Adaptive audio signal source vector quantization device and adaptive audio signal source vector quantization method that search for pitch period based on variable resolution

Abstract

An adaptive sound source vector quantization device includes a first pitch cycle instructor, a search range calculator, and a second pitch cycle instructor. The first pitch cycle instructor 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 calculator 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 instructor successively instructs the pitch cycle search candidates in the search range for the second sub-frame.