A Fast Huffman Decoding Algorithm by Multiple Bit Length Search Scheme for the MPEG-4 AAC

• Main Authors: Han-chang ho, 何函璋
• Other Authors: Sheau-Fang Lei
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/04149818862470676859

碩士 === 國立成功大學 === 電機工程學系碩博士班 === 97 === Huffman coding is an important part in MPEG-4 Advanced Audio Coding（AAC）standard. The function of Huffman coding is to encode the input data stream with shorter length of bit string so that the audio samples can be compressed into smaller size. The compressed data can be recovered by Huffman decoding in decoder side. The process of Huffman decoding requires long delay because long computational time is consumed by the excessive number of searches for the decoded symbols. In this paper, a fast Huffman decoding algorithm is proposed to reduce the number of searches required in Huffman decoding. The algorithm uses a forward search scheme that 5-bit length is used for each search basis for decoding the symbols. The experimental results show that a 5-bit search scheme can be hit with the probability of 72% to decode the symbols. Thus the proposed method can reduce the number of searches, thus lead to the reduced processing delay and increasing processing speed for Huffman decoding. Comparing with other algorithms for Huffman decoding, the proposed algorithm can reduce the number of searches by 27% to 58%, the number of instructions by 40% to 67%.