How to fix subtitles that are out of sync with video

[Mam]

MKVToolnix creates a .mkv and ffmpeg can put text-based subtitles in a .mkv container.

Not sure about the ts, I only use mkv.

TS = Transport Stream = a lot of unneeded garbage.
Strip it off, encode to PS (Program Stream), save up to 2/3 space without losing any quality.

So my storage only contains reencoded MKV files, saving a lot of disk space...

Unless you do not want to re-broadcast the video, TS is not needed.

[Cypheros]

TS is a very special format. ffmpeg, tsmuxer and other tools like that often have problems with this kind of files if there are errors in the stream. When receiving Transport Stream via satellite, cable or antenna, reception interference occurs from time to time, especially during bad weather or poor reception paths.

Missing or bad packets often leads to sync problems between audio, video and text streams if you convert them to other container formats.

Personally, I leave the format untouched and don't waste time and expensive electricity on conversion just to save a bit of disk space. Storage space is so cheap these days.