[Five]

another dated but useful article from 2004

Originally Posted by RainDawg

FLAC Fingerprints

As an alternative to the wholefile md5 scheme required for .shn files, a newer format called the Free Lossless Audio Codec addressed this issue by making an md5 check of just the audio data contained within the file an inherent part of the file's structure. This elegant concept adds a short segment to the header of the FLAC file itself which contains an md5 of the original uncompressed PCM .wav data. This value is called the "fingerprint", a fitting title as it only validates the audio, not the extra data appended to the file. Using the FLAC fingerprint method, users could add or remove tags or change the compression setting and not change the actual audio contained within. Since the fingerprint only checks audio data, traders could change these values at will and they will still verify as identical to the original.

.flac gained rapid support of lossless traders over .shn for several other reasons. First, the filetype is both seekable and seamless, meaning no seek table data had to be appended to the file to use it in your favorite media player. It also contains a check during decoding that actually performs a check of the stored fingerprint value to what's actually inside the file, and if they don't match, the file will not decode. This double-checking ensures that files corrupted during transfer are unusable and therefore the error will not be passed on.

FLAC's use of the fingerprint allows users much more versatility while still maintaining the same core functionality : verifiying that the audio in your files has not altered since it was seeded. Of course, a user may still use wholefile md5 checks on .flac files if they see fit, but this is a practice performed out of ignorance rather than functionality. Using FLAC's fingerprinting is much more useful than wholefile md5 checking, and should be used 100% of the time.

• Creating a FLAC Fingerprint File Using FLAC Frontend