flac

FLAC stands for Free Lossless Audio Codec, a widely used open-source audio compression format designed for lossless data reduction. As a lossless codec, a FLAC file can be decoded to reproduce the exact original PCM audio without any loss of information, ensuring identical playback quality to the source.

In typical use, FLAC achieves substantial reductions in file size while preserving audio integrity. Compression ratios often fall around 40–60% of the original uncompressed data, depending on the program material. The format supports a broad range of audio specifications, including sample rates up to 655,350 Hz and bit depths from 4 to 32 bits, with up to eight audio channels. It employs a block-based encoding model and offers robust metadata capabilities, including Vorbis-style comments, album artwork, and cue sheets.

A FLAC file usually uses the .flac filename extension and is stored as a stream that can be packaged within various containers or carried as standalone FLAC files. The format is designed to be free of royalties, with reference implementations such as libFLAC that provide decoder and encoder functionality. The FLAC specification and tooling are openly available, encouraging broad adoption in software and hardware alike.

FLAC is widely used for music archiving, high-fidelity distribution, and scenarios where exact audio reproduction is essential. It is supported by major media players, operating systems, and hardware devices, making it a common choice for preserving and sharing high-quality recordings without the compromises of lossy formats like MP3 or AAC.