Subtitles out of sync

[Pebas]

I have the same problem and I think I tried toggling every single option available on the server side in the Playback/Transcoding menu, including hardware acceleration to start with, and for instance, I even added and then removed alternative fonts.

On the client side, strange things start to happen: it replicates the problem on the TV (AndroidTV), but not on the phone (Android)... and on the PC, it also gets out of sync in Brave and Firefox (installed from scratch only for this test), but not in Chrome (?).

Note: looking at the server dashboard: in playback information, while playing in Brave and Chrome it reports that it is performing exactly the same transcodification, which is quite logical since they are very similar or even identical players since both are based on Chromium.

In all cases, the subtitles are external SRT and in some very similar movies (same audio/video codecs, etc.) it happens and in others it doesn't. You can never know in advance.

In summary:

- TV (AndroidTV), internal player: Yes
- Phone (Android), internal and web player: No
- PC Ubuntu 24.04, Brave: Yes
- Same PC, Firefox (fresh installation): Yes
- Same PC, Chrome: No

From my limited knowledge, this is becoming extremely odd.

In the last test I did, which I think could help a lot in finding a solution to the problem, is that on the phone, if I switch to the commentary audio track, the subtitle gets out of sync, and when I switch back to the main track, it adjusts again. This process can be repeated countless times with the same result, and it only happens when using the internal player; if I switch to the web player, the subtitles sync correctly with any audio track.

Then, it throws me off again: this -can't be reproduced- on ANY of the other clients.

For what is worth:
Main track codec: E-AC3 Dolby Digital Plus 5.1
Commentary track codec: AC3 Dolby Digital 2.0

EDIT: I almost forgot: In any case nothing ever changes if I skip forward or backward. Waiting or not.

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Jellyfin Server, Web and Build: 10.9.11
GPU: NVIDiA RTX 3060 Ti LHR (NVENC)
SO for Server and Browsers: Ubuntu 24.04 (6.8.0-44-generic)
Brave: 1.69.168 Chromium: 128.0.6613.138 (Build oficial) (64 bits)
Chrome: 128.0.6613.137 (Build oficial) (64 bits)
Firefox: 130.0 (64-bit)
Phone: Android 14 and Jellyfin App 2.6.2 (using internal and web player)
TV: AndroidTV 12 and Jellyfin App 0.17.5 (using internal player)