From SubExtractor Team:
DVD Subtitle Extractor converts subtitles from DVDs and PGS (Bluray .sup) files using OCR (optical character recognition). It can extract subtitles from (unencrypted or on hard drive) DVDs and convert them to advanced substation alpha or SRT text format. It can also convert individual sup (PGS) and sub/idx files. It's a wizard-style app, allowing you to pick program chains, angles, audio, and subtitle tracks from a DVD folder and create mpg, d2v, and bin files for each. DGIndex is used to help line up the subs to the video since DVD programs often have discontinuities that mess up sync.