Syndication/spec/s:duration

From Steeple

s:duration is used to give the total duration of the item/entry. Where there is only one media:group / media:content / enclosure, the duration is the same as that of that element. In case of a media:group, s:duration is the duration of the default media:content item. However, where there are several media:groups, the s:duration is understood to be the total duration of all items included.

<s:duration>seconds</s:duration>
<s:duration>minutes:seconds</s:duration>
<s:duration>hours:minutes:seconds</s:duration>