www.makemkv.com

Hi,
I've just started to digitize my media library and one major point is retaining the ability to play ATMOS sound when available.
Using the "Deepwater Horizon" Blu Ray Disk as guinea pig, which plays with ATMOS on my PC (LG BD Drive) through Denon AVR X4400R.
Loading it into MakeMKV, the Audio tracks are recognized as "TrueHD Surround 7.1" with the following details:
Codec: TrueHD Atmos
Channels: 8
Channel layout: 7.1

By Dolby naming, I would have expected 5.1.2 for ATMOS with 8 channels or even 5.1.4 or 7.1.4 (with 10 or 12 channels respectively).

I have the PC and a Fire TV Cube hooked up to my Receiver, both are capable of playing ATMOS sound. However, when trying to play the extracted file created form the Disk mentioned above, it will not play the ATMOS sound.
On PC, it will only play Dolby surround. I assume that is b/c Plex is playing through the browser and maybe the browser can't handle it. Bummer, but no deal breaker for me.
The real pain is playing it through the Fire TV Cube, which is perfectly capable of playing ATMOS.
However, when playing the file through the Plex App, the sound is transcoded to "TRUEHD - EAC3" and it states as reason "TrueHD sound is not supported on this device".
The receiver recognizes the stream as "Dolby Digital+" instead of ATMOS as a result.
Plex App is set to HDMI passthrough.

So I can't play the original soundtrack through the Fire TV Cube. Is that known behaviour / does it work as designed?
Is there any way to assess whether the file is created correctly?

Any help appreciated!

Plex server tailors the file to whatever the capabilities of the client are. I don't know what the capabilities are of the Plex client on a Fire TV Cube.

In my Plex setup, I generally use MakeMKV to create lossless FLAC versions of the lossless TrueHD or DTS-MA tracks. This suits the capabilities of my client, an AppleTV, and lets me have Direct Play. https://support.plex.tv/articles/200250 ... ct-stream/

As for understanding what's in the MKV files you've created, MediaInfo is a common tool people use. https://en.wikipedia.org/wiki/MediaInfo

Thanks, dcoke22!
I was fiddeling a bit with the file and since my PC can play ATMOS through the AVR I finally could verify that the file is indeed ok and contains the correct Audio stream. However, there seem to be two different ways of adding ATMOS to the stream, one used by streaming services and one used on BD. Plex only supports the former, not the latter and neither when playing on Fire TV (only on Shield Pro). Bummer.