One document matched: draft-ietf-vpim-vpimv2r2-dur-00.txt

Network Working Group                                    Greg Vaudreuil
Internet Draft                                      Lucent Technologies
Document: <draft-ietf-vpim-vpimv2r2-dur-00.txt>           Glenn Parsons
Obsoletes: RFC 2424                                     Nortel Networks
Category: Standards Track                             November 16, 2000
 
 
                            Content Duration 
                         MIME Header Definition 
    
 
 
Status of this Memo 
 
   This document is an Internet-Draft and is in full conformance with 
   all provisions of Section 10 of RFC2026.  
    
   Internet-Drafts are working documents of the Internet Engineering 
   Task Force (IETF), its areas, and its working groups. Note that 
   other groups may also distribute working documents as Internet-
   Drafts. Internet-Drafts are draft documents valid for a maximum of 
   six months and may be updated, replaced, or obsoleted by other 
   documents at any time. It is inappropriate to use Internet- Drafts 
   as reference material or to cite them other than as "work in 
   progress."  
    
   The list of current Internet-Drafts can be accessed at 
   http://www.ietf.org/ietf/1id-abstracts.txt  
    
   The list of Internet-Draft Shadow Directories can be accessed at 
   http://www.ietf.org/shadow.html. 
    
    
1. Abstract 
    
   This document describes the MIME header Content-Duration that is 
   intended for use with any time varying media content (typically   
   audio/* or video/*). The length of time is represented in seconds   
   without any units indication. 
    
   This document obsoletes RFC 2424. 
    
2. Conventions used in this document 
    
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in 
   this document are to be interpreted as described in RFC-2119. 
    
    
3. Content-Duration Header Field 
 
   Time varying media contents, for example, a spoken voice message or 
   a video clip, have an inherent time duration.  Many audio and video 
   encodings may include their duration as header information or may 
   allow accurate calculation based on the byte length of the data. 
   However, it may be useful to present the time duration of the 
   content in a MIME header to allow its simple determination without 
   dealing with the actual content. 
    
  
Vaudreuil & Parsons       Expires: 16/05/01                          1 
                           Content Duration          November 16, 2000 
 
 
    
2.1 Syntax 
    
   The Content-Duration field's value is a single number specifying the 
   time duration in seconds of the content.  Formally: 
    
   duration := "Content-Duration" ":" 1*10DIGIT 
    
   Note that practically (though highly unlikely in MIME media), the 
   upper bound on the numerical value of the time duration is (2^^31 -
   1) or 2147483647. 
    
2.2 Semantics 
    
   This field represents the time duration of the associated time 
   varying media content. The time duration is noted in seconds with no 
   units tag. The time value should be exact, however the exact value 
   of the time duration cannot be known without opening the content and 
   playing it. If an exact value must be known, then the latter method   
   should be used. This mechanism simply allows placing a sender 
   determined time duration value in the header for easy access. 
    
   Though there are several ways to present this duration to the 
   recipient (e.g. with the inbox headers, when audio attachment 
   opened), the actual use of this field on reception is a local 
   implementation issue. 
    
2.3 Example 
    
   In this example the content duration represents 33 seconds: 
    
        Content-Duration: 33 
    
3. VPIM Usage 
    
   The Content-Duration header field for the audio/32KADPCM sub-type is   
   a useful component of the VPIM specification [VPIM2]. All VPIM 
   Messages MUST contain this sub-type to carry the audio of a voice 
   message. It may be useful in some instances (e.g. viewing on a 
   simple MIME or non-MIME desktop) to have the time duration of the 
   voice message available without having to open the audio content. 
    
    
4. Security Considerations 
 
   This definition introduces the option of explicitly identifying the   
   time duration of an audio/* or video/* content outside of the binary 
   data that forms the content. In some environments (though likely not 
   the majority), the identification of the actual time duration in a 
   header field may be a security issue and as a result should not be 
   noted. Reliance on the time indicated in this header field cannot be 
   trusted for the purposes of determining the exact size of the data. 
   The exact length of the data must be determined by examining the 
   data itself. 
    
    
5. References 
    
  
Vaudreuil & Parsons       Expires: 16/05/01                          2 
                           Content Duration          November 16, 2000 
 
 
   [DUR] G. Parsons and G. Vaudreuil, "Content Duration MIME Header 
   Definition", RFC 2424, September 1998.  
    
   [MIME2] Freed, N., and N. Borenstein, "Multipurpose Internet Mail 
   Extensions (MIME) Part Two: Media Types", RFC 2046, November 1996. 
    
   [VPIM2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet 
   Mail - version 2", RFC 2421, September 1998. 
    
   [VPIM2R2] Vaudreuil, G., and G. Parsons, "Voice Profile for Internet 
   Mail - version 2", <draft-ietf-vpim-vpimv2r2-01.txt>, November 2000. 
    
6. Authors' Addresses 
    
   Glenn W. Parsons 
   Nortel Networks 
   P.O. Box 3511, Station C 
   Ottawa, ON  K1Y 4H7 
   Canada 
    
   Phone: +1-613-763-7582 
   Fax:   +1-416-597-7005 
    
   EMail: gparsons@nortelnetworks.com 
    
    
   Gregory M. Vaudreuil 
   Lucent Technologies 
   17080 Dallas Parkway 
   Dallas, TX  75248-1905 
   United States 
    
   Phone/Fax: +1-972-733-2722 
   EMail: gregv@lucent.com 
    
    
    
    




















  
Vaudreuil & Parsons       Expires: 16/05/01                          3 
                           Content Duration          November 16, 2000 
 
 
    
7. Full Copyright Statement 
 
   Copyright (C) The Internet Society (2000).  All Rights Reserved. 
    
   This document and translations of it may be copied and furnished to 
   others, and derivative works that comment on or otherwise explain it 
   or assist in its implementation may be prepared, copied, published 
   and distributed, in whole or in part, without restriction of any 
   kind, provided that the above copyright notice and this paragraph 
   are included on all such copies and derivative works.  However, this 
   document itself may not be modified in any way, such as by removing 
   the copyright notice or references to the Internet Society or other 
   Internet organizations, except as needed for the purpose of 
   developing Internet standards in which case the procedures for 
   copyrights defined in the Internet Standards process must be 
   followed, or as required to translate it into languages other than 
   English. 
    
   The limited permissions granted above are perpetual and will not be 
   revoked by the Internet Society or its successors or assigns. 
    
   This document and the information contained herein is provided on an 
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING 
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING 
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION 
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF 
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 






























  
Vaudreuil & Parsons       Expires: 16/05/01                          4