FLAC 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 typesaudio/x-flacaudio/flac
Signatures
664c6143 at byte 0
664c614300000022 at byte 0
PRONOMfmt/279
WikidataQ27881556Q131481410
Library of Congressfdd000198

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Open it

Convert it

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ToWithFidelityCommand and losses
WAVFFmpegLosslessffmpeg -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.
WAVFFmpeg (WebAssembly)Losslessin browser
Lossless for decoded audio; a lossy source stays as degraded as it was.
Advanced Audio CodingFFmpeg (WebAssembly)Lossyin browser
Lossy re-encoding.
MatroskaFFmpegLossyffmpeg -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.
MP3FFmpegLossyffmpeg -i in.flac out.mp3
Lossy re-encoding.
MP3FFmpeg (WebAssembly)Lossyin browser
Lossy re-encoding.
MP4FFmpegLossyffmpeg -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.
OggFFmpegLossyffmpeg -i in.flac out.ogg
Lossy re-encoding.
OggFFmpeg (WebAssembly)Lossyin browser
Lossy re-encoding.
Ogg Opus Codec Compressed Multimedia FileFFmpeg (WebAssembly)Lossyin browser
Lossy re-encoding.
WebMFFmpegLossyffmpeg -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.
0

Sources

From Converters (FFmpeg, ImageMagick, Pandoc, LibreOffice), WebAssembly engines (ImageMagick, FFmpeg, Pandoc, 7-Zip, GDAL, Assimp, resvg), Just Solve the File Format Problem (File Formats Wiki), PRONOM, Wikidata. Updated 2026-10-26.

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