Information processing device, tempo detection device and video processing system

1. An information processing device comprising:

an acquisition part that acquires samples of musical sound signals in a time series, wherein the samples of the musical sound signals comprises a current sample of the musical sound signals and a past sample of the musical sound signals;

an evaluation part that has an adaptive filter using the current sample as a reference signal and using the past sample of the musical sound signals, acquired a predetermined time earlier than the current sample of the musical sound signals, as an input signal; and

a tempo determination part that sequentially inputs the samples of the musical sound signals to the adaptive filter and determines a tempo corresponding to a musical sound based on the predetermined time when a value of a filter coefficient of the adaptive filter converges to a predetermined value in accordance with a periodicity of the musical sound signals.

2. The information processing device according to claim 1 ,

wherein the filter coefficient comprises a plurality of coefficients, and

wherein the tempo determination part inputs a sample group of a plurality of past samples of the musical sound signals acquired within a predetermined period as the input signal to the adaptive filter.

3. The information processing device according to claim 2 , wherein the tempo determination part determines a value corresponding to a time difference between a sample of the input signal multiplied by a coefficient indicating a maximum value among a plurality of converged coefficients and the reference signal as the tempo corresponding to the musical sound.

4. A video processing system comprising:

the information processing device according to claim 3 ; and

a control device that switches between a plurality of video sources respectively corresponding to a plurality of cameras at a timing in accordance with a tempo determined by the information processing device.

5. A video processing system comprising:

the information processing device according to claim 2 ; and

a control device that switches between a plurality of video sources respectively corresponding to a plurality of cameras at a timing in accordance with a tempo determined by the information processing device.

6. The information processing device according to claim 1 ,

wherein the filter coefficient comprises a plurality of coefficients, and

wherein the input signal comprises a plurality of first input signals and a plurality of second input signals, and

wherein the tempo determination part inputs a sample group of a plurality of musical sound signals acquired within a first period as the first input signals and inputs a sample group of a plurality of musical sound signals acquired within a second period as the second input signals to the adaptive filter, and

wherein the second period has a length of a multiple of n times the first period and continues from the first period, and n is an integer equal to or greater than 2.

7. The information processing device according to claim 6 , wherein the tempo determination part determines a value corresponding to a time difference between a sample of the first and second input signals multiplied by a coefficient indicating a maximum value among a plurality of converged coefficients and the reference signal as the tempo corresponding to the musical sound.

8. A video processing system comprising:

the information processing device according to claim 6 ; and

a control device that switches between a plurality of video sources respectively corresponding to a plurality of cameras at a timing in accordance with a tempo determined by the information processing device.

9. A video processing system comprising:

the information processing device according to claim 1 ; and

a control device that switches between a plurality of video sources respectively corresponding to a plurality of cameras at a timing in accordance with a tempo determined by the information processing device.”

10. A tempo detection device comprising:

a musical sound signal acquisition part that acquires musical sound signals; and

a tempo detection part that comprises:

a sampling part that uses signals obtained after the musical sound signals are sampled at a predetermined frequency, as samples of the musical sound signals;

a signal delaying part that delays the samples of the musical sound signals by a predetermined number of time steps to generate samples, which are past samples, generated earlier than a latest time step by the predetermined number of time steps; and

an adaptive filter unit using a sample of the latest time step as a reference signal, using a sample of the past samples as an input signal, and updating a filter coefficient of the adaptive filter unit so that an error between the input signal and the reference signal is a minimum, and

wherein the tempo detection part sequentially inputs the samples of the musical sound signals and determines a tempo corresponding to a musical sound based on the predetermined number of time steps when a value of the filter coefficient of the adaptive filter unit converges to a predetermined value in accordance with a periodicity of the musical sound signals.

11. The tempo detection device according to claim 10 ,

wherein the filter coefficient comprises a plurality of coefficients, and

wherein the tempo detection part inputs a sample group of the plurality of past samples of the musical sound signals acquired within a predetermined period as the input signal to the adaptive filter unit.

12. The tempo detection device according to claim 11 , wherein the tempo detennination part determines a value corresponding to a time difference between a sample of an input signal multiplied by a coefficient indicating a maximum value among a plurality of converged coefficients and the reference signal as the tempo corresponding to the musical sound.

13. The tempo detection device according to claim 10 ,

wherein the filter coefficient comprises a plurality of coefficients,

wherein the input signal comprises a plurality of first input signals and a plurality of second input signals, and

wherein the tempo detection part inputs a sample group of a plurality of past samples of musical sound signals acquired within a first period as the first input signals and a sample group of a plurality of past samples of musical sound signals acquired within a second period as the second input signals to the adaptive filter unit, and

wherein the second period has a length of a multiple of n times the first period and continues from the first period, and n is an integer equal to or greater than 2.

14. An information processing method comprising:

acquiring samples of musical sound signals in a time series, wherein the samples of the musical sound signals comprising a current sample of the musical sound signals and a past sample of the musical sound signals;

using an adaptive filter by treating the current sample as a reference signal and using the past sample of the musical sound signals, acquired a predetermined time earlier than the current sample of the musical sound signals, as an input signal; and

sequentially inputting the samples of the musical sound signals to the adaptive filter; and

determining a tempo corresponding to a musical sound based on the predetermined time when a value of a filter coefficient of the adaptive filter converges to a predetermined value in accordance with a periodicity of the musical sound signals.

15. The information processing method according to claim 14 ,

wherein the filter coefficient comprises a plurality of coefficients, and

sequentially inputting the samples of the musical sound signals to the adaptive filter comprises inputting a sample group of a plurality of past samples of the musical sound signals acquired within a predetermined period as the input signal to the adaptive filter.

16. The information processing method according to claim 15 , wherein determining the tempo comprises determining a value corresponding to a time difference between a sample of the input signal multiplied by a coefficient indicating a maximum value among a plurality of converged coefficients and the reference signal as the tempo corresponding to the musical sound.

17. The information processing method according to claim 14 ,

wherein the filter coefficient comprises a plurality of coefficients,

wherein the input signal comprises a plurality of first input signals and a plurality of second input signals, and

wherein sequentially inputting the samples of the musical sound signals to the adaptive filter comprises inputting a sample group of a plurality of musical sound signals acquired within a first period as the first input signals and inputting a sample group of a plurality of musical sound signals acquired within a second period as the second input signals to the adaptive filter, and

wherein the second period has a length of a multiple of n times the first period and continues from the first period, and n is an integer equal to or greater than 2.