My Sony TV is connected to my Soundbar through the eARC/ARC port on the TV to the ARC port on the Soundbar
I have a Shield TV connected to the TV’s HDMI 1 port
I have Plex installed in both the TV and the Shield, and they both have the pass-through option enabled
Now, when I play a video file with a TrueHD default track, where’s what I get:
With the Plex app on the TV:
The audio track gets transcoded to AC3 (verified through Plex Dash)
With the Plex app on the Shield:
The audio track does not get transcoded by Plex (verified through Plex Dash)
My Soundbar reports that a “Dolby D+” track is being decoded, which makes sense because there’s a DD+ track within the TrueHD audio track
Given that in both cases the audio is being routed from the TV to the Soundbar through the ARC ports on both the TV/Soundbar, I don’t understand why Plex on the TV feels the need to transcode the TrueHD audio, while Plex on the Shield TV doesn’t.
Hi @rfgamaral … There is currently no TV on the market that supports passthrough of the HD audio tracks via HDMI, when using the internal apps. This will include TrueHD, DTS-HD and DTS-X.
Unfortunately this is the way the industry has decided to go for the time being.
EDIT: And also to note, that if your soundbar does not support EARC, then it will also not support passthrough of the HD audio tracks. This may be the reason why you are seeing DD+ on your soundbar when playing from the Shield, rather than TrueHD.
Hi @axemanuk666, thank you for your reply, but maybe I didn’t make myself clear…
I know there are no TVs on the market that supports HD passthrough, such as TrueHD. But that’s not what I’m saying. Most TrueHD tracks have something in them called “Core Audio”, which is a sort of DD+ track within the TrueHD one. TVs on the market today can passthrough DD+ tracks, there’s no argument there.
The problem is that Plex installed on the TV is not taking advantage of this “Core Audio” track, and it’s force transcoding the TrueHD track. But if only it could use the “Core Audio” track from within the TrueHD one, the problem would be solved. I mean, this is my setup:
Plex on TV → Soundbar over ARC
Plex on Shield → TV over HDMI → Soundbar over ARC
So, no matter if I’m using Plex on the TV or the Shield, the audio is reaching the Soundbar over ARC. How come Plex on the Shield is able to send the “Core Audio” track to the Soundbar, and Plex on the TV can’t?
The only explanation I can think of, is that the one that is “extracting” the core audio track from within the TrueHD track is actually the Shield itself, and not Plex. But I’d love to get a confirmation from Plex employees on this.
TrueHD is completely separate from, and not backward compatible with, AC3, EAC3, or any other Dolby format.
From Wikipedia: “the Dolby TrueHD bitstream has no data in common with the AC-3 bitstream”
Movies released on Blu-ray disc with TrueHD audio must also include an AC3 version of the same audio track (TrueHD is optional, AC3 is mandatory if TrueHD is on the disc).
Either the Shield or the TV is converting TrueHD to DD+.
Plex Dash / Plex Dashboard only shows what happens on the Plex Server.
The Shield itself (not the Plex app) or the TV could be converting TrueHD to DD+ independently of Plex. There is no feedback to Plex Media Server when this happens, so Plex Dash/Dashboard show Direct Play.
The Shield itself (not the Plex app) or the TV could be converting TrueHD to DD+ independently of Plex.
Maybe, but I don’t think it’s the TV, otherwise it should’ve worked when playing through the Plex app on the TV too. I wouldn’t be surprised if it was the Shield doing it, I just wish I could confirm this somehow.
Either way, decided to test Emby for comparison (installed the Android app on my TV), and it looks like Emby can decode do software decoding for TrueHD audio tracks. I wish Plex could do the same, so there would be no need for transcoding.
