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研究了小波包变换在声音编码中的应用，通过利用小波包变换在时域和频域都具有良好局部性的特点，提出了一种新的中低码率混合域声音编码算法。这是一种可调码率算法，它根据输入信号段的特性来进行变换和编码，使得编码过程可以同时在时域、频域以及从时域向频域过渡的任一时频域中进行，从而使编码算法不仅在量化编码阶段，而且在变换阶段就对输入信号具有自适应性。其编码效果比在单一固定时频域中进行变换与编码有较大改善，有助于和高码率的声音编码算法相接轨。
The application of wavelet packet transform in sound coding is studied. By utilizing the characteristics of wavelet packet transform in both time and frequency domain, a new low-bit-rate hybrid domain sound coding algorithm is proposed. This is a tunable rate algorithm which transforms and encodes according to the characteristics of the input signal segment so that the encoding process can be performed simultaneously in either the time domain, the frequency domain, or any time-frequency domain that transitions from the time domain to the frequency domain, So that the encoding algorithm not only in the quantization coding stage, but also in the transformation phase on the input signal adaptive. Its coding effect is better than that of transform and coding in a single fixed time-frequency domain, which helps to connect with the high bit rate audio coding algorithm.