Patent ID: 7884276

Claim:
A method of generating tempo data from an audio signal, the method comprising: determining a set of reference tempos; determining a set of reference note durations, each reference note duration representing a length of time that a predetermined note type lasts at each reference tempo; determining a tempo extraction window, representing a contiguous portion of the audio signal extending from a first time location to a second time location; generating a set of note onset events by locating the note onset events occurring within the contiguous portion of the audio signal; generating a note spacing for each note onset event, each note spacing representing the time interval between the note onset event and the next-subsequent note onset event in the set of note onset events; generating a set of error values, each error value being associated with an associated reference tempo, wherein generating the set of error values comprises: dividing each note spacing by each of the set of reference note durations; rounding each result of the dividing step to a nearest multiple of the reference note duration used in the dividing step; and evaluating the absolute value of the difference between each result of the rounding step and each result of the dividing step; identifying a minimum error value of the set of error values; and determining an extracted tempo associated with the tempo extraction window, wherein the extracted tempo is the associated reference tempo associated with the minimum error value.