Z-coder: a fast adaptive binary arithmetic coder
Patent 6225925 Issued on May 1, 2001. Estimated Expiration Date: 
March 13, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 13, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References Re35781 Probability adaptation for arithmetic coders Coding method of image information Coding system Digital information encoding device, digital information decoding device, digital information encoding/decoding device, digital information encoding method, and digital information decoding method Merged VLSI implementation of hardware optimized Q-Coder and software optimized QM-Coder Patent #: 5859604 InventorsApplicationNo. 042007 filed on 03/13/1998US Classes:341/107, To or from code based on probability341/106Coding by table look-up techniquesExaminersPrimary: Young, BrianAssistant: Wamsley, Patrick Attorney, Agent or FirmForeign Patent References
International ClassH03M 007/00AbstractA 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 that subdivides the coding interval into sub-intervals according to the relative probabilities that an MPS or an LPS occurs in the position. A first sub-interval extends from the lower bound A to the test value Z; the second sub-interval extending from the test value Z to 1. If C is greater than Z, the decoder emits an MPS for the current position in the decoded symbol string and sets the lower bound A to the test variable Z for use during decoding of the next position in the decoded symbol string. If C is less than Z, the decoder emits an LPS and computes a new lower bound A and a new binary fraction C for use during decoding of the next position in the decoded symbol string. The encoder operates according to analogous techniques to compose coded data from original data.Other References
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