FLAC 1.2.1
Writableaudio
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 0664c614300000022 at byte 0 |
| PRONOM | fmt/279 |
| Wikidata | Q27881556Q131481410 |
| Library of Congress | fdd000198 |
Not sure your file is this? Identify it from its first bytes, in your browser.
Open it
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Convert it
Convert a file in your browser The steps marked “in browser” run on your machine; nothing is uploaded.
| To | With | Fidelity | Command and losses |
|---|---|---|---|
| WAV | FFmpeg | Lossless | ffmpeg -i in.flac out.wavLossless for decoded audio; a lossy source stays as degraded as it was. WAV may reduce bit depth or drop metadata. |
| WAV | FFmpeg (WebAssembly) | Lossless | in browser Lossless for decoded audio; a lossy source stays as degraded as it was. |
| Advanced Audio Coding | FFmpeg (WebAssembly) | Lossy | in browser Lossy re-encoding. |
| Matroska | FFmpeg | Lossy | ffmpeg -i in.flac out.mkvRe-encoded with lossy codecs by default; try `-c copy` to remux without re-encoding when the codecs fit the container. |
| MP3 | FFmpeg | Lossy | ffmpeg -i in.flac out.mp3Lossy re-encoding. |
| MP3 | FFmpeg (WebAssembly) | Lossy | in browser Lossy re-encoding. |
| MP4 | FFmpeg | Lossy | ffmpeg -i in.flac out.mp4Re-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.oggLossy re-encoding. |
| Ogg | FFmpeg (WebAssembly) | Lossy | in browser Lossy re-encoding. |
| Ogg Opus Codec Compressed Multimedia File | FFmpeg (WebAssembly) | Lossy | in browser Lossy re-encoding. |
| WebM | FFmpeg | Lossy | ffmpeg -i in.flac out.webmRe-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), 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.