| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 87 === Wavelets and sinusoidal representations are two promising tools for high efficient audio coding. However, the study of these two techniques on audio coding just started. Many unknown areas remain to be explored. This thesis is an attempt of combining both sinusoidal analysis and wavelet filter together to form an efficient audio compression system. First, we adopt a linear-prediction technique to estimate the tonal components in an audio sequence. To increase the accuracy of sinusoidal representation, an audio frame may be split into two segments, each containing a set of sinusoids. After the sinusoids are removed from the audio sequence, the residues are passing through a set of wavelet packets. Then, the redundancy among subbands are reduced by inter-subband prediction. The final outputs are quantized perceptually. There are a number of detailed steps in each technique of the preceding algorithm. For example, in sinusoidal analysis (extracting sinusoidals), a proper screening process is needed to eliminate incorrect candidates. Another novel technique, audio frame segmentation, requires a careful check through different layers of wavelet packet outputs. To examine the effectiveness of the techniques employed in this thesis, numerous simulations have been conducted and reported. Several techniques are shown to increase the coding efficiency, while the others may need further study to clarify their usefulness.
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