External .srt subtitles make Plex turn off HDR in LG WebOS 3.5 (OLED B7)



Hey guys, I see there's a common issue with embedded subtitles for Plex in WebOS TVs, especially PSG subtitles.

However, I noticed that even external .srt subtitles will mess up reproduction, turning HDR off, even though direct play continues.

Plex direct plays 4K HDR content normally in my LG OLED B7 as long as there's no subtitle involved at all. This include internal and **external **subtitles.

So, to reproduce the issue, you just have to turn on or off the subtitles before or during playing 4K HDR content. In my LG TV the HDR flag wont come up and image will be washed and bland if I try to load a subtitle along. Changing the subtitle during reproduction will also set the change.

Has someone managed to circumvent this problem? (Xplay reads the external subtitles normally, maintaining HDR). The native player also has no issue playing 4K HDR + subtitles through DLNA or USB.

Thanks a lot, and let me know if I can provide further assistance towards the solution of the issue.


When the sound is set to 7.1 TrueHD with subtitle, my plex doesn’t process the HDR, but when i change the sound to 5.1 the plex processes the HDR with the subtitle.


With the LG WebOS 3.5 app, enabling any subtitle forces a video transcode.

The Plex transcoder does not currently support HDR video. The colors appear washed out because the a) transcoder converts the 10 bit HDR video to 8 bit SDR video, and b) does not currently support tonemapping from 10-bit to 8-bit video. Also, IIRC, 4K video is transcoded to 1080p.

Plex has said fixing the problems with subtitles is on their to do list. However, they don’t publish priorities or due dates.

So, for right now, your options are to a) not use subtitles in the Plex client, b) use something like XPlay, or c) use a Nvidia Shield, Apple TV, or similar set top box.

EDIT: Another thread on same topic: https://forums.plex.tv/discussion/303380/plex-app-on-lg-webos-transcoding-with-subtitles-enabled#latest