@"Tom D." said:
Thank you all for replying, strange that my Plex (on Shield TV) does not show e.g. DTS-MA. I now checked my PMS (version 3.53.7) and here too DTS-MA mkv is displayed as DTS 5.1 >:) :# ! My previous versions of Plex did not have this!
So, is there a fix for this? Can I downgrade to a previous version of PMS, or should I look into my Plex settings? Though when playing on my Shield, the audio stream is DTS-MA.
3.53.7 is not a PMS version. It is a version for the Plex web client. The current PMS version is 1.13. You can see installed versions for your clients and servers in Settings -> Devices (Plex Web: https://app.plex.tv/desktop#!/settings/devices).
As previously mentioned, there are inconsistencies between Plex clients. What you see with one client may not be the same as on other clients.
Plex Web does not display a difference between dts and dts-HD 5.1 streams. They both display as dts 5.1. If you see dts 7.1, you can infer that it is a dts-HD stream, since there are no non-HD dts 7.1 audio streams.
The Nvidia Shield Plex Client (Plex Android TV client), currently at v7.0.3, does display dts-HD streams as DTSHD.
This is a Plex client display issue, not a PMS issue. As you noted, the audio plays correctly, so PMS is correctly identifying and processing the audio stream. Changing to a different PMS release will not change how the client displays things.
You can verify that PMS is correctly identifying the audio streams by looking at the Media Info window. Both dts and dts-HD MA audio tracks will be listed with the Codec = DCA. The dts-HD MA audio tracks have Profile = ma. "Regular" dts audio tracks have Profile = dts.
I've been using Plex for ~2.5 years. I do not remember Plex Web ever identifying dts and dts-HD audio tracks differently. Android TV clients currently identify the tracks correctly, but I won't say they have always done so. YMMV may vary with clients on other platforms (Roku, ATV, etc), as each platform has its own capabilities.