Wowza Transcoder Add-on throws ArrayIndexOutOfBoundsException - wowza

Question

I'm running Wowza 3.6.2 on Windows 8.1 (64 bit) and have enabled the Transcoder add-on. I'm using the transcoder to take JPEG-snapshots from the live stream. I've built a custom HTTPProvider, similar to what is described here. This works fine and I can get JPG-snapshots from the stream through my HTTPProvider.
The problem is that since I enabled the transcoder I get irritating error messages in my server log on onPublish and onUnPublish of any stream.
As a transcoder template I used the default transrate.xml that comes with the Wowza installation, without any modifications made to it.
When i publish to a stream asdf I get errors similar to this:
ERROR server comment - TranscoderSessionDestination.init[livereceiver/_definst_/asdf]: [asdf_160p]:java.lang.ArrayIndexOutOfBoundsException: 1
java.lang.ArrayIndexOutOfBoundsException: 1
at com.foo.wms.module.IncomingStreamEventHandler.getQueryStringMap(IncomingStreamEventHandler.java:191)
at com.foo.wms.module.IncomingStreamEventHandler.onPublish(IncomingStreamEventHandler.java:83)
at com.wowza.wms.stream.MediaStream.notifyActionPublish(Unknown Source)
at com.wowza.wms.stream.publish.Publisher.publish(Unknown Source)
at com.wowza.wms.stream.publish.Publisher.publish(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSessionDestination.init(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSession.a(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSession.handleOnMetadata(Unknown Source)
at com.wowza.wms.transcoder.model.LiveStreamTranscoder.handleOnMetadata(Unknown Source)
at com.wowza.wms.stream.live.LiveStreamTranscoderRunner.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
And when I unpublish the stream I get this:
ERROR server comment - TranscoderSessionDestination.shutdown: [asdf_160p]:java.lang.NullPointerException
java.lang.NullPointerException
at com.foo.wms.module.IncomingStreamEventHandler.onUnPublish(IncomingStreamEventHandler.java:166)
at com.wowza.wms.stream.MediaStream.notifyActionUnPublish(Unknown Source)
at com.wowza.wms.stream.publish.Publisher.publish(Unknown Source)
at com.wowza.wms.stream.publish.Publisher.unpublish(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSessionDestination.shutdown(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSession.c(Unknown Source)
at com.wowza.wms.transcoder.model.TranscoderSession.shutdown(Unknown Source)
at com.wowza.wms.transcoder.model.LiveStreamTranscoder.shutdown(Unknown Source)
at com.wowza.wms.stream.live.LiveStreamTranscoderRunner.run(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:744)
I get three of each exception when I publish/unpublish (one for each Encode block that is enabled in the transrate.xml file).
Does anyone have an idea on what might be causing this?

Answer 1

Here is a better way to determine if the stream is a transcoded stream and not a source stream
if(stream.isTranscodeResult()) return;

Answer 2

After posting my question I had another look at the stacktrace and realized what the problem was - I had been looking in the wrong direction the whole time. Since the problem appeared when I enabled the transcoder, I concluded that's where the problem must be. What I didn't realize was that onPublish and onUnPublish fires multiple times when you use the transcoder - one time for the incoming stream, and one time for every transcoded stream.
Within the onPublish and onUnPublish methods of my module I do stuff, like read querystring-paramters, which are not present on the transcoded streams. That is why the exceptions are thrown when the onPublish and onUnPublish methods are called for the transcoded streams.
To remedy this, I added two lines at the beginning of onPublish and onUnPublish methods.
if (streamName.contains("_"))
return;
A somewhat ugly solution, but I am in control of all stream names and do not allow underscore in them anyway, so in my case this works fine.
Update:
#flux has provided a much nicer solution for how to check if the stream is the result of a transcode operation. See his answer for more info.