Patent ID: 8099275
Filing Date: 2012-01-17
Classification: G10L

Abstract:
1. A speech coding apparatus that performs coding having a layered structure composed of a plurality of layers, the speech coding apparatus comprising: an analyzer, including a first circuit, that analyzes a spectrum of a decoded signal of a lower layer to calculate a decoded spectrum of the lower layer; a selector, including a second circuit, that selects one nonlinear transform function from among a plurality of nonlinear transform functions based on a degree of variation of the decoded spectrum of the lower layer, the degree of variation being a standard deviation of the decoded spectrum of the lower layer; an inverse transformer, including a third circuit, that inverse transforms a nonlinear transformed residual spectrum using the one nonlinear transform function selected by the selector to obtain an inverse transformed residual spectrum; and an adder, including a fourth circuit, that adds the inverse transformed residual spectrum to the decoded spectrum of the lower layer to obtain a decoded spectrum of an upper layer.