We know the FFMPEG is very helpful on Multimedia oriented task, like video/Audio conversion, change the formats, make different formats and etc. Also burn subtitles into your video using the libass library.
To enable libass library you need to configure FFmpeg with --enable-libass.
also build with libavcodec and libavformat to convert the add subtitles file to ASS (Advanced Substation Alpha) subtitles format.
Install and configure with FFmpeg,
Do you need to create a subtitle set the format on .srt file (subtitle.srt)