Well this should really go in the immersive upmix thread but since you asked:
Windows 10 doesn't
decode atmos, but it has the ability to
encode atmos on the fly. This is mainly for games. It's a way to get more than 8 channels (or many sound "objects") over hdmi (hdmi spec can handle more than 8, but AFAIK no HT or PC audio driver does more than 8).
Games can say, this particular sound is coming above and behind your right ear, and dolby Atmos will take care of rendering that in headphones, or speakers, so the sound does come from there. Of course MS has their own technology, Windows Sonic, to do something similar (at least with headphones) but they have partnered with Dolby so that Atmos can be used as well (but the interface for programmers is Windows Sonic either way and the end user gets to choose which they use to listen with).
I saw DTS:X is also supported in some flavor of windows 10, but I think you have to pay extra for that. Originally you had to pay $14 for a Dolby Access app for Atmos, but I'm not clear if that is still the case or not, as Windows 10 matures.
Up until recently the only file player that could play 12 channels via this Dolby Atmos on the fly over HDMI method was a MS "Universal App" example that had two or three files hardcoded in. I didn't have the chops to teach it to load files, MS "Universal Apps" being completely alien to what little MS stuff I do know.
But over months I've kept googling and watching for anybody doing anything with the API call to windows sonic and finally found a guy in Japan working on a Audiophile Player and managed to get him interested in doing a 12 channel player using all this. The first result of this is here:
https://sourceforge.net/projects/playpcmwin/files/others/WWSpatialAudioPlayer020.zip/download
but it's not very polished at this stage, but as I say will play a loaded 12 channel file, so could be used to listen to immersive audio coming out of the work I'm doing or from Penteo 16 (set for Dolby Atmos output).
Note there are some nuances to 12 channel audio files. First (assuming you had a 12 channel audio card connected to your speakers) foobar2000 and other apps won't play them unless they have channel mapping in the wav header, which can be done with ffmpeg like this:
ffmpeg.exe" -i
input.wav -acodec pcm_s24le -ar 48000 -af "pan=7.1+TFL+TFR+TBL+TBR|FL=c0|FR=c1|FC=c2|LFE=c3|BL=c4|BR=c5|SL=c6|SR=c7|TFL=c8|TFR=c9|TBL=c10|TBR=c11"
output.wav"
and like all things surround there are multiple standards for what order those channels should be in.
Anyway the other challenge is the file size. These things are huge, at any sample rate. (6 times larger than a stereo wav, 2x larger than 5.1, and no flac support beyond 8 channels so you have to deal with the 4GB wav file limit and probably switch to one of the updated formats, based on wav, but supporting files larger than 4GB.
Hmm, haven't checked with the player and larger than 4GB files...
You can PM me for sample stereo to 7.1.4 upmixed files if you have an Atmos System.
And by the way yes, HT's have their own built in upmixers. My Marantz AV7704 has built 7.1.4 upmix from Dolby and DTS:X and 12.1 (think 7.1.4 plus a directly overhead "top" or "voice of god" speaker) from Auro 3D but just like the stereo to 5.1 capabilities in older HTs, I think we can do better.
Similar with Penteo 16 and 7.1.4 output. I think we can do better.
However to date it's been very hard to find anyone with atmos, etc. speaker systems to help in testing.
An interesting (to me anyway) other platform is VR. Yes we are back to headphones but since you have head tracking (and visual queues) you really can get very convincing immersive sound, and for more fun you can interact with the sound objects. Move closer to the drums, etc. You could even remix by moving objects around.
FYI Ambisonics is big with the VR Developers, so any immersive upmixer should optionally output in 1st, 2nd or even 3rd order ambisonics, as well as in 12 channels.
I've got an Oculus Rift and have been goofing on that.
Cheers,
Z