Adaptive sound source vector quantization device, adaptive sound source vector inverse quantization device, and method thereof

• US 8,200,483 B2
• Filed: 12/14/2007
• Issued: 06/12/2012
• Est. Priority Date: 12/15/2006
• Status: Active Grant

• Current Assignee: III Holdings 12, LLC (Intellectual Ventures LLC)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Sato, Kaoru, Morii, Toshiyuki
• Primary Examiner(s): Godbold, Douglas
• Application Number:
  US12/518,944
• Publication Number:
  US 20100082337A1
• Time in Patent Office: 1,642 Days
• Field of Search: 704200-201, 704500-503
• US Class Current: 704/222
• CPC Class Codes: G10L 19/038 Vector quantisation, e.g. TwinVQ audio
• CPC Class Codes: G10L 19/12 the excitation function being a code excitation, e.g. in code excited linear prediction [CELP] vocoders

Abstract

Disclosed is an adaptive excitation vector quantization device capable of improving quantization accuracy of adaptive excitation vector quantization while suppressing increase of the calculation amount in CELP encoding which performs encoding in sub-frame units. An adaptive excitation vector generator cuts out an adaptive excitation vector of a frame length (n) from an adaptive excitation codebook. An impulse response matrix former forms a n×n impulse response matrix using impulse response matrixes of sub-frames inputted from a synthesis filter. A target vector generator adds a linear prediction residual vector of each sub-frame to form a target vector of frame length (n). An evaluation measure calculator calculates an evaluation measure of the adaptive excitation vector quantization by using the adaptive excitation vector, the impulse response matrix, and the target vector.

Claims

1. An adaptive excitation vector quantization apparatus that is used in code excited linear prediction speech encoding to generate linear prediction residual vectors of a length m and linear prediction coefficients by dividing a frame of a length n into a plurality of subframes of the length m and performing a linear prediction analysis, (the length n and the length m being integers, the length n being a multiple of the length m, the apparatus comprising:

an adaptive excitation vector generator including at least one of at least one processor and at least one circuit that cuts out an adaptive excitation vector of the length n from an adaptive excitation codebook;

a target vector generator including at least one of the at least one processor and the at least one circuit that forms a target vector of the length n by adding the linear prediction residual vectors of the plurality of subframes;

a synthesis filter including at least one of the at least one processor and the at least one circuit that generates m×

m impulse response matrixes using the linear prediction coefficients of the plurality of subframes;

an impulse response matrix former including at least one of the at least one processor and the at least one circuit that forms a n×

n impulse response matrix using the m×

m impulse response matrixes;

an evaluation measure calculator including at least one of the at least one processor and the at least one circuit that calculates an evaluation measure of an adaptive excitation vector quantization per each pitch period candidate, using the adaptive excitation vector of the length n, the target vector of the length n and the n×

n impulse response matrix; and

an evaluation measure comparator including at least one of the at least one processor and the at least one circuit that compares the evaluation measure with respect to each pitch period candidate and calculates a pitch period of a highest evaluation measure as a quantization result.

2. A code excited linear prediction speech encoding apparatus comprising the adaptive excitation vector quantization apparatus according to claim 1.

3. The adaptive excitation vector quantization apparatus according to claim 1, wherein a new impulse response matrix is formed by extracting components of the n×

n impulse response matrix and the m×

m impulse response matrixes and by rearranging the extracted components.

4. The adaptive excitation vector quantization apparatus according to claim 1, further comprising:

a pitch period designator including at least one of the at least one processor and the at least one circuit that sequentially designates pitch periods of a pitch period search range to the adaptive excitation vector generator when a first subframe of the plurality of subframes is received and that does not sequentially designate the pitch periods to the adaptive excitation vector generator when a second subframe of the plurality of subframes is received.

5. An adaptive excitation vector quantization method that is used in code excited linear prediction speech encoding to generate linear prediction residual vectors of a length m and linear prediction coefficients by dividing a frame of a length n into a plurality of subframes of the length m and performing a linear prediction analysis, (the length n and the length m being integers, the length n being a multiple of the length m, the method comprising:

cutting out, with at least one of at least one processor and at least one circuit, an adaptive excitation vector of the length n from an adaptive excitation codebook;

forming, with at least one of the at least one processor and the at least one circuit, a target vector of the length n by adding the linear prediction residual vectors of the plurality of subframes;

generating, with at least one of the at least one processor and the at least one circuit, m×

m impulse response matrixes using the linear prediction coefficients of the plurality of subframes;

forming, with at least one of the at least one processor and the at least one circuit, a n×

n impulse response matrix using the m×

m impulse response matrixes;

calculating, with at least one of the at least one processor and the at least one circuit, an evaluation measure of adaptive excitation vector quantization per pitch period candidate, using the adaptive excitation vector of the length n, the target vector of the length n and the n×

n impulse response matrix; and

comparing, with at least one of the at least one processor and the at least one circuit, the evaluation measures with respect to the pitch period candidates and calculating a pitch period of a highest evaluation measure as a quantization result.

6. The adaptive excitation vector quantization method according to claim 5, wherein the impulse response matrix former forms a new impulse response matrix by extracting components of the n×

n impulse response matrix and the m×

m impulse response matrixes and by rearranging the extracted components.

7. The adaptive excitation vector quantization method according to claim 5, further comprising:

sequentially designating pitch periods of a pitch period search range to the adaptive excitation vector generator when a first subframe of the plurality of subframes is received,

wherein the pitch periods are not sequentially designated to the adaptive excitation vector generator when a second subframe of the plurality of subframes is received.