| 摘要 |
PROBLEM TO BE SOLVED: To improve the processing speed of quantization processing and to improve the quality of a reproduced signal. SOLUTION: When an output signal mc from an MDCT circuit is a threshold K and more, "exponentiation approximate value" (pow_spec_av) is calculated by using a linear equation based on respective coefficients and shift values which are respectively acquired from a 1st coefficient storage part 603, a 1st shift value storage part 605 and a 2nd coefficient storage part 607, and a 2nd shift value storage part 609. When the signal mc is less than the threshold K, a "exponentiation value" (pow_spec_ac) stored in a exponentiation value storage part 611 is acquired. A exponentiation value corresponding to the signal mc less than the threshold K is previously calculated and stored in the exponentiation value storage part 611. COPYRIGHT: (C)2005,JPO&NCIPI
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