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https://github.com/libass/libass

libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format.
https://github.com/libass/libass

advanced-substation-alpha ass c cross-platform libass ssa substation-alpha subtitle-format subtitle-formats subtitles

Last synced: 6 days ago
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libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format.

Host: GitHub
URL: https://github.com/libass/libass
Owner: libass
License: isc
Created: 2013-07-26T23:11:51.000Z (over 11 years ago)
Default Branch: master
Last Pushed: 2024-12-12T21:48:35.000Z (11 days ago)
Last Synced: 2024-12-13T15:18:07.181Z (10 days ago)
Topics: advanced-substation-alpha, ass, c, cross-platform, libass, ssa, substation-alpha, subtitle-format, subtitle-formats, subtitles
Language: C
Homepage:
Size: 3.28 MB
Stars: 949
Watchers: 56
Forks: 217
Open Issues: 144
Metadata Files:
- Readme: README.md
- Changelog: Changelog
- License: COPYING

Awesome Lists containing this project

README

        libass [![Coverity scan build status](https://scan.coverity.com/projects/3531/badge.svg)](https://scan.coverity.com/projects/3531) [![Build status](https://github.com/libass/libass/actions/workflows/ghci.yml/badge.svg?branch=master&event=push)](https://github.com/libass/libass/actions/workflows/ghci.yml?query=branch%3Amaster+event%3Apush)

======

libass is a portable subtitle renderer for the ASS/SSA (Advanced Substation Alpha/Substation Alpha) subtitle format. It is mostly compatible with VSFilter.

Get it

======

See [GitHub releases](https://github.com/libass/libass/releases) for the latest release 0.17.3 (released 2024-07-02).

See the [changelog](https://github.com/libass/libass/blob/master/Changelog) for a detailed list of changes.

Source code is available from our [GitHub repository](https://github.com/libass/libass).

Contact

=======

Please use the [issue tracker](https://github.com/libass/libass/issues?state=open) to report bugs or feature requests.

We have an IRC channel, too. Talk to us on [irc.libera.chat/#libass](https://web.libera.chat/#libass). Note that we cannot be online all the time and we cannot answer IRC questions if you leave the channel. Even if you do not get an immediate response, keep your IRC client open, and we will eventually get back to you.

Building

========

libass offers two build systems to choose from: Autotools and Meson.

Autotools is preferred for development since it integrates with our testing

infrastructure and is feature-complete on all platforms supported by Autotools.  

If you are packaging libass for distribution, Autotools is recommended;

when packaging for Windows Meson should work equally well.

Meson lacks integration with testing infrastructure, but works otherwise well on

Windows. It is suited for static-only builds on any platform well supported by

Meson and as a Meson subproject.

Notably, Meson supports MSVC and generation of VS project files.

Macro defines

-------------

Unless developing libass there’s usually no need to manually define macros

and there are no stability guarantees for these manual defines.

- `DEBUG_LEVEL=0..3`

  - `0` use the default set of asserts; implied if macro is not defined at all

  - `1`, `2` *unused*

  - `3` additionally assert assumptions usually pledged to the compiler for optimization purposes

Information about the ASS format:

=================================

- [ASS format overview](https://github.com/libass/libass/wiki/ASS-File-Format-Guide)

- [ASS override tags (Aegisub manual)](http://docs.aegisub.org/latest/ASS_Tags/)

- [VSFilter source code (Guliverkli2)](http://sourceforge.net/p/guliverkli2/code/HEAD/tree/src/subtitles/)

Other ASS/SSA implementations:

==============================

- VSFilter:

  - [xy-VSFilter/XySubFilter](https://github.com/Cyberbeing/xy-VSFilter/)

    - [pfmod](https://github.com/pinterf/xy-VSFilter/)

  - VSFilter in [MPC-HC](https://github.com/clsid2/mpc-hc/tree/develop/src/filters/transform/VSFilter/)

  - [VSFilterMod](https://code.google.com/archive/p/vsfiltermod/) with custom format extensions (defunct, subsumed by forks)

    - [sorayuki fork](https://github.com/sorayuki/VSFilterMod/) with some bugfixes (defunct)

    - various forks focussing on internal use

  - [Threaded VSFilter](https://code.google.com/p/threaded-vsfilter/) (defunct)

  - VSFilter in [Guliverkli2](http://sourceforge.net/projects/guliverkli2/) (defunct, subsumed by all of the above)

  - VSFilter in [guliverkli](http://sourceforge.net/projects/guliverkli/) (defunct, forked as Guliverkli2)

- [ffdshow](http://ffdshow-tryout.sourceforge.net/) (defunct)

- [Perian](https://github.com/MaddTheSane/perian) (defunct)

- [asa](https://web.archive.org/web/20110906033709/http://asa.diac24.net/) (defunct)

- [libjass](https://github.com/Arnavion/libjass) (defunct)

- [ASS.js](https://github.com/weizhenye/ASS)

Packaging status

================

[![Packaging status](https://repology.org/badge/vertical-allrepos/libass.svg?columns=3&header=libass&exclude_unsupported=1)](https://repology.org/project/libass/versions)