| Summary: | 碩士 === 國立交通大學 === 電機與控制工程系 === 89 === This thesis presents a new Huffman decoder by numerical methods with the sectioning technique for increasing the decoding speed and reducing the memory requirement. The decoder is realized by first concatenating zeros in the rear of each codeword of a
variable-length Huffman code and then reordering the resulting codewords to form a monotonic decreasing or increasing data sequence; this sequence is used as the data reference for decoding.
The decoding is accomplished by numerical method using the input data for finding the corresponding codeword from the data reference. The numerical method mainly uses the Newton's method. Since the Newton's method, although
fast in searching, may be unable to converge, the bisection (or Regula Falsi) approach is integrated to ensure the convergence of the numerical method.
The variable-length Huffman code may make the data sequence having irregular slopes which make the numerical method converge slowly. This thesis tackles the problem by dividing
the entire data sequence into a number of smaller sections such that the slopes of each section is smoother.
This sectioning technique highly increases the searching speed at the cost of only small memory increment.
In the thesis, the memory requirement and decoding speed are analyzed and simulated by using the example for decoding MP3 data. The analysis and simulation results are demonstrated to verify the usefulness of our approach.
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