Frequency domain parameter sequence generating method, encoding method, decoding method, frequency domain parameter sequence generating apparatus, encoding apparatus, decoding apparatus, program, and recording medium
First Claim
1. An encoding method, implemented by an encoding apparatus having processing circuitry, comprising:
- where p is an integer equal to or greater than 1, γ
is an adjustment factor which 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],generating, by the processing circuitry, an adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p] by adjusting the linear prediction coefficient sequence a[1], a[2], . . . , a[p] by calculating aγ
[i]=a[i]×
γ
i using the adjustment factor γ
;
generating, by the processing circuitry, an adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] using the adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p];
encoding, by the processing circuitry, the adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] to generate adjusted LSP codes and an adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] corresponding to the adjusted LSP codes;
with a frequency domain parameter sequence ω
[1], ω
[2], . . . , ω
[p] being the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p], determining, by the processing circuitry, 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 to thereby generate the converted frequency domain parameter sequence ˜
ω
[1], ˜
ω
[2], . . . , ˜
ω
[p] as an approximate quantized LSP parameter sequence ^θ
app[1], ^θ
app[2], . . . , ^θ
app[p];
generating, by the processing circuitry, an adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p] by converting the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] into linear prediction coefficients;
calculating, by the processing circuitry, a quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N] which is a series in frequency domain corresponding to the adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p];
generating, by the processing circuitry, frequency domain signal codes by encoding a frequency domain sample sequence X[1], X[2], . . . , X[N] corresponding to the audio signals using the quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N];
generating, by the processing circuitry, an LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] using the linear prediction coefficient sequence a[1], a[2], . . . , a[p];
encoding, by the processing circuitry, the LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] to generate LSP codes and a quantized LSP parameter sequence ^θ
[1], ^θ
[2], . . . , ^θ
[p] corresponding to the LSP codes; and
encoding, by the processing circuitry, the audio signals to generate time domain signal codes using either the generated quantized LSP parameter sequence for a preceding time segment or the generated approximate quantized LSP parameter sequence for the preceding time segment, and the quantized LSP parameter sequence for the predetermined time segment,whereinthe processing circuitry 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].
1 Assignment
0 Petitions
Accused Products
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].
-
Citations
11 Claims
-
1. An encoding method, implemented by an encoding apparatus having processing circuitry, comprising:
-
where p is an integer equal to or greater than 1, γ
is an adjustment factor which 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],generating, by the processing circuitry, an adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p] by adjusting the linear prediction coefficient sequence a[1], a[2], . . . , a[p] by calculating aγ
[i]=a[i]×
γ
i using the adjustment factor γ
;generating, by the processing circuitry, an adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] using the adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p];encoding, by the processing circuitry, the adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] to generate adjusted LSP codes and an adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] corresponding to the adjusted LSP codes;with a frequency domain parameter sequence ω
[1], ω
[2], . . . , ω
[p] being the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p], determining, by the processing circuitry, 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 to thereby generate the converted frequency domain parameter sequence ˜
ω
[1], ˜
ω
[2], . . . , ˜
ω
[p] as an approximate quantized LSP parameter sequence ^θ
app[1], ^θ
app[2], . . . , ^θ
app[p];generating, by the processing circuitry, an adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p] by converting the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] into linear prediction coefficients;calculating, by the processing circuitry, a quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N] which is a series in frequency domain corresponding to the adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p];generating, by the processing circuitry, frequency domain signal codes by encoding a frequency domain sample sequence X[1], X[2], . . . , X[N] corresponding to the audio signals using the quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N];generating, by the processing circuitry, an LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] using the linear prediction coefficient sequence a[1], a[2], . . . , a[p];encoding, by the processing circuitry, the LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] to generate LSP codes and a quantized LSP parameter sequence ^θ
[1], ^θ
[2], . . . , ^θ
[p] corresponding to the LSP codes; andencoding, by the processing circuitry, the audio signals to generate time domain signal codes using either the generated quantized LSP parameter sequence for a preceding time segment or the generated approximate quantized LSP parameter sequence for the preceding time segment, and the quantized LSP parameter sequence for the predetermined time segment, wherein the processing circuitry 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]. - View Dependent Claims (3, 6, 7, 11)
-
-
2. An encoding method, implemented by an encoding apparatus having processing circuitry, comprising:
-
where p is an integer equal to or greater than 1, γ
is an adjustment factor which 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],generating, by the processing circuitry, an adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p] by adjusting the linear prediction coefficient sequence a[1], a[2], . . . , a[p] by calculating aγ
[i]=a[i]×
γ
i using the adjustment factor γ
;generating, by the processing circuitry, an adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] using the adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p];encoding, by the processing circuitry, the adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] to generate adjusted LSP codes and an adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] corresponding to the adjusted LSP codes;with a frequency domain parameter sequence ω
[1], ω
[2], . . . , ω
[p] being the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p], determining, by the processing circuitry, 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 to thereby generate the converted frequency domain parameter sequence ˜
ω
[1], ˜
ω
[2], . . . , ˜
ω
[p] as an approximate quantized LSP parameter sequence ^θ
app[1], ^θ
app[2], . . . , ^θ
app[p];calculating, by the processing circuitry, a quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N] based on the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p];generating, by the processing circuitry, frequency domain signal codes by encoding a frequency domain sample sequence X[1], X[2], X[N] corresponding to the audio signals using the quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N];generating, by the processing circuitry, an LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] using the linear prediction coefficient sequence a[1], a[2], . . . , a[p];encoding, by the processing circuitry, the LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] to generate LSP codes and a quantized LSP parameter sequence ^θ
[1], ^θ
[2], . . . , ^θ
[p] corresponding to the LSP codes; andencoding, by the processing circuitry, the audio signals to generate time domain signal codes using either the generated quantized LSP parameter sequence obtained in the LSP encoding step for a preceding time segment or an approximate quantized LSP parameter sequence obtained in the LSP linear transformation step for the preceding time segment, and the quantized LSP parameter sequence for the predetermined time segment, wherein the processing circuitry 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].
