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View Full Version : How to use FLAC"s test function?????


bob francais
2007-11-09, 01:49 AM
What does it mean to "test" a FLAC file?
A feature that sets FLAC apart from all other major lossless formats is it's ability to self-test itself. Basically, any FLAC file stores an md5 checksum of the audio content contained within the file (also called the FLAC Fingerprint) within the header of the file itself. By using FLAC's "test" function, you are able to run the check on the audio, compare it to the fingerprint stored when the file was encoded, and confirm that they are the same.
Since the flac file stores an md5 checksum of the audio content contained within the header of the file itself, how do you run the test itself? so I can compare it to the fingerprint when the file was encoded? Thank you.

Tubular
2007-11-09, 12:39 PM
To test them, just drop them into FLAC Frontend or Trader's Little Helper and hit 'test'.

To verify them with a FLAC fingerprint, install Trader's Little Helper, then double click the FLAC fingerprint (.ffp) file that came with the show. Sometimes they are named .txt files, just rename them to .ffp files. It will verify the integrity of the files. If they all test green (not red) there are no errors and your show was correctly downloaded and complete.

Tubular
2007-11-09, 01:07 PM
You might get a show that tests OK, but the .ffp that came with the show and/or the .ffp that is listed in a database won't match. In that case someone has changed the audio data by fixing SBEs, going FLAC > audio CD > EAC > FLAC, or by going FLAC > mp3 > FLAC, or changed it in some other way.

Five
2007-11-09, 01:24 PM
the checksum stored in the header is not md5, it is something else, the same thing that 'shntool md5' aka st5 uses and is generated using the decompressed audio. APE files are also able to be self-tested, but I don't know what checksum they are using in the header and recommend using st5 because its useful for comparing lossless transcodes to verify if they are identical or not. TLH does all this and more. Of the lossless formats allowed here, only SHN cannot be self-tested. The self-test just checks that the file will decode properly.