Roku not playing DD or DTS

[davz289 1]

I apologize if this question has been answered previously, but I have read quite a few threads on this topic and I still can't figure out why Emby is transcoding the file during playback when the DD or DTS audio track is selected.  

 

Here is the setup:

 

--Roku 4 with Emby App version 2.15 

--Roku is connected to a fully capable audio receiver via optical audio cable.  (I have confirmed the DD is passed through from a different app)

--Roku audio settings are set to auto-detect and to pass through DD and DTS

--Emby app streaming settings are set to maximum (30Mbps)

--All devices (server, Roku, etc.) are running on a wired 1Gbps LAN.

--The media files are encoded with the first audio channel as AAC stereo and the second channel as the pass-through DD or DTS.  (medio info is attached)

 

The file will direct play fine if I do nothing and leave the default audio track.  If I switch to the second audio track and then play the file, the file will be transcoded and only stereo sound is passed on to the receiver.  

 

As a secondary question, assuming I am able to get the DD or DTS playback to work, is it possible to have the DD or DTS track played by default so I don't have to manually select it each time I play a new video?  Also related is that I can switch the audio track in the app before I start playing the video, but if I bring up the pop-up menu with the options button during playback menu will say "audio selection not available."  

 

Thanks for your help.