This is a great post that captures what a spectrogram does, and a must read for people who want to understand how audio fingerprinting works.
There are similar approximate algorithms available for other media as well, so anyone who wishes to understand real world hashing should take their time to study this article.
The normal spectrogram technique was already invented by Phillips prior to Shazam. What Shazam did was to hash things combinatorial to reduce false positives.
This is a great post that captures what a spectrogram does, and a must read for people who want to understand how audio fingerprinting works.
There are similar approximate algorithms available for other media as well, so anyone who wishes to understand real world hashing should take their time to study this article.