Content Duration MIME Header Definition
obsoleted by
- rfc-3803 — Content Duration MIME Header Definition
Extracted elements (7)
The Content-Duration header allows simple determination of media duration without parsing the actual content. While many audio/video encodings include duration internally, a MIME header provides easy access for systems that handle metadata without opening the content.
The time value should be exact but acknowledged as sender-determined; if an exact value is required, the content itself must be examined. The header merely conveys a sender-asserted duration for convenience.
The actual use of the Content-Duration field on reception is a local implementation issue. How the duration is presented to the recipient (e.g., in inbox headers or when an attachment is opened) is not specified by this document.
All VPIM Messages MUST contain the audio/32KADPCM sub-type with the Content-Duration header to carry the audio of a voice message.
The Content-Duration MIME header field specifies the time duration in seconds of time-varying media content such as audio/* or video/*. It is a single integer value with no units tag.
In some environments, explicitly identifying the time duration of audio/* or video/* content in a header may be a security issue and should not be noted. The duration value in the header cannot be trusted for determining exact data size; the actual data must be examined directly.
The Content-Duration field value is encoded as 1 to 10 decimal digits representing seconds: `duration := "Content-Duration" ":" 1*10DIGIT`. The practical upper bound is 2147483647 (2^31 - 1).