-999 required=5 tests=[AWL=0.001, BAYES_00=-2.599]
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 DWZfi1m8ugNK for <rtcweb@ietfa.amsl.com>; Wed, 12 Oct 2011 07:58:18 -0700 (PDT)
Received: from zimbra.westhawk.co.uk (zimbra.westhawk.co.uk [192.67.4.167]) by ietfa.amsl.com (Postfix) with ESMTP id 06EE921F8B87 for <rtcweb@ietf.org>; Wed, 12 Oct 2011 07:58:17 -0700 (PDT)
Received: from [192.168.0.14] (unknown [93.89.81.113]) by zimbra.westhawk.co.uk (Postfix) with ESMTP id 3E15D37A902; Wed, 12 Oct 2011 16:11:04 +0100 (BST)
Mime-Version: 1.0 (Apple Message framework v1084)
Content-Type: text/plain; charset="us-ascii"
From: Tim Panton <tim@phonefromhere.com>
In-Reply-To: <4E959D48.3090401@mozilla.com>
Date: Wed, 12 Oct 2011 15:58:11 +0100
Content-Transfer-Encoding: quoted-printable
Message-Id: <9E790044-DE19-46DD-89D8-C4F2973F8D65@phonefromhere.com>
References: <CA+9kkMBi9BzDu=WOq3RG-o5nbfnUTftDg3LRBU3DFh=Kc4W5ZQ@mail.gmail.com> <CALiegfmYgQ+yb=pDp1J2_PVa1SkxTOuaUCM02Vt6-iGabwif1g@mail.gmail.com> <CA+9kkMCUTiPO3eASjn0mbRA9YCF6TMmGGOjQ4NkVkvzVMN39Gg@mail.gmail.com> <CALiegfnx=qoS_pqyC45WVEYEFqj-3eP9g_kyhAUaOO6He_UEfw@mail.gmail.com> <CA+9kkMCibnPLrEq1234bUMXpiKBK0+22mqwYOM__CpcO2nOayg@mail.gmail.com> <CALiegfms2bt-WPtMeosFQz3-aSf2L6mfX+i68tw45sSgix561Q@mail.gmail.com> <4E8D6507.8000707@ericsson.com> <CALiegf=VyViX2arp0gr0dK4WN_jv=bjwP0LUAxRf=quTxrYrUQ@mail.gmail.com> <CALiegfn15szv-2yXeWptWjsQC2CwVODg_X90gD4odZkCR0LzvA@mail.gmail.com> <4E955775.10206@alvestrand.no> <CABRok6n6UA_nFfLzQ4K+H0+idspEsymW29OZH0J5q1ewF3PpRw@mail.gmail.com> <4E956526.2090604@alvestrand.no> <380E325E-A7EF-489A-AA24-0270224FC87A@phonefromhere.com> <4E957C55.9020706@alvestrand.no> <13C2526B-E7B1-408C-BD1D-EC5E8C8F6472@phonefromhere.com> <4E95871F.9010605@alvestrand.no> <E21755ED-205F-4D80-BB97-CF32E989EB3F@phonefromhere.com> <4E959D48.3090401@mozill a.com>
To: "Timothy B. Terriberry" <tterriberry@mozilla.com>
X-Mailer: Apple Mail (2.1084)
Cc: rtcweb@ietf.org
Subject: Re: [rtcweb] Making progress on the signaling discussion (NB: Action items enclosed!)
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, 12 Oct 2011 14:58:18 -0000

On 12 Oct 2011, at 14:59, Timothy B. Terriberry wrote:

>> Lets assume we use a subset/variant of SDP as a codec capability
>> description 'language' - (i.e. we won't be using the parts that relate
>> to network properties).
> 
> I've seen this proposed a couple of times now, and I would like to point out that this is a terrible assumption. There are many things that one might want to control about a codec that will never show up in SDP, because they don't require explicit negotiation between sender and receiver (e.g., the sender gets to make a unilateral decision and the receiver simply deals with it... like, say, the amount of time a video encoder is willing to spend doing a motion search, etc.).
> 
> Limiting yourself to the parameters that do happen to show up in SDP is a pretty poor half-solution, if you really do think you need a low-level API of this kind, and may not have obvious extension points to get to a full solution.

Which leaves us with the choice of:
	a) having 2 different APIs - one for SDP params and one for everything else
	b) extending SDP to include things that will only be used locally 
	c) describing a mapping from SDP to javascript objects for a 'full' codec description object
	d) ?

Tim (P).