slackbuilds/multimedia/subtitleripper/README

DVD Subtitle Ripper for Linux

If you want to convert DVD subtitles into text format (e.g. subrip
format) or VobSub format this program could be useful for
you. However, it is only one tiny tool that you need in the process
of producing srt files. This software depends heavily on transcode
for its input and is therefore part of the transcode package (see
transcode's contrib directory). So, if you want to convert some
subtitles, grap a copy of the latest transcode distribution.

For srt file production the output of this program should be processed 
by some OCR software. 

For VobSub output no other tools are required.