Introduction to FLAC

What’s Flac?

FLAC stands for Free Lossless Audio Codec. FLAC is an audio compression codec that is lossless. That means that unlike lossy codecs such as Mp3, Vorbis or AAC, FLAC doesn’t remove any information from the audio stream: it’s a perfect copy of CD track it originates from, and as such can restore the original waveform flawlessly.

FLAC project artwork

In this way, FLAC acts very much like general compression algorithms like Zip. Except that while Zip usually compresses about 20-40% a CD quality audio file, FLAC achieves higher compression rates of 30-70%.

"Free" means that the specification of the stream format is in the public domain, and that neither the FLAC format nor any of the implemented encoding/decoding methods are covered by any patent. Encoders and decoders are available on most popular operating system and players. This warrants the long term durability of your music collection.

Why is it so popular?

FLAC is currently the most popular lossless codec, due to its numerous advantages:

 Lossless: the encoding of audio data incurs no loss of information, so that we can reverse back to the original signal. It includes CRC and MD5 signatures to ensure integrity.

 Free: the format specifications are in the public domain, and no patent cover any part of the encoding/decoding methods. There are also open-source implementations available.

 Fast: FLAC is an assymetric algorithm; it is the fastest lossless decoder while its encoder is in the high average.

 Software support: FLAC is available on most modern operating systems, players and audio tools.

 Hardware support: FLAC is the only lossless codec supported by hardware devices such as home stereo, car stereo and portable/handheld devices.

 Best candidate for online music shop: and as a matter of fact, this is the first lossless format to be already sold online.

 Streamable: FLAC streams can be instantly played anywhere within their stream: decoding a frame doesn’t rely on previous ones.

 Seekable: FLAC supports fast sample-accurate seeking. This is useful for playback, but above all for editing applications.

 Flexible metadata: FLAC format allows storing of meta-data blocks such as Vorbis comments, CUE-Sheets or seektables. It is forward-compatible, meaning that future metadata will work on older implementations.

 Error resistant: if an error/corruption happens, this will damage the single related frame (meaning a small fraction of second), whereas in most lossless formats this would mean lost of the whole remainder of the stream.

 No SDMI/DRM or any “protection” methods: you’re still the owner of your files and nobody else can determine on your behalf your level of freedom.