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Aften is an audio encoder which generates compressed audio streams based on ATSC A/52 specification. This type of audio is also known as AC-3 or Dolby® Digital and is one of the audio codecs used in DVD-Video content.


The most recent release is Aften 0.0.8. View the Changelog for a list of changes for this version. Older versions can also be found on the Aften Sourceforge project page.


The Aften project started as a stand-alone commandline version of the FFmpeg AC-3 encoder. Since then, there have been many functional and structural changes and several additional features added. The project Changelog details much of the development history.

The name, Aften, is an acronym for:
A Fifty-Two ENcoder
It is also Danish and Norwegian for 'evening'.

The reference specification for the encoding algorithm and bitstream format is ATSC Standard A/52: Digital Audio Compression (AC-3), Revision A. There is also now a Revision B, which includes the specification for E-AC-3 (a.k.a. Dolby® Digital Plus), one of the codecs used in HD-DVD and Blu-ray. E-AC-3 encoding is one of the future goals of the Aften project.


Development of Aften is very active, and there are some major changes currently in-the-works. There are several ways to keep up-to-date on the latest improvements, make suggestions, and report bugs.

The best way is to join the Aften-devel mailing list. The Sourceforge project page has bug reporting features and access to the current git source code repository. There is a thread about Aften on the Doom9 forum. Development ponderings are posted by Justin to the Aftenblog. As a last resort, you can simply email Justin.

The command to checkout the latest git version is:
git clone git://
You can also view the git repository online.


 • Commandline help
 • Building Aften with CMake


Licensing and Disclaimer

The majority of this software is licensed under the GNU Lesser General Public License. Portions of this software are licensed under the variant of the BSD license. Each source file specifies the license under which it is released.

The authors make no claims that this software or any content created with this software is Dolby® Digital compliant. As such, any content which is created with this software should not be labeled as containing Dolby® Digital technology, nor should it bear any registered trademarks of Dolby Laboratories or any other trademark holder unless otherwise authorized. Logo