You know the old story – if you put a frog in a pot of cold water and gradually heat the pot up, the frog won’t notice and will happily sit in the pot until the water boils and the frog is turned into frog soup. This story is at the core of my winter break programming project called Boil the Frog. Boil the Frog will take you from one music style to another gradually enough so that you may not notice the changes in music style. Just like the proverbial frog sitting in a pot of boiling water, with a Boil the Frog playlist, the Justin Bieber fan may find themselves listening to some extreme brutal death metal such as Cannibal Corpse or Deicide (the musical equivalent to sitting in a pot of boiling water).
To use Boil the Frog, you type in the names of any two artists you’ll be given a playlist that connects the two artists. Click on the first artist to start listening to the playlist. If you don’t like the route taken to connect two artists, you can make a new route by bypassing an offending artist. The app uses Rdio to play the music. If you are an Rdio subscriber, you’ll hear full tracks, if not you’ll hear a 30 second sample of the music.
You can create some fun playlists with this app such as:
- Miley Cyrus to Miles Davis
- Justin Bieber to Jimi Hendrix
- Patti Smith to the Smiths
- Elvis to Elvis
- The Carter Family to Rammstein
- Kanye West to Taylor Swift
- Cage the Elephant to John Cage
- Ryan Adams to Bryan Adams
- Righteous Brothers to Steven Wright
How does it work? To create this app, I use The Echo Nest artist similarity info to build an artist similarity graph of about 100,000 of the most popular artists. Each artist in the graph is connected to it’s most similar neighbors according to the Echo Nest artist similarity algorithm.
To create a new playlist between two artists, the graph is used to find the path that connects the two artists. The path isn’t necessarily the shortest path through the graph. Instead, priority is given to paths that travel through artists of similar popularity. If you start and end with popular artists, you are more likely to find a path that takes you though other popular artists, and if you start with a long-tail artist you will likely find a path through other long-tail artists. Without this popularity bias many routes between popular artists would venture into back alleys that no music fan should dare to tread.
Once the path of artists is found, we need to select the best songs for the playlist. To do this, we pick a well-known song for each artist that minimizes the difference in energy between this song, the previous song and the next song. Once we have selected the best songs, we build a playlist using Rdio’s nifty web api.
This is the second version of this app. I built the first version during a Spotify hack weekend. This was a Spotify app that would only run inside Spotify. I never released the app (the Spotify app approval process was a bit too daunting for my weekend effort), so I though I’d make a new version that runs on the web that anyone can use.
I enjoy using Boil the Frog to connect up artists that I like. I usually end up finding a few new artists that I like. For example, this Boil The Frog playlist connecting Deadmau5 and Explosions in the Sky is in excellent coding playlist.