Server Version#: 1.20.4.3517 (FreeBSD 12)
Player Version#: 5.5.1 Preview
TV Model#: LG OLED65GX
TV webOS version#: 03.11.30
Logs#: can be provided upon request
Hi guys,
I would like to report the fact that the WebOS Plex App does not work as designed / described.
Direct Play Media can be Direct Played on a device if the source media is compatible with the client’s playback capabilities.
Scenario #1 (compatible audio with subs):
When I play a movie with compatible video (4K HEVC) + compatible audio (AC3) + compatible subtitles (SRT) in a compatible container (MKV) this leads to a direct play -> works as designed / described
Partially-Transcoded Direct Stream You might have a file that has a stream-compatible video track, but an audio track that needs transcoding. For example, your playback device cannot handle DTS tracks, but works with AC3.
Scenario #2 (incompatible audio without subs):
When I play a movie with compatible video (4K HEVC) + incompatible audio (TrueHD) in a compatible container (MKV) this leads to a partially-transcoded direct stream where only the audio track is being transcoded. -> works as designed / described
Scenario #3 (incompatible audio with subs):
When I play a movie with compatible video (4K HEVC) + incompatible audio (TrueHD) + compatible subtitles (SRT) in a compatible container (MKV) this leads to a transcode of both video and audio. -> does not work as designed / described
This essentialy means that I am unable to play such videos with incompatible audio + subtitles.
Run into the same problems (LG OLED55B8 PLA) as described above. Only happens with 4k files in combination with HDR + HD audio codec + subtitels. Hope this can get fixed soon!
This is a longstanding issue with the Plex SmartTV app for LG & Samsung TVs.
Enabling image based subtitles, PGS & VOBSUB, forces a video transcode. Enabling SSA/ASS subtitles with position/font/color/etc information forces a video transcode.
If the audio is transcoding, enabling any subtitle forces a video transcode.
If the audio is direct playing, SRT (text) subtitles direct play.
Plex knows about it. There are some old threads (which I can no longer find) where a couple of Plex employees provide some details. They mention limitations with the underlying transport protocols, underlying player app on the TVs, and other things. They didn’t want to do so, but under certain conditions Plex had to burn in the subtitles (transcode the video) to keep the video, audio, & subtitles in sync with each other.
Plex uses different players on different platforms. For example, ExoPlayer, part of Android, is used on Android/Android TV devices and mpv.io is used on Apple devices (I do not know what is used on webOS systems).
Each player has their own set of capabilities and limitations. What audio/video codecs each manufacturer chooses to implement also affects behavior. As a result, what direct plays/direct streams/transcodes on one platform or device is independent of what does so on another platform/device.
Example 1: AndroidTV devices such as the Shield can direct play PGS & VOBSUB subtitles when audio is transcoding. The Plex client on webOS & Tizen based systems cannot.
Example 2: The Nvidia Shield and Amazon FireTV devices both run AndroidTV, but only the Shield will passthrough TrueHD audio. Plex transcodes the audio when playing TrueHD on a FireTV. Amazon chose not to add TrueHD passthrough capability to their devices.
I wouldn’t know, but maybe something has changed since these old threads? A new app architecture, for one? Android version stopped this behaviour relatively recently, too.
I guess the fact that LG dropped DTS support in new TVs suddenly made this problem more important?
But again, I wouldn’t know. Would be great to have an official word on this, or just employee’s comment, otherwise the threads will just keep springing up…
If a file has more than one audio stream in it:
Depending on whether the audio stream which has been selected for playback is the one at the top position in Plex, the decision to transcode can be different.
If the first (top) audio stream is compatible with the client, transcoding of the video stream can be avoided in more cases.
If you however have to select one of the other audio streams, (e.g. because they are in the desired language), then chances are higher that the video stream gets transcoded as well.
All of this is highly dependent on the client type and the makeup of the particular media file, so it cannot be generalized.
But the OP states from the get go that the issue is about
In other words, about the audio that is not compatible. Are you saying that even when selecting incompatible audio this unnecessary transcode of (compatible) video when the subtitles are also present can be avoided if the first audio stream (not the selected one) is actually compatible?
Consider it expected behavior with the Plex app on LG webOS TVs.
I have a LG B7 OLED TV. The behavior has not changed since I purchased the TV in Nov 2017. I’ve not seen any posts that the behavior is different with more recent models.
Well, now after I learned it’s broken like that, it’s expected in that sense, yeah. Still, not desirable, right? Nor correct. Nor, working as described as this (and other) thread signals. (I actually learned about this from your post, @FordGuy61, after wasting a day on useless tests, so thank you very much!
Have to agree with you here Matt. I sincerely hope that Plex will do something about it.
I just installed Emby on my server and Emby app on my LG TV to check if they are able to this properly. They have to release an update for the webOS app to support LG “non-DTS TVs”: emby topic. I am really curious if they will be able to handle the scenario #3 in my first post.
edit: as a temporary solution (hopefully…) I use FFmpeg to create a MKV file with a DTS > AC3 converted audio track:
Started using my new LG GX today and was quite bummed out this was not working as I expected.
I’m seeing the exact same scenarios as OP described. As soon as I’m having incompatible audio with compatible video and compatible subs in a compatible container, Plex Server is trying to transcode both video and audio.
Funny detail is that I bought this LG TV to replace my Samsung UE55KS8000 which handled all the mentioned scenarios perfectly while direct playing from the same server.
The newer TV’s do not support DTS, that why the old Samsung worked. The latest update should have by default turned off DTS audio. Most DTS tracked Movies come with a second track of DD+
It doesn’t matter if the TV supports DTS or not. Aside from that, this is a TrueHD audio stream. It’s about Plex needing to transcode video even though it only has to transcode audio.
I have a 4K HDR movie with a TrueHD sound track and Dutch subtitles.
If I check my Plex Server to see what’s happening when playing this file I see the following:
With subtitles on:
On my Samsung the video is Direct Play, and the audio is being transcoded. (as expected).
On my LG the video is being transcoded, and the audio is being transcoded. (This is not expected).
With subtitles off:
On my Samsung the video is Direct Play, and the audio is being transcoded (as expected).
On my LG the video is Direct Play, and the audio is being transcoded (as expected).
So as soon as there is an audio format that needs to be transcoded and you turn subtitles on, the video is going to be transcoded as well on the LG. The Samsung Plex app has no issues doing that.
Subtitles are SRT btw. I know that makes a difference as well.
Movies with TrueHD audio usually have secondary DD track. Selecting it helps to get around this issue. However there are lots of movies/shows with sole DTS track and it is not possible to watch those with subtitles on my 2020 LG TV.
