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    HIGH-SPEED ARITHMETIC COMPRESSION CODING USING CONCURRENT VALUE UPDATING.
    1.
    发明公开
    HIGH-SPEED ARITHMETIC COMPRESSION CODING USING CONCURRENT VALUE UPDATING. 失效
    由于同时更新值快速算法压缩编码。

    公开(公告)号：EP0079333A4

    公开(公告)日：1987-07-06

    申请号：EP81901825

    申请日：1981-03-30

    Applicant: IBM

    Inventor： LANGDON GLEN GEORGE JR ,  RISSANEN JORMA JOHANNES

    IPC: H03M7/40

    CPC classification number: H03M7/4006

    Abstract: A method and apparatus for recursively generating an arithmetically compressed binary number stream responsive to the binary string from conditional sources. Throughput is increased by reducing the number of operations required to encode each binary symbol so that only a single shift of k bits is required upon receipt of each least-probable symbol or an "add time", followed by a decision and a one-bit shift in response to each most-probable symbol encoding. The concurrent augmentation of the compressed stream and an internal variable involves only the function of a probability interval estimate of the most-probable symbol, and not upon the past encoding state of either variable (2 , 49, 63, C, T). Each binary symbol may be recovered by subtracting 2 from the q-most-significant bits of the compressed stream and testing the leading bit of the difference.

    5.
    发明专利
    未知

    公开(公告)号：DE3787898T2

    公开(公告)日：1994-05-05

    申请号：DE3787898

    申请日：1987-01-02

    Applicant: IBM

    Inventor： MOHIUDDIN KOTTAPPURAM MOHAMMED ,  RISSANEN JORMA JOHANNES

    IPC: H03M7/40 ,  H03M7/42

    Abstract: Method and apparatus which cyclically generate a compressed, arithmetically-coded binary stream in response to binary occurrence counts of symbols in an uncoded string. The symbols in the uncoded string are drawn from a multi-character alphabet which is not necessarily a binary one. Coding operations and hardware are simplified by deriving from the binary occurrence counts an estimate of the probability of each unencoded symbol at its precise lexical location. The probability estimation eliminates any requirement for division or multiplication by employing magnitude-shifting of the binary occurrence counts. The encoded stream is augmented by the estimated symbol probability at the same time that an internal variable is updated with an estimate of the portion of a probability interval remaining after coding the current symbol, the interval estimate being obtained from the left-shifted occurrence counts. Decoding is the dual of encoding. The unencoded symbol stream is extracted, symbol-by-symbot, by substracting the estimated symbol probability that comes closest to, but does not exceed the magnitude of the compressed stream, re-estimating the symbol probabilities based upon the decoding, and testing the difference of the subtraction against the re-estimated probability.

    7.
    发明专利
    未知

    公开(公告)号：DE3787898D1

    公开(公告)日：1993-12-02

    申请号：DE3787898

    申请日：1987-01-02

    Applicant: IBM

    Inventor： MOHIUDDIN KOTTAPPURAM MOHAMMED ,  RISSANEN JORMA JOHANNES

    IPC: H03M7/40 ,  H03M7/42

    Abstract: Method and apparatus which cyclically generate a compressed, arithmetically-coded binary stream in response to binary occurrence counts of symbols in an uncoded string. The symbols in the uncoded string are drawn from a multi-character alphabet which is not necessarily a binary one. Coding operations and hardware are simplified by deriving from the binary occurrence counts an estimate of the probability of each unencoded symbol at its precise lexical location. The probability estimation eliminates any requirement for division or multiplication by employing magnitude-shifting of the binary occurrence counts. The encoded stream is augmented by the estimated symbol probability at the same time that an internal variable is updated with an estimate of the portion of a probability interval remaining after coding the current symbol, the interval estimate being obtained from the left-shifted occurrence counts. Decoding is the dual of encoding. The unencoded symbol stream is extracted, symbol-by-symbot, by substracting the estimated symbol probability that comes closest to, but does not exceed the magnitude of the compressed stream, re-estimating the symbol probabilities based upon the decoding, and testing the difference of the subtraction against the re-estimated probability.

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