it has been designed for timing and styling of subtitles, as well as the creation of karaoke. aegisub's native subtitle format is advanced substation alpha text, which supports subtitle positioning and styling. the program also supports other common formats such as subrip. features include support for timing to both audio and video, and can use many video processing bindings to process those, such as ffmpeg and avisynth. it can also be extended with the lua and moonscript scripting languages.