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Convert FLAC Audio Free

.flac Free Lossless Audio Codec

Lossless: decoding gives back every original sample, bit for bit, and STREAMINFO carries an MD5 of them to prove it. Open a FLAC file (or the sample written here) to see its metadata blocks and walk every frame header with its CRC-8 checked.

folder_openOpen .flacSample written heresample-tone.flac (written here)

sample rate44100 Hz

channels · bits2 · 16-bit

duration2.00 s

frames found22

block size2184, 4096

file0.34 MB

audio data0.34 MB

raw PCM would be0.35 MB

ratio96.5% of PCM

avg bitrate1362 kb/s

offsetblockbytescontents

0fLaC4stream marker

4STREAMINFO3844100 Hz · 2 ch · 16-bit · 88,200 samplesblocks 4096-4096MD5 (not set)

42VORBIS_COMMENT77vendor FileFormerTITLE=Sample toneARTIST=FileFormerDATE=2026

119PADDING516zeros reserved for later tag edits without rewriting the file

635frames34046622 frames, each header CRC-8 verified, each frame ends with a CRC-16

frames · first-channel subframe types

VERBATIM 100%

check_circleFrame headers found22 frames with valid sync code 0xFFF8 and CRC-8; fixed block size.

check_circleFrame count fits the sample total22 × 4096 ≈ 88,200 samples

infoAudio MD5 in STREAMINFOnot set (the sample here leaves it zero): decoders can’t verify the audio

infoPrediction usedmostly VERBATIM subframes: the encoder stored raw samples (the sample here does, on purpose), so nothing was compressed

Reference sheet

MIMEaudio/flac

Extension.flac (.oga when FLAC is wrapped in Ogg)

Magic bytes66 4C 61 43 “fLaC” at offset 0

StandardRFC 9639 (IETF, 2024)

Bit depth4-32 bits per sample

Sample rate1 Hz: 1,048,575 Hz (20-bit field)

Channels1-8, with left/side, right/side and mid/side stereo

Block size16-65,535 samples; 4096 is libFLAC’s default

Predictionfixed polynomials of order 0-4, or LPC up to order 32, plus Rice-coded residuals

ChecksCRC-8 per frame header, CRC-16 per frame, MD5 of all decoded audio

2000First releaseJosh Coalson publishes FLAC 0.5.

2001FLAC 1.0Stable bitstream; it has stayed compatible since.

2003Xiph.OrgThe project joins the Xiph.Org Foundation.

2014Android & Windows 10Native FLAC playback arrives on major platforms.

2017iOS 11Apple adds FLAC to the Files app.

2024RFC 9639The IETF publishes FLAC as a standard.

Audio Converter (writes FLAC)WAV to FLAC FLAC to MP3 WAV format RFC 9639