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FLAC is currently in the beta stage and the format has been frozen. The current version is 0.9. See here for the changes since 0.8. There might be one more beta before the final release. In CVS, the decoder has been sped up by almost a factor of 2 already since 0.9 and there will be some assembly optimizations on the encoder side to test out soon.

Remember, since FLAC is still technically beta, always use the verify option (-V) when encoding before deleting your originals.

If you use FLAC and have suggestions or bugs, please join the mailing list or developers group and help us move to an official 1.0 version.

what is FLAC?

FLAC stands for Free Lossless Audio Codec. Grossly oversimplified, FLAC is similar to MP3, but lossless. The FLAC project consists of:

  • the stream format
  • libFLAC, which implements a reference encoder, stream decoder, and file decoder
  • flac, a command-line wrapper around libFLAC to encode and decode .flac files
  • input plugins for various music players (Winamp, XMMS, and more in the works)

"Free" means that the specification of the stream format is in the public domain (the FLAC project reserves the right to set the FLAC specification and certify compliance), and that neither the FLAC format nor any of the implemented encoding/decoding methods are covered by any patent. It also means that the source for libFLAC is available under the LGPL and the sources for flac and the plugins are available under the GPL.

See the features page, documentation page, or FLAC format page for more info, the comparison page to see how the reference encoder measures up, or the goals page for what the FLAC project hopes to achieve.


Visit the download page for links to the source code or pre-built binaries, or go directly to the source on SourceForge.


The documentation is available online as well as in the distributions. The general installation and usage documentation for flac and the plugins is here. For a detailed description of the FLAC format and reference encoder see the FLAC format page.

id registration

If you have an application that uses FLAC and would like it to be able to tag .flac files with custom metadata, visit the registration page to register an ID for your application.

message from the maintainer

I came up with FLAC because no audio compression format I could find did everything I needed. Since I couldn't mash them all together (most are closed-source), I solidified all my requirements (now the FLAC goals) and wrote the first implementation. I intended to open-source it from the beginning for two reasons: 1) so that people who knew more about audio compression than me could help improve it; and 2) I wanted to give something back to the OS community, whose huge body of work I rely on so much.

So I started the FLAC project on SourceForge as soon as I had a relatively complete first implementation. Now I'm the maintainer of the FLAC project. You can get in touch with me about it through the mailing list or directly

--Josh Coalson

31-Mar-2001 :
  Version 0.9 released
05-Mar-2001 :
  Version 0.8 released
12-Feb-2001 :
  Version 0.7 released
28-Jan-2001 :
  FLAC gets FASTER for version 0.6
15-Jan-2001 :
  FLAC goes beta with version 0.5
23-Dec-2000 :
  Version 0.4 released
10-Dec-2000 :
  FLAC debuts on SourceForge

SourceForge project page
Freshmeat page
First Principles
Audio encoding tools
S/W that uses FLAC:
Baudline signal analyzer
Split_wav WAV+CUE splitter

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