Open source tools for working with subtitles. …
Linux, Mac, and Windows. Waveform and keyframe support. Probably more full featured and complicated than the average user needs.
Linux (Gnome). Supports text-based formats. Requires mono.
Linux (GTK) and Windows. Supports text-based formats. Spellchecking. Beta. It's what I use on Windows, but I miss not having waveform and keyframe support.
Linux, Mac, and Windows (Java). Supports binary and text-based formats. Supports frame rate conversion.
Linux (KDE). Edit, make and save subtitles in SRT format. Some poor reviews.
Linux (command line tool). Convert subtitles from microdvd or subrip (.sub) to .srt format. It does not convert DVD subtitles or vobsub, which despite also having the extension .sub are different formats. No man file, but sub2srt –help is helpful.
Linux (KDE). Supports basic operations as well as more advanced ones, aiming to become an improved version of Subtitle Workshop. Beta.
Linux, BSD (GTK). Supports text and binary formats. Waveform and keyframe support. Beta. It's what I use on Linux, but controls are not intuitive or efficient.
Subtitle Files Handling Under Linux: dated but still useful