I don't know about Shazam's current algorithm specifically, but years ago I worked at a place with a mathematician that worked on gracenote's algorithms, and asked him for the basics on how it works.
Basically, it records audio chopping it up into small segments and throwing them through a FFT. Then it takes that, and thinking of the data like a greyscale spectrograph image, runs it through a quantization filter that helps reject some noise, then converts that to locality sensitive hashes that are sent to the server. So basically FFT, filter, hash, lookup.
Basically, it records audio chopping it up into small segments and throwing them through a FFT. Then it takes that, and thinking of the data like a greyscale spectrograph image, runs it through a quantization filter that helps reject some noise, then converts that to locality sensitive hashes that are sent to the server. So basically FFT, filter, hash, lookup.