[roann]

Originally Posted by johnnydesoto

Hello,

I hope this isn't too dumb a question but can someone explain this message received when testing encoded audio? :

"file is decodable without error, but flac fingerprint does not match"

I've also gotten this message when verifying files

"failed verification (checksum in file header does match, but checksum of audio data does not match"

I'm using the most recent Traders helper

thanks

At first sight the answer may be confusing because it's a lengthy technical one. So please read carefully.

(1) Error message "file is decodable without error, but flac fingerprint does not match"

When encoding a wav file to flac format the flac encoder calculates a checksum of the raw wave data (the so called flac fingerprint) and stores it in the header of the flac file. When decoding a flac file back to wav format the flac decoder not only decodes the data but additionally creates a checksum of the decoded data and compares it against the flac fingerprint.

So the error message tells you that a) there weren't any errors in the decoding process but b) the re-calculated checksum does not match the fingerprint. In other words, either the checksum header part or the audio data part of the flac file is corrupt.

Most times it's the audio data simply because it is by far the biggest part of the flac file (the checksum part is only a few bytes long). Usually this happens when you backup files on CD or DVD (either there was a bad write or the CD/DVD becomes corrupt over the years).

(2) Error message "failed verification (checksum in file header does match, but checksum of audio data does not match"

When testing a .ffp file three checksums are involved with each flac file listed in the checksum file. The first checksum (#1) is the one given in the checksum file, of course. The second one (#2) is the flac fingerprint (see above). The third one (#3) is the re-calculated checksum from the decoded audio data (see above).

TLH compares each checksum against the other ones. The error message tells you that a) the checksum in the .ffp file (#1) matches the flac fingerprint (#2) but b) the re-calculated checksum of the decoded data (#3) does not match these two ones. In other words, either the checksum header part or the audio data part of the flac file is corrupt.

For creating a .ffp checksum file all programs that are able to do that just read the fingerprint from the flac file header, but there isn't any checking done whether the file is still valid or not. So most likely the following has happened: The checksum header part or the audio part of the flac file for any reason became corrupt. A .ffp checksum file was created after the corruption took place. So checksums #1 and #2 do match but checksum #3 does not match.

Robert