I use an older Windows app called Subtitle Processor 7.7.1, which doesn’t seem to have been updated since 2009 or so but still works fine for me. I looked very briefly at SubtitleEdit which was mentioned in this thread to see if it is better, but Subtitle Processor seems to me to have more comprehensive subtitle adjustment abilities than SubTitleEdit, though I could be mistaken.

Source:
over 2 years ago