Spectrum coding apparatus, spectrum decoding apparatus, acoustic signal transmission apparatus, acoustic signal reception apparatus and methods thereof
AssigneePanasonic Corporation
InventorMasahiro Oshikiri
Life of this patent
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Abstract
A spectrum coding apparatus capable of performing coding at a low bit rate and with high quality is disclosed. This apparatus is provided with a section that performs the frequency transformation of a first signal and calculates a first spectrum, a section that converts the frequency of a second signal and calculates a second spectrum, a section that estimates the shape of the second spectrum in a band of FL≦k<FH using a filter having the first spectrum in a band of 0≦k<FL as an internal state and a section that codes an outline of the second spectrum determined based on a coefficient indicating the characteristic of the filter at this time.
Claims13
A spectrum coding apparatus comprising:
- an acquisition section that acquires a first spectrum which frequency k is in a band of 0≦k<FL;
- an acquisition section that acquires a second spectrum which frequency k is in a band of 0≦k<FH;
- an estimation section that estimates a shape of said second spectrum in a band of FL≦k<FH by the following expression
- D(k)=D(k−T)
- where D(k) in 0≦k<FL is the first spectrum, D(k) in FL≦k<FH is the estimated second spectrum, and T is a pitch coefficient;
- and
- a coding section that codes a pitch coefficient minimizing a distortion between the shape of the estimated second spectrum and the shape of said second spectrum in the band of FL≦k<FH,
- wherein the pitch coefficient minimizing the distortion maximizes the following:
- (
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- S
-
- (
- k
- )
- ·
- D
-
- (
- k
- )
- )
- 2
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- D
-
- (
- k
- )
- 2
- wherein S(k) is the second spectrum and D(k) is the estimated second spectrum.
A spectrum decoding apparatus comprising:
- a decoding section that decodes a pitch coefficient from coding information;
- an acquisition section that acquires a spectrum which frequency k is in a band of 0≦k<FL;
- and
- a generation section that generates an estimated spectrum in a band of FL≦k≦FH by the following expression
- D(k)=D(k−T)
- where D(k) in 0≦k<FL is said spectrum, D(k) in FL≦k<FH is the estimated second spectrum, and T is a pitch coefficient,
- wherein the pitch coefficient minimizing the distortion maximizes the following:
- (
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- S
-
- (
- k
- )
- ·
- D
-
- (
- k
- )
- )
- 2
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- D
-
- (
- k
- )
- 2
- where S(k) is the second spectrum and D(k) is the estimated second spectrum.
A spectrum coding method comprising the steps of:
- performing a frequency transformation of a first signal which frequency k is in a band of 0≦k<FL and calculating a first spectrum;
- performing a frequency transformation of a second signal which frequency k is in a band of 0≦k<FH and calculating a second spectrum;
- estimating the shape of said second spectrum in a band of FL≦k<FH using said first spectrum by the following expression
- D(k)=D(k−T)
- where D(k) in 0≦k<FL is the first spectrum, D(k) in FL≦k<FH is the estimated second spectrum, and T is a pitch coefficient;
- and
- coding a pitch coefficient indicating minimizing a distortion between the shape of the estimated second spectrum and the shape of said second spectrum in the band of FL≦k<FH,
- wherein the pitch coefficient minimizing the distortion maximizes the following:
- (
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- S
-
- (
- k
- )
- ·
- D
-
- (
- k
- )
- )
- 2
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- D
-
- (
- k
- )
- 2
- where S(k) is the second spectrum and D(k) is the estimated second spectrum.
A spectrum decoding method comprising the steps of:
- decoding a pitch coefficient from coding information;
- performing a frequency transformation of a first signal to obtain a first spectrum which frequency k is in a band of 0≦k<FL;
- and
- generating an estimated spectrum in a band of FL≦k<FH by the following expression
- D(k)=D(k−T)
- where D(k) in 0≦k<FL is the first spectrum, D(k) in FL≦k<FH is an estimated second spectrum, and T is a pitch coefficient,
- wherein the pitch coefficient minimizing the distortion maximizes the following:
- (
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- S
-
- (
- k
- )
- ·
- D
-
- (
- k
- )
- )
- 2
- ∑
- FH
- -
- 1
- k
- =
- FL
-
- D
-
- (
- k
- )
- 2
- where S(k) is the second spectrum and D(k) is the estimated second spectrum.
Dependencies are inferred from the claim text.