libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format. It is mostly compatible with VSFilter.
See GitHub releases for the latest release 0.13.6 (released 2017-01-03). This is mainly a security and bug fix release. This release breaks ABI compatibility with prior releases. See the changelog for a detailed list of changes.
Source code is available from our GitHub repository.
Please use the issue tracker to report bugs or feature requests. We have an IRC channel, too. Talk to us on irc.freenode.net/#libass.
The following projects/companies use libass:
- GStreamer (assrender plugin)
- Kodi (XBMC)
- PunkGraphicsStream (BD subtitle encoder)
- MX Player
Information about the ASS format:
- ASS specification (incomplete)
- ASS override tags (Aegisub manual)
- VSFilter source code (Guliverkli2)