Abstract: In an audio analysis apparatus, a component acquirer acquires a component matrix composed of an array of component values, columns of the component matrix corresponding to the sequence of unit periods of an audio signal and rows of the component matrix corresponding to a series of unit bands of the audio signal arranged in a frequency-axis direction. A difference generator generates a plurality of shift matrices each obtained by shifting the columns of the component matrix in the time-axis direction with a different shift amount, and generates a plurality of difference matrices each composed of an array of element values in correspondence to the plurality of the shift matrices, the element value representing a difference between the corresponding component values of the shift matrix and the component matrix.

Abstract: Character value of a sound signal is extracted for each unit portion, and degrees of similarity between the character values of the individual unit portions are calculated and arranged in a matrix configuration. The matrix has arranged in each column the degrees of similarity acquired by comparing, for each of the unit portions, the sound signal and a delayed sound signal obtained by delaying the sound signal by a time difference equal to an integral multiple of a time length of the unit portion, and it has a plurality of the columns in association with different time differences. Repetition probability is calculated for each of the columns corresponding to the different time differences in the matrix. A plurality of peaks in a distribution of the repetition probabilities are identified. The loop region in the sound signal is identified by collating a reference matrix with the degree of similarity matrix.

Abstract: In a musical analysis apparatus, a spectrum acquirer acquires a spectrum for each frame of an audio signal representing a piece of music. A beat specifier specifies a sequence of beats of the audio signal. A feature amount extractor divides an interval between the beats into a plurality of analysis periods such that one analysis period contains a plurality of frames, and separates the spectrum of the frames contained in one analysis period into a plurality of analysis bands so as to set a plurality of analysis units in one analysis period in correspondence with the plurality of the analysis bands, such that one analysis unit contains components of the spectrum belonging to the corresponding analysis band.

Abstract: Mask generation section generates an evaluating mask, indicative of a degree of dissonance with a target sound per each frequency along a frequency axis, by setting, for each of a plurality of peaks in spectra of the target sound, a dissonance function indicative of relationship between a frequency difference from the peak and a degree of dissonance with a component of the peak. Index calculation section collates spectra of an evaluated sound with the evaluating mask to thereby calculate a consonance index value indicative of a degree of consonance or dissonance between the target sound and the evaluated sound.

Abstract: In a musical analysis apparatus, a spectrum acquirer acquires a spectrum for each frame of an audio signal representing a piece of music. A beat specifier specifies a sequence of beats of the audio signal. A feature amount extractor divides an interval between the beats into a plurality of analysis periods such that one analysis period contains a plurality of frames, and separates the spectrum of the frames contained in one analysis period into a plurality of analysis bands so as to set a plurality of analysis units in one analysis period in correspondence with the plurality of the analysis bands, such that one analysis unit contains components of the spectrum belonging to the corresponding analysis band.

Abstract: In an audio analysis apparatus, a component acquirer acquires a component matrix composed of an array of component values, columns of the component matrix corresponding to the sequence of unit periods of an audio signal and rows of the component matrix corresponding to a series of unit bands of the audio signal arranged in a frequency-axis direction. A difference generator generates a plurality of shift matrices each obtained by shifting the columns of the component matrix in the time-axis direction with a different shift amount, and generates a plurality of difference matrices each composed of an array of element values in correspondence to the plurality of the shift matrices, the element value representing a difference between the corresponding component values of the shift matrix and the component matrix.

Abstract: The apparatus for converting an information signal from a time to a variable spectral representation includes a means for windowing the information signal, a means for converting the windowed information signal to a spectral representation, and a means for weighting a set of information signal spectral coefficients with several sets of complex base function coefficients provided from a means for providing the sets of base function coefficients. The sets of base function coefficients are derived from base functions of various frequencies by windowing and transform, wherein several sets of base function coefficients are provided for one and the same base function for base functions of higher frequencies, wherein the windows for providing these sets are related to various time portions of the base function. The variable spectral representation exhibits variable bandwidth of the variable spectral coefficients, which are efficient and accurate to calculate and especially suited for music analysis purposes.

Abstract: Analysis section divides waveform data of a given music piece into waveform data of a plurality of fragments and divides the waveform data of each of the fragments into one or more events of sound, and obtains a character value indicative of a character of the waveform data pertaining to each of the divided events. Storage section stores respective music piece data and music piece composing data of one or more music pieces. The music piece composing data include a character value indicative of a character of the waveform data pertaining to each of the events of each of the fragments. Search section searches (or retrieves) for, from among the stored music piece composing data, one event or a plurality of successive events having a character value of a high degree of similarity to one or more events included in a designated fragment.

Abstract: Storage section has stored therein music piece data sets of a plurality of music pieces, each of the music piece data sets including respective tone data of a plurality of fragments of the music piece and respective character values indicative of musical characters of the fragments. Each of the fragments of a selected main music piece is selected as a main fragment, and each one, other than the selected main fragment, of a plurality of fragments of two or more music pieces is selected as a sub fragment. A similarity index value indicative of a degree of similarity between the character value of the main fragment and the character value of the specified sub fragment is calculated. For each of the main fragments, a sub fragment presenting a similarity index value that satisfies a predetermined selection condition is selected for processing the tone data of the main music piece.

Abstract: An apparatus for determining a type of chord has a means for providing a reference vector for the type of chord, a means for providing a reference vector from a test signal, and a means for comparing the reference vector with the test signal vector. The means for providing a reference vector is configured to provide, for the type of chord, a reference vector from a plurality of different reference vectors. In addition, the means for providing a test signal vector from the test signal is configured to provide the test signal vector having a plurality of test signal vector elements.

