Cannot stream TrueHD to Samsung TV

Plex Players Smart TVs
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So, here is my issue. I have a 2020 Samsung Smart TV, everything is up to date, firmware and apps. I have an LG SK10Y Dolby Atmos soundbar connected to it via ARC, I get Dolby Atmos from apps that support it (ie. Netflix) and in the Samsung onboard media player (provided it is E-AC3* and not TrueHD). The problem is, I have tried everything and I cannot get Dolby Atmos from Plex. It ALWAYS transcodes TrueHD to AAC 2channel, no matter where I choose to play it, PC or Smart TV. Is there a way I can transcode TrueHD to E-AC3 or any other way I can stream the Atmos information to my TV?
Thanks in advance!

  • Yes, E-AC3 carries Atmos information, Dolby’s own sample videos are encoded in E-AC3.

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Using the Plex TV app, a video file with EAC3 + Atmos should direct play (passthrough) the audio to your soundbar.

Using the Plex TV app, a video file with TrueHD, including TrueHD + Atmos, will transcode the audio.

Reasons:

  1. Unless Samsung changed things for their 2020 sets, the TV does not support TrueHD audio, including passthrough of TrueHD audio from installed apps. This means Plex must transcode the audio.

Note 1: I’m not aware of any TV that supports TrueHD passthrough from an installed app. TVs with HDMI-eARC will passthrough TrueHD from devices attached to HDMI inputs if the attached receiver/soundbar also supports HDMI-eARC and TrueHD audio.

  1. Looking at the Owner’s Manual, the LG SK10Y supports HDMI-ARC, not HDMI-eARC. HDMI-ARC does not have the bandwidth for lossless codecs such as TrueHD and dts-HD MA.

Either of the above will block TrueHD audio between the Samsung TV and the LG soundbar, resulting in Plex transcoding the audio.

Solution: Purchase an Nvidia Shield. Connect it directly to the soundbar. The Shield is the only off-the-shelf product that passes TrueHD & TrueHD + Atmos audio.

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Thanks for the very detailed reply! The only reason I am not buying a Shield is because I hate the hypocrisy. While being the only Atmos enabled super-tv box, the Netflix app on Android TV STILL lacks Atmos output. I know it’s a bit weird, but if I were to buy something I would expect it to replace the Smart portion of my TV altogether. I also know it’s one click of the remote but I refuse to be a part of something so stupid.
However, again thanks for your very detailed answer, you completely made me figure the issue.

One more question is, can i force Plex server to transcode the TrueHD to E-AC3 so my TV can pass it through to the soundbar?

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I do not know of a way to do this.

Are you sure it is transcoding to AAC 2.0? Using the Plex app on my LG OLED, TrueHD 7.1 transcodes to AAC 5.1.

Edit: TheDigitalTheater.com has a TrueHD 7.1 channel check video from Dolby. You can use it to see how the channels are mapped when transcoding to AAC.

Consider using the AC3 5.1 audio track instead of the TrueHD audio track. AC3 5.1 will pass over HDMI-ARC, giving you 5.1 audio. AC3 5.1 passthrough should sound better than TrueHD transcoded to AAC.

Every Blu-ray with TrueHD audio includes an AC3 5.1 version of the audio, so you should have an AC3 version available (you might have to re-rip or re-download).

Plex remembers the selected audio track for a given movie/show. Once you select the AC3 audio track you should not have to do so the next time you play the same video (there is no global “always choose AC3” type setting in Plex).

Plex defaults to the first audio track in a video file. If desired, you can remux the file using MKVToolNix or XMedia Recode to place the AC3 track ahead of the TrueHD track.

Yep. I hear you. However, you can’t put that, or the TV not supporting TrueHD, on Plex (not that you are).

Netflix & Amazon Video lack of Atmos audio on AndroidTV is why I use the apps on my LG (and also because my pre-2019 Shield does not support Dolby Vision). My Shield is basically used just for Plex these days.

One other reason to consider the Shield is subtitle support.

With the Plex app on my LG, enabling PGS or VOBSUB subtitles forces a video transcode. I’m pretty sure the same happens with all Plex SmartTV apps, including Samsung (let me know if I am wrong).

The Shield direct plays both PGS & VOBSUB subtitles.

Note that on either, if audio is transcoding then the video will transcode as well when subtitles of any type are enabled, including SRT.

However, if you’ve a Shield connected directly to the soundbar, you will have minimal audio transcoding.

This can be a big help when playing HDR video, since the transcoding process loses HDR information and the resulting output generally looks quite poor due to a lack of tonemapping.

It can be hard to justify the cost of a Shield just for Plex, and it has its quirks just like any other device. However, it is the closest I’ve come to a client that lets me just rip & play, without worrying about video/audio/subtitle formats.

Cheers.

My setup:
Shield ← HDMI → Denon AVR-X4300H ← HDMI-ARC → LG B7 OLED

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Using Xmedia Recode one can remux while ‘Creating’ an AC3 5.1 track and backing up the original (in another slot) from any of those Super-Duper tracks - saving a lot of time I would imagine over a re-rip or download.

XR is quite spiffy in a downmix situation and for the record - when working with multiple audio/sub tracks, go no higher than Version 3.4.5.2
(Until those wacky Germans come to their senses):
https://www.xmedia-recode.de/en/version.php

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