[MMUSIC] Help needed on SDP capneg example using media titles

<Simo.Veikkolainen@nokia.com> Fri, 28 June 2013 10:36 UTC

Return-Path: <Simo.Veikkolainen@nokia.com>
X-Original-To: mmusic@ietfa.amsl.com
Delivered-To: mmusic@ietfa.amsl.com
Received: from localhost (localhost []) by ietfa.amsl.com (Postfix) with ESMTP id 1994821F9ECD for <mmusic@ietfa.amsl.com>; Fri, 28 Jun 2013 03:36:14 -0700 (PDT)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -5.399
X-Spam-Status: No, score=-5.399 tagged_above=-999 required=5 tests=[AWL=-0.600, BAYES_00=-2.599, HTML_MESSAGE=0.001, J_CHICKENPOX_12=0.6, J_CHICKENPOX_14=0.6, J_CHICKENPOX_15=0.6, RCVD_IN_DNSWL_MED=-4]
Received: from mail.ietf.org ([]) by localhost (ietfa.amsl.com []) (amavisd-new, port 10024) with ESMTP id jeIjAYLhYNin for <mmusic@ietfa.amsl.com>; Fri, 28 Jun 2013 03:36:04 -0700 (PDT)
Received: from mgw-da01.nokia.com (smtp.nokia.com []) by ietfa.amsl.com (Postfix) with ESMTP id 228A721F9CAA for <mmusic@ietf.org>; Fri, 28 Jun 2013 03:36:04 -0700 (PDT)
Received: from vaebh101.NOE.Nokia.com (vaebh101.europe.nokia.com []) by mgw-da01.nokia.com (Sentrion-MTA-4.2.2/Sentrion-MTA-4.2.2) with ESMTP id r5SAZvVI013134 for <mmusic@ietf.org>; Fri, 28 Jun 2013 13:36:00 +0300
Received: from smtp.mgd.nokia.com ([]) by vaebh101.NOE.Nokia.com over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Fri, 28 Jun 2013 13:35:57 +0300
Received: from 008-AM1MPN1-024.mgdnok.nokia.com ([]) by 008-AM1MMR1-009.mgdnok.nokia.com ([]) with mapi id 14.02.0328.011; Fri, 28 Jun 2013 10:37:50 +0000
From: <Simo.Veikkolainen@nokia.com>
To: <mmusic@ietf.org>
Thread-Topic: Help needed on SDP capneg example using media titles
Thread-Index: Ac5z6tzYxi9pUps9SKq5CIiGnRaTGw==
Date: Fri, 28 Jun 2013 10:37:49 +0000
Message-ID: <D09DAE6B636851459F7575D146EFB54B2409AED4@008-AM1MPN1-024.mgdnok.nokia.com>
Accept-Language: en-US
Content-Language: en-US
x-tituslabs-classifications-30: TLPropertyRoot=Nokia; Confidentiality=Nokia Internal Use Only; Project=None;
x-headerinfofordlp: None
x-tituslabs-classificationhash-30: /l7IPXixAhc7RTUH/zCwpl3wa+q/EbJEBCNLK0yb5eP+UqiYUwkVkCFEF4dEqkOVhwhiOaW0snSvlTJ3Qnti4sMkDYWJaJHzP51hjzxhduMJZaKm1QIsti9AQ5E6SXh9TMrG5akNTsT6bYCSbnWZtrfB1z7l4yJkpXdeTO7LdmRWOq2JRJ/5xC7jr+6lzLwQN6KzrJGPRJIJfq4O1N6jey527uoQQimSLuB2+RBRdl7oN9QGKCHNyacO1b4IiWWJMfZsZ/eZUAoTRWUjKlt5vw==
x-originating-ip: []
Content-Type: multipart/alternative; boundary="_000_D09DAE6B636851459F7575D146EFB54B2409AED4008AM1MPN1024mg_"
MIME-Version: 1.0
X-OriginalArrivalTime: 28 Jun 2013 10:35:57.0825 (UTC) FILETIME=[46898710:01CE73EB]
X-Nokia-AV: Clean
Subject: [MMUSIC] Help needed on SDP capneg example using media titles
X-BeenThere: mmusic@ietf.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: Multiparty Multimedia Session Control Working Group <mmusic.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/mmusic>, <mailto:mmusic-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www.ietf.org/mail-archive/web/mmusic>
List-Post: <mailto:mmusic@ietf.org>
List-Help: <mailto:mmusic-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/mmusic>, <mailto:mmusic-request@ietf.org?subject=subscribe>
X-List-Received-Date: Fri, 28 Jun 2013 10:36:14 -0000

Hello WG,

http://tools.ietf.org/html/draft-ietf-mmusic-sdp-miscellaneous-caps extends SDP Capability Negotiation with a media or session title capability attribute ("a=icap").

I would like to add an example to this draft showing an SDP Offer with a title capability using a different character encoding than that offered in the "i=" line, so that if the potential configuration gets selected, the title would be interpreted in a different charset.  I'm not an expert on internationalization, so I would appreciate some help with this.

I'm expecting the SDP Offer to look something like this:


      o=- 25678 753849 IN IP4


      c=IN IP4

      t=0 0


      m=video 53456 RTP/AVP 100

      a=rtpmap:100 H264/90000

      i=some text using the default charset

      a=icap:1 some text in other charset

      a=acap:1 charset:ISO-8859-5

      a=pcfg:1 a=1 i=1

where the "i=" line is the media title, and an alternative media title is offered in the "a=icap" attribute line. For the title capability, we need to also indicate the character set which is used to interpret it (in this example ISO-8859-5 but it could be anything other than the default ISO-10646).

How is the text in the "a=icap" attribute line to be encoded using this alternative character set?

I also copy the relevant text from http://tools.ietf.org/html/draft-ietf-mmusic-sdp-miscellaneous-caps which specifies the usage of charsets with the "a=icap" attribute:

   As defined in SDP [RFC4566<http://tools.ietf.org/html/rfc4566>;], the session information field ("i=",

   referred to as "title" in this document) is subject to the

   "a=charset" attribute in order to support different character sets

   and hence internationalization.  The title capability attribute

   itself ("a=icap") is however not subject to the "a=charset" attribute

   as this would preclude the inclusion of alternative session/title

   information each using different character sets.  Instead, the

   session/title value embedded in an "a=icap" attribute (title

   capability) will be subject to the "a=charset" value used within a

   configuration that includes that title capability.  This provides for

   consistent SDP operation while allowing for capabilities and

   configurations with different session/title information values with

   different character set encodings (with each such configuration

   including an "a=charset" value with the relevant character set for

   the session/title information in question).