What is FLAC file?

Free Loss Audio Codec (FLAC) is an audio codec for lossless audio data compression, primarily authored by Josh Coalson.

FLAC is specifically designed for efficient packing of audio data, unlike general purpose lossless algorithms such as DEFLATE which is used in ZIP and grip. While ZIP may compress a CD-quality audio file by 10-20%, FLAC achieves compression rates of 30-50% for most music, with significantly greater compression for voice recordings. By contrast, lossy codecs can achieve ratios of 80% or more by discarding data from the original stream.

FLAC accomplishes data compression without sacrificing the integrity of the audio source, since it does not discard any part of the data. A digital audio recording (such as a CD track) converted by FLAC can be decompressed into an identical copy of the audio data. Audio sources encoded to FLAC are typically reduced to 50%-60% of their original size.