Fujitsu Corporation

Akira Kamano

Yohei Kishi

Masanao Suzuki

Takeshi Otani

Shunsuke Takeuchi

Miyuki Shirakawa

Nobuyuki Washio

Naoshi Matsuo

Shouji Harada

A method for encoded-sound determination performed by a computer includes: executing a first process that includes obtaining information indicating intensities of sound signals, the frequencies being calculated from the sound signals and corresponding to frequencies; and executing a second process that includes determining whether or not the sound signals are signals of encoded sound, based on whether or not the intensities of the sound signals in predetermined frequency bands that are adjacent to each other in a frequency direction have a difference that is larger than or equal to a predetermined threshold.

Encoded-sound determination method

There is provided an audio encoding apparatus including a memory, and a processor coupled to the memory and the processor configured to determine whether a tone is included in a boundary between a low-frequency that is a frequency bandwidth below a predetermined frequency of an input signal and a high-frequency that is a frequency bandwidth above the predetermined frequency of the input signal, suppress a tone in one of the low-frequency and the high-frequency, encode the input signal having the low-frequency to generate a low-frequency code, encode the input signal having the high-frequency to generate a high-frequency code, and generate an encoded stream by multiplexing the low-frequency code and the high-frequency code.

Audio encoding apparatus and audio encoding method

A pitch extraction device includes a processor configured to perform a process including: dividing a first bit stream in encoded data into a plurality of sections each having a prescribed section length, the encoded data being obtained by performing entropy encoding on a residual signal calculated by performing linear prediction analysis on a sound signal; allocating a first value or a second value to each of the plurality of sections in the first bit stream in accordance with a bit value in each of the plurality of sections; generating a second bit stream obtained by re-encoding the first bit stream according to the first value and the second value that have been allocated to each of the plurality of sections in the first bit stream; and calculating a fundamental frequency of the sound signal in accordance with an autocorrelation of the second bit stream.

Pitch extraction device and pitch extraction method by encoding a bitstream organized into equal sections according to bit values

An abnormality detecting device includes a memory, and a processor coupled to the memory and configured to: detect an envelope of an audio signal indicating a periodic sound emitted by a target object and a periodic sound emitted by another object; execute time-to-frequency conversion on the envelope to calculate a frequency spectrum of the audio signal; and determine whether or not the target object has an abnormality, based on a frequency component included in the frequency spectrum and corresponding to a time interval between time points when the sound is emitted by the target object.

Abnormality detecting device, abnormality detection method, and recording medium storing abnormality detection computer program

An audio coding device includes a filter configured to extract a low-band signal having a first frequency component from an input signal, a memory, and a processor coupled to the memory and configured to extract envelope information relating to an envelope of a high-band signal having a second frequency component which is higher than the first frequency component in the input signal, detect tone information that is information on a tone signal included in a high-band signal spectrum from the input signal, correct the envelope information based on a difference between frequency of the tone signal and frequency of a peak of the envelope, and code the low-band signal, the tone information, and the envelope information that is corrected.

Audio coding device and audio coding method

An audio encoding device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute: calculating a similarity in phase of a first channel signal and a second channel signal contained in a plurality of channels of an audio signal; and selecting, based on the similarity, a first output that outputs one of the first channel signal and the second channel signal, or a second output that outputs both of the first channel signal and the second channel signal.

Audio encoding device and audio coding method

A plurality of candidates of prediction coefficients of a channel signal out of a plurality of channel signals are extracted from a code book storing a plurality of prediction coefficients, each candidate having a predictive error falling within a specific range of predictive error of predictive encoding of two other channel signals, and a prediction coefficient is selected from the extracted candidates as a result of the predictive encoding in accordance with a specific data embedding rule and embedding embed target data into the selected prediction coefficient.

Data embedding device, data embedding method, data extractor device, and data extraction method for embedding a bit string in target data

A device for embedding data upon a prediction coding of a multi-channel signal includes a storage unit to store a code book that includes a plurality of prediction parameter sets, each of the plurality of prediction parameter sets including a plurality of kinds of prediction parameters for a processing regarding the prediction coding. The device extracts a plurality of candidates of a prediction parameter set for the multi-channel signal from the code book, wherein the plurality of candidates are capable of suppressing a prediction error in the prediction coding within a predetermined range, converts an embedding object that is at least part of the data in accordance with a number corresponding to a number of the candidates, selects, from the plurality of candidates, the prediction parameter set corresponding to the converted embedding object, and multiplexes the selected prediction parameter set with coded data which are down-mixed from the multi-channel signal.

