An efficient VLC decompression scheme for user-defined coding tables

With the increase of information and data types, high-throughput and flexible memory-based VLC decoder is required for userdefined coding tables to achieve higher compression ratio. In this paper, we present a memory-based VLC decoder which is quite suitable for the applications with user-defined tables. By parallel loading data into memories, the coding tables can be changed with much less time. The codeword-boundary prediction algorithm breaks the recursive dependency of decoding procedures. As a result, the VLC decoder can be realized on multi-processor architecture and hence the decoding throughput is enhanced significantly. Additionally, the INDEXOFFSET symbols that can recover all data with pure VLC codeword and smaller table size are presented. Simulation results show that the combination of the proposed VLC decoder and user-defined table can achieve high decompression rate. As a result, it is quite suitable for high data rate applications with user-defined coding tables, such as MPEG-4. AN EFFICIENT VLC DECOMPRESSION SCHEME FOR USER-DEFINED CODING TABLES* Bai-Jue Shie and Chen-Yi Lee Department of Electronics Engineering, National Chiao Tung University, -+. 1001, Ta Hsueh Road, Hsinchu, 300, Taiwan, R.O.C. used coding tables are stored in VLC decoder. Consequently, the decoding information is loaded when they are requested. If the tables are changed for each part of bit stream, the time for loading tables will reduce decoding throughput and system performance. This may not be accepted for high data rate applications. On the other hand, the procedure of data recovery includes codeword decoding to symbol and symbol converting to practical value. To achieve high decompression rate, not only codeword bit stream has to be suitable for high throughput VLC decoder, but also symbol representation needs to be modified to simplify data recovery procedure.