Jellyfin struggles to play video files 2/3rds of the time

[sekondchakra]

I'm running the latest Jellyfin server under Docker on a Synology NAS. The client is the latest Jellyfin on my Nvidia Shield.  About a third of the time, videos take 20 - 30 seconds before they start playing.  Another third of the time they won't play at all (I get an error message).

I don't have a lot of experience with Jellyfin--mostly because it's been very frustrating to use it with such a high failure rarte.  My Emby setup almost never fails to play whatever I throw at it.  I'm wondering if there's a setting in Jellyfin that I've missed or should modify?

[TheDreadPirate]

Can you share your full Jellyfin logs via privatebin.net? And which model Synology NAS you have.

[sekondchakra]

By "full Jellyfin logs" do you mean the the FFMmpeg.transcode and FFmpeg.DirectStream.xx logs as well as the "log_2025.03.xx.log" files?

[edit] Here's all of it in an archive.

https://privatebin.net/?a7f34c7343dfda54...L4YiyXiz77

[sekondchakra]

And, sorry, it's a Synology DS920+

[TheDreadPirate]

It is extracting subtitles, but very slowly. Between 20-30 seconds. I don't see a lot of Jellyfin related activity in the log during those times, but I don't know what else is running on your NAS to cause it to take this long. Subtitle extract should only take a second or two on a lightly loaded system (either CPU or storage).

You COULD disable on-the-fly subtitle extraction, which is what is causing the playback delay. But doing so will trigger a subtitle burn-in + transcode. Not ideal for the low power CPU in your NAS. Subtitles are extracted for some clients that support directly displaying the embedded subtitle, but don't support doing so directly from the video file.

You could install the "Subtitle Extract" plugin and then run the job for that (Dashboard > Scheduled Tasks > Subtitle extract) and that will pre-extract the subtitles, instead of on the fly, and store them in Jellyfin's appdata dir.

[wilberfan]

What would explain the 'unplayable' files a third of the time? (30 second delay, then an error message.) Could that be subtitle related as well?

[TheDreadPirate]

Probably subtitle related. And you are likely hitting some sort of timeout limit.