Real-Time Huffman Encoder with Pipelined CAM-Based Data Path and Code-Word-Table Optimizer

Takeshi KUMAKI  Yasuto KURODA  Masakatsu ISHIZAKI  Tetsushi KOIDE  Hans Jurgen MATTAUSCH  Hideyuki NODA  Katsumi DOSAKA  Kazutami ARIMOTO  Kazunori SAITO  

IEICE TRANSACTIONS on Information and Systems   Vol.E90-D   No.1   pp.334-345
Publication Date: 2007/01/01
Online ISSN: 1745-1361
Print ISSN: 0916-8532
Type of Manuscript: PAPER
Category: Image Processing and Video Processing
content addressable memory,  CAM,  Huffman coding,  parallel processing,  pipeline,  code word table,  

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This paper presents a novel optimized real-time Huffman encoder using a pipelined data path based on CAM technology and a parallel code-word-table optimizer. The exploitation of CAM technology enables fast parallel search of the code word table. At the same time, the code word table is optimized according to the frequency of received input symbols and is up-dated in real-time. Since these two functions work in parallel, the proposed architecture realizes fast parallel encoding and keeps a constantly high compression ratio. Evaluation results for the JPEG application show that the proposed architecture can achieve up to 28% smaller encoded picture sizes than the conventional architectures. The obtained encoding time can be reduced by 95% in comparison to a conventional SRAM-based architecture, which is suitable even for the latest end-user-devices requiring fast frame-rates. Furthermore, the proposed architecture provides the only encoder that can simultaneously realize small compressed data size and fast processing speed.