How Shazam and Google Music Search store audio.

1. Searching for sounds

2. Looking for a song
● Title O(1)
● Artist O(n)
● Lyrics O(n^2)
● Sounds Oh man ...

3. Is it even possible?
● Shazam
● Google Sound Search
● Sony TrackID
● Sound Hound
● Bing Music

4. Sound files
● Store the whole file
● Not all audio files are created equal
(.wav .wv .ape .flac. .m4p .mp3)
● Index on a blob file
● Any difference in frequency or intensity wil
result in a non-match

5. Sound waves
● Represent the sounds in wave form instead
● The whole file is now an array of frequency
over time
● However, intensity is ignored

6. Adding intensity
● No loss of information
● Complex data

7. Dealing with the complexity
● Shazam stores only the top 10% most intense
sounds
● Google Sound Search applies Fourier
transform to the data

8. What about indexes
● The remaining information is stored in a hash
● Several frequencies are combined to minimize
collisions