A new approach of group-based VLC codec system with full table programmability

In this paper, the algorithm and architecture of a variable-length-code (VLC) codec system using a new group-based approach and achieving full table programmability are presented. According to the proposed codeword grouping and symbol memory mapping, both group searching and encoding/decoding procedures are completed by applying numerical properties and arithmetic operations to codewords and symbol addresses. By a novel symbol conversion, the memory requirement of the encoding process is reduced and the programmability of codewords and symbols is achieved. For MPEG applications, a 0.6-μm CMOS design that performs concurrent VLC codec processes is shown. This VLSI implementation occupies an area of 5.0 ×4.5 mm² with 110 k transistors and satisfies a coding table up to 256-entry 12-bit symbols and 16-bit codewords. In addition, both encoding and decoding throughputs of this design achieve 100 Msymbols/s at a 100-MHz clock rate. Therefore, the proposed VLC codec system is suitable for applications which require high operation throughput, such as HDTV, and simultaneous compression and decompression, such as videoconferencing.