-
-
4. An encoding apparatus comprising:
-
where p is an integer equal to or greater than 1, γ
is an adjustment factor which 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],processing circuitry configured to implement a linear prediction coefficient adjusting unit that generates an adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p] by adjusting the linear prediction coefficient sequence a[1], a[2], . . . , a[p] by calculating aγ
[i]=a[i]×
γ
i using the adjustment factor γ
;an adjusted LSP generating unit that generates an adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] using the adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p];an adjusted LSP encoding unit that encodes the adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] to generate adjusted LSP codes and an adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] corresponding to the adjusted LSP codes;an LSP linear transformation unit that, with a frequency domain parameter sequence ω
[1], ω
[2], . . . , ω
[p] being the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p], executes a parameter sequence converting unit that determines 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 to thereby generate the converted frequency domain parameter sequence ˜
ω
[1], ˜
ω
[2], . . . , ˜
ω
[p] as an approximate quantized LSP parameter sequence ^θ
app[1], ^θ
app[2], ^θ
app[p];a quantized linear prediction coefficient sequence generating unit that generates an adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p] by converting the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] into linear prediction coefficients;a quantized smoothed power spectral envelope series calculating unit that calculates a quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N] which is a series in frequency domain corresponding to the adjusted quantized linear prediction coefficient sequence ^aγ
[1], ^aγ
[2], . . . , ^aγ
[p];a frequency domain encoding unit that generates frequency domain signal codes by encoding a frequency domain sample sequence X[1], X[2], . . . , X[N] corresponding to the audio signals using the quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , Wγ
[N];an LSP generating unit that generates an LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] using the linear prediction coefficient sequence a[1], a[2], . . . , a[p];an LSP encoding unit that encodes the LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] to generate LSP codes and a quantized LSP parameter sequence ^θ
[1], ^θ
[2], . . . , ^θ
[p] corresponding to the LSP codes; anda time domain encoding unit that encodes the audio signals to generate time domain signal codes using either the quantized LSP parameter sequence obtained in the LSP encoding unit for a preceding time segment or the approximate quantized LSP parameter sequence obtained in the LSP linear transformation unit for the preceding time segment, and the quantized LSP parameter sequence for the predetermined time segment, wherein the parameter sequence conversion unit 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 a [i] and one or more frequency domain parameters adjacent to ω
[i]. - View Dependent Claims (8, 9, 10)
-
-
5. An encoding apparatus comprising:
-
where p is an integer equal to or greater than 1, γ
is an adjustment factor which 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],processing circuitry configured to implement a linear prediction coefficient adjusting unit that generates an adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p] by adjusting the linear prediction coefficient sequence a[1], a[2], a[p] by calculating aγ
[i]=a[i]×
γ
i using the adjustment factor γ
;an adjusted LSP generating unit that generates an adjusted LSP parameter sequence θ
γ
[1], θ
γ
[2], . . . , θ
γ
[p] using the adjusted linear prediction coefficient sequence aγ
[1], aγ
[2], . . . , aγ
[p],an adjusted LSP encoding unit that encodes the adjusted LSP parameter sequence θ
1[1], θ
γ
[2], . . . , θ
γ
[p] to generate adjusted LSP codes and an adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p] which is determined by quantization of values in the adjusted LSP parameter sequence corresponding to the adjusted LSP codes;an LSP linear transformation unit that, with a frequency domain parameter sequence ω
[1], ω
[2], . . . , ω
[p] being the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p], executes a parameter sequence converting unit that determines 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 to thereby generate the converted frequency domain parameter sequence ˜
ω
[1], ˜
ω
[2], . . . , ˜
ω
[p] as an approximate quantized LSP parameter sequence ^θ
app[1], ^θ
app[2], . . . , ^θ
app[p];a quantized smoothed power spectral envelope series calculating unit that calculates a quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N] based on the adjusted quantized LSP parameter sequence ^θ
γ
[1], ^θ
γ
[2], . . . , ^θ
γ
[p];a frequency domain encoding unit that generates frequency domain signal codes by encoding a frequency domain sample sequence X[1], X[2], . . . , X[N] corresponding to the audio signals using the quantized smoothed power spectral envelope series ^Wγ
[1], ^Wγ
[2], . . . , ^Wγ
[N];an LSP generating unit that generates an LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] using the linear prediction coefficient sequence a[1], a[2], . . . , a[p];an LSP encoding unit that encodes the LSP parameter sequence θ
[1], θ
[2], . . . , θ
[p] to generate LSP codes and a quantized LSP parameter sequence ^θ
[1], ^θ
[2], . . . , ^θ
[p] corresponding to the LSP codes; anda time domain encoding unit that encodes the audio signals to generate time domain signal codes using either the quantized LSP parameter sequence obtained in the LSP encoding unit for a preceding time segment or the approximate quantized LSP parameter sequence obtained in the LSP linear transformation unit for the preceding time segment, and the quantized LSP parameter sequence for the predetermined time segment, wherein the parameter sequence conversion unit 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].
-
Specification