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Comment by gkoberger | Hacker News Reader

A bit of background on this post:

http://yro.slashdot.org/story/10/07/08/2311225/Open-Source-M...

Basically, Shazam sent the author a cease and desist. The post was removed for a bit, but it's now back up.

Interesting that they sent a C&D considering the algorithm is likely patent pending at best. Aren't there other services, like Midori, that likely use the same 'obvious' algorithm of storing a database of frequency points per song and comparing it to the sample?

It shows how sick the patent system has become. The whole reason for patents is to provide public disclosure of the methods in the patent for the public benefit, so that they can be discussed, improved upon and not lost to humanity when a particular invention is no longer made by its inventor. It is explicitly part of their purpose that they become public knowledge and can be openly discussed.

Perhaps that's why the post is back up - I don't believe the bits and pieces described in the article are patentable. (Fourier has been used in signal processing for decades. Adding a nearest-neighbor lookup - also know for decades - is a trivial extension.)

I did a master degree on pattern matching on text in 1999 (same year Shazam started), and it was obvious then that much of the same concepts (many of them from textbooks stemming from the 1970s) could be used for pattern matching on music. (We even discussed implementing music matching, but couldn't see a market for it.)

There may very well be other parts of music fingerprint algorithms that are patentable, but I have a hard time believing that the parts described in the article could be.

One nontrivial part is transforming the spectrogram into some representation that is robust to the things that can affect the query audio, like background noise. Another nontrivial part is figuring out, given this representation, how to quickly match the query with a song or database of songs.

Philips and Fraunhofer have a whole pile of patents on audio fingerprinting, it would be hard to not violate any patents in this subfield.

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