FLAC (Free Lossless Audio Codec) is a codec (compressor-decompressor) which allows digital audio to be losslessly compressed such that file size is reduced without any information being lost.

Digital audio compressed by FLAC's algorithm can typically be reduced to 50–60% of its original size, and decompressed into an identical copy of the original audio data.

FLAC is an open format with royalty-free licensing and a reference implementation which is free software. FLAC has support for metadata tagging, album cover art, and fast seeking.

Though FLAC playback support in portable audio devices and dedicated audio systems is limited compared to formats like MP3 or uncompressed PCM, FLAC is supported by more hardware devices than competing lossless compressed formats like WavPack.


The FLAC project consists of:

The stream formats
A simple container format for the stream, also called FLAC (or Native FLAC)
libFLAC, a library of reference encoders and decoders, and a metadata interface
libFLAC++, an object wrapper around libFLAC
flac, a command-line program based on libFLAC to encode and decode FLAC streams
metaflac, a command-line metadata editor for .flac files and for applying ReplayGain
Input plugins for various music players (Winamp, XMMS, foobar2000, musikCube, and many more)
With Xiph.org incorporation, the Ogg container format, suitable for streaming (also called Ogg FLAC)
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