RFC 3803 (rfc3803) - Page 2 of 5

Content Duration MIME Header Definition

RFC 3803        Content Duration MIME Header Definition        June 2004


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.











Vaudreuil, et al.           Standards Track