From Music Hack Day
Automello is an automatic sampler that takes a pile of music, extracts individual notes & beats, and assigns them to keys according to pitch.
Zeke Runyon and Colin Raffel
 About the hack
Automello takes in a set of audio files and analyzes all of them using the echonest remix API. Each audio file is chopped up into individual segments which correspond to individual notes and beats in the song. The echonest noisiness feature is used to select the most tonal snippets for each song. For each of these hopefully tonal snippets, a "harmonic monophonicity" feature is calculated. This feature is a modified spectral crest factor which divides the maximum magnitude in all bins of harmonics of a given frequency to the spectral mean of all other bins and should be large for snippets which are single notes, and small for drums or chords The non-noisy segments are sorted by this feature for each note in the chromatic scale. For each note, the pitch of the snippets with the largest harmonic monophonicity is calculated using the YIN algorithm. The snippet with the correct pitch and maximal harmonic monophonicity for any given note is used as the sample for that note. Once samples for every note have been found, the samples are loaded into a VST instrument. This software instrument can be loaded into any digital audio workstation and can be played with standard MIDI messages.
 What APIs, tools or kit did you use?