www.makemkv.com

Is it possible to flag subs as hearing impaired? I've tried hearing-impaired, but it just detects the "d" and flags it as "default".

I think MakeMKV produces .mkv files that are version 2.

FlagHearingImpaired is a version 4 element according to Matroska v4 element specification

You could use mkvpropedit or the full blown MKVToolNix GUI to set the flag after ripping.

Yeah, setting it after ripping I'm on top of, I was just hoping to avoid the extra step.