Subtitles will usually be embedded in video files, but the server also supports external subtitles. Supported formats include ass, srt, ssa, sub, idx, and vtt files.
Normally the server will only attempt to scan for local files, but if any subtitle plugins are installed there is also support for downloading remote subtitles automatically.
Jellyfin will search for subtitles that exactly match the video filename. They can optionally include a language code or name that will get picked up as well.
/Movies /Film (1946) Film.mkv Film.vtt Film.de.vtt Film.german.vtt
Subtitles can be labeled as default by appending
.default at the end of the filename.
/Movies /Film (1986) Film.mkv Film.srt Film.default.srt
Subtitles can be set to forced by appending
.foreign to the end of the file.
/Movies /Film (2010) Film.mkv Film.ass Film.forced.ass Film.foreign.ass