# Audio/Video synchronization issue on multicast frame drops in DASH (Chrome browser)

**URL:** <https://community.wowza.com/t/audio-video-synchronization-issue-on-multicast-frame-drops-in-dash-chrome-browser/50199>\
**Category:** Wowza Streaming Engine\
**Tags:** server-administration, transcoder\
**Created:** [November 21, 2017, 4:02pm UTC](https://community.wowza.com/t/audio-video-synchronization-issue-on-multicast-frame-drops-in-dash-chrome-browser/50199 "2017-11-21T16:02:14Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Przemyslaw\_Sobala](https://avatars.discourse-cdn.com/v4/letter/p/977dab/32.png) [@Przemyslaw\_Sobala](https://community.wowza.com/u/Przemyslaw_Sobala)\
**Post date:** [November 21, 2017, 4:02pm UTC](https://community.wowza.com/t/audio-video-synchronization-issue-on-multicast-frame-drops-in-dash-chrome-browser/50199/1 "2017-11-21T16:02:14Z")

</div>

Hello

I’ve got a source multicast stream that’s being transcoded by Wowza Streaming Engine Transcoder and packaged into DASH stream.

The source stream is configured like this:

```auto
{
  uri : "udp://239.239.6.16:1234",
  mpegtsMapTimeToSystemTime : "true",
  mpegtsLogIncompleteVideoFrames : "true"
}

```

The rest is configured as a standard Live HTTP Origin application.

After playing the transcoded DASH stream for more than 5 minutes in Chrome (regardless the player - Shaka, DASH-IF) I can see/hear an audio/video delay that grows over time. I think it can be related with UDP frame drops that happens occasionally with the source stream.

```auto
2017-11-21 16:41:07 WARN server comment - RTPDePacketizerMPEGTS[9/_definst_/9.stream]: RTPDePacketizerMPEGTS.flushVideoBuffer: Video frame incomplete, dropping[54527:0:false]: 12866545844070

```

Restarting the playback helps for a while but after another few mintues this problem comes back.

This WARNing happens ~50 times every 10 minutes, so with input stream FPS=25 the delay grows 2 seconds every 10 minutes.

It’s related only with Google Chrome browser as Firefox, VLC or other browsers/players seem to handle those drops.

I can provide more information if requested: transcoded stream or my application’s configuration.

Also, please make sure you read the issue that I created on GitHub’s page of Google Shaka Player: [https://github.com/google/shaka-player/issues/1132](https://github.com/google/shaka-player/issues/1132) and the the one that Shaka Player developers referenced there: [https://github.com/google/shaka-player/issues/707](https://github.com/google/shaka-player/issues/707)