VECTOR QUANTISATION DEVICE AND VECTOR QUANTISATION METHOD

摘要

Disclosed is a vector quantisation device which can reduce the computational complexity of an audio codec without reducing the audio quality when encoding a wideband digital signal. A vector quantisation device (112) searches a codebook using code vectors, with which the impulse response of an audibility weighted synthesis filter is convolved and which configure the codebook, and target vectors. A filtering unit (201) applies a filter exhibiting a low pass and/or a high pass characteristic to the impulse response. If the filter has a high pass characteristic, a compaction unit (202) then compacts the degree of the post-filtering impulse response. A convolution unit (203) convolves the post-filtering impulse response with each of the code vectors. If the filter has a low pass characteristic, a search unit (204) thins out elements of the plurality of code vectors with which the impulse response has been convolved, and elements of the target vectors. The search unit (204) then carries out a search.