wire / magic / flac

FLAC signature (fLaC)

A native FLAC audio stream begins with the 4-byte ASCII marker 'fLaC' (0x66 0x4C 0x61 0x43), immediately followed by the STREAMINFO metadata block.

magic kind signature status standard verification verified tier B file-signature@1

aka: FLAC magic · fLaC

file signature

magic: 66 4C 61 43 @ offset 0

ascii: fLaC

.flac audio/flac

spec: FLAC format specification (Xiph.Org)

The marker is exactly the ASCII 'fLaC' (note the capitalization).
Immediately followed by metadata blocks, the first of which must be STREAMINFO.
FLAC audio can also be carried inside an Ogg container (then the outer magic is 'OggS').