I sometimes watch movies/scenes with sutitles downloaded from this site.

SRT always works. VTT does not work with my TV.

Has anybody tested VTT succesfully with a TV? Which brand?

VTT does not work with my TV either.
The best way is to convert VTT into SRT.
TV supported only certain files and with certain rules.
For example, my TV can't display an SRT with two subtitles at the same time, my TV stop the video or turns off. But my SmartTV is old.

In reply to Lionfacial:

For example, my TV can't display an SRT with two subtitles at the same time, my TV stop the video or turns off. But my SmartTV is old.

I actually never tried that. Interesting thought.

Example:

movie.mp4
movie.en.srt
movie.de.srt
movie.fr.srt

Correct?

I never tried that.

I assumed only this syntax works:

movie.mp4
movie.srt

I think it works for me with MKV and subtitles within, but I guess that works for yours, too.

Sorry for the confusion, that's not exactly what i meant, it's more something like in the same SRT when you got two lines at the same time.

Found a very good free site to convert files from a lot of formats to a lot of other formats. It does VTT to SRT among other formats.

https://gotranscript.com/subtitle-converter

I don't think it's a format issue, but rather a player issue. Smart TVs typically come with very limited multimedia players, technically, with few options and features. My experience is based on LG and Samsung smart TVs. Frankly, they're pathetic. I later got a Sony Bravia, which worked better with multimedia files, but it wasn't great either. Solution: download VLC for smart TV (only for Android TVs). It recognizes all formats, all audio tracks, and all subtitle formats.

By the way, more online tools for subtitle formats: https://subtitletools.com/

I have an LG, definitely not smart enough and not Android. I go via Firestick for apps.

For VLC on Android Smart TV, my problem is that my SD videos are just pixelated, without antialiasing. It's not the case with the TV's default player. Same for you?
Maybe i didn't see the option. :/

That doesn't happen to me. And I have a lot of videos in SD. It seems like a problem with the VLC app settings, or even with the smart TV's system.

Thanks Nochvemo.
I think VLC makes the video too sharp. Maybe I will try again later, if a new version fixes the problem.