Advanced SubStation Alpha (.ass) subtitles don't work with PMS 1.43 with webOS app

Plex Players Smart TVs
1

Server Version#: 1.43.0.10231
Player Version#: 5.92.3

When trying to play a video with enabled ASS subtitles on LG OLED TV (OLED65C24LA, webOS24 / 9.2.2-61), I’m getting “Playback Error” screen.

It works, when disable .ass subtitles.

It works with .srt subtitles enabled.

It works with .ass subtitles, but if downgrade PMS to 1.41.6.9685.

Logs from the server and TV combined are in the attached file, it’s the chunk just before the click on the video and getting the error screen. Let me know if you need more.

log.txt (57.4 KB)

2

The supported media formats of a smart tv Plex app are a factor, especially when the logs refer to problems with the video and the audio, e.g.

Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih] [MDE] Application decision, directPlay: false, directStreamVideo: false, directStreamAudio: false
Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih]     Cannot direct play with protocol: http, codec: h264. Reason: Video stream exceeded a max bit depth of 8
Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih]     Cannot direct stream with protocol: hls, codec: h264. Reason: Video stream exceeded a max bit depth of 8
Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih]     Cannot direct play with protocol: http, codec: flac. Reason: Unsupported container mkv
Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih]     Cannot direct stream with protocol: hls, codec: flac. Reason: Unsupported container mpegts
Oct 26, 2025 14:41:07.737 [135601108028216] Info — [Req#b75] [Plex for LG] [Varya & Seva:p6o4jymxctz85jn0lwg4chih]     Cannot direct play or stream. App does not provide full ass subtitle support.

The major issue → video has a 10bit color profile when the player only supports H.264 8bit
A secondary issue is → video is in an mkv container, when the player needs mp4.
A slight issue → The audio is in FLAC format, but PMS could transcode it.
It’s likely your ASS subs will work if the first two issues are addressed.

3

Hey @nibbles , thanks for replying! I think this log indicates that there could be no direct streaming between my PMS and my Smart TV, and that’s justified, and I’m fine with it. I’d expect it to transcode everything it needs and burn subtitles into the video, with additional CPU utilisation cost, of course. So it’s all fine, but something prevents it to burn .ass subtitles into the video in this particular case.

Thing is, weirdly the same files are working with PMS 1.41, but stops working with 1.43. So I was wondering what could be the major change between 1.41 and 1.43 that broke this.

1 Like
4

You’re welcome. There were major changes in PMS due to a security vulnerability and other things causing a recommended upgrade past 1.41.x.

The 1.43.1.10231 is a beta version of PMS where they have done a major upgrade to the included FFMPEG now at v6. This upgrade has bugs in the transcoder which have affected numerous people.

The best PMS at the moment is the stable version, also called Public,
now at 1.42.2.10156.

Would it be possible for you to roll back to 1.42.2 and see if that fixes things?

5

Yes, absolutely, no problem! Thanks for explaining this in such great details!

I’ve tried 1.42.2.10156 now, unfortunately it’s not working with the same symptoms as for 1.43. I’ve attached new log in case it might be helpful. So I guess it’s narrowing down to some change between 1.41.6.9685 and 1.42.2.10156.

log.txt (59.9 KB)

6

Fudge. You’re getting the same errors trying to transcode this in 1.42.2 as you did in 1.43.x,
and I don’t know why it would have worked in 1.41.x.

Sure is a nice TV though :slight_smile:

Do you have another video with ASS subs that doesn’t work?
Hopefully you have one that’s a simple 8-bit H264 1080p which we can test.

7

As a matter of fact, I did have something easier for Plex to digest hahah. It’s exactly 8-bit H264 1080p, but the audio is still FLAC. Unfortunately still doesn’t work on 1.42.2. Here is the fresh log:

log_failed.txt (57.8 KB)

For fun, I’ve disabled subtitles and took the log of the TV successfully starting and playing the same file, just for reference:

log_success.txt (9.3 KB)

8

Nice. Looks the only thing different about the two files was the decision by PMS to burn in the subs. I’m wondering if there’s a setting for your subs where it always burns them. Maybe check the player. I think you want to try the option Never introduced in 2022.

9

What did you end up doing? I have same issue with .ASS subtitles not working after PMS update. It used to work always and now I get Playback error

10

Unfortunately nothing helped, so I’m just sticking with 1.42.2 for now.