If your audio is AC-3 then you should know that due to the licensing requirements necessary to decode and encode AC3 codecs, we have not yet reached an agreement to use that codec within Wowza Streaming Engine. It looks like your Ericsson AVP4000 supports AAC audio if you have purchased a license for that codec.
We do not have a timeframe to provide you when we will be able to implement this feature.
More information regarding supported codecs with Transcoder can be found in the article below:
We have a section in the article you referenced above on how to include AC3 audio in your output streams.