| 摘要 |
<p>A sound encoder having an improved quantization performance while suppressing an increase of the bit rate to a lowest level. In a second layer encoding unit (40), a standard deviation calculating section (408) calculates the standard deviation sc of a first layer decoding spectrum after decoding scale factor ratio multiplication and outputs the standard deviation sc to a selecting section (409), the selecting section (409) selects a linear transform function as the function for nonlinear transform of the residual spectrum according to the standard deviation sc, a nonlinear transform function section (410) selects one of prepared nonlinear transform functions #1 to #N according to the result of the selection by the selecting section (409) and outputs the selected one to an inverse transform section (411), and the inverse transform section (411) subjects inverse transform (expansion) to a residual spectrum candidate stored in a residual spectrum code book (412) using the nonlinear transform function outputted from the nonlinear transform function section (410) and outputs the result to an adder (413).</p> |
