Embedded code-excited linear prediction speech coding and decoding apparatus and method
First Claim
1. A speech coding apparatus comprising:
- a core speech coding unit which presents a speech signal with an excitation signal;
a transmission rate determination unit which allocates the number of bits that are additionally allowed due to a capacity change in a transmission channel; and
an embedded excitation signal coding unit for determining which one of a multiple pulse excitation coding method and a gain compensation method is optimal for coding a residual excitation signal, that is not coded in the core speech coding unit, with the additionally allowed bits, and generating the residual excitation signal coded by the determined method,wherein the gain compensation method derives a gain compensation value for compensating a gain obtained from an algebraic codebook search, the gain compensation value being multiplied with the gain obtained from the algebraic codebook search to update the gain,wherein the embedded excitation signal coding unit comprises a multiple pulse search unit for selecting a position and a sign of multiple pulses that minimize a square error ε
m of the residual excitation signal,the embedded excitation signal coding unit further comprises a gain compensation unit for determining the gain compensation value that minimizes a square error ε
g of the residual excitation signal, andthe embedded excitation signal coding unit compares ε
m with ε
g, selects the multiple pulse excitation coding method when ε
m<
ε
g, and selects the gain compensation method when ε
m>
ε
g.
1 Assignment
0 Petitions
Accused Products
Abstract
Provides is an embedded code-excited linear prediction speech coding/decoding apparatus and method that can deal with the capacity change of speech transmission channel by modeling an error signal not coded at a core speech coder based on a transmission rate in a multiple pulse search mode or gain compensation mode and then transmitting it in an optimum mode. The apparatus includes a core speech coding unit for coding an input speech signal with spectral envelop and an excitation signal, a transmission rate determination unit for allocating the number of bits additionally allowed depending on a capacity of a transmission channel, and an embedded excitation signal coding unit for coding a residual excitation signal that is not coded in the core speech coding unit based on the number of additionally allowed bits using one of a multiple pulse excitation coding mode and a gain compensation mode.
-
Citations
18 Claims
-
1. A speech coding apparatus comprising:
-
a core speech coding unit which presents a speech signal with an excitation signal; a transmission rate determination unit which allocates the number of bits that are additionally allowed due to a capacity change in a transmission channel; and an embedded excitation signal coding unit for determining which one of a multiple pulse excitation coding method and a gain compensation method is optimal for coding a residual excitation signal, that is not coded in the core speech coding unit, with the additionally allowed bits, and generating the residual excitation signal coded by the determined method, wherein the gain compensation method derives a gain compensation value for compensating a gain obtained from an algebraic codebook search, the gain compensation value being multiplied with the gain obtained from the algebraic codebook search to update the gain, wherein the embedded excitation signal coding unit comprises a multiple pulse search unit for selecting a position and a sign of multiple pulses that minimize a square error ε
m of the residual excitation signal,the embedded excitation signal coding unit further comprises a gain compensation unit for determining the gain compensation value that minimizes a square error ε
g of the residual excitation signal, andthe embedded excitation signal coding unit compares ε
m with ε
g, selects the multiple pulse excitation coding method when ε
m<
ε
g, and selects the gain compensation method when ε
m>
ε
g. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A speech decoding apparatus comprising:
-
an excitation signal reproduction unit which reconstructs a basic excitation signal using an adaptive codebook index and gain, and an algebraic codebook index and gain of a core speech coder; an embedded excitation signal reproduction unit for decoding a residual excitation signal from a bit stream added in an embedded type according to a determination made by an embedded coder as to which one of a multiple pulse excitation coding method and a gain compensation method is optimal for coding the residual excitation signal, that is not coded in the core speech coding unit, with the additionally allowed bits; and a linear prediction synthesis filter unit which reconstructs a speech signal by performing a linear prediction synthesis of the reconstructed basic excitation signal at the excitation signal reproduction unit and the decoded residual excitation signal at the embedded excitation signal reproduction unit, wherein the gain compensation method derives a gain compensation value for compensating a gain obtained from an algebraic codebook search, the gain compensation value being multiplied with the gain obtained from the algebraic codebook search to update the gain, and wherein the embedded coder selects a position and a sign of multiple pulses that minimize a square error ε
m of the residual excitation signal, determines the gain compensation value that minimizes a square error ε
g of the residual excitation signal, compares ε
m with ε
g, selects the multiple pulse excitation coding method when ε
m<
ε
g, and selects the gain compensation method when ε
m>
ε
g. - View Dependent Claims (8, 9)
-
-
10. A speech coding method comprising the steps of:
-
a) presenting, by a speech coding apparatus, a speech signal with an excitation signal; b) allocating, by the speech coding apparatus, the number of bits that are additionally allowed due to a capacity change in a transmission channel; and c) determining, by the speech coding apparatus, which one of a multiple pulse excitation coding method and a gain compensation method is optimal for coding a residual excitation signal, that is not coded in the core speech coding unit, with the additionally allowed bits, and generating the residual excitation signal coded by the determined method, wherein the gain compensation method derives a gain compensation value for compensating a gain obtained from an algebraic codebook search, the gain compensation value being multiplied with the gain obtained from the algebraic codebook search to update the gain, wherein the step c) comprises; c1) calculating the residual excitation signal, c2) determining a pulse position and a sign which minimize a square error ε
m of the residual excitation signal;c3) determining the gain compensation value which minimizes a square error ε
g of the residual excitation signal; andc4) comparing ε
m with ε
g, selecting the multiple pulse excitation coding method when ε
m<
ε
g, and selecting the gain compensation method when ε
m>
ε
g. - View Dependent Claims (11, 12, 13, 14, 15)
-
-
16. A speech decoding method comprising the steps of:
-
a) reconstructing, by a speech decoding apparatus, a basic excitation signal using an adaptive codebook index and gain, and an algebraic codebook index and gain of a speech coder; b) decoding, by the speech decoding apparatus, a residual excitation signal from a bit stream added in an embedded type according to a determination made by an embedded coder as to which one of a multiple pulse excitation coding method and a gain compensation method is optimal for coding the residual excitation signal, that is not coded in the core speech coding unit, with the additionally allowed bits; and c) reconstructing, by the speech decoding apparatus, a speech signal by performing a linear prediction synthesis of the reconstructed basic excitation signal and the decoded residual excitation signal, wherein the gain compensation method derives a gain compensation value for compensating a gain obtained from an algebraic codebook search, the gain compensation value being multiplied with the gain obtained from the algebraic codebook search to update the gain, wherein the embedded coder selects a position and a sign of multiple pulses that minimize a square error ε
m of the residual excitation signal, determines the gain compensation value that minimizes a square error ε
g of the residual excitation signal, compares ε
m with ε
g, selects the multiple pulse excitation coding method when ε
m<
ε
g, and selects the gain compensation method when ε
m>
ε
g. - View Dependent Claims (17, 18)
-
Specification