Scalable encoding apparatus, scalable decoding apparatus, scalable encoding method, scalable decoding method, communication terminal apparatus, and base station apparatus
View Patent ↗A scalable encoding apparatus, a scalable decoding apparatus and the like are disclosed which can achieve a band scalable LSP encoding that exhibits both a high quantization efficiency and a high performance. In these apparatuses, a narrow band-to-wide band converter receives and converts a quantized narrow band LSP to a wide band, and then outputs the quantized narrow band LSP as converted (i.e., a converted wide band LSP parameter) to an LSP-to-LPC converter. The LSP-to-LPC converter converts the quantized narrow band LSP as converted to a linear prediction coefficient and then outputs it to a pre-emphasizer. The pre-emphasizer calculates and outputs the pre-emphasized linear prediction coefficient to an LPC-to-LSP converter. The LPC-to-LSP converter converts the pre-emphasized linear prediction coefficient to a pre-emphasized quantized narrow band LSP as wide band converted, and then outputs it to a prediction quantizer.
1. An scalable encoding apparatus that performs predictive quantization of a wideband LSP parameter using a narrowband quantized LSP parameter, the scalable encoding apparatus comprising:
a classifier that performs classification using the wideband LSP parameter and generates class information; and
a multistage vector quantization codebook that comprises a plurality of codebooks, at least one of the plurality of codebooks comprising a plurality of sub-codebooks, selects a sub-codebook according to the class information from the plurality of sub-codebooks and performs multistage vector quantization of the wideband LSP parameter using the selected sub-codebook.
2. The encoding apparatus according to claim 1 , wherein the multistage vector quantization codebook comprises the plurality of sub-codebooks in a codebook in which an average energy of stored code vectors is maximum among the plurality of codebooks.
3. A scalable decoding apparatus that performs predictive quantization of a wideband LSP parameter using a narrowband quantized LSP parameter, the scalable encoding apparatus comprising a multistage vector quantization codebook, that comprises a plurality of codebooks, at least one of the plurality of codebooks comprising a plurality of sub-codebooks, selects a sub-codebook according to the class information from the plurality of sub-codebooks, and performs multistage vector quantization of the wideband LSP parameter using the selected sub-codebook.
4. The decoding apparatus according to claim 3 , wherein the multistage vector quantization codebook comprises the plurality of sub-codebooks in a codebook in which an average energy of stored code vectors is maximum among the plurality of codebooks.