ASS

ASS (Advanced SubStation Alpha, sometimes spelled .ssa for its predecessor SubStation Alpha) is the styled-subtitle format used by Aegisub, fansubbed anime, and nearly every video player that supports advanced typesetting (VLC, MPV, mpv-style, IINA, PotPlayer). It's a section-based INI: `[Script Info]` for metadata, `[V4+ Styles]` for fonts/colors/positioning, `[Events]` for the actual `Dialogue:` lines. Captions can specify per-line styling, hard breaks (`\N`), inline override codes (`{\b1}bold{\b0}`, `{\i1}italic{\i0}`, `{\fnArial}font`), karaoke effects, and absolute screen positioning — none of which SRT or WebVTT express. Created in 2003; libass is the de-facto rendering engine across mpv, ffmpeg, and most modern players.