I found 2 different recordings are constantly related to a same acoutID

[chaban]

You seem to be misunderstanding the purpose of AcoustID. It’s not meant to distinguish recordings but to identify files:

acoustID 2-minute mark

How did you find out they do not end at 2:00? Picard explicitly calls the AcoustID fingerprinting tool with fpcalc -length 120 to limit the audio to 2 minutes. That’s also the default value for fpcalc. The reason behind that decision was that in order to identify a file, you don’t need more than that, so running the algorithm on the whole file is a waste of time. The fingerprinting algorithms MusicBrainz used before only used 60 seconds (MusicIP) and 30 seconds (TRM, if I remember correctly).

acoustID 2-minute mark

It’s mostly just CPU. Back when I was designing AcoustID, I really wanted it to be super fast. For Picard-style lookups, even the 2 minutes was too much, but I though it’s a nice compromise. I didn’t realize AcoustIDs would get used for other purposes, like checking which recordings are the same, it was only meant as a search tool. I’d like to upgrade the database to full fingerprints, but the server code currently doesn’t handle that, so I need to first make it possible to replace those short …

ID generation and calculation

The process of assigning individual audio fingerprints to “AcoustIDs” is a little flawed, unfortunately. There are two main factors: It takes the reported duration into consideration and that is often reported incorrectly. It uses a simple average of the difference scores over the entire duration of the fingerprint. This is not OK if we are dealing with small song variations, like exactly the same background track with different vocals. Or slight mixing changes. The algorithm is tuned to …

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