FLAC (Free Lossless Audio Codec) 1.2.1

Writable

audio

FLAC stands for Free Lossless Audio Codec, an audio format similar to MP3, but lossless, meaning that audio is compressed in FLAC without any loss in quality. The basic structure of a FLAC stream is: •The four byte string "fLaC" •The STREAMINFO metadata block •Zero or more other metadata blocks •One or more audio frames The first four bytes are to identify the FLAC stream. The metadata that follows contains all the information about the stream except for the audio data itself. After the metadata comes the encoded audio data.

Identify it

Extensions	`.flac`
MIME types	`audio/x-flacaudio/flac`
Signatures	`664c6143` at byte 0 `664c614300000022` at byte 0
PRONOM	`fmt/279`
Wikidata	`Q27881556Q131481410`
Library of Congress	`fdd000198`

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Open it

FFmpegOpen sourcereads and writes · LGPL-2.1-or-later / GPL-2.0-or-later
Free Lossless Audio CodecOpen sourcereads and writes · 3-clause BSD License / GNU General Public License, version 2.0 / GNU Library General Public License, version 2.0
Q141674392Open sourcereads and writes · Apache Software License 2.0 / MIT License
Q191782Open sourcewrites · GNU General Public License, version 3.0
Q6928182Open sourcereads and writes · GNU General Public License
EasyTAGOpen sourcereads · GNU General Public License, version 2.0 or later
ElisaOpen sourcereads · GNU Lesser General Public License, version 3.0
Ex FalsoOpen sourcereads · GNU General Public License
GravemanOpen sourcereads · GNU General Public License
LiquidsoapOpen sourcereads · GNU General Public License, version 2.0
mutagenOpen sourcereads · GNU General Public License, version 2.0
PhotoRecOpen sourcereads · GNU General Public License
PuddletagOpen sourcereads · GNU General Public License
Q117725Open sourcereads · GNU General Public License, version 2.0
Q1576579Open sourcereads · GNU General Public License, version 2.0 or later
Q201809Open sourcereads · GNU General Public License, version 2.0
RubyripperOpen sourcereads · GNU General Public License
VLC media playerOpen sourcereads · GNU Lesser General Public License, version 2.1 or later
Audify Music Playerreads · proprietary license
Jaikozreads
JetAudioreads
Praatreads
Q300915reads · freeware
thousand tunes playerreads · proprietary license

Convert it

To	With	Fidelity	Command and losses
Waveform Audio	FFmpeg	Lossless	`ffmpeg -i in.flac out.wav` Lossless for decoded audio; a lossy source stays as degraded as it was. WAV may reduce bit depth or drop metadata.
Matroska 1-4	FFmpeg	Lossy	`ffmpeg -i in.flac out.mkv` Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.
MPEG 1/2 Audio Layer 3	FFmpeg	Lossy	`ffmpeg -i in.flac out.mp3` Lossy re-encoding.
MPEG-4 Part 14	FFmpeg	Lossy	`ffmpeg -i in.flac out.mp4` Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.
Ogg	FFmpeg	Lossy	`ffmpeg -i in.flac out.ogg` Lossy re-encoding.
WebM	FFmpeg	Lossy	`ffmpeg -i in.flac out.webm` Re-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container.

Sources

From Converters (FFmpeg, ImageMagick, Pandoc, LibreOffice), Just Solve the File Format Problem (File Formats Wiki), PRONOM, Wikidata. Updated 2026-10-24.

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