Why PMS burns VTT subtitles when subtitle is disabled?

Plex Media Server
, , ,
1

Server Version#: 1.41.4.9463
Player Version#: 8.45 (iPadOS, 18.3.1)

My PMS automatically burns the VTT file (with the same name as the .mp4 file) into the video while streaming (at original quality within the local network) on an iPad. But, this issue does not occur when you play on Plex Web. I am 100% sure it is a bug with PMS.
If the subtitle is enabled on my iPad, I will get 2 layers of subtitles. If the subtitle is disabled, i can still see a layer of subtitles.

2

IMG_7E1377A998A8-1
IMG_7E1377A998A8-1817×612 55.8 KB

If I enabled the subtitle on Plex 8.4.5 on iPadOS 18.3.1.

3

lol

have you never heard of burned-in subs? :joy:

4

Thank you for your time but it was not helpful at all.
The video file does not have any burned in subs or subtitle tracks. That’s why I ran whisper-cpp to create subs for those files and put them in the same directory with the same name.
It is an unexpected behaviour for streaming on Plex (iPadOS) for sure, as this issue was not observed when streaming on Plex Web or directly play from mpv.

5

Screenshot 2025-02-23 at 08.58.40
Screenshot 2025-02-23 at 08.58.40556×488 29.5 KB

The subtitle has been explicitly disabled in the Plex Player, but on the backend, it indicates that the subtitles were embedded in the stream and transcoding was triggered.

6

I say upload the video and subtitles to the cloud so the Plex team can examine it. I can test it on my end as well.

7

Thanks, I hope it helps - Video Link

You can download the video using yt-dlp by yt-dlp [url]. Attached is the .vtt file transcribed by Whisper-cpp project.

AI for networking, and networking for AI [i6DvbfIUPSg].vtt.zip (20.5 KB)