Scalable decoding apparatus and scalable encoding apparatus
First Claim
1. A scalable decoding apparatus comprising:
- a first decoder that decodes low frequency band coded information and obtains a low frequency band decoded signal; and
a second decoder that obtains a high frequency band decoded signal from the low frequency band decoded signal and high frequency band coded information, wherein the second decoder comprises;
a transformer that transforms the low frequency band decoded signal and obtains a low frequency band spectrum;
an adjuster that carries out amplitude adjustment on the low frequency band spectrum using an adjustment coefficient, selected from a plurality of prepared coefficients according to an index indicating a depth of valleys of spectrum harmonics of the low band decoded signal; and
a generator that generates a high frequency band spectrum using the amplitude-adjusted low frequency band spectrum and the high frequency band coded information.
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Abstract
A scalable decoding apparatus capable of providing decoded audio signals of high quality having less degradation of a high frequency spectrum even when decoding audio signals by generating the high frequency spectrum by use of a low frequency spectrum. In the apparatus, an amplitude adjusting part uses different adjustment coefficients in accordance with the characteristic of first layer spectrum information to adjust the amplitude of a first layer decoded signal spectrum, and then outputs the amplitude-adjusted first layer decoded signal spectrum to a pseudo-spectrum generating part. Using amplitude-adjusted first layer decoded signal spectrum received from the amplitude adjusting part, the pseudo-spectrum generating part generates and outputs a pseudo-spectrum of high frequencies to a scaling part. The scaling part scales the spectrum received from the pseudo-spectrum generating part and then outputs it to an adder.
33 Citations
7 Claims
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1. A scalable decoding apparatus comprising:
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a first decoder that decodes low frequency band coded information and obtains a low frequency band decoded signal; and a second decoder that obtains a high frequency band decoded signal from the low frequency band decoded signal and high frequency band coded information, wherein the second decoder comprises; a transformer that transforms the low frequency band decoded signal and obtains a low frequency band spectrum; an adjuster that carries out amplitude adjustment on the low frequency band spectrum using an adjustment coefficient, selected from a plurality of prepared coefficients according to an index indicating a depth of valleys of spectrum harmonics of the low band decoded signal; and a generator that generates a high frequency band spectrum using the amplitude-adjusted low frequency band spectrum and the high frequency band coded information. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification