An improved implementation of predictive coding compression

An algorithm for reversible data compression based on predictive coding is presented. From the input data, a sequence of integer-valued residuals is generated by a linear or nonlinear operation. The size of the alphabet for residuals is reduced by performing a modular operation on its symbols. The reconstruction process recovers the original data exactly. The modular operation results in a smaller-size codebook and prevents data expansion when the source is not matched to the code. For the encoder designed for compression of ECG (electrocardiogram) signals studied in an example, the encoded data volume was 78% larger than the input data volume when the input signal was white noise with a uniform amplitude distribution. For modular prediction, the expansion was reduced to 45%. The modular operation also reduces the entropy of the residuals, which theoretically should result in a higher degree of data compression, but this seems to be of little practical significance.<
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