发明名称 |
Z-coder: A fast adaptive binary arithmetic coder |
摘要 |
<p>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 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. <IMAGE></p> |
申请公布号 |
EP0895361(A2) |
申请公布日期 |
1999.02.03 |
申请号 |
EP19980305952 |
申请日期 |
1998.07.27 |
申请人 |
AT&T CORP. |
发明人 |
BENGIO, YOSHUA;BOTTOU, LEON;HOWARD, PAUL G. |
分类号 |
H03M7/40;(IPC1-7):H03M7/40 |
主分类号 |
H03M7/40 |
代理机构 |
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