Coding device, decoding device, and method and program thereof
View Patent ↗A technology of accurately coding and decoding coefficients which are convertible into linear prediction coefficients even for a frame in which the spectrum variation is great while suppressing an increase in the code amount as a whole is provided. A coding device includes: a first coding unit that obtains a first code by coding coefficients which are convertible into linear prediction coefficients of more than one order; and a second coding unit that obtains a second code by coding at least quantization errors of the first coding unit if (A−1) an index Q commensurate with how high the peak-to-valley height of a spectral envelope is, the spectral envelope corresponding to the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to a predetermined threshold value Th1 and/or (B−1) an index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to a predetermined threshold value Th1′.
1 . A coding device comprising:
circuitry configured to:
execute first coding processing in which the circuitry obtains a first code by coding coefficients which are convertible into linear prediction coefficients of more than one order; and
execute second coding processing in which the circuitry obtains a second code by coding at least quantization errors of the first coding processing if an index Q commensurate with how high a peak-to-valley height of a spectral envelope is, the spectral envelope corresponding to the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to a predetermined threshold value Th1 and/or an index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to a predetermined threshold value Th1′, wherein
in the second coding processing the circuitry obtains the second code whose bit number becomes greater as the index Q increases and/or the index Q′ decreases.
2 . A non-transitory computer-readable recording medium having recorded thereon a program for making a computer function as the coding device according to claim 1 .
3 . A decoding device comprising:
circuitry configured to:
execute first decoding processing in which the circuitry obtains first decoded values by decoding a first code, the first decoded values corresponding to coefficients which are convertible into linear prediction coefficients of more than one order;
execute second decoding processing in which the circuitry obtains second decoded values of more than one order by decoding a second code if an index Q commensurate with how high a peak-to-valley height of a spectral envelope is, the spectral envelope corresponding to the first decoded values of the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to a predetermined threshold value Th1 and/or an index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to a predetermined threshold value Th1′; and
execute addition processing in which the circuitry obtains third decoded values corresponding to the coefficients which are convertible into the linear prediction coefficients of more than one order by adding the first decoded values and the second decoded values of corresponding orders if the index Q commensurate with how high the peak-to-valley height of the spectral envelope is, the spectral envelope corresponding to the first decoded values of the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to the predetermined threshold value Th1 and/or the index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to the predetermined threshold value Th1′, wherein
in the second decoding processing the circuitry obtains the second decoded values from a large number of candidates for decoded values by decoding the second code with a bit number depending on a magnitude of the index Q and the index Q′, such that the larger the index Q and/or the smaller the index Q′, the greater the bit number.
4 . A non-transitory computer-readable recording medium having recorded thereon a program for making a computer function as the decoding device according to claim 3 .
5 . A coding method, implemented by a coding device that includes circuitry, comprising:
a first coding step in which the circuitry obtains a first code by coding coefficients which are convertible into linear prediction coefficients of more than one order; and
a second coding step in which the circuitry obtains a second code by coding at least quantization errors of the first coding step if when an index Q commensurate with how high a peak-to-valley height of a spectral envelope is, the spectral envelope corresponding to the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to a predetermined threshold value Th1 and/or an index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to a predetermined threshold value Th1′, wherein
in the second coding step the circuitry obtains the second code whose bit number becomes greater as the index Q increases and/or the index Q′ decreases.