Abstract: For each of a plurality of music pieces, a storage device stores respective tone data of a plurality of fragments of the music piece and respective musical character values of the fragments. Similarity determination section calculates a similarity index value indicative of a degree of similarity between the character values of each of the fragments of a main music piece and the character values of each individual fragment of a plurality of sub music pieces. Each of the similarity index values calculated for the fragments of each of the sub music pieces can be adjusted in accordance with a user's control. Processing section processes the tone data of each of the fragments of the main music piece on the basis of the tone data of any one of the fragments of the sub music pieces of which the similarity index value indicates sufficient similarity.

Abstract: Mask generation section generates an evaluating mask, indicative of a degree of dissonance with a target sound per each frequency along a frequency axis, by setting, for each of a plurality of peaks in spectra of the target sound, a dissonance function indicative of relationship between a frequency difference from the peak and a degree of dissonance with a component of the peak. Index calculation section collates spectra of an evaluated sound with the evaluating mask to thereby calculate a consonance index value indicative of a degree of consonance or dissonance between the target sound and the evaluated sound.

Abstract: Character value of a sound signal is extracted for each unit portion, and degrees of similarity between the character values of the individual unit portions are calculated and arranged in a matrix configuration. The matrix has arranged in each column the degrees of similarity acquired by comparing, for each of the unit portions, the sound signal and a delayed sound signal obtained by delaying the sound signal by a time difference equal to an integral multiple of a time length of the unit portion, and it has a plurality of the columns in association with different time differences. Repetition probability is calculated for each of the columns corresponding to the different time differences in the matrix. A plurality of peaks in a distribution of the repetition probabilities are identified. The loop region in the sound signal is identified by collating a reference matrix with the degree of similarity matrix.

Abstract: The apparatus for converting an information signal from a time to a variable spectral representation includes a means for windowing the information signal, a means for converting the windowed information signal to a spectral representation, and a means for weighting a set of information signal spectral coefficients with several sets of complex base function coefficients provided from a means for providing the sets of base function coefficients. The sets of base function coefficients are derived from base functions of various frequencies by windowing and transform, wherein several sets of base function coefficients are provided for one and the same base function for base functions of higher frequencies, wherein the windows for providing these sets are related to various time portions of the base function. The variable spectral representation exhibits variable bandwidth of the variable spectral coefficients, which are efficient and accurate to calculate and especially suited for music analysis purposes.

Abstract: Analysis section divides waveform data of a given music piece into waveform data of a plurality of fragments and divides the waveform data of each of the fragments into one or more events of sound, and obtains a character value indicative of a character of the waveform data pertaining to each of the divided events. Storage section stores respective music piece data and music piece composing data of one or more music pieces. The music piece composing data include a character value indicative of a character of the waveform data pertaining to each of the events of each of the fragments. Search section searches (or retrieves) for, from among the stored music piece composing data, one event or a plurality of successive events having a character value of a high degree of similarity to one or more events included in a designated fragment.

Abstract: Storage section has stored therein music piece data sets of a plurality of music pieces, each of the music piece data sets including respective tone data of a plurality of fragments of the music piece and respective character values indicative of musical characters of the fragments. Each of the fragments of a selected main music piece is selected as a main fragment, and each one, other than the selected main fragment, of a plurality of fragments of two or more music pieces is selected as a sub fragment. A similarity index value indicative of a degree of similarity between the character value of the main fragment and the character value of the specified sub fragment is calculated. For each of the main fragments, a sub fragment presenting a similarity index value that satisfies a predetermined selection condition is selected for processing the tone data of the main music piece.

Abstract: For each of a plurality of music pieces, a storage device stores respective tone data of a plurality of fragments of the music piece and respective musical character values of the fragments. Similarity determination section calculates a similarity index value indicative of a degree of similarity between the character values of each of the fragments of a main music piece and the character values of each individual fragment of a plurality of sub music pieces. Each of the similarity index values calculated for the fragments of each of the sub music pieces can be adjusted in accordance with a user's control. Processing section processes the tone data of each of the fragments of the main music piece on the basis of the tone data of any one of the fragments of the sub music pieces of which the similarity index value indicates sufficient similarity.

Abstract: An audio encoding method of coding audio signals into a layered data stream having a first layer and a second layer is presented. The second layer serves as an enhancement of the first layer. The method involves forming an original digital audio signal, encoding the original signal to obtain a first layer signal, producing a residual signal to reflect a difference between the original signal and the first layer signal, selecting either the original signal or the residual signal for encoding, and producing a second layer signal by encoding the selected signal. Moreover, the residual signal is evaluated and, in case the result of the evaluation meets given criteria, a predetermined low-entropy signal is selected to be encoded as the second layer signal, instead of the original signal or the residual signal.

Abstract: An apparatus for determining a type of chord has a means for providing a reference vector for the type of chord, a means for providing a reference vector from a test signal, and a means for comparing the reference vector with the test signal vector. The means for providing a reference vector is configured to provide, for the type of chord, a reference vector from a plurality of different reference vectors. In addition, the means for providing a test signal vector from the test signal is configured to provide the test signal vector having a plurality of test signal vector elements.

Abstract: An audio encoding method of coding audio signals into a layered data stream having a first layer and a second layer is presented. The second layer serves as an enhancement of the first layer. The method involves forming an original digital audio signal, encoding the original signal to obtain a first layer signal, producing a residual signal to reflect a difference between the original signal and the first layer signal, selecting either the original signal or the residual signal for encoding, and producing a second layer signal by encoding the selected signal. Moreover, the residual signal is evaluated and, in case the result of the evaluation meets given criteria, a predetermined low-entropy signal is selected to be encoded as the second layer signal, instead of the original signal or the residual signal.