Trying to accomplish this non trivial task i have tested command line tools to convert blu-ray/mkv/.sup hdmv_pgs_subtitle codec to text based .srt subtitle using Tesseract and made two Slackbuilds in case anyone is interested.
This one seems to work the best for old and recent files, require Dotnet:
PgsToSrt
This one works well for recent files and don't have any other dependency than Tesseract:
sup2srt
After conversion running Gaupol (Slackbuild) to "Correct text" and "Spellcheck" is required for a result simmilar to what can be found on Opensubtitles.
note: they only have been tested on Current.
