External subs don't play correctly with Anime .mkv with embedded subs (.ass

[Reveur]

I've downloaded a few anime .mkv with embedded subs and I've tried downloading external subs, or even extract the subs from the .mkv, in order to be able to play it on my TV (because TV does not display embedded subs, needs external subs). However, I've noticed that whenever I download external subs, even on my computer, when I add these subs in the folder with the .mkv and then play the video on my computer, it totally screws up the subs.

Using both BSPlayer and VLC Player, with these external subtitles (added in folder and renamed to the name of the .mkv file), both BSPlayer and VLC Player no longer can display the embedded subs (or maybe they can but they are screwy). I can choose both the external subs and embedded subs, but they will always display desynchronized.

Only when I delete the external subs do the embedded subs play correctly on my computer. My problem is that I don't understand why adding external subs makes these embedded subs screwed up, nor why the external subs are themselves screwed up. I've download other movies that are not anime movies with embedded subs and have always been able to add external subs without messing up any of the subs.

For one anime .mkv, the embedded subs are .ass subs. For the other, they are .idx and .sub subtitles. Can anyone provide an insight on what exactly messes up the subs? When I add external subs and play it on my TV, they are desynchronized, just like when I play the file on my computer.

Any help will be appreciated.

[kontrolluz]

My problem is that I don't understand why adding external subs makes these embedded subs screwed up, nor why the external subs are themselves screwed up. I've download other movies that are not anime movies with embedded subs and have always been able to add external subs without messing up any of the subs.