摘要:
Disclosed is a spectral smoothing device with a structure whereby smoothing is performed after a nonlinear conversion has been performed for a spectrum calculated from an audio signal, and with which the amount of processing calculation is significantly reduced while maintaining excellent audio quality. With this spectral smoothing device, a sub band division unit (102) divides an input spectrum into multiple sub bands; a representative value calculation unit (103) calculates a representative value for each sub band using an arithmetic mean and a geometric mean; with respect to each representative value, a nonlinear conversion unit (104) performs a nonlinear conversion the characteristic of which is further emphasized as the value increases; and a smoothing unit (105) that smoothes the representative value which has undergone the nonlinear conversion for each sub band, at the frequency domain.
摘要:
A hierarchy encoding apparatus capable of calculating appropriate delay amounts and also capable of suppressing increase in the bit rate. In this apparatus, a first layer encoding part (101) encodes the input signal of the n-th frame to produce a first layer encoded code. A first layer decoding part (102) generates a first layer decoded signal from the first layer encoded code and applies it to a delay amount calculating part (103) and a second layer encoding part (105). The delay amount calculating part (103) uses the first layer decoded signal and input signal to calculate the delay amount to be added to the input signal, and applies the calculated delay amount to a delay part (104). The delay part (104) delays the input signal by the delay amount applied from the delay amount calculating part (103) and then applied it to a second layer encoding part (105). The second layer encoding part (105) uses the first layer decoded signal and the input signal from the delay part (104) for encoding.
摘要:
It is possible to improve quality of a decoding signal in a band spread for estimating a high band from a low band of a decoding signal. A first layer encoding unit (202) encodes a lower band portion below a predetermined frequency of an input signal so as to generate first layer encoded information. A first layer decoding unit (203) decodes the first layer encoded information so as to generate a first layer demodulated signal. A second layer encoding unit (206) divides a high band portion higher than a predetermined frequency of an input signal into a plurality of sub-bands and estimates each of the sub-bands from the input signal or the first layer decoded signal by using the estimation result of the sub-band adjacent to the lower band side so as to generate second encoded information including the estimation results of the sub-bands.
摘要:
A subband coding apparatus carries out subband coding which prevents deterioration in coding performance and improves audio quality of decoded signals. The subband coding apparatus includes a low-band coding section (103) to code a low-band spectrum (S13). A low-band decoding section (106) decodes a low-band coded data (S14) and outputs a decoded low-band spectrum (S18) to a high-band coding section (107). A spectrum rearranging section (105) rearranges to make each frequency component of a high-band spectrum (S16) in reverse order on the frequency axis and outputs a modified high-band spectrum (S17) after rearranging to a high-band coding section (107). The high-band coding section (107) uses the decoded low-band spectrum (S18) output from the low-band decoding section (106) to code the modified high-band spectrum (S17) output from the spectrum rearranging section (105).
摘要:
Provided is an encoding device which can reduce the encoding distortion as compared to the conventional technique and can obtain a preferable sound quality for auditory sense. In the encoding device, a shape quantization unit (111) quantizes the shape of an input spectrum with a small number of pulse positions and polarities. The shape quantization unit (111) sets a pulse amplitude width to be searched later upon search of the pulse position to a value not greater than the pulse amplitude width which has been searched previously. A gain quantization unit (112) calculates a gain of a pulse searched by the shape quantization unit (111) for each of bands.
摘要:
Provided is an encoding device which can obtain a sound quality preferable for auditory sense even if the number of information bits is small. The encoding device includes a shape quantization unit (111) having: a section search unit (121) which searches for a pulse for each of bands into which a predetermined search section is divided; and a whole search unit (122) which performs search for a pulse over the entire search section. The shape of an input spectrum is quantized by a small number of pulse positions and polarities. A gain quantization unit (112) calculates a gain of the pulse searched by the shape quantization unit (111) and quantizes the gain for each of the bands.
摘要:
It is an object to disclose a voice coding device, etc. in which the deterioration of a voice quality of a decoded signal can be reduced in the case that low frequency domain components of a spectrum are used for coding high frequency domain components and that no low frequency domain components exist. In this voice coding device, a frequency domain transform unit (101) generates an input spectrum from an input voice signal, a first layer coding unit (102) codes a lower frequency domain portion of the input spectrum to generate first layer coded data, a first layer decoding unit (103) decodes the first layer coded data to generate a first layer decoded spectrum, a lower frequency domain component judging unit (104) judges if there are low frequency domain components of the first layer decoded spectrum, and a second decoding unit (105); codes high frequency domain components of the input spectrum to generate second layer coded data in the case that the low frequency domain components exist and codes high frequency domain components by using a predetermined signal disposed in the low frequency domain components to generate second layer coded data in the case that the low frequency domain components do not exist.
摘要:
A sound encoder enabling prevention of deterioration of the sound quality of a reproduced signal even if the harmonic structure is broken in a part of the sound signal. The filter state position determining section (111) of the sound encoder judges the noise characteristic of the first-layer decoding spectrum and thereby determines the band of the first-layer decoding spectrum to be used to set the filter state. A filter state setting section (112) sets the first-layer decoding spectrum contained in the determined band out of the first-layer decoding spectrum as the filter state. A filtering section (113) performs filtering of the first-layer decoding spectrum according to the set filter state and the pitch coefficient and computes an estimate spectrum of the input spectrum. An optimal pitch coefficient is determined by a closed loop processing from the filtering section (113) through a search section (114) to a filter information setting section (115).
摘要:
A speech encoding method and apparatus including analyzing, using a codebook expressing speech parameters within a predetermined search range, an input speech signal in an audibility weighting filter corresponding to a pitch period longer than the search range of the codebook, and searching, from the codebook, on the basis of the analysis result, a combination of speech parameters by which the distortion of the input speech signal is minimized, and encoding the combination. The apparatus uses an adaptive codebook of pitch and a noise codebook. The codebooks search a group formed by extracting vectors of predetermined length from one original code vector, while sequentially shifting position so that the vectors overlap each other. The search group is further restricted and another preselection is made before the final search. Search is based on inversely convoluted, orthogonally transformed vectors.
摘要:
A stereo signal encoding device is provided that enables a lower bitrate without decreasing quality when applying an intermittent transmission technique to a stereo signal. A stereo encoding unit generates first stereo encoded data by encoding the stereo signal when the stereo signal of the current frame is an audio section. A stereo DTX encoding unit is a means for encoding the stereo signal when the stereo signal of the current frame is a non-audio section. The stereo DTX encoding unit generates second stereo encoded data by encoding each of a monaural signal spectral parameter that is a spectral parameter of a monaural signal generated using the first channel signal and the second channel signal, first channel signal information relating to the first channel signal, and second channel signal information relating to the second channel signal.