Predictive encoder or decoder with selection of one of two or more prediction signals according to prediction error signal amplitudes
First Claim
1. A system for carrying out prescribed one of predictive encoding of an autocorrelated signal into a prediction error signal and predictive decoding of said prediction error signal into a reproduction of said autocorrelated signal, said autocorrelated signal taking those values at equally spaced successive instants which are substantially correlated to the values said autocorrelated signal takes each of at least two predetermined durations after said instants, a first of said predetermined durations being equal at least to the equal spacing between two adjacent ones of said instants, a second of said predetermined durations being longer than said first predetermined duration, said prediction error signal having an amplitude variable from one of said instants to another thereof in complicance with said autocorrelated signal, said system comprising:
- a plurality of prediction signal producing means responsive to a first signal for producing at least two prediction signals, a first and a second of said prediction signals being predictive, at the respective ones of said instants, of the values said autocorrelated signal takes said first and second predetermined durations, respectively, after said respective instants;
control signal producing means responsive to said prediction error signal for producing a control signal depending on the amplitude said prediction error signal has at each of said instants;
switching means responsive to said control signal for selecting one of said at least two prediction signals to produce a second signal at an instant next succeeding said each instant;
adder means for producing a sum signal of said second signal and said prediction error signal;
means for supplying said sum signal to all of said prediction signal producing means as said first signal; and
input means responsive to said autocorrelated signal and said second signal for producing said prediction error signal when said system is for carrying out the predictive encoding and output means responsive to said sum signal for producing said reproduction when said system is for carrying out the predictive decoding.
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Abstract
A system carries out predictive encoding or decoding by selecting a prediction signal for a longer period among two or more prediction signals at the beginning of an autocorrelated signal to be encoded or of a prediction error signal to be decoded. At least one of the prediction signals may be a composite prediction signal. A sampling interval after each instant at which the prediction error signal exceeds in absolute value a threshold level, the encoding or decoding is carried out with the prediction signals switched from one to another. A control circuit for two prediction signals comprises a two-input Exclusive OR gate supplied with a result of comparison of the prediction error signal with the threshold level and a sample delay supplied with the Exclusive OR output. The delayed signal is supplied back to the Exclusive OR gate and forward to a switch for switching the prediction signals.
24 Citations
6 Claims
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1. A system for carrying out prescribed one of predictive encoding of an autocorrelated signal into a prediction error signal and predictive decoding of said prediction error signal into a reproduction of said autocorrelated signal, said autocorrelated signal taking those values at equally spaced successive instants which are substantially correlated to the values said autocorrelated signal takes each of at least two predetermined durations after said instants, a first of said predetermined durations being equal at least to the equal spacing between two adjacent ones of said instants, a second of said predetermined durations being longer than said first predetermined duration, said prediction error signal having an amplitude variable from one of said instants to another thereof in complicance with said autocorrelated signal, said system comprising:
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a plurality of prediction signal producing means responsive to a first signal for producing at least two prediction signals, a first and a second of said prediction signals being predictive, at the respective ones of said instants, of the values said autocorrelated signal takes said first and second predetermined durations, respectively, after said respective instants; control signal producing means responsive to said prediction error signal for producing a control signal depending on the amplitude said prediction error signal has at each of said instants; switching means responsive to said control signal for selecting one of said at least two prediction signals to produce a second signal at an instant next succeeding said each instant; adder means for producing a sum signal of said second signal and said prediction error signal; means for supplying said sum signal to all of said prediction signal producing means as said first signal; and input means responsive to said autocorrelated signal and said second signal for producing said prediction error signal when said system is for carrying out the predictive encoding and output means responsive to said sum signal for producing said reproduction when said system is for carrying out the predictive decoding. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification