| 摘要 |
a spectrum parameter calculation circuit (100) for calculating a spectrum parameter for a signal x(n) obtained by decoding a first code; a coefficient calculation circuit (130) for receiving a spectrum parameter and converting it into a coefficient of the signal subjected to band extension; a noise generation circuit (120) for outputting a noise signal whose band is limited; a gain circuit (140) for multiplying the output signal of the noise generation circuit by a gain; a combining filter circuit (170) for receiving the output signal from the noise generation circuit (120) and the coefficient from the coefficient calculation circuit (130) and outputting a high-band signal y(n) for band extension; a sampling frequency conversion circuit (180) for outputting a signal s(n) which is the signal x(n) up-sampled to a predetermined sampling frequency; an adder (190) for adding the high-band signal y(n) and the signal s(n) to form a band-extension signal z(n); and a second encoding circuit (195) for encoding the band-extension signal z(n) by the second encoding method and outputting the result.
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