Hello Community,
i have the problem that DTS audio tracks (5.1 / 7.1) are only transcoded to LPCM 2.0.
Of course, “eArc” and “Passthrough” are activated in the TV.
In the LG Plex app under “Settings”, “Audio”, the tick for “DTS” is removed - so that DTS is transcoded.
My setup:
LG C2
Bose 900 Soundbar
PMS on a Synology server
Can anyone help me? 
Probably same problem as these:
https://forums.plex.tv/t/lg-oled-g3-ddp-7-1-truehd-7-1-eac3-channels-not-working/
https://forums.plex.tv/t/truehd-eac3-lpcm-2-0-warum/
Mind if I merge the two threads?
I ask that all threads be merged. Hopefully this will result in more attention. It’s really annoying and spoils the enjoyment of the film. Thank you
Hallo,
ich habe das Problem, dass 7.1 TrueHD zwar korrekterweise zu EAC3 transcodiert wird, aber bei meiner Soundbar (Bose 900, inkl. Sub und Rear-Speaker) nur LPCM 2.0 ankommt.
Ist das als Bug irgendwie bekannt?! Woran könnte das liegen?
Danke für die Unterstützung
Server: Synolgy NAS
Fernseher: LG C2 mit Plex App
Soundbar via eARC/HDMI am Fernseher
As you noted, the Plex server is transcoding the audio correctly, but it is the TV that is outputting LPCM to your soundbar.
Check your TV settings to see if you are able to passthrough the audio instead of outputting LPCM.
Also, check the Plex app settings on the TV, there may be an audio passthrough setting available there?
Wie Sie festgestellt haben, transkodiert der Plex-Server den Ton korrekt, aber der Fernseher gibt LPCM an Ihre Soundbar aus.
Überprüfen Sie Ihre TV-Einstellungen, um zu sehen, ob Sie in der Lage sind, den Ton durchzuschleifen, anstatt LPCM auszugeben.
Prüfen Sie auch die Einstellungen der Plex-App auf dem Fernseher, vielleicht gibt es dort eine Einstellung für Audio-Passthrough?
Danke für deine Antwort.
Im LG Fernseher ist “Passthrough” bereits aktiviert.
Kann ich irgendwo genauer sehen, wieviel Kanale Plex transkodiert? Also woher weiß ich, ob EAC3 wirklich 7.1 LPCM ist?
Hier hat jemand das gleiche Problem: LG OLED G3 DDP 7.1 / TrueHD 7.1->EAC3 Channels not working
Danke, hatte dort schon geschrieben. Wie kann ich das Problem jetzt richtig melden, damit sich um eine Fehlerbehebung bemüht?
Plex hat leider keinen richtigen öffentlichen Bugtracker. Du kannst nur hoffen, dass ein Entwickler die Posts hier im Forum sieht und sich dem Problem annimmt.
Everything except AC3 busted for me in the webos plex app on a LG C2.
It was working before.
Now even if the server says it’s transcoding to AC3, I still just get stereo sound.
Files with native AC3 play correctly.
Everything works fine in the plex app on Chromecast, something bugged in the webos version.
Server Version#: 1.32.8.7639
I have tried several files to check codec/transcoding compatibility and found that DDP7.1 and TrueHD7.1 which converts to EAC3 does not work with the correct channels.
All rear or side channels + the LFE are not working correctly.
Can anyone else confirm and maybe elaborate why this does not reproduce correctly?
I am using a HW-Q935GC Soundbar via HDMI eARC
I used the following files:
TrueHD 7.1 m2ts
DDP 7.1 mkv
Hi, I confirm nothing to do for LG with Plex. The LFE on Plex in general, I have the impression that it bug or the volume is not there… I tested Jellyfin etc similar… I advise you to go on Zidoo with their application Homethearter, you will see that everything works perfectly. Forget Plex unfortunately they do not do the right thing.
Can confirm.
TRUEHD7.1 Audio → Transcoding to EAC3 → but Bose soundbar only outputs LPCM 2.0
Connected via eARC with LG OLED C2
Threads have been merged into this thread.
I own a LG C1.
I confirm LG has problems.
My receiver is a slightly less capable Onkyo TX-RZ-610 which accepts ARC.
It worked flawlessly until an LG WebOS update for the LG C2 models. It has not worked at all since. I have no ARC back to the receiver from the TV.
It doesn’t matter which app I use on the TV.
It worked flawlessly until an LG WebOS update for the LG C2 models
I’m not sure you can put the blame on LG.
The way Plex handles surround audio transcodes was already questionable.
Like how it uses AAC (see this and this).
And the bug that forces video transcode when using audio transcode and subtitles at the same time, even if there is no need for that.
Also things seem to be working fine for me outside of the Plex app on my LG C2. The problem is just that the webos plex client only plays 2 channel audio, even if the plex server is showing it’s transcoding 5.1 audio to 5.1 audio.
Plex’s transcodes (some are DASH and others are HLS) protocols are not something I understand well.
I do know AAC encoding isn’t licensed but AC-3 encoding is licensed by Dolby.
(All their stuff is licensed at the per-item level)
I have asked and awaiting the answer but won’t be surprised if this entirely licensing driven.
UPDATE:
I have the answer.
AAC was chosen because it’s better than AC-3 (frequency handling)
AAC is a state-of-the-art audio compression algorithm that provides compression superior to that provided by older algorithms such as AC-3. AAC and AC-3 are both transform coders, but AAC uses a filterbank with a finer frequency resolution that enables superior signal compression. AAC also uses a number of new tools such as temporal noise shaping, backward adaptive linear prediction, joint stereo coding techniques and Huffman coding of quantized components, each of which provide additional audio compression capability. Furthermore, AAC is much more flexible than AC-3, in that AAC supports a wide range of sampling rates and bitrates, from one to 48 audio channels, up to 15 low frequency enhancement channels, multilanguage capability and up to 15 embedded data streams.
