A "music mixer", as described herein, provides a capability for automatically mixing arbitrary pieces of music, regardless of whether the music being mixed is of the same music genre, and regardless of whether that music has strong beat structures. In automatically determining potential mixes of two or more songs, the music mixer first computes a frame-based energy for each song. Using the computed frame-based energies, the music mixer then computes one or more potentially optimal alignments of the digital signals representing each song based on correlating peaks of the computed energies across a range of time scalings and time shifts without the need to ever compute or evaluate a beats-per-minute (BPM) for any of the songs. Then, once one of the potentially optimal time-scalings and time-shifts has been selected, the songs are then simply blended together using those parameters.