Entropy encoder/decoder including a context extractor

Abstract From the Canadian patent

Abstract, In entropy, e.g. arithmetic or adaptive Huffman encoding/decoding a, context based on prior symbols is needed to provide accurate predictions of symbols to be encoded/decoded. Encoding/decoding efficiency is improved by employing an adaptive context extractor. The adaptive context extractor automatically adjusts the configuration of the lag intervals used to define the context. This is realized by adaptively incorporating into the context configuration at least one lag interval found to have a "good" predictive value relative to the particular symbol stream being encoded/decoded. The context configuration adjustment is such that the at least one found lag interval is exchanged …