Re: [Stox] stox-media: format parameter translation

Saúl Ibarra Corretgé <saul@ag-projects.com> Tue, 25 March 2014 08:58 UTC

Return-Path: <saul@ag-projects.com>
X-Original-To: stox@ietfa.amsl.com
Delivered-To: stox@ietfa.amsl.com
Received: from localhost (ietfa.amsl.com [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 7897F1A03A1 for <stox@ietfa.amsl.com>; Tue, 25 Mar 2014 01:58:46 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: 0.91
X-Spam-Level:
X-Spam-Status: No, score=0.91 tagged_above=-999 required=5 tests=[BAYES_20=-0.001, HELO_MISMATCH_NET=0.611, MIME_8BIT_HEADER=0.3] autolearn=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id OibRAi8bBz1N for <stox@ietfa.amsl.com>; Tue, 25 Mar 2014 01:58:45 -0700 (PDT)
Received: from mail.sipthor.net (node16.dns-hosting.info [81.23.228.161]) by ietfa.amsl.com (Postfix) with ESMTP id 063B91A0379 for <stox@ietf.org>; Tue, 25 Mar 2014 01:58:44 -0700 (PDT)
Received: from imac.saghul.lan (ip3e830637.speed.planet.nl [62.131.6.55]) by mail.sipthor.net (Postfix) with ESMTPSA id 5EAFE16DC6C6; Tue, 25 Mar 2014 09:58:43 +0100 (CET)
Mime-Version: 1.0 (Apple Message framework v1085)
Content-Type: text/plain; charset="iso-8859-1"
From: Saúl Ibarra Corretgé <saul@ag-projects.com>
In-Reply-To: <532A6584.7000105@stpeter.im>
Date: Tue, 25 Mar 2014 09:58:42 +0100
Content-Transfer-Encoding: quoted-printable
Message-Id: <7D07DA47-ED22-47F6-A892-0541B83A60F9@ag-projects.com>
References: <1CFAA181-4E37-42EF-A5B4-70737C697B9E@vidyo.com> <532A6584.7000105@stpeter.im>
To: Peter Saint-Andre <stpeter@stpeter.im>
X-Mailer: Apple Mail (2.1085)
Archived-At: http://mailarchive.ietf.org/arch/msg/stox/GSWNefSbHy3NLaC8lISP3Tq2wBg
Cc: Jonathan Lennox <jonathan@vidyo.com>, "stox@ietf.org" <stox@ietf.org>
Subject: Re: [Stox] stox-media: format parameter translation
X-BeenThere: stox@ietf.org
X-Mailman-Version: 2.1.15
Precedence: list
List-Id: SIP-TO-XMPP Working Group discussion list <stox.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/stox>, <mailto:stox-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/stox/>
List-Post: <mailto:stox@ietf.org>
List-Help: <mailto:stox-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/stox>, <mailto:stox-request@ietf.org?subject=subscribe>
X-List-Received-Date: Tue, 25 Mar 2014 08:58:46 -0000

On Mar 20, 2014, at 4:50 AM, Peter Saint-Andre wrote:

> On 1/9/14, 10:22 AM, Jonathan Lennox wrote:
>> This is the issue I brought up at the Interim -- I'll try to put it
>> in writing.
>> 
>> The point I raised is that the stox-media draft's section on format
>> parameter translation should try to focus on media types which are
>> actually used by existing, deployed Jingle clients, since this is
>> probably a relatively small set.  The important question is which
>> payload formats in use by existing Jingle clients have SDP fmtp
>> formats that don't follow the normal semicolon-separated parameter
>> model.
>> 
>> I of course haven't done a full inventory of such payload formats,
>> but two that seem reasonably likely and I think should be
>> particularly called out are:
>> 
>> audio/telephone-event: RFC 4733: the fmtp contains the value of an
>> implicit "events" parameter.
> 
> That one seems relevant.
> 
>> audio/red: RFC 2198, with its media type registration in RFC 3555:
>> the fmtp is the payload types of the encompassed formats.  The RFC
>> 3555 definition of the actual media type parameters is weird (in an
>> attempt to make it self-contained), and I doubt that any Jingle
>> client that does RED would actually use it that way. So we need to
>> figure out what any actual Jingle implementations do.
>> 
>> Does anyone have a reasonably-authoritative list of which RTP payload
>> formats are supported by existing Jingle clients?
> 
> I do not, but it's a small enough universe that we can poll the developers. (I expect it's mostly limited to common audio and video payloads - Speex, Opus, etc. - but we'll find out.)
> 
>> Does anyone know
>> of any other real-world usage of codecs that have unusual fmtp
>> encodings?
> 
> I think audio/telephone-event is a possibility.
> 
>> Someone on the call mentioned that they thought that
>> Speex's was weird, but as far as I can tell, it's a normal
>> semicolon-separated encoding.
> 
> Agreed.
> 

Same goes for H264 format AFAIS. It has many parameters, but in the end it's just a list of attribute=value separated by semicolons.

--
Saúl Ibarra Corretgé
AG Projects