Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A decoding device includes: a separating unit separating first encoded data, a spectrum including a low-band spectrum of audio signals having been encoded, and second encoded data, a high-band spectrum of a higher band having been encoded, based on the first encoded data; a first decoding unit decoding the first encoded data and generating a first decoded spectrum; a first amplitude normalizer dividing amplitude of the first decoded spectrum into sub-bands, normalizing the spectrum of each sub-band by the largest amplitude of the first decoded spectrum within each sub-band, and generating a normalized spectrum; an addition unit adding noise spectrum to the normalized spectrum and generating a noise-added normalized spectrum; a second decoding unit decoding the second encoded data using the noise-added normalized spectrum, and generating a second noise-added spectrum; and a converter performing time-frequency conversion regarding a spectrum coupled based on the first decoded spectrum and second noise-added spe

Abstract: 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.

Abstract: A decoding device includes: a separating unit separating first encoded data, a spectrum including a low-band spectrum of audio signals having been encoded, and second encoded data, a high-band spectrum of a higher band having been encoded, based on the first encoded data; a first decoding unit decoding the first encoded data and generating a first decoded spectrum; a first amplitude normalizer dividing amplitude of the first decoded spectrum into sub-bands, normalizing the spectrum of each sub-band by the largest amplitude of the first decoded spectrum within each sub-band, and generating a normalized spectrum; an addition unit adding noise spectrum to the normalized spectrum and generating a noise-added normalized spectrum; a second decoding unit decoding the second encoded data using the noise-added normalized spectrum, and generating a second noise-added spectrum; and a converter performing time-frequency conversion regarding a spectrum coupled based on the first decoded spectrum and second noise-added spe

Abstract: A coding apparatus, including a processor that performs operations including encoding a first band of an input audio signal to be a first spectrum, dividing the first spectrum into a plurality of subbands, at equal intervals each including a predetermined number of samples for flattening the first spectrum, searching a largest amplitude value of the divided first spectrum in each of the subbands, normalizing the divided first spectrum with the largest amplitude values searched in each of the subbands, searching best bands among each normalized divided first spectrum which has a largest correlation value between each divided band of a second band spectrum and each normalized divided 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A coding apparatus normalizes a low-frequency spectrum included in each of sub-bands obtained from dividing a low band part, using a largest amplitude value among the low-frequency spectrum included in each sub-band, obtains a normalized low-frequency spectrum by decoding the first encoded data, and calculates a correlation between each divided band of a high-frequency spectrum and a plurality of candidate bands of the normalized low-frequency spectrum. The best bands of a plurality of candidate bands are identified, each candidate band having a starting frequency position with non-zero amplitude in the normalized low-frequency spectrum, the high-frequency spectrum being in a high band part of the input audio signal that is higher than the predetermined frequency, and the high-frequency spectrum is encoded using lag information identifying the best band for transmitting the lag information to a decoder.

Abstract: A speech/audio coding apparatus and method is provided. The number of encoding bits allocated to encoding of extended-band spectrum is reduced while degradation of sound quality in the extended band is suppressed. A band compression unit creates combinations of sub-band spectra in pairs of two samples each in order from a low-range side in a band compression target sub-band, selects a spectrum having a large absolute-value amplitude among the combinations, and arranges the selected spectrum close to the low-range side on a frequency axis. A number-of-units recalculation unit redistributes bits saved in the sub-band for which band compression was performed to a low range outside the extended band, and redistributes the number of units on the basis of the redistributed bits.

Abstract: 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.

Abstract: An audio signal coding apparatus includes a time-frequency transformer that outputs sub-band spectra from an input signal; a sub-band energy quantizer; a tonality calculator that analyzes tonality of the sub-band spectra; a bit allocator that selects a second sub-band on which quantization is performed by a second quantizer on the basis of the analysis result of the tonality and quantized sub-band energy, and determines a first number of bits to be allocated to a first sub-band on which quantization is performed by a first quantizer; the first quantizer that performs first coding using the first number of bits; the second quantizer that performs coding using a second coding method; and a multiplexer.

Abstract: Provided is a speech/audio encoding apparatus with which it is possible to code a significant frequency domain region with high precision, and to enable high audio quality. A speech/audio encoding apparatus codes a linear prediction coefficient. A significant frequency domain region detection unit identifies a frequency domain region which is aurally significant from the linear prediction coefficient. A frequency domain region repositioning unit repositions the significant frequency domain region which is identified by the significant frequency domain region detection unit. A bit allocation computation unit determines a coding bit allocation on the basis of the significant frequency domain region which is repositioned by the frequency domain region repositioning unit.

Abstract: 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.

Abstract: A threshold amplitude is calculated for each subband obtained by splitting an extension band. For each subband, an amplitude of transform coefficients is compared with the threshold amplitude to extract a transform coefficient having an amplitude larger than the threshold amplitude as a representative transform coefficient. When a number of the extracted representative transform coefficients is less than a predetermined number, the threshold amplitude is updated in accordance with an amount by which the number of the representative transform coefficients is less than the predetermined number. A transform coefficient is extracted again using the updated threshold amplitude. For each of the subbands, a value of correlation is calculated between the representative transform coefficient and a normalized core encoded low-band transform coefficient. A subband having a largest value of correlation is selected when the number of the extracted representative transform coefficients reaches the predetermined number.