# NullPointerException when playing MPEG-DASH stream coming from WebRTC

**URL:** <https://community.wowza.com/t/nullpointerexception-when-playing-mpeg-dash-stream-coming-from-webrtc/92850>\
**Category:** Wowza Streaming Engine\
**Created:** [February 18, 2021, 10:04am UTC](https://community.wowza.com/t/nullpointerexception-when-playing-mpeg-dash-stream-coming-from-webrtc/92850 "2021-02-18T10:04:07Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Dmitry\_Smith](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/dmitry_smith/32/666_2.png) [@Dmitry\_Smith](https://community.wowza.com/u/Dmitry_Smith)\
**Post date:** [February 18, 2021, 10:04am UTC](https://community.wowza.com/t/nullpointerexception-when-playing-mpeg-dash-stream-coming-from-webrtc/92850/1 "2021-02-18T10:04:07Z")

</div>

When we try to transcode a stream coming from WebRTC in order to publish it using mpegdashstreamingpacketizer or cmafstreamingpacketizer eventually (the time is completely random) we start seeing the following exception:

```
HTTPStreamerMPEGDashLiveIndex.indexFile[live/_definst_/streamName_720p] : java.lang.NullPointerException
at com.wowza.wms.httpstreamer.mpegdashstreaming.livestreampacketizer.MPEGDashWriterHandler.indexStream(MPEGDashWriterHandler.java:2274)
at com.wowza.wms.httpstreamer.mpegdashstreaming.livestreampacketizer.LiveStreamPacketizerMPEGDash.indexStream(LiveStreamPacketizerMPEGDash.java:377)
at com.wowza.wms.httpstreamer.cmafstreaming.livestreampacketizer.LiveStreamPacketizerCmaf.indexStream(LiveStreamPacketizerCmaf.java:374)
at com.wowza.wms.httpstreamer.mpegdashstreaming.file.HTTPStreamerMPEGDashLiveIndexItem.indexStream(HTTPStreamerMPEGDashLiveIndexItem.java:354)
at com.wowza.wms.httpstreamer.mpegdashstreaming.file.HTTPStreamerMPEGDashLiveIndex.indexFile(HTTPStreamerMPEGDashLiveIndex.java:423)
at com.wowza.wms.httpstreamer.mpegdashstreaming.httpstreamer.HTTPStreamerSessionMPEGDash.createIndexLive(HTTPStreamerSessionMPEGDash.java:85)
at com.wowza.wms.httpstreamer.mpegdashstreaming.httpstreamer.HTTPStreamerSessionMPEGDash.getIndexLive(HTTPStreamerSessionMPEGDash.java:122)
at com.wowza.wms.httpstreamer.mpegdashstreaming.httpstreamer.HTTPStreamerAdapterMPEGDashStreamer.onManifest(HTTPStreamerAdapterMPEGDashStreamer.java:1481)
at com.wowza.wms.httpstreamer.mpegdashstreaming.httpstreamer.HTTPStreamerAdapterMPEGDashStreamer.serviceMsg(HTTPStreamerAdapterMPEGDashStreamer.java:240)
at com.wowza.wms.httpstreamer.mpegdashstreaming.httpstreamer.HTTPStreamerAdapterMPEGDashStreamer.service(HTTPStreamerAdapterMPEGDashStreamer.java:202)
at com.wowza.wms.server.ServerHandler.a(ServerHandler.java:703)
at com.wowza.wms.server.ServerHandler.a(ServerHandler.java:423)
at com.wowza.wms.server.ServerHandler.messageReceived(ServerHandler.java:552)
at com.wowza.wms.server.ServerHandlerThreaded.messageReceived(ServerHandlerThreaded.java:79)

```

As a result the stream can not be played anymore in MPEG-DASH player. Neither restart of the app nor the server restart solves the problem. The problem just appears and disappears randomly and only when we publish using WebRTC. With a RTMP stream coming from OBS everything works fine.

Our configuration:  
WebRTC stream (H.264/Opus) is being transcoded into H.264/AAC (Key Frame Interval: we tried “Same as source”, 15 and 30 frames).

- WebRTC client based on your example: [https://github.com/WowzaMediaSystems/webrtc-examples](https://github.com/WowzaMediaSystems/webrtc-examples)
- Wowza Streaming Engine ver. 4.8.8.1
- CMAF Streaming Packetizer Settings:
  - cmafSegmentDurationTarget = 1000
  - cmafMaxSegmentCount = 50
  - cmafPlaylistSegmentCount = 12
  - cmafRepeaterSegmentCount = 12

---

<div class="post-metadata">

**Author:** ![Rose\_Power-Wowza\_Com](https://sea2.discourse-cdn.com/flex002/user_avatar/community.wowza.com/rose_power-wowza_com/32/431_2.png) [@Rose\_Power-Wowza\_Com](https://community.wowza.com/u/Rose_Power-Wowza_Com)\
**Post date:** [February 19, 2021, 7:28pm UTC](https://community.wowza.com/t/nullpointerexception-when-playing-mpeg-dash-stream-coming-from-webrtc/92850/2 "2021-02-19T19:28:23Z")

</div>

Thank you for all the information you provided. What version of Java are you using and do you have Engine properly pointed to that version?

This was a bug that we had addressed back in 4.8.5 so I see you’re on 4.8.8.1 which is interesting.

If you are using Java 9 through 12 and that’s properly configured in Engine as shown [here](https://www.wowza.com/docs/manually-install-and-troubleshoot-java-on-wowza-streaming-engine), please send us a support ticket so we can further investigate this for you. The engineers would like to see it and test it. Thanks…

[https://www.wowza.com/support/open-ticket](https://www.wowza.com/support/open-ticket)