Why Blu-ray subtitles make a media server transcode

A Blu-ray subtitle makes a media server transcode because it isn’t text. PGS tracks on Blu-ray and VobSub tracks on DVD are pictures, one small image for each line of dialogue, and when the player can’t draw them the server has one way left to show them: paint each picture into the video and encode the whole film again. Quven is a self-hosted media server by Quven Technologies S.R.L., free for personal use, and its native apps draw those pictures themselves, so the film stays exactly as it came off the disc.

Why is a Blu-ray subtitle different from an SRT file?

An SRT or WebVTT track is a few kilobytes of text, which the player sets in its own font while the server sends it beside the video. A PGS track carries no letters at all: each cue is a bitmap with a place on the screen, made for a disc player that knows how to lay it over the picture, and VobSub, the format of a DVD, works the same way at a lower resolution.

The trouble starts the day a remux enters the library: the film plays cleanly, someone picks a track from the disc and the picture begins to buffer, although nothing is wrong with the file. So why does a perfectly good remux suddenly stall? Because the server has stopped sending it and started rebuilding it.

What does burning in actually cost?

Burning in means decoding every frame, drawing the subtitle over it and encoding the result again, which many graphics chips can’t do themselves. Jellyfin’s codec support page, read on 30 September 2026, calls it “the most intensive method of transcoding”, and the subtitle then becomes part of the image for the rest of the session (every trigger).

What do Plex and Emby do with PGS subtitles?

	Quven	Plex	Emby
Blu-ray and DVD picture subtitles	Drawn by the native apps, file untouched	Transcoded and burned in “for the majority of apps”	Burned in “in many cases” during a transcode
Hardware for the transcodes that remain	Free on every plan	“Requires an active Plex Pass subscription”	Emby Premiere

Plex’s page on local subtitles, last modified on 1 July 2025, says both formats require a transcode for the majority of its apps, which on a server without the pass is the processor’s job, and Emby’s overview says most graphics chips can’t do the burn-in step.

How do you play a Blu-ray subtitle without transcoding?

1. Download Quven and point it at the folder of remuxes you already have.
2. Start a film in a native app: the desktop app, the iPhone and iPad app, or the Android app on phones, tablets, Android TV and Fire TV.
3. Open the subtitle menu and pick the PGS or VobSub track.
4. Open the player’s stats panel and read the decision, which stays direct.

The app draws the track over the picture itself, much as a disc player would, so you may change language halfway through and the server’s graphics card stays free.

What happens in a browser?

A browser can’t draw PGS, so the web client at app.quven.tv, which comes with Pro, offers every picture track as a subtitle the server burns in. That starts a transcode, as on any server, though its hardware is free on every Quven plan (comparison).

Can a picture subtitle become text?

Yes, as part of translation. With Max or Lifetime, Quven reads a PGS or VobSub track into text on your own server, and only that text may go on to be translated, once you’ve given consent. The result is plain text that a browser shows with no burn-in (translation guide, engineering notes on PGS).

Which screens play it all?

Every native app draws the subtitle, and the web client covers any browser. If your library sits on Plex today, the import brings its history across without changing anything there, and Apple TV and Samsung and LG apps are on the way.

Why decide now?

Point Quven at the remuxes you already have and pick a Blu-ray subtitle on the television tonight, at no cost, which you should do before deciding anything else. The plans page shows what Pro and Max add, and Lifetime is every Max capability for a single payment.

Frequently asked questions