Audio encoding apparatus, audio decoding apparatus, audio encoding method, and audio decoding method
First Claim
1. A speech encoding apparatus, comprising:
- a memory that stores instructions;
a processor that executes the instructions;
a time-frequency domain transformer that transforms a time domain input speech signal to a frequency domain signal;
a calculator; and
a parameter encoder,wherein, when executed by the processor, the instructions cause the processor to perform operations comprising;
dividing the frequency domain signal into a plurality of sub-vectors and quantizing spectral coefficients of each of the resultant sub-vectors;
encoding codebook indication values of all of the sub-vectors, the codebook indication values being obtained by the quantization, the codebook indication values representing codebook numbers in which larger numbers are given according to an energy amount of the plurality of sub-vectors, wherein the larger the codebook numbers, the larger a number of bits are used by each of the codebook indication values;
identifying, of the entire band, a band of a sub-vector with a codebook indication value having a largest used bit count among all of the codebook indication values; and
estimating a number of bits used by the codebook indication value having the largest used bit count, based on a total number of bits available in transmission units of the input speech signal and a number of used bits of a codebook indication value other than the codebook indication value having the largest used bit count;
wherein the calculator calculates, with respect to a number of bits necessary for encoding a codebook indication value of the band, a difference between an actual value and an estimated value, the actual value being an actual number of used bits of the codebook indication value having the largest used bit count, which is obtained by encoding the codebook indication value having the largest used bit count, and the estimated value being the estimated number of used bits of the codebook indication value having the largest used bit count, and the estimated value is obtained as the number of bits obtained by subtracting the total number of bits required for encoding a codebook indication value, other than that of the band, from the total number of bits usable for a codebook indication value of the entire band; and
wherein the parameter encoder encodes the identified position information of the sub-vector and the calculated difference information.
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Accused Products
Abstract
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 (121) 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 (122) encodes the positional information of the determined sub-vector. Codebook indication value estimating unit (124) estimates a number of used bits for a codebook indication value of the largest number of used bits by use of the (N−1) other codebook indication values, and generates a number-of-used-bits estimation value. Difference calculating unit (125) 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 (126) encodes the difference information.
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Citations
13 Claims
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1. A speech encoding apparatus, comprising:
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a memory that stores instructions; a processor that executes the instructions; a time-frequency domain transformer that transforms a time domain input speech signal to a frequency domain signal; a calculator; and a parameter encoder, wherein, when executed by the processor, the instructions cause the processor to perform operations comprising; dividing the frequency domain signal into a plurality of sub-vectors and quantizing spectral coefficients of each of the resultant sub-vectors; encoding codebook indication values of all of the sub-vectors, the codebook indication values being obtained by the quantization, the codebook indication values representing codebook numbers in which larger numbers are given according to an energy amount of the plurality of sub-vectors, wherein the larger the codebook numbers, the larger a number of bits are used by each of the codebook indication values; identifying, of the entire band, a band of a sub-vector with a codebook indication value having a largest used bit count among all of the codebook indication values; and estimating a number of bits used by the codebook indication value having the largest used bit count, based on a total number of bits available in transmission units of the input speech signal and a number of used bits of a codebook indication value other than the codebook indication value having the largest used bit count; wherein the calculator calculates, with respect to a number of bits necessary for encoding a codebook indication value of the band, a difference between an actual value and an estimated value, the actual value being an actual number of used bits of the codebook indication value having the largest used bit count, which is obtained by encoding the codebook indication value having the largest used bit count, and the estimated value being the estimated number of used bits of the codebook indication value having the largest used bit count, and the estimated value is obtained as the number of bits obtained by subtracting the total number of bits required for encoding a codebook indication value, other than that of the band, from the total number of bits usable for a codebook indication value of the entire band; and wherein the parameter encoder encodes the identified position information of the sub-vector and the calculated difference information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A speech encoding method, comprising:
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transforming a time domain input speech signal to a frequency domain signal; dividing the frequency domain signal into a plurality of sub-vectors and quantizing spectral coefficients of each of the divided sub-vectors; encoding codebook indication values of all of the sub-vectors, the codebook indication values being obtained by the quantizing, the codebook indication values representing codebook numbers in which larger numbers are given according to an energy amount of the plurality of sub-vectors, wherein the larger the codebook numbers, the larger a number of bits are used by each of the codebook indication values; identifying, of the entire band, a band of a sub-vector with a codebook indication value having a largest used bit count among all of the codebook indication values; estimating a number of bits used by the codebook indication value having the largest used bit count based on a total number of bits available in transmission units of the input speech signal and a number of used bits of a codebook indication value other than the codebook indication value having the largest used bit count; calculating, with respect to a number of bits necessary for encoding a codebook indication value of the band, a difference between an actual value and an estimated value, the actual value being an actual number of used bits of the codebook indication value having the largest used bit count, which is obtained by encoding the codebook indication value having the largest used bit count, and the estimated value being the estimated number of used bits of the codebook indication value having the largest used bit count, and the estimated value is obtained as the number of bits obtained by subtracting the total number of bits required for encoding a codebook indication value, other than that of the band, from the total number of bits usable for a codebook indication value of the entire band; and encoding the identified position information of the sub-vector and the calculated difference information as parameters. - View Dependent Claims (13)
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Specification