Why subtitles are so troublesome on jellyfin?

[thiagohds]

While I was using plex, subtitles were just normal. You could switch them on the go but with jellyfin each time you switch subtitles or select one to start watching something you have to wait for like 5 minutes for the file so start. Is this a problem with jellyfin or is something I need to configure so it can work properly? It happens with all kinds of subtitles except srt.

[xaque]

I'm not sure how to diagnose or fix your issue, but I will say I have subtitles working beautifully without your said issue. So I don't think it's necessarily a jellyfin issue. Sorry I can't be of more help.

[TheDreadPirate]

I'm thinking that the subs are getting burned in because of some font issue on the client device. Which is requires transcoding. Since it is taking so long I am assuming you don't have a GPU accelerating the transcode.

What OS is the jellyfin server running
What hardware does your server have
What is the client device
What app are you using on the client device

[thiagohds]

I'm not sure how to diagnose or fix your issue, but I will say I have subtitles working beautifully without your said issue. So I don't think it's necessarily a jellyfin issue. Sorry I can't be of more help.

Actually I have NVENC enabled. My system is a RTX 3060 with ryzen 5 5600. It takes longer when I'm using the LG TV app but even when I tested it through the browser I have to wait a while. Every media is being transcoded and I don't know why. Emby is about the same but its faster. And Plex doesn't have this issue but I can't play HDR files on plex free plan.

[Perseverant]

PGS subtitles, which are very common on Bluray-sourced content, used to only work if they were burned into the video on AndroidTV client via transcoding, but now play without transcoding the video on that client. It's possible that the fix hasn't made it into other releases of Jellyfin.

[notfound_404]

Tip for users who want to use custom subtitle fonts:

1. Install the Stylus extension for Firefox.
2. Play a video and make sure the current URL is XXX/web/index.html#!/video.
3. Open Stylus, select "manage" > "write new style"
4. Paste as follows from this https://pastebin.com/0LYxvZAX
5. Change the font and weight as desired.
6. Ctrl + S.
7. Enjoy!

Edit: This only works on Firefox for now. Chromium browser dev tools are buggy so I can't find the specific tag for them.

[bitmap]

Need mediainfo or ffprobe of the media file. As somebody already said, it's likely a graphics-based subtitle format. These formats require transcoding with a ton of clients (not all). In addition, other information (OS of your install, virtualization or host installed, version numbers of server and apps) would help to investigate as well.

As a counterpoint to your specs, I run a headless Linux box (Ubuntu 22.04 LTS) with a non-compliant kernel that by all accounts shouldn't be able to use the full extent of the iGPU and I can watch a high-bitrate remux with PGS subs on that require transcoding with very little delay. There is a "restart" as the transcode job begins, but it's in the realm of less than five seconds before playback resumes. I have no additional hardware, just standard QuickSync enabled with a some hacked-together drivers since I didn't want to upgrade my OS.