Weird problem streaming 4K with LG Plex App

Plex Players Smart TVs
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I just bought a new LG OLED65B9PUA and installed the Plex app. Connected to my media server with no problem. Blu Ray content streams perfectly. Audio is streaming in Dolby Digital.

I have one 4K movie (Avengers Endgame) that I ripped to my media server. When I play it directly on my media server (which is connected via HDMI to a 1080P TV) the movie plays perfectly.

But when I stream it to the new OLED using the Plex app, the problems arise. First, the screen goes white with a black box in the top left corner taking up about 1/16 of the screen. This only lasts a second or two and then the “cold open” opening sequence starts (with Hawkeye and his fam). Everything’s good, but as soon as that scene ends and when the title sequence brings, the screen goes mostly white and the black box returns to the top left 1/16th of the screen. In that box, I can see some pixelation and a small portion of the title sequence.

Ok that’s all I got. Please now tell me the easy fix for this!

1 Like
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everything you need to know is in this thread @ Plex, 4k, transcoding, and you

read the whole thread.

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Thanks. I read the entirety of the first post and the first 20 or so responses in that thread? Are you saying my issue is addressed somewhere else in the thread?

I’m not having an audio problem - the audio is being passed from TV to my receiver via optical as Dolby Digital. No problem.

And I don’t think I’m transcoding. I’m playing 4k content via the app on a 4K TV.

So are you saying I just need to get an nvidia shield if I want this to work? Is it the LG app that’s the problem?

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By the way, this thread appears to describe my problem.

The solution appears to be that I re-rip the disk to MKV and strip out TrueHD audio?

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Is the file an encode or the full uncompressed file in an MKV (or other container?
I have seen this many times with encodes (handbrake etc…) on my LG.
What about the receiver…does that support 4K.
Any reason to use optical rather than HDMI?

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Uncompressed video made with MakeMKV.

I had the OLED connected to my receiver just to see what audio was passing through (Dolby Digital) so I think maybe the audio is being transcoded maybe? I’ll have to see what the receiver says when I play it direct from my HTPC.

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You cannot simply guess about this.

I would suggest installing tautulli (or varys ios app), it will easily tell you if you are transcoding.

Or use a plex pass trial, plex can show more details @ Plex Web > settings > dashboard with an active plex pass.

TRUEHD audio streams will not direct play on smart tvs with plex and will be transcoded to ac3 or similar.

audio transcoding + enabling subtitles, will cause the video to be transcoded (so audio/subtitles can stay in sync).

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Ok. First, I played the movie on the HTPC through my Windows Plex app, and the receiver now says Dolby HD. So, the LG app is definitely converting the audio to DD5.1 (which I’m fine with as long as it works).

Second, I installed Tautulli and played the 4K Avengers Endgame on the LG Plex app. Tautulli says:
Quality: Original (42.7mbps)
Steam: Transcode (Throttled)
Container: Transcode (MKV - MPEGTS)
Video: Direct Stream (HEVC 4K)
Audio: Transcode (TrueHD 7.1 - AAC 5.1)
Subtitle: None

Thoughts? Can I change settings in the LG App to avoid the transcoding?

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The lg app isn’t doing the converting, the server is.

Like explained in the faq, to avoid that conversion/transcode you must use a compatible audio stream, like dd/ac3/aac whatever.

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Ok. Does that mean I need to re-rip? Or can I make a change on the Plex Server?

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4K/Blu-ray disks always include both hd audio and a 5.1 audio, so if you ripped all the audio tracks, you only need to select that track.

Otherwise yes you’ll probably want to re-rip with the extra tracks.

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Ok so I only had to pester you with a few posts to get to that easy solution. :slight_smile:

Selecting the 5.1 track works great. Unfortunately, the 5.1 track is a visually impaired narrative (which strikes me as odd to even be available on a 4K disc but I digress). There’s a also a TrueHD Stereo track but I’m guessing that means only 2 channels?

So not really sure I have any options for streaming this particular movie in 4K unless I want to listen to it in stereo or for visually impaired… Any other suggestions?

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The solution was in the faq…

If the audio tracks included on the disk don’t have a useable compatible track then I guess you would probably want to use handbrake to convert the audio only to something that is.

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The Plex LG app will direct play Dolby Digital and dts audio up to 5.1 channels. It will also direct play dts-HD MA audio, but it only plays the dts core, ignoring the “-HD MA” part of the stream.

TrueHD is not supported by the TV and will be transcoded by PMS to a supported format.

Transcoding audio does not require much CPU, but can lead to other issues such as video transcoding. Whenever possible, you should choose an audio stream that will direct play.

Regarding subtitles and the Plex LG app:

Enabling PGS or VOBSUB subtitles results in a video transcode, and should be avoided, especially with 4K material.

SRT subtitles will direct play.

However, if the audio is transcoding and SRT subtitles are enabled, the video will also transcode. Plex does this to keep the video, audio, & subtitles in sync with each other.

Given the above, you can see why it is a) best to choose audio that direct plays; and b) avoid subtitles whenever possible.

Every Blu-ray with TrueHD audio includes a Dolby Digital audio track. Every Blu-ray with dts-HD MA audio includes a dts audio track. This is part of the Blu-ray standard.

There may be other audio tracks on the disc, such as Descriptive Audio or Director Commentary.

Rip the disc again, making sure to include the Dolby Digital 5.1 audio track for the primary audio stream.

Here is a screenshot from MakeMKV. The English audio (US disc) is in dts-HD MA 5.1. The second, inset entry is the same audio track, but in dts 5.1 format. Discs with TrueHD & Dolby Digitial look the same (with DD inset). Any commentary, etc tracks are not inset, the same as the French, German, etc audio tracks in the screenshot.

Screenshot (128)

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