Coding device and a decoding device
First Claim
Patent Images
1. A predictive coding device comprising:
- (a) coding means for outputting a differential code of m bits quantizing a differential value between an input sample value of n bits and a predictive value, m and n being integers, and m being smaller than n;
(b) local decoding means for outputting a local decoded value of n bits for said input sample value, said local decoded value being determined according to said differential code; and
(c) predictive means for calculating said predictive value by using said local decoded value,wherein characteristics of said coding means and said local decoding means are set so that a width of a range of values which said local decoded value is permitted to have is narrower than a width of a range of values which said input sample value is permitted to have, irrespective of said input sample value.
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Abstract
A coding device comprises a coding circuit in which a range of values, which local decoded values are permitted to have is made narrower than a range of values, which input sample values are permitted to have when coding a differential value between an input sample value and its predictive value. A decoding device substitutes a decoded value to be subsequently decoded for a decoded value in which a gradient overload is produced when decoding a code provided by coding a differential value between an input sample value and its predictive value.
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Citations
32 Claims
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1. A predictive coding device comprising:
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(a) coding means for outputting a differential code of m bits quantizing a differential value between an input sample value of n bits and a predictive value, m and n being integers, and m being smaller than n; (b) local decoding means for outputting a local decoded value of n bits for said input sample value, said local decoded value being determined according to said differential code; and (c) predictive means for calculating said predictive value by using said local decoded value, wherein characteristics of said coding means and said local decoding means are set so that a width of a range of values which said local decoded value is permitted to have is narrower than a width of a range of values which said input sample value is permitted to have, irrespective of said input sample value. - View Dependent Claims (2, 3, 4, 5)
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6. A predictive coding device comprising:
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(a) coding means for outputting a differential code provided by quantizing a differential value between an input sample value and a predictive value, the differential value being limited within a predetermined range of values a width is narrower than a width of a range of a values which said differential value is permitted to have, irrespective of said input sample value; (b) local decoding means for outputting a local decoded value corresponding to said differential code; and (c) predictive means for calculating said predictive value using said local decoded value. - View Dependent Claims (7)
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8. A predictive coding device comprising:
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(a) coding means for selectively outputting a first differential code provided by quantizing a differential value between an input sample value and a predictive value within a first range of values and a second differential code provided by quantizing said differential value within a second range of values a width of which is narrower a width of said first range of values; (b) local decoding means for outputting a local decoded value corresponding to a selected one of the first and second differential code output from said coding means; and (c) predictive means for calculating said predictive value using said local decoded value. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A predictive decoding device comprising:
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(a) decoding means for receiving a differential code provided by coding a differential value between an input sample value and its predictive value, and for outputting a decoded value corresponding to said input sample value; (b) discrimination means for discriminating that a slope overload is produced in the decoded value which said decoding means outputs; (c) delays means for delaying said decoded value; and (d) selection means for selectively outputting the decoded value which said decoding means outputs and the decoded value which said delay means outputs in accordance with an output of said discrimination means. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A predictive decoding device comprising:
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(a) decoding means for having selectively input thereto first and second differential codes provided by quantizing a differential value between an input sample value and a predictive value within first and second quantization ranges, and for outputting a decoded value corresponding to said input sample value; (b) detection means for detecting that the differential value corresponding to said second differential code is situated at an end of its quantization range; and (c) switching means for switching a decoding characteristic of said decoding means in accordance with an output from said detection means. - View Dependent Claims (29, 30, 31, 32)
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Specification