Recursively excited linear prediction speech coder
First Claim
1. A method for determining an excitation signal in an analysis-by-synthesis speech coder, the excitation signal being a sum of at least three vector terms, each vector term k being a product of a codebook vector Zk and an associated gain term gk, the method comprising:
- determining a first vector term g0z0 representative of a target excitation vector x; and
recursively determining each remaining vector term k as a vector term gkzk representative of the difference between the target excitation vector x and the sum of previously determined vector terms, andwherein the gain term of each vector term is determined by minimizing an error function E representative of the difference between the target excitation vector x and the sum of that vector term and all previously determined vector terms,
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Abstract
The excitation in a CELP-like speech coder is recursively calculated. For a given bitrate and a given complexity, the recursive approach described lowers the complexity with minimum impact on speech quality. The excitation signal is a sum of at least three vector terms, each vector term being a product of a codebook vector zk and an associated gain term gk. A first vector term g0z0 is determined that is representative of a target excitation vector x. Each remaining vector term is recursively determined as a vector term gkzk representative of the difference between the target excitation vector x and the sum of previously determined vector terms,
35 Citations
12 Claims
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1. A method for determining an excitation signal in an analysis-by-synthesis speech coder, the excitation signal being a sum of at least three vector terms, each vector term k being a product of a codebook vector Zk and an associated gain term gk, the method comprising:
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determining a first vector term g0z0 representative of a target excitation vector x; and
recursively determining each remaining vector term k as a vector term gkzk representative of the difference between the target excitation vector x and the sum of previously determined vector terms, and wherein the gain term of each vector term is determined by minimizing an error function E representative of the difference between the target excitation vector x and the sum of that vector term and all previously determined vector terms, - View Dependent Claims (2, 3, 4, 5, 6)
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7. A computer program for determining an excitation signal in an analysis-by-synthesis speech coder, the excitation signal being a sum of at least three vector terms, each vector term k being a product of a codebook vector Zk and an associated gain term gk, the program comprising:
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a first vector logic for determining a first vector term g0z0 representative of a target excitation vector x; and
a second vector logic for recursively determining each remaining vector term k as a vector term gk, Zk representative of the difference between the target excitation vector x and the sum of previously determined vector terms, and wherein the gain term of each vector term gkZk is determined by minimizing an error function E representative of the difference between the target excitation vector x and the sum of that vector term and all previously determined vector terms, - View Dependent Claims (8, 9, 10, 11, 12)
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Specification