Efficient Vlsi Implementation of a Vlc Decoder for Golomb-rice Code Using Alternating Coding

Variable length code (VLC) is used in a large variety of lossless compression applications. Golomb-Rice code (GR code) is one type of VLC that is often encountered in the coding of video and image data. In this work we develop an efficient decoder for GR codes. Unlike the conventional variable length decoders, this new type of decoder needs neither codeword tables nor barrel shifters, while the codeword tables and barrel shifters usually occupy the largest part of the area in the design and both are included in the critical timing path. This proposed decoder is built on the basis of a new coding method for GR codes, which is also proposed in this paper, under the name “Alternating Coding” (ALT). We compare the ALT decoder with the decoder called “VLC decoder using plane separation” (PLS) which is claimed to be one of the most effective VLC decoders. Our results show that the ALT decoder is up to 1.52 times faster, two times smaller, and consumes at most 28% power of the PLS decoder. Moreover, its unique structure also gives this GR decoder great flexibility in decoding different sets of GR codes with constant performances.