The predictive-substitutional compression scheme and its effective implementation

The predictive-substitutional compression scheme combines string-oriented and symbol-oriented models to improve compression speed and effectiveness. There are several hybrid compression algorithms known. In this paper, two new one-pass predictive-substitutional algorithms are introduced. The improved algorithm (PLZ+) implements fast switching cost evaluation making it capable of doing a substitution only when the substitution identifier´s codeword length is shorter than the sum of codeword lengths of the literals that the string is composed of. Experimental results show the predictive-substitutional scheme is one of the best available data compression methods for data transmission purposes in medium bandwidth range.