Hi all
I’ve been frustrated by the apparent inability of ANY media players on xbox one x (other than the blu ray player) to output Atmos sound.
I’m also frustrated by the lack of media (I actually still have no idea whether my atmos speakers are working, as there are so few effects to try it out!! If anyone can recommend a movie scene to use as a tester it would be appreciated!).
So, in the quest for understanding I’ve been doing some research - and made some interesting discoveries 
Base assumptions:
- Atmos enabled sound system attached. In my case a Denon 4200h and atmos speaker system
- In xbox settings bitstream output, Atmos app installed, and Atmos output.
First, lets be clear. There MUST be a mechanism - somewhere - for xbox one x to do sound passthrough: when I put an Atmos disk in the Denon automatically picks up that it is Atmos and auto-selects that as the audio type.
Now, where it gets curious…
There seems to be no documentation anywhere as to how to do this.
So I went looking for UWP samples of Atmos handling, and found one published by Dolby no less.
I’m already in the App Developer Program, and have Visual Studio Community installed, so it was a simple matter to install the Dev Mode Activation App so I could push the Github Dolby Atmos UWP app out to the xbox.
Now the interesting part 
It turns out that even the Dolby app has to use the Spatial Sound Libraries, and when the app is running the Denon picks it up as ‘Virtual’
In all my time fooling around with Plex - and the other xbox media players - I have never been given this as an audio type to select on the Denon.
However… since I used the Dolby app (no longer even installed) suddenly this option is also there for Plex media 
It’s like pushing this app out to the xbox has unlocked some hidden capability, and (wonderfully!) not closed it back up. I presume that the app has downloaded an additional dll that enables the spatial capabilities.
There are still limited capabilities for testing, as Microsoft’s apps just can’t deal with Dolby 7.1 (Media Player says the media format isn’t supported, and TV and Film app plays it, but with no sound!).
So, if anyone else want to go fool around with this stuff - and report back - I’ve hopefully provided a starting point.
In particular, if anyone can recommend a scene of something to try out to see if it is - actually - providing Atmos output I’d really, really appreciate it 
Niki