MPlayer supports mounting .utf .idx .sub .srt .smi .rt .txt .ssa .aq .jss .js .ass and other format files. You can easily add subtitles via tools-plug-in subtitles or right-click menu

The popular subtitle formats are divided into two types: graphic format and text format.
The graphic format subtitles are composed of idx and sub files. Idx is equivalent to the index file, which includes the time code of the subtitles and the attributes of the subtitles. The sub file is the subtitle data itself. Because it is a picture format, it is relatively large and easily exceeds 10M ( However, we can compress it into a rar file, which is the same as without compression with the support of unrar.dll, but it can save a lot of space). idx + sub can store subtitles in multiple languages, which can be conveniently selected during playback.
The extension of text format subtitles is usually srt, smi, ssa or sub (same as the graphic format suffix above, but the data format is different), because it is a text format, so the size is very small, usually not more than one hundred kilobytes. Among them, srt text subtitles are the most popular because they are very simple to make and modify: a sentence of time code + a sentence of subtitles.