[Flac] Re: flac fingerprint

[Harry Sack]

2007/10/15, David W. Tamkin <dattier at panix.com>:
>
> Harry,
>
> > so i was wondering what advantages it could give me to make a ffp
> > file, because there is already a internally stored md5 checksum on the
> > decoded audio data inside the flac file?
>
> Testing the .flac file against its internally stored fingerprint lets
> you know that you have a properly encoded .flac file of *something*.  If
> you also certify that internally stored fingerprint against a list of
> correct fingerprints in another file, then you know you have a properly
> encoded .flac file of the *right* audio, and that the person who sent
> you the .flac files didn't accidentally provide a wrong file instead.
>
> Yes, a miscreant who would intentionally switch .flac files on you would
> also alter the .ffp file to show the fingerprint of the wrong file
> instead of the right one, but that could not happen by accident.
> Sending a set of .flac files with an .ffp file says, "I wouldn't
> deliberately deceive you"; sending a set of .flac files with no
> checksums at all says "I never make mistakes."  There are people whom
> I'd trust not to deceive me deliberately but nobody from whom I'd accept
> a claim of infallibility.
>
> Moreover, if a set of .flac files is being shared, a copy of the
> fingerprints can be kept at a URL distributed with them, so that
> everyone receiving them can make sure that the fingerprints of the files
> (s)he gets match those of the original set.



yes, I all understand that, but I mean advantages when you don't send those
files over the internet. So just encode them and burn them to a cd. Or is a
ffp file only useful when you want to upload those files?

> i was also wondering how files encoded by using the new
> > --keep-existing-metadata option are verified when using -verify. Is
> > there a separate internally stored md5 for metadata next to the md5
> > for decoded audio data or how is everything verified?
>
> Until we hear from someone who knows, I'd venture to say that --verify
> does just what it always did, and it has nothing to do with existing
> metadata in the uncompressed input.  As it encodes each segment of the
> audio, it re-decodes it and compare the result to the original input.



but how can you verify the metadata of the input files then if there is no
check for this?

> Is making a ffp file for such files also possible for the non-audio
> > data (so all metadata)?
>
> No, fingerprints are defined only for audio.



same question as above

> i was also wondering if there exists a GUI program for win32 to verify
> > flac files using a ffp file (so not md5check.exe)
>
> Yes: Trader's Little Helper at http://thor.prohosting.com/roh0205/.



thx, it's exactly what i'm looking for! unfortunately the file is offline,
can you maybe email the file to me if you still have it?
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