6 . A decoding method, implemented by a decoding device that includes circuitry, comprising:
a first decoding step in which the circuitry obtains first decoded values by decoding a first code, the first decoded values corresponding to coefficients which are convertible into linear prediction coefficients of more than one order;
a second decoding step in which the circuitry obtains second decoded values of more than one order by decoding a second code if when an index Q commensurate with how high a peak-to-valley height of a spectral envelope is, the spectral envelope corresponding to the first decoded values of the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to a predetermined threshold value Th1 and/or an index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to a predetermined threshold value Th1′; and
an addition step in which the circuitry obtains third decoded values corresponding to the coefficients which are convertible into the linear prediction coefficients of more than one order by adding the first decoded values and the second decoded values of corresponding orders if when the index Q commensurate with how high the peak-to-valley height of the spectral envelope is, the spectral envelope corresponding to the first decoded values of the coefficients which are convertible into the linear prediction coefficients of more than one order, is larger than or equal to the predetermined threshold value Th1 and/or the index Q′ commensurate with how short the peak-to-valley height of the spectral envelope is, is smaller than or equal to the predetermined threshold value Th1′, wherein
in the second decoding step the circuitry obtains the second decoded values from a large number of candidates for decoded values by decoding the second code with a bit number depending on a magnitude of the index Q and the index Q′, such that the larger the index Q and/or the smaller the index Q′, the greater the bit number.
7. A coding device comprising:
circuitry configured to:
execute first coding processing in which the circuitry obtains a first code by coding line spectrum pair parameters of more than one order; and
execute second coding processing in which the circuitry obtains a second code by coding at least quantization errors of the first coding processing if a minimum value of differentials between adjacent parameters of quantized line spectrum pair parameters of all orders or low orders corresponding to the first code and a lowest-order quantized line spectrum pair parameter is smaller than or equal to a predetermined threshold value Th1′, wherein the quantization errors are quantization errors of low orders of the more than one order.
8. A non-transitory computer-readable recording medium having recorded thereon a program for making a computer function as the coding device according to claim 7 .
9. A decoding device comprising:
circuitry configured to:
execute first decoding processing in which the circuitry obtains first decoded values by decoding a first code, the first decoded values corresponding to line spectrum pair parameters of more than one order;
execute second decoding processing in which the circuitry obtains second decoded values of more than one order by decoding a second code if a minimum value of differentials between adjacent parameters of quantized line spectrum pair parameters of all orders or low orders corresponding to the first code and a lowest-order quantized line spectrum pair parameter is smaller than or equal to a predetermined threshold value Th1′; and
execute addition processing in which the circuitry obtains third decoded values corresponding to the line spectrum pair parameters of more than one order by adding the first decoded values and the second decoded values of corresponding orders if the minimum value is smaller than or equal to the predetermined threshold value Th1′, wherein
orders of the second decoded values are lower than orders of the first decoded values, and
as for orders higher than the orders of the second decoded values, the addition processing uses the first decoded values of corresponding orders as the third decoded values without change.
10. A non-transitory computer-readable recording medium having recorded thereon a program for making a computer function as the decoding device according to claim 9.
11. A coding method, implemented by a coding device that includes circuitry, comprising:
a first coding step in which the circuitry obtains a first code by coding line spectrum pair parameters of more than one order; and
a second coding step in which the circuitry obtains a second code by coding at least quantization errors of the first coding step when a minimum value of differentials between adjacent parameters of quantized line spectrum pair parameters of all orders or low orders corresponding to the first code and a lowest-order quantized line spectrum pair parameter is smaller than or equal to a predetermined threshold value Th1′, wherein
the quantization errors are quantization errors of low orders of the more than one order.
12. A decoding method, implemented by a decoding device that includes circuitry, comprising:
a first decoding step in which the circuitry obtains first decoded values by decoding a first code, the first decoded values corresponding to line spectrum pair parameters of more than one order;
a second decoding step in which the circuitry obtains second decoded values of more than one order by decoding a second code when a minimum value of differentials between adjacent parameters of quantized line spectrum pair parameters of all orders or low orders corresponding to the first code and a lowest-order quantized line spectrum pair parameter is smaller than or equal to a predetermined threshold value Th1′; and
an addition step in which the circuitry obtains third decoded values corresponding to the line spectrum pair parameters of more than one order by adding the fist decoded values and the second decoded values of corresponding orders when the minimum value is smaller than or equal to the predetermined threshold value Th1′, wherein
orders of the second decoded values are lower than orders of the first decoded values, and
as for orders higher than the orders of the second decoded values, the addition step uses the first decoded values of corresponding orders as the third decoded values without change.