Coded data generation or conversion – Digital code to digital code converters – To or from differential codes
Patent
1997-11-25
1999-10-26
Williams, Howard L.
Coded data generation or conversion
Digital code to digital code converters
To or from differential codes
341143, 375246, H03M 304
Patent
active
059736291
ABSTRACT:
A compressive encoding-decoding system is provided specifically for the realization of the lossless encoding system having a good efficiency. Herein, input signals are subjected to analog-to-digital conversion to generate a series of linear PCM data. Then, the system generates a series of difference value data, each representing a difference between adjacent samples of the linear PCM data, which are then combined with respect to each frame. Requantization is performed on the difference value data on the basis of a word length. In a first mode, the word length is determined to coincide with a minimum number of bits which are required to represent the difference value data having a maximum absolute value within the difference value data contained in each frame. In a second mode corresponding to word extension, a value of `L` is determined as a unit of bits for partitioning in such a way that an overall length of each frame becomes the shortest when each of the difference value data contained in each frame is subjected to partitioning starting from a LSB thereof by every L bits. In addition, a single bit representing as to whether or not each portion of L bits within each difference value data is a last portion (or last word) is added as a flag to the word length. Herein, one of the modes which provides a shorter length for the frame is selected, so the system produces data of each frame (i.e., bit stream) containing the difference value data requantized based on the word length, and information of the word length as well as information of the selected mode.
REFERENCES:
patent: 4646148 (1987-02-01), Lienard et al.
patent: 5128963 (1992-07-01), Akagiri
patent: 5365553 (1994-11-01), Veldhuis et al.
Williams Howard L.
Yamaha Corporation
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