ok, you need to edit the wdtv profile to transcode DTS audio into AC3
open up profiles.xml in notepad (note you can find this in the config folder of your serviio install.
search for "wdtv" and find this section
<Transcoding>
<Video targetContainer="mpeg">
<Matches container="wtv" />
</Video>
<Video targetContainer="mpeg" targetVCodec="mpeg2video" targetACodec="ac3" aBitrate="384">
<Matches container="flv" /> <!-- this is used by online content, assuming WDTV cannot play local flv either -->
<Matches container="matroska" vCodec="vp8" />
<Matches container="rm" />
</Video>
</Transcoding>
you need to add this to the profile.
<Audio targetContainer="ac3" forceInheritance="true">
<Matches container="adts" />
</Audio>
This should be the end result.
<Transcoding>
<Video targetContainer="mpeg">
<Matches container="wtv" />
</Video>
<Video targetContainer="mpeg" targetVCodec="mpeg2video" targetACodec="ac3" aBitrate="384">
<Matches container="flv" /> <!-- this is used by online content, assuming WDTV cannot play local flv either -->
<Matches container="matroska" vCodec="vp8" />
<Matches container="rm" />
</Video>
<Audio targetContainer="ac3" forceInheritance="true">
<Matches container="adts" />
</Audio>
</Transcoding>