US 2017/0249947 A1 · FREQUENCY DOMAIN PARAMETER SEQUENCE GENERATING METHOD, ENCODING METHOD, DECODING METHOD, FREQUENCY DOMAIN PARAMETER SEQUENCE GENERATING APPARATUS, ENCODING APPARATUS, DECODING APPARATUS, PROGRAM, AND RECORDING MEDIUM

Abstract

The present invention reduces encoding distortion in frequency domain encoding compared to conventional techniques, and obtains LSP parameters that correspond to quantized LSP parameters for the preceding frame and are to be used in time domain encoding from coefficients equivalent to linear prediction coefficients resulting from frequency domain encoding. When p is an integer equal to or greater than 1, a linear prediction coefficient sequence which is obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p], and ω[1], ω[2], . . . , ω[p] are a frequency domain parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p], an LSP linear transformation unit (300) determines the value of each converted frequency domain parameter ˜ω[i] (i=1, 2, . . . , p) in a converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] using the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] as input, through linear transformation which is based on the relationship of values between ω[i] and one or more frequency domain parameters adjacent to ω[i].

Claims30

Dependent claims

A frequency domain parameter sequence generating method comprising:

where p is an integer equal to or greater than 1, γ1 is a positive constant equal to or smaller than 1, a linear prediction coefficient sequence which is obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p], and ω[1], ω[2], . . . , ω[p] are a frequency domain parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
a parameter sequence conversion step of determining a converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] using the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] as input, wherein
the parameter sequence conversion step determines a value of each converted frequency domain parameter ˜ω[i] (i−1, 2, . . . , p) in the converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] through linear transformation which is based on a relationship of values between ω[i] and one or more frequency domain parameters adjacent to ω[i], and
each ω[i] (i=1, 2, . . . , p) in the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] is a frequency domain parameter equivalent to aγ1[1], aγ1[2], . . . , aγ1[p], or a quantized value of said frequency domain parameter, where aγ1[i]=a[i]×(γ1)i.

1 more element

A frequency domain parameter sequence generating method comprising:

where p is an integer equal to or greater than 1, and a linear prediction coefficient sequence obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p];
ω[1], ω[2], ω[p] is one of
an LSP parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
an ISP parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
an ISF parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
an ISF parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p], and
a frequency domain parameter sequence which is derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p] and in which all of ω[1], ω[2], . . . , ω[p−1] are present from 0 to π and, when all of linear prediction coefficients contained in the linear prediction coefficient sequence are 0, ω[1], ω[2], . . . , ω[p−1] are present from 0 to π at equal intervals;
and
each γ1 and γ2 is a positive constant equal to or smaller than 1, and K is a predetermined p×p band matrix in which diagonal elements and elements that neighbor the diagonal elements in row direction have non-zero values,
a parameter sequence conversion step of generating a converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] defined by a following formula.
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94 more elements

A frequency domain parameter sequence generating method comprising:

where p is an integer equal to or greater than 1, a linear prediction coefficient sequence which is obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p], and ω[1], ω[2], . . . , ω[p] are a frequency domain parameter sequence which is derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p] and in which all of ω[1], ω[2], . . . , ω[p−1] are present from 0 to π and, when all of linear prediction coefficients contained in the linear prediction coefficient sequence are 0, ω[1], ω[2], . . . , ω[p−1] are present from 0 to π at equal intervals, and
where each γ1 and γ2 is a positive constant equal to or smaller than 1, and K is a predetermined p×p band matrix in which diagonal elements and elements that neighbor the diagonal elements in row direction have non-zero values,
a parameter sequence conversion step of determining a converted frequency domain parameter sequence ˜ω[1], ˜θ[2], . . . , ˜ω[p] using the frequency domain parameter sequence ω[1], θ[2], . . . , ω[p] as input, wherein
the parameter sequence conversion step determines each ˜ω[i] (i=1, 2, . . . , p) in the converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] such that
when ω[i] is closer to ω[i+1] relative to a midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i+1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that a value of ˜ω[i+1]−˜ω[i] will be smaller than ω[i+1]−ω[i], and
when ω[i] is closer to ω[i−1] relative to the midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i−1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that the value of ˜ω[i]−˜ω[i−1] will be smaller than ω[i]−ω[i−1], and
a converted frequency domain parameter sequence ˜ω[1], ˜θ[2], . . . , ˜θ[p] defined by
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is generated.

92 more elements

A frequency domain parameter sequence generating method comprising:

where p is an integer equal to or greater than 1, γ1 is a positive constant equal to or smaller than 1, a linear prediction coefficient sequence which is obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p], and ω[1], ω[2], . . . , ω[p] are a frequency domain parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
a parameter sequence conversion step of determining a converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] using the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] as input, wherein
the parameter sequence conversion step determines each ˜ω[i] (i=1, 2, . . . , p) in the converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] such that
when ω[i] is closer to ω[i+1] relative to a midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i+1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that a value of ˜ω[i+1]−˜ω[i] will be smaller than ω[i+1]−ω[i], and
when ω[i] is closer to ω[i−1] relative to the midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i−1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that the value of ˜ω[i]−˜ω[i−1] will be smaller than ω[i]−ω[i−1], and
each ω[i] (i=1, 2, . . . , p) in the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] is a frequency domain parameter equivalent to aγ1[1], aγ2[2], . . . , aγ1[p], or a quantized value of said frequency domain parameter, where aγ1[i]=a[i]×(γ1)i.

3 more elements

A frequency domain parameter sequence generating method comprising:

where p is an integer equal to or greater than 1, γ1 is a positive constant equal to or smaller than 1, a linear prediction coefficient sequence which is obtained by linear prediction analysis of audio signals in a predetermined time segment is represented as a[1], a[2], . . . , a[p], and ω[1], ω[2], . . . , ω[p] are a frequency domain parameter sequence derived from the linear prediction coefficient sequence a[1], a[2], . . . , a[p],
a parameter sequence conversion step of determining a converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] using the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] as input, wherein
the parameter sequence conversion step determines each ˜ω[i] (i=1, 2, . . . , p) in the converted frequency domain parameter sequence ˜ω[1], ˜ω[2], . . . , ˜ω[p] such that
when ω[i] is closer to ω[i+1] relative to the midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i+1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that a value of ˜ω[i+1]−˜ω[i] will be greater than ω[i+1]−ω[i], and
when ω[i] is closer to ω[i−1] relative to the midpoint between ω[i+1] and ω[i−1], then ˜ω[i] is determined so that ˜ω[i] will be closer to ˜ω[i−1] relative to the midpoint between ˜ω[i+1] and ˜ω[i−1] and that the value of ˜ω[i]−˜ω[i−1] will be greater than ω[i]−ω[i−1], and
each ω[i] (i=1, 2, p) in the frequency domain parameter sequence ω[1], ω[2], . . . , ω[p] is a frequency domain parameter equivalent to aγ1[1], aγ1[2], . . . , aγ1[p], or a quantized value of said frequency domain parameter, where aγ1[i]=a[i]×(γ1)i.

3 more elements