Evaluation of beats, chords and downbeats from a musical audio signal

摘要

A server system 500 is provided for receiving video clips having an associated audio/musical track for processing at the server system. The system comprises a beat tracking module for identifying beat time instants (t_i) in the audio signal and a chord change estimation module for determining a chord change likelihood from chroma accent information in the audio signal at the beat time instants (t_i). Further, first and second accent-based estimation modules are provided for determining respective first and second accent-based downbeat likelihood values from the audio signal at the beat time instants (t_i) using respective different algorithms. A final stage of processing identifies downbeats occurring at beat time instants (t_i) using a predefined score-based algorithm that takes as input numerical representations of chord change likelihood and the first and second accent-based downbeat likelihood values at the beat time instants (t_i).