US 6,787,689 B1Granted

Fast beat counter with stability enhancement

AssigneeIndustrial Technology Research Institute Computer & Communication Research Laboratories

InventorFang-Chu Chen

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Abstract

A real time, multi-function beat counting system used in machine perception of musical rhythms employs a high speed stable algorithm including down sampling and group summing of the original signal, pulse matching on peak points, and check-frame decision making. The down sampled and group summed signal is utilized to derive an onset peak train formed of a series of data points. The onset peak train is divided into frames, and a threshold value is determined for each frame. In each frame, peak profiles are determined, each comprising successive data points within the frame having values greater than the threshold value. Within each peak profile, a peak point is identified. An algorithm is employed to compare the onset peak train with a plurality of unit data pulse sequences having different periods, and a match is determined between the onset peak train and the closest one of the unit data pulse sequences to identify the period of the rhythm.

Claims10

Dependent claims

A method of determining a rhythmic beat of a digital sound signal, said method comprising:

(a) down sampling the digital signal by a predetermined factor to produce a decimated signal comprising a plurality of first data points;
(b) grouping said plurality of first data points into groups each comprising a predetermined number of said first data points of said decimated signal and summing absolute values of said data points in each of said groups to produce a group-summed signal comprising a plurality of second data points;
(c) dividing said plurality of second data points of said onset peak train into a plurality of successive frames of uniform duration;
(d) determining for each of said frames a threshold value and detecting, within each of said frames, peak profiles each comprising successive ones of said second data points having values greater than said threshold value;
(e) detecting, within each of said peak profiles, a peak point having a greatest value among said successive ones of said second data points;
and
(f) determining a match between (i) said peak point and ones of said second data points located at least one of before and after said peak point and (ii) one of a plurality of unit data pulse sequences, having different periods, in accordance with an algorithm, wherein said rhythmic beat is determined to correspond to the period of said one of said unit pulse sequences, wherein
said threshold value is defined by a relation (A+M′)/2, where A is the average of the values of all of said second data points within one of said frames and M′ is the maximum of the values of all of said second data points within said one of said frames.

5 more elements

An apparatus for determining a rhythmic beat of a digital sound signal, said apparatus comprising:

(a) decimation means for down sampling the digital signal by a predetermined factor to produce a decimated signal comprising a plurality of first data points;
(b) group summation means for grouping said plurality of first data points into groups each comprising a predetermined number of said first data points of said decimated signal and summing absolute values of said data points in each of said groups to produce a group-summed signal comprising a plurality of second data points;
(c) means for dividing said plurality of second data points of said onset peak train into a plurality of successive frames of uniform duration;
(d) determination means for determining for each of said frames a threshold value and for detecting, within each of said frames, peak profiles each comprising successive ones of said second data points having values greater than said threshold value;
(e) detection means for detecting, within each of said peak profiles, a peak point having a greatest value among said successive ones of said second data points;
and
(f) match detection means for determining a match between (i) said peak point and ones of said second data points located at least one of before and after said peak point and (ii) one of a plurality of unit data pulse sequences, having different periods, in accordance with an algorithm, wherein said rhythmic beat is determined to correspond to the period of said one of said unit pulse sequences, wherein said threshold value is defined by a relation (A+M′)/2, where A is the average of the values of all of said second data points within one of said frames and M′ is the maximum of the values of all of said second data points within said one of said frames.

4 more elements

Dependencies are inferred from the claim text.