Dear Plex Community
I have an LG oled 55C8PLA with a Synology ds2018play. Everything is working fine, except, any 4k movie with TrueHD 7.1 sound, Plex starts buffering and never goes till the end.
If I start the same video on TV built-in media player, it says no supported sound, but the audio is available. I tested in any way, with cabel or wifi there is obvious the problem is with the TrueHD via Plex. I tested on Shield that is fine, but I don’t want to use Shield at all, so that is not a solution.
Anyone has any idea how to solve this? I do not need the 7.1 at all, but i need to hear the audio itself
When there is 7.1 dolby true audio there is virtually always a regular dolby digital 5.1 stream with it, just chose that one. Another option would be to re-encode the audiostream down to something your LG can handle. Xmedia recode is free and will do it. It is much faster than video re-encoding. https://www.xmedia-recode.de/en/index.php
The TV does not support TrueHD audio, so Plex Media Server must transcode it to a supported format. This happens with any movie with TrueHD audio, not just 4K (some 1080p movies also have TrueHD audio).
The best solution is to avoid TrueHD audio. As @mervincm mentions, Blu-ray movies with TrueHD audio also have the same soundtrack in AC3 (Dolby Digital 5.1). You should choose that audio track if possible.
Regarding TrueHD audio…
It does not require many CPU cycles to transcode audio. However, if you’re using a low end CPU, it may not have the necessary horsepower to keep up.
You can check the status via the Plex Dashboard. During playback, go to Plex Web -> Activity -> Dashboard. It will show you if the video or audio is transcoding.
Regarding the Plex app on LG TVs…
You also have to watch out for subtitles causing video transcoding.
The basic rules are:
Displaying image subtitles, PGS & VOBSUB, forces a video transcode.
SRT subtitles direct play. However,…
If the audio is transcoding, displaying any subitle, including SRT, forces a video transcode.
The TV will direct play AAC, AC3, EAC3 (+ Atmos), dts, and dts-HD MA audio. TrueHD will always transcode. When playing a dts-HD MA track, only the core dts 5.1 audio is used. The “-HD MA” part is discarded.
thank you the answers. Accidently, i choose NO subtitles at all, and all the 4k\trueHD\HDR everything runs smoothly. So as far as I see, tha PSG subt. kills the movie playing.
So, as i see, not the sound is the problem, just a little tiny thing, the subtitles what is PSG.
Is there any workaround for this issue?
Thank you
Use an application such as Subtitle Edit to convert PGS/VOBSUB to SRT.
Use an application such as aforementioned XMediaRecode to convert TrueHD to a format that does not transcode, or choose a separate audio track that does not transcode.
If you want subtitles you must do both. Subtitles + transcoded audio = transcoded video.
I believe that audio transcoding is single threaded, and thus it can be an issue for the cpus that rely on multi-core (arm/atom) to do any heavy lifting.
If the audio is transcoding, displaying any subitle, including SRT, forces a video transcode.
But why is this happening? Isn’t this a bug?
I don’t care if it transcodes the audio. It should because lossless isn’t supported. But why also transcode the video based on if you use subtitles or not?
It doesn’t make any sense.
