Transcoder failed to optimize file with VOSBSUB

Plex Media Server
1

Server Version#: v1.41.8.9834 Ubuntu 22.04.5

Hello! I’m running into an issue where transcoding fails anytime I try to optimize a media file with VOBSUB subtitles.
The files play back fine when I disable subtitles, or switch to SRT so it’s really just VOBSUB that trips it up.

attached log shows the error that occured during optimizing both for TV and Mobile

Plex Media Server.log (2.7 MB)

it seems to be the same issue as mentioned here, and i’ve also followed all the steps that they mentioned: Transcoding fails with VOBSUB subtitles

2

Looking at the log file (thanks for providing), I see:

  1. PMS sees the card on the PCI bus as it starts
  2. PMS loads the drivers for it
  3. HOWEVER, PMS can’t access it to use it for transcoding

Is PMS running as user plex or some other user ?

3

PMS is indeed running as user plex

> ps aux | grep plex

plex      134609  0.6  0.8 210820 70412 ?        Ssl  Jun17   1:16 /usr/lib/plexmediaserver/Plex Media Server
plex      134643  0.1  0.5  64844 43224 ?        SNl  Jun17   0:15 Plex Plug-in [com.plexapp.system] /usr/lib/plexmediaserver/Resources/Plug-ins-071366d65/Framework.bundle/Contents/Resources/Versions/2/Python/bootstrap.py --server-version 1.41.8.9834-071366d65 /usr/lib/plexmediaserver/Resources/Plug-ins-071366d65/System.bundle
plex      134683  0.1  0.1  43932 12488 ?        Sl   Jun17   0:24 /usr/lib/plexmediaserver/Plex Tuner Service /usr/lib/plexmediaserver/Resources/Tuner/Private /usr/lib/plexmediaserver/Resources/Tuner/Shared 1.41.8.9834-071366d65 32600
plex      135452  2.1  0.0   2596  1176 ?        S    Jun17   3:50 Plex EAE Service

i also forgot to mention that other files are successfully being transcoded, using “optimize for TV”

4

Please check for me?

  1. ls -la /dev/dri
  2. groups plex

Copy the text and paste to a code (preformatted text) block .

5

Do you also have the idx file? Vobsub subtitles won’t work without them.

6 
❯ ls -la /dev/dri
total 0
drwxr-xr-x  3 root root        100 Jun 12 10:48 .
drwxr-xr-x 19 root root       4560 Jun 13 00:34 ..
drwxr-xr-x  2 root root         80 Jun 12 10:48 by-path
crw-rw----  1 root render 226,   0 Jun 12 10:48 card0
crw-rw----  1 root render 226, 128 Jun 12 10:48 renderD128

❯ groups plex
plex : plex video render
7

yep, they are in the same folder as the .sub files. the files are correct, Plex can also use them while transcoding on-the-fly:

Screenshot 2025-06-18 at 09.49.18
Screenshot 2025-06-18 at 09.49.18582×704 105 KB

8

AFAIR external VOBSUBs are like asking or trouble.

9

mmkay, but who/what is to blame? is this a fault/bug in PMS?
just declaring “VOBSUB are trouble” doesn’t seem very productive..

10

I don’t know the inner workings of Plex server so intimately that I am able to point the finger.
Just that in the 11 years I’ve been using it and participating in this forum, that external VOBSUB always meant trouble.

Just try to mux them in as an experiment. See if the behaviour changes.
MKVtoolnixGUI

11

try to burn them in using an external tool, so that Plex doesn’t need to do that anymore? obviously that will work. but that’s not a solution…

a real solution would be to fix PMS… no? (or help me help you fix PMS, like ChuckPa seems to be doing)

12

I don’t mean burning in the subtitles into the video picture.
Multiplexing the subtitle stream into the same file as the video and the audio doesn’t change the video.
The subtitles remain “soft”, i.e. they can be enabled and disabled just like before.
Just that there is now only one file, instead of two.

13

ohh. i’m sorry, i didn’t understand your request..
i’ll have a look at it…

14

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