solution from https://stackoverflow.com/a/17584272/2627873

This solution adds the subtitles to the video as a separate optional (and user-controlled) subtitle track.

So you can choose the subtitle in VLC for example, it's not hard-coded or burned-in. And it won't re-encode the entire file so it's really fast.

• ffmpeg is required
• movie = great_movie.mp4 (works with mkv too)
• subtitle = great_movie.english.srt