Panasonic Corporation

Panasonic Intellectual Property Corporation of America

Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Masahiro Oshikiri

Tomofumi Yamanashi

Takuya Kawashima

Hiroyuki Ehara

Toshiyuki Morii

Zongxian Liu

Katsunori Daimou

Koji Yoshida

Kok Seng Chong

Srikanth Nagisetty

Kaoru Sato

Takako Hori

Michiyo Goto

Provided are a voice audio encoding device, voice audio decoding device, voice audio encoding method, and voice audio decoding method that efficiently perform bit distribution and improve sound quality. Dominant frequency band identification unit identifies a dominant frequency band having a norm factor value that is the maximum value within the spectrum of an input voice audio signal. Dominant group determination units and non-dominant group determination unit group all sub-bands into a dominant group that contains the dominant frequency band and a non-dominant group that contains no dominant frequency band. Group bit distribution unit distributes bits to each group on the basis of the energy and norm variance of each group. Sub-band bit distribution unit redistributes the bits that have been distributed to each group to each sub-band in accordance with the ratio of the norm to the energy of the groups.

Voice audio encoding device, voice audio decoding device, voice audio encoding method, and voice audio decoding method

A coding apparatus includes a processor and a memory that stores instructions, which when executed causes the processor to perform operations, including encoding a first band of an input audio signal to be a first spectrum and dividing the first spectrum into a plurality of sub-bands. The operations also include searching a largest amplitude value of the divided first spectrum in each of the plurality of sub-bands, and normalizing the divided first spectrum in each of the plurality of sub-bands. The operations further include emphasizing a harmonic structure in the normalized first spectrum, and searching a best band that has a largest correlation value between each divided band of a second band spectrum and the emphasized first spectrum in which the harmonic structure is emphasized, and encoding the second band spectrum using lag information identifying the best band and transmitting the lag information to a decoder side.

Encoding apparatus, decoding apparatus, and methods

A coding apparatus, including a memory and a processor that, when executing instructions stored in the memory, performs operations including encoding low-band transform coefficients in a first band and calculating, for each extension-band subband obtained by splitting an extension band, a threshold amplitude based on an analysis of statistics on extension-band transform coefficients included in the subband. The processor further compares, for each of the extension-band subbands, an amplitude of the extension-band transform coefficients with the threshold amplitude to extract a representative transform coefficient, updates, when a number of the extracted representative transform coefficients is less than a predetermined number, the threshold amplitude, performs processing to again extract a transform coefficient using the updated threshold amplitude, calculates, for each of the extension-band subbands, a value of correlation between the representative transform coefficient and a normalized encoded low-band transform coefficient.

Encoding apparatus and encoding method

An audio/speech encoding method is provided that includes transforming a time domain input signal to a frequency spectrum, and dividing the frequency spectrum to a plural of bands. The method also includes calculating a level of energies for each band, quantizing the energies for the each band, and calculating differential indices. The method additionally includes modifying a range of the differential indices for the Nth band when N is an integer of 2 or more, and replacing the differential index with the modified differential index, and not modifying a range of the differential indices for the Nth band when N is an integer of 1. The method further includes encoding the differential indices using a Huffman table selected based on a minimum value and a maximum value of the differential indices, and transmitting the encoded differential indices and a flag signal for indicating the selected Huffman table.

Audio/speech encoding apparatus and method, and audio/speech decoding apparatus and method

A speech/audio coding apparatus includes a receiver that receives a time-domain speech input signal. The apparatus also includes a processor that transforms a time-domain speech input signal into a frequency-domain spectrum, and divides a frequency region of the spectrum in an extended band into a plurality of bands. The processor sets a limited band for each divided band in the current frame, a width of the limited band in the current frame being narrower than the divided band and the limited band including a first frequency. The processor further encodes the spectrum in the limited band within each divided band in the current frame, wherein the width of the limited band is predetermined and is set to 31.

Speech audio encoding device, speech audio decoding device, speech audio encoding method, and speech audio decoding method

A speech/audio encoding device for selectively allocating bits for higher precision encoding. The speech/audio encoding device receives a time-domain speech/audio input signal, transforms the speech/audio input signal into a frequency domain, and quantizes an energy envelope corresponding to an energy level for a frequency spectrum of the speech/audio input signal. The speech/audio encoding device further groups quantized energy envelopes into a plurality of groups, determines a perceptual significant group including one or more significant bands and a local-peak frequency, and allocates bits to a plurality of subbands corresponding to the grouped quantized energy envelopes, in which each of the subbands is obtained by splitting the frequency spectrum of the speech/audio input signal. The speech/audio encoding device encodes the frequency spectrum using the bits allocated to the subbands.

Speech/audio encoding apparatus and method thereof

A coding apparatus, including a processor that performs operations, including encoding a first band of an input audio signal to be a first spectrum and dividing the first spectrum into a plurality of subbands at equal intervals, each interval including a predetermined number of samples. The operations also include searching a largest amplitude value of the divided first spectrum in each of the subbands, and normalizing the divided first spectrum with the largest amplitude values searched in each of the subbands to obtain a flattened first spectrum. The operations further include searching a best band which has a largest correlation value between each divided band of a second band spectrum and the flattened first spectrum, the second spectrum being higher than a predetermined frequency, and encoding the second spectrum using lag information identifying the best bands for transmitting the lag information to a decoder side.

A speech/audio decoding apparatus is provided that includes a receiver that receives encoded data including a limited-band mode flag, and a memory that stores information on a position of a maximum amplitude spectrum frequency of a previous frame in a divided band. The speech/audio decoding apparatus also includes a processor that identifies whether a decoding band is encoded using a limited-band mode based on the decoded limited-band mode flag. Additionally, the processor decodes the spectrum in a limited band within each of the divided bands in a current frame using the stored information. Furthermore, the limited-band mode is set at an encoder side, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in the current frame is below a threshold.

An audio/speech encoding apparatus/method and an audio/speech decoding apparatus/method are provided. The audio/speech encoding apparatus includes a memory that stores instructions, and a processor that performs operations. The operations include transforming a time domain input audio/speech signal to a frequency spectrum, dividing the frequency spectrum to a plural of bands, calculating norm factors, and quantizing the norm factors. The operations also include calculating differential indices between an Nth band index and an (N&#x2212;1)th band index, and modifying a range of the differential indices for the Nth band when N is 2 or more. The operations further include replacing the differential index with the modified differential index, and not modifying a range of the differential indices for the Nth band when N is 1. The apparatus encodes the differential indices using a selected Huffman table, and transmits the encoded differential indices and a flag signal over a communication network.

A speech/audio coding apparatus is provided that includes a receiver that receives a time-domain speech input signal and a processor. The processor transforms a time-domain speech input signal into a frequency-domain spectrum, and divides a frequency region of the spectrum in an extended band into a plurality of bands. The processor also sets a limited band for each divided band in the current frame, when a difference between a first frequency with a first maximum amplitude in a spectrum of the divided band in a preceding frame and a second frequency with a second maximum amplitude in a spectrum of the divided band in a current frame is below a threshold. The processor further encodes the spectrum in the limited band within each divided band in the current frame, and does not encode a spectrum outside the limited band within each divided band in the current frame.

A coding apparatus encodes a first band of an input audio signal, normalizes a first spectrum included in each sub-band of the first band using a spectrum power envelope, performs a clipping process on the normalized first spectrum, the clipping process comparing between a predetermined threshold and the absolute value of an amplitude of the spectrum and replaces the amplitude value of the spectrum with the threshold if the absolute value of the amplitude of the spectrum exceeds the threshold, calculates a correlation between a spectrum in each divided band of a second band and a spectrum in a plurality of candidate bands containing the clipped normalized first spectrum, the second spectrum being higher than a predetermined frequency, identifies the best bands of the plurality of candidate bands, and encodes the second spectrum using lag information identifying the best band for transmitting the lag information to a decoder.

In this invention, the design of the Huffman table can be done offline with a large input sequence database. The range of the quantization indices (or differential indices) for Huffman coding is identified. For each value of range, all the input signal which have the same range will be gathered and the probability distribution of each value of the quantization indices (or differential indices) within the range is calculated. For each value of range, one Huffman table is designed according to the probability. And in order to improve the bits efficiency of the Huffman coding, apparatus and methods to reduce the range of the quantization indices (or differential indices) are also introduced.

Device and method for execution of huffman coding

An audio encoding apparatus capable of reducing the bit rate even if a codebook having a larger codebook number is selected in a split multi-rate lattice vector quantization is provided. Sub-vector determining unit () determines, in the spectrum of an input signal having been divided into a predetermined number of sub-vectors, a sub-vector using the largest number of bits. Positional information encoding unit () encodes the positional information of the determined sub-vector. Codebook indication value estimating unit () estimates a number of used bits for a codebook indication value of the largest number of used bits by use of the (N&#x2212;1) other codebook indication values, and generates a number-of-used-bits estimation value. Difference calculating unit () calculates a difference by subtracting the number-of-used-bits estimation value from the actual value of the codebook indication value of the largest number of used bits. Difference encoding unit () encodes the difference information.

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Kanagawa, Japan

Masahiro Oshikiri