Z-coder: a fast adaptive binary arithmetic coder

Abstract From the Canadian patent

A binary arithmetic coder and decoder provides improved coding accuracy due to improved probability estimation and adaptation. They also provide improved decoding speed through a "fast path" design wherein decoding of a most probable symbol requires few computational steps. Coded data represents data that is populated by more probable symbols ("MPS") and less probable symbols ("LPS"). In an embodiment a decoder, receives a segment of the coded data as a binary fraction C. It defines a coding interval of possible values of C, the interval extending from a variable lower bound A to a constant upper bound 1. For each position in the decoded symbol string, the decoder computes a test value Z …