subtitle out of sync when transcoding

[shinobiii163]

This issue respects the following points:

• This issue is not already reported on GitHub (I've searched it).
• I agree to follow Jellyfin's Code of Conduct.
• This report addresses only a single issue; If you encounter multiple issues, kindly create separate reports for each one.

Describe the bug

1. video name: Squid.Game.S02E01.2021.2160p.NF.WEB-DL.DDP5.1.Atmos.DV.HDR.H.265-HHWEB.mkv
2. subtitle out of sync when transcoding play
3. the issue happens both on androidtv app and web.
4. On the web, if I set "Always burn in subtitle when transcoding", the issue solved.
5. But androidtv app doesn't have this option，the issue can't be avoided.

Logs

No response

Application version

0.18.3

Where did you install the app from?

None

Device information

Xiaomi TV，HK1 RBOX X4，X96X10pro

Android version

Android9，Android 11

Jellyfin server version

10.10.3

Other sources

No response

[GertSallaerts]

From what I understand, subtitle sync issues during transcoding are a problem that's not easy to solve and a new option was introduced in Jellyfin 10.10 to help out people who are affected. (1, 2).

Subtitles often have synchronization issues after video transcoding. This option allows the client to opt-in to always burn in all subtitles, preventing out-of-sync subtitles at the cost of transcoding performance.

The option is already implemented in jellyfin-web where I tested it out and (for me at least) it solved the sync issues I was seeing when transcoding. Would it be a good idea to add the same "Always burn in subtitle when transcoding" option in this project?

I was browsing around the code a bit to see if I could whip up a quick PR for it as it sounded like an easy one (looking at the changes that were required on web) but -- unless I'm mistaken -- it's a bit more complicated as that part of the code is currently using an older Jellyfin SDK that's no longer being updated and to make this change a significant part of the code should be migrated to the modern SDK. Again, that's just what I gleaned from scanning the code and some issues, please do correct me if I'm wrong about that and there is an easier way. 😅

(While this comment is mainly about finding a solution, I am also affected by this issue, if I can help out by providing more details, do let me know.)