WhoSampled for iPhone app review Once you've started the app and created an account, WhoSampled will scan your music library and compare it to its vast database. It takes a moment or two, depending on the size of your library, and then you will be able to explore the connections in your music. The result is enlightening and addictive. Choose an artist or a track and WhoSampled will list songs that have sampled it or in which it has been sampled and will do the same if the song is a cover version or has been covered. Choose, for example, to see where a song has been sampled and WhoSampled will provide a YouTube clip of the song in question and even tell you how many seconds into the track the sample occurs. The WhoSampled database, which is also available online, conatins 150,000 tracks and is growing at a rate of 1,000 entries per week so most music collections will deliver at least some hits. That's not to say there aren't gaps in the database, particularly with more obscure tracks. The Venetian Snares track Hajnal, for example, the entry for which is in the picture above, also contains samples of Bartok's first string quartet and Mahler's third symphony, neither of which is in the WhoSampled database. It would be great to see WhoSampled extended into a Mac app for those whose entire music collection is not on the phone or perhaps somehow extended so that it can scan iTunes Match songs from the cloud. I could also see enormous potential for WhoSampled as a Spotify app. As it is, it's well-designed, simple to use and essential for any music fan's phone.