# MPEG-DASH(MPD@type='dynamic)/MPD@availabilityStartTime **URL:** \ **Category:** Wowza Streaming Engine\ **Created:** [November 27, 2014, 2:10pm UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159 "2014-11-27T14:10:34Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Alex\_Pokotilo](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Pokotilo](https://community.wowza.com/u/Alex_Pokotilo)\ **Post date:** [November 27, 2014, 2:10pm UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/1 "2014-11-27T14:10:34Z")
According to the standard MPD@availabilityStartTime should not be updated between MPD updates 8.4.2 Media Presentation Description constraints - When the MPD is updated, the value of MPD@availabilityStartTime shall be the same in the original and the updated MPD But wowza update MPD@availabilityStartTime after every segment goes out of SegmentTimeline for sergment duration value. But according to following requirements this increase segment availability start time more and more from it’s valid value as both MDP segment start time grow and availabilityStartTime grows as well. 5.3.9.5.3 Media Segment information For services with MPD@type=‘dynamic’, the Segment availability start time of a Media Segment is the sum of  the value of the MPD@availabilityStartTime,  the PeriodStart time of the containing Period as defined in 5.3.2.1,  the MPD start time of the Media Segment, and  the MPD duration of the Media Segment. This makes segment availability start time invalid after short period of time after live session start ---
**Author:** ![Daren\_Johnson](https://avatars.discourse-cdn.com/v4/letter/d/ee59a6/32.png) [@Daren\_Johnson](https://community.wowza.com/u/Daren_Johnson)\ **Post date:** [December 10, 2014, 2:37pm UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/2 "2014-12-10T14:37:09Z")
Hi, The availabilityStartTime requirement is actually new in Version 2 of the DASH spec, which we do not support as of yet. Our initial implementation worked with the previous versions of the players we had available. We are planning to update our DASH implementation based on the latest spec and latest dash.js player. Not sure when that will be though, but it is coming. Daren ---
**Author:** ![Daren\_Johnson](https://avatars.discourse-cdn.com/v4/letter/d/ee59a6/32.png) [@Daren\_Johnson](https://community.wowza.com/u/Daren_Johnson)\ **Post date:** [May 10, 2015, 10:26pm UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/3 "2015-05-10T22:26:47Z")
Hi There isn’t a update for this yet. No time line at the moment. Daren ---
**Author:** ![Alex\_Pokotilo](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Pokotilo](https://community.wowza.com/u/Alex_Pokotilo)\ **Post date:** [December 11, 2014, 8:42am UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/4 "2014-12-11T08:42:06Z")
Daren, thanks a lot ! It makes sense now. ---
**Author:** ![Thomas\_Stephens](https://avatars.discourse-cdn.com/v4/letter/t/f08c70/32.png) [@Thomas\_Stephens](https://community.wowza.com/u/Thomas_Stephens)\ **Post date:** [May 8, 2015, 1:30pm UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/5 "2015-05-08T13:30:41Z")
Daren, Is there an updated timeline on when this issue might be fixed? Thanks, –Thomas ---
**Author:** ![Thomas\_Stephens](https://avatars.discourse-cdn.com/v4/letter/t/f08c70/32.png) [@Thomas\_Stephens](https://community.wowza.com/u/Thomas_Stephens)\ **Post date:** [May 12, 2015, 10:21am UTC](https://community.wowza.com/t/mpeg-dash-mpd-type-dynamic-mpd-availabilitystarttime/37159/6 "2015-05-12T10:21:13Z")
Daren, Thanks for getting back to me. Is there a version of Dash.js known to work with the latest Wowza Streaming Engine? Thanks, –Thomas