| 摘要 |
An audio CODEC(Coder Decoder) using wavelet packet decomposition/composition based on a code book and a method for restoring an audio signal using the audio CODEC are provided to replace a sub-band signal of a high frequency band among wavelet packet decomposition sub-band signals with the code book, thereby reducing the quantity of calculation during restoration and improving a compression rate while maintaining high quality of sound. A CODEC(1) includes an encoding unit(3) and a decoding unit(5). Each of the encoding unit and the decoding unit includes a code book(7). The code book includes a process for normalizing amplitude of a signal by extracted sub-bands in order to reduce a noise component, which occurs when a sub-band signal of a high frequency band is replaced with the code book and a phase of a corresponding sub-band signal is not equal to that of a low frequency band.
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