  In this work, we pose and address the following "cover song analogies"
problem: given a song A by artist 1 and a cover song A' of this song by artist
2, and given a different song B by artist 1, synthesize a song B' which is a
cover of B in the style of artist 2. Normally, such a polyphonic style transfer
problem would be quite challenging, but we show how the cover songs example
constrains the problem, making it easier to solve. First, we extract the
longest common beat-synchronous subsequence between A and A', and we time
stretch the corresponding beat intervals in A' so that they align with A. We
then derive a version of joint 2D convolutional NMF, which we apply to the
constant-Q spectrograms of the synchronized segments to learn a translation
dictionary of sound templates from A to A'. Finally, we apply the learned
templates as filters to the song B, and we mash up the translated filtered
components into the synthesized song B' using audio mosaicing. We showcase our
algorithm on several examples, including a synthesized cover version of Michael
Jackson's "Bad" by Alien Ant Farm, learned from the latter's "Smooth Criminal"
cover.'
