Apparatus for encoding a speech signal employing ACELP in the autocorrelation domain

Patent metadata

Field	Value
Publication number	US-10170129-B2
Application number	US-201514678610-A
Country	US
Kind code	B2
Filing date	Apr 3, 2015
Priority date	Oct 5, 2012
Publication date	Jan 1, 2019
Grant date	Jan 1, 2019

Abstract

An apparatus for encoding a speech signal by determining a codebook vector of a speech coding algorithm is provided. The apparatus includes a matrix determiner for determining an autocorrelation matrix R, and a codebook vector determiner for determining the codebook vector depending on the autocorrelation matrix R. The matrix determiner is configured to determine the autocorrelation matrix R by determining vector coefficients of a vector r, wherein the autocorrelation matrix R includes a plurality of rows and a plurality of columns, wherein the vector r indicates one of the columns or one of the rows of the autocorrelation matrix R, wherein R(i, j)=r(|i−j|), wherein R(i, j) indicates the coefficients of the autocorrelation matrix R, wherein i is a first index indicating one of a plurality of rows of the autocorrelation matrix R, and wherein j is a second index indicating one of the plurality of columns of the autocorrelation matrix R.

First claim

The invention claimed is:

1. An apparatus for encoding a speech signal by determining a codebook vector of a speech coding algorithm for encoding the speech signal, wherein the apparatus comprises:
a matrix determiner for determining an autocorrelation matrix R, and
a codebook vector determiner for determining the codebook vector of the speech coding algorithm for encoding the speech signal depending on the autocorrelation matrix R,
wherein the matrix determiner is configured to determine the autocorrelation matrix R by determining vector coefficients of a vector r, wherein the autocorrelation matrix R comprises a plurality of rows and a plurality of columns, wherein the vector r indicates one of the columns or one of the rows of the autocorrelation matrix R, wherein
R ( i,j )= r (| i−j |),

wherein R(i, j) indicates the coefficients of the autocorrelation matrix R, wherein i is a first index indicating one of a plurality of rows of the autocorrelation matrix R, and wherein j is a second index indicating one of the plurality of columns of the autocorrelation matrix R,
wherein the codebook vector determiner is configured to determine the codebook vector of the speech coding algorithm for encoding the speech signal by applying the formula

f
⁡

(

e
^

)

=

(

d
T

⁢

e
^

)

2

e
^

T

⁢
R
⁢

e
^

wherein R is the autocorrelation matrix, wherein R is a Hermitian Toeplitz matrix, and wherein ê is one of the codebook vectors of the speech coding algorithm for encoding the speech signal, wherein f(ê) is a normalized correlation, and wherein d T is defined according to

(

e
T

⁢
R
⁢

⁢

e
^

)

2

(

e
^

T

⁢
R
⁢

e
^

)

=

(

d
T

⁢
e

)

2

(

e
^

T

⁢
R
⁢

⁢

e
^

)

,

wherein e is an original, unquantized residual signal,
wherein T indicates a transpose of a vector, and
wherein at least one of the matrix determiner and the codebook vector determiner comprises a hardware implementation.

2. The apparatus according to claim 1 ,
wherein the matrix determiner is configured to determine the vector coefficients of the vector r by applying the formula:
r ( k )= h ( k )* h (− k )=Σ l h ( l ) h ( l−k )

wherein h(k) indicates a perceptually weighted impulse response of a linear predictive model, and wherein k is an index being an integer, and wherein l is an index being an integer.

3. The apparatus according to claim 1 ,
wherein the matrix determiner is configured to determine the autocorrelation matrix R depending on a perceptually weighted linear predictor.

4. The apparatus according to claim 1 ,
wherein the codebook vector determiner is configured to determine that codebook vector ê of the speech coding algorithm which maximizes the normalized correlation

f
⁡

(

e
^

)

=

(

d
T

⁢

e
^

)

2

e
^

T

⁢
R
⁢

e
^

.

5. The apparatus according to claim 1 , wherein the codebook vector determiner is configured to decompose the autocorrelation matrix R by conducting a matrix decomposition.

6. The apparatus according to claim 5 , wherein the codebook vector determiner is configured to conduct the matrix decomposition to determine a diagonal matrix D for determining the codebook vector.

7. The apparatus according to claim 6 ,
wherein the codebook vector determiner is configured to determine the c

Assignees

• Farunhofer Ges Zur Foerderung Der Angewandten Forschung E V
• Fraunhofer Ges Forschung

Inventors

• Baeckstroem Tom
• Multrus Markus
• Fuchs Guillaume
• Helmrich Christian
• Dietz Martin

Classifications

• G10L19/038 Primary

  Vector quantisation, e.g. TwinVQ audio · CPC title

• G10L2019/0001

  Codebooks · CPC title

• G10L19/107 Primary

  Sparse pulse excitation, e.g. by using algebraic codebook · CPC title

• G10L19/04

  using predictive techniques · CPC title

• G10L19/10

  the excitation function being a multipulse excitation · CPC title