How does Shazam work?

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  Kaustubh Katdare

  Shazam is definitely one of the most interesting apps that surely creates 'WOW' when you use it for the first time. At the bottom of the post, I will link to the article that explains it all in depth (it's a 11000 word article!) but if you only want to know a summary, then here it is: -
  
  The technology that is used by Shazam is a work of Avery Li-Chun Wang, who has published a paper #-Link-Snipped-#
  The technique used is called audio fingerprinting. The technique is very complicated to understand but it basically creates a digital map of the audio file. What Shazam does is - it computes the digital map of large number of audio tracks, tens of thousands of GBs. This map is stored on the fingerprint database cluster of servers. As you'd guess, Shazam keeps this map updated with new tracks it discovers.
  
  The magic happens when you make the app listen to any sound track. The app quickly creates a digital fingerprint of the track it has recorded and then sends this map information to the central search server. The server then matches the input fingerprint with its database and finds out the most relevant match. If you have used Shazam, you'd know that it does it with impeccable accuracy!
  
  Shazam also keeps track of the metadata associated with each song. Metadata basically is the information associated with every track: the song file name, the URL, artwork, iTunes or Amazon URL etc.
  
  Now this may look relatively easy; but when you look deeper; Shazam does lot of backdoor work to filter out the noise while converting the track digitally. The blog linked below gives a very detailed information on how it all works. Do go through it!
  
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