An Audio-based Real-time Beat Tracking System and Its Applications

This paper describes a real-time beat tracking system that recognizes a rhythmic structure in real-world audio signals sampled from popular-music compact discs. Most previous beat-tracking systems dealt with MIDI signals and had difficulty in processing, in real time, audio signals containing sounds of various instruments and in tracking beats above the quarter-note level. Our system can process music without drums and music with drums and can — on the basis of three kinds of musical knowledge (of onset times, of chord changes, and of drum patterns) — recognize the hierarchical beat structure comprising the quarter-note, half-note, and measure levels. This paper also introduces several beat-tracking applications, such as beat-driven real-time computer graphics and lighting control.