Device and method data for embedding data upon a prediction coding of a multi-channel signal

An orthogonal transform apparatus includes: an interchanging unit which interchanges MDCT coefficients contained in a first half of a prescribed interval with MDCT coefficients contained in a second half thereof; an inverting unit which inverts the sign of the MDCT coefficients contained in the second half of the prescribed interval after the interchange; an inverse cosine transform unit which computes the real components of QMF coefficients by applying an IMDCT using FFT to the MDCT coefficients contained in the first half and the sign-inverted MDCT coefficients contained in the second half; an inverse sine transform unit which computes the imaginary components of the QMF coefficients by applying an IMDST using FFT to the MDCT coefficients contained in the first half and the sign-inverted MDCT coefficients contained in the second half; and a coefficient adjusting unit which computes the QMF coefficients by combining the real components with the imaginary components.

Orthogonal transform apparatus, orthogonal transform method, orthogonal transform computer program, and audio decoding apparatus

An audio encoding device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute: detecting a plurality of lobes based on a frequency signal constituting an audio signal; calculating a masking threshold value of the frequency signal; allocating an amount of bits per unit frequency region to be allocated for encoding of the frequency signal on a basis of the masking threshold value; selecting a main lobe on a basis of bandwidth and power of the lobes; and controlling the encoding by reducing the amount of bits in a first region including a maximum value of the power in the main lobe.

Audio encoding device and audio encoding method

An audio coding device includes a memory; and a processor configured to execute a plurality of instructions stored in the memory, the instructions comprising: selecting a main lobe among a plurality of lobes detected from a frequency signal configuring an audio signal on a basis of bandwidth and power of the lobes; and coding the audio signal in such a manner that a first amount of bits per a unit frequency domain allocated to coding of the frequency signal of the main lobe is larger than a second amount of bits per the unit frequency domain allocated to the coding of the frequency signal of a side lobe as a lobe other than the main lobe.

Audio coding device, audio coding method, and audio codec device

An audio coding device that performs predictive coding on a third-channel signal included in a plurality of channels in an audio signal according to a first-channel signal and a second-channel signal, which are included in the plurality of channels, and to a plurality of channel prediction coefficients included in a coding book, the device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute, selecting channel prediction coefficients corresponding to the first-channel signal and the second-channel signal so that an error, which is determined by a difference between the third-channel signal before predictive coding and the third-channel signal after predictive coding, is minimized; and controlling the first-channel signal or the second-channel signal so that the error is further reduced.

Audio coding device and method

An orthogonal transform apparatus computes either one of the real and imaginary components of the quadrature mirror filter coefficient contained in a first subinterval of a plurality of subintervals among which a coefficient sequence containing a plurality of quadrature mirror filter coefficients is divided so that the values of basis functions are symmetrically placed, by computing a sum of products of the plurality of modified discrete cosine transform coefficients and the basis functions corresponding to the subinterval, computes the other one of the real and imaginary components of the quadrature mirror filter coefficient contained in the first subinterval and the real and imaginary components of the quadrature mirror filter coefficient contained in another subintervals by performing a butterfly operation using a computed value produced as a result of the sum of products and computes each quadrature mirror filter coefficient by combining the real component and imaginary component thereof.

An audio decoding device includes a processor; and a memory which stores a plurality of instructions, which when executed by the processor, cause the processor to execute, decoding, using a first channel signal and a second channel signal included in a plurality of channels of an audio signal having a first frequency range and a second frequency range, a first prediction coefficient of the first frequency range and a second prediction coefficient of the second frequency range, both selected from a code book when prediction-encoding a third channel signal that is not subjected to prediction encoding and that is included in the plurality of channels; decoding a residual signal included in the first frequency range, the residual signal representing an error occurring in prediction encoding; and prediction-decoding the third channel signal subjected to prediction-encoding in the second frequency range from the first channel signal, the second channel signal.

Audio decoding device and audio decoding method

An utterance state detection device includes an user voice stream data input unit that gets user voice stream data of an user, a frequency element extraction unit that extracts high frequency elements by frequency-analyzing the user voice stream data, a fluctuation degree calculation unit that calculates a fluctuation degree of the high frequency elements thus extracted every unit time, a statistic calculation unit that calculates a statistic every certain interval based on a plurality of the fluctuation degrees in a certain period of time, and an utterance state detection unit that detects an utterance state of a specified user based on the statistic obtained from user voice stream data of the specified user.

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Kawasaki, Japan

Akira Kamano