Howard Jones wrote:
Chuck Swiger wrote:
[ ...ID'ing skips in music... ]
Sort of...GraceNote and a few other companies ("Shazam", seems to be
from India?) sell a service where music files can be fingerprinted and
identified.  Good audio files ought to ID as what they are; bad music
files with skips or garbage will fail to ID.

Shazam (at least) works on a fragment the song. In the UK they provide a
phone-based service, which only needs 20-30 seconds of clear music to
identify a song.

Yeah, that's right. But there's also a fingerprinting tool which creates something called QCF files (Qualcom something-or-other) which analyses the entire song and should notice major skips or distortions better.

[ ... ]
I'm also looking for a blip-detecting MP3 tool. I haven't had time to
look at it yet, but I was going to try something like libmad on the
assumption that somewhere internally it knows when it's only had half an
frame of data, even if there is no CRC. That way, it'll work on any
obscure music I have, without relying on some external giant database of
correctness.

That's the rub of the matter: most home-grown tools are going to find it hard to recognize a skip from Trent Reznor or a lot of rap music, or a dropout with silences common in classic music, etc. :-)

With the external giant database of correctness, you've got something which actually can tell that a song isn't correct, rather than making guesses, even if you have to break your samples down into 10 to 30 second pieces and check them all individually.

[ Again, I would try using the QCF fingerprinting tool instead of exhaustive submatch checking. On the other hand, if you can manage to put together something which can guess well, I'd be interested in seeing it... ]

--
-Chuck
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