slackbuilds/python/python3-pysrt

python3-pysrt (Python parser for SubRip (srt) files)

pysrt is a Python library used to edit or create SubRip files.

pysrt is mainly designed as a library, but if you are experiencing
troubles with bad subtitles you can first try to use ruby-osdb which
will try to find the best subtitle for your movie. If you are still
unlucky pysrt also provide an srt command useful for either shift,
split, or rescale a .srt file.