The stock Android TV system does not come with a video or media player, some vendors may include one, for example, Nvidia Shield, however the player may not have too many features, in fact, the most important and the basic one, subtitle displaying, is often missing.

Subtitle: SRT, SSA, ASS extensions

When downloading a video file, it often includes another file with extensions like .srt, .ssa, or .ass. These files are formatted text files that contain timeline information and subtitle text. It’s recommended to open them with a text viewer and ensure they are encoded in UTF-8 to support multiple languages. Additionally, the Video Player for Android TV can display two subtitles simultaneously, which can be useful for language learning purposes.

Video: MKV/MP4/M2TS/AVI

Files in MKV/MP4/M2TS/AVI extensions are video files, it is a volume of multiple video and audio tracks, it is possible to store multiple audio tracks in one video file so you can possibly select which audio track to use when playing back this video. (note, not all devices support AVI)

How to play video files with subtitle on Android TV or Mi Box

Today we are gonna show you how to play MKV/MP4/M2TS/AVI video files with subtitle files on Android TV Mi box s systems such as Mi Box, Nvidia Shield and Amazon Fire TV. Now please watch this tutorial video

Video Player for Android TV Google Play Store link

https://play.google.com/store/apps/details?id=com.tvdevfactory.miboxvideoplayer&hl=en