Waltzify - turn any 4/4 song into a waltz with Echo Nest remix
Tristan Jehan, one of the founders here at the Echo Nest, has created a Python script that will take a 4/4 song and turn it into a waltz. The script uses Echo Nest remix, a Python library that lets you algorithmically manipulate music. Here's an example of the output of the script when applied to the song 'Fame':
[soundcloud url="http://api.soundcloud.com/tracks/40686045" iframe="true" /]
Turning a 4/4 song into a 3/4 song while still keeping the song musical is no easy feat. But Tristan's algorithm does a pretty good job. Here's what he does:
Start with a 4/4 measure
Cut the 4/4 measure into 2 bars with 2 beats in each bar
Stretch the first beat of each bar by 100%
Adjust the tempo to a typical waltz tempo
Here's a graphic that shows the progression:
Here are some more examples:
[soundcloud url="http://api.soundcloud.com/playlists/1776722" height="200" iframe="true" /]
Tristan has made the waltzifier code available on github. If you want to make your own waltzes, get yourself an Echo Nest API key and grab Echo Nest remix and start enjoying the power of 3.