An ASS (Advanced SubStation Alpha) file is a subtitle format that supports text styling, animation, and karaoke-like graphics.

• ASS is a text-based subtitle format.
• Any text editor can open .ass files.

ASS is a more advanced subtitle format than SRT since ASS allows for more advanced display features such as text positioning, fonts, animation, and graphics besides the plain text styling.

• SRT is more popular than ASS.

ffmpeg -i input.mp4 -vf ass=subtitle.ass output_ass.mp4