JPH03261290A - Prediction coding circuit - Google Patents

Abstract

PURPOSE:To reduce the cost by providing a subtractor, an adder, a prediction device receiving the result of addition as a feedback input and calculating a predicted value with respect to a succeeding current sample and an output terminal through which the result of addition is outputted. CONSTITUTION:A subtractor 5 takes a difference between a current sample value given via an input terminal 1 and a predicted value calculated by a prediction device 7, and an adder 6 adds a difference sample given via an input terminal 3 and a predicted value calculated by the prediction device 7. The result of subtraction by the subtractor 5 is sent from an output terminal 2 and the result of addition at the adder 6 is given to the prediction device 7 as a feedback input and sent to an output terminal 4. The prediction device 7 based on the given feedback input calculates the prediction value with respect to a succeeding current sample value given via the input terminal 1 and gives the predicted value to the subtractor 5 and the adder 6. Thus, it is possible to build up a prediction decoding circuit by using part of the function and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a predictive coding circuit suitable for use in digitally transmitting television signals.

[Conventional technology]

Traditionally, this type of predictive encoding circuit has been
It is composed of IC. This predictive encoding circuit serves as a transmitter when digitally transmitting a television signal, for example.

[Problem to be solved by the invention]

However, the conventional predictive encoding circuit is configured as a dedicated circuit, and cannot be shared with the predictive decoding circuit forming the receiving section.

In other words, when attempting to implement LSI, the LSI for the predictive coding circuit that makes up the transmitting section and the LSI for the predictive decoding circuit that makes up the receiving section must be made separately, which is one of the factors that increases the cost. was.

[Means to solve the problem]

The present invention was proposed to solve such problems, and includes a subