So I remux a lot of mkv's into mp4's with subtitles. My usual method for this is to extract the .ass/.ssa subtitles with MKVTools and re-save them as .srt with Jubler, and then I remux it all into an mp4/m4v with Subler. Naturally, you lose some of the formatting, etc., the .ssa/.ass had when changing to the .srt. Of all the solutions I've tried, saving it again with Jubler has been the most successful in retaining good timing for the subtitles, but for complicated subtitles, there can still be problems, such as when you have three lines of subtitles, etc. Most of the time, I don't discover these flaws until watching the remuxed mp4/m4v. As you may imagine, going through the trouble of re-extracting the .ass/.ssa, converting to .srt, editing the .srt, and remuxing again is *quite* cumbersome for multiple episodes of a show if I've already done all that once just to fix one scene, but somewhat necessary if I want something watchable on iDevices without painstakingly re-encoding and hardsub everything. So are there any ways to edit an subtitle file *while it's already in an mp4*? Or sparring that, are there at least any ways to extract an .srt from an mp4, without having to go back to the original mkv? None of the searches I've tried have come up with anything only stuff about adding subtitles to mp4's, but nothing about editing ones that are already in them.