# A/V sync with "elst" track atom **URL:** \ **Category:** Wowza Developer Dojo\ **Tags:** wowza-streaming-server-java-api\ **Created:** [February 19, 2011, 2:37am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968 "2011-02-19T02:37:27Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![quan\_quan](https://avatars.discourse-cdn.com/v4/letter/q/b19c9b/32.png) [@quan\_quan](https://community.wowza.com/u/quan_quan)\ **Post date:** [February 19, 2011, 2:37am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/1 "2011-02-19T02:37:27Z")
We are using WMS (European Institution) for VOD applications. For some not (A/V) synchronized file, we are using some tools to introducing some start delay on ncertain tracks. ( add track elst atom ). The introduced delay can be correctly playbacked with VLC or Quicktime player, but the WMS didn’t take into account of this delay. Could you fix this problem? ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 19, 2011, 5:49am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/2 "2011-02-19T05:49:48Z")
We do not take into account elst atoms. Charlie ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 19, 2011, 8:19am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/3 "2011-02-19T08:19:58Z")
We have no short term plans to add support for this. Charlie ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [February 21, 2011, 3:16pm UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/4 "2011-02-21T15:16:29Z")
No, not on a per-track basis. Charlie ---
**Author:** ![Charlie\_Good](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/charlie_good/32/383_2.png) [@Charlie\_Good](https://community.wowza.com/u/Charlie_Good)\ **Post date:** [March 7, 2011, 5:24am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/5 "2011-03-07T05:24:26Z")
At this time there is just no way to do this. We do not have a way to introduce a delay into a video on demand stream. Charlie ---
**Author:** ![quan\_quan](https://avatars.discourse-cdn.com/v4/letter/q/b19c9b/32.png) [@quan\_quan](https://community.wowza.com/u/quan_quan)\ **Post date:** [February 19, 2011, 8:05am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/6 "2011-02-19T08:05:53Z")
Could you consider to implement this feature in the WMS? It is important for our applications. If needed I can provide a sample MP4 video with the “elst” atoms. ---
**Author:** ![quan\_quan](https://avatars.discourse-cdn.com/v4/letter/q/b19c9b/32.png) [@quan\_quan](https://community.wowza.com/u/quan_quan)\ **Post date:** [February 21, 2011, 3:06am UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/7 "2011-02-21T03:06:32Z")
Is it possible to implement some Server Side Module or client module to give some start delay on certain audio or video tracks? If so, can you give me some advices? ---
**Author:** ![Greg\_K](https://avatars.discourse-cdn.com/v4/letter/g/ecccb3/32.png) [@Greg\_K](https://community.wowza.com/u/Greg_K)\ **Post date:** [March 5, 2011, 3:53pm UTC](https://community.wowza.com/t/a-v-sync-with-elst-track-atom/33968/8 "2011-03-05T15:53:56Z")
Charlie, would it be possible to implement a workaround on module level using the MediaReaderListener API? Or perhaps some other way to sync the tracks? We are ready to get as deep as possible into the API if needed. This is extremely important for us… Thank you, Greg