Adaptive excitation vector quantization device and adaptive excitation vector quantization method

Abstract

Provided is an adaptive sound source vector quantization device which can always perform a pitch cycle search with a resolution appropriate for any section of the pitch cycle search range of a second sub-frame when a pitch cycle search range of the second sub-frame changes in accordance with a pitch cycle of a first sub-frame. The device includes a first pitch cycle instruction unit (111), a search range calculation unit (112), and a second pitch cycle instruction unit (113). The first pitch cycle instruction unit (111) successively instructs pitch cycle search candidates in a predetermined search range having a search resolution which transits over a predetermined pitch cycle candidate for the first sub-frame. The search range calculation unit (112) calculates a predetermined range before and after the pitch cycle of the first sub-frame as the pitch cycle search range for the second sub-frame, if the predetermined range includes the predetermined pitch cycle search candidate. In the predetermined range, the search resolution transits over a boundary defined by the predetermined pitch cycle. The second pitch cycle instruction unit (113) successively instructs the pitch cycle search candidates in the search range for the second sub-frame.

Description

technical field [0001] The invention relates to an adaptive excitation vector quantization device and an adaptive excitation vector quantization method for carrying out adaptive excitation vector quantization in speech coding of the CELP (Code Excited Linear Prediction, Code Excited Linear Prediction) mode. In representative packet communication systems and mobile communication systems, etc., AVQ devices and AVQ methods for performing adaptive excitation vector quantization are used by speech encoding / decoding devices that transmit speech signals. Background technique [0002] In the field of digital wireless communication, packet communication represented by Internet communication, or voice storage, audio signal encoding / decoding technology is essential in order to realize efficient use of transmission path capacity such as radio waves and storage media. In particular, CELP-based speech encoding / decoding technology has become a mainstream technology (see, for example, Non-P...

AI Technical Summary

Problems solved by technology

On the other hand, when the pitch period of the first subframe is equal to or greater than a predetermined threshold, the search range of the pitch period of the second subframe is made wider to further reduce the search resolution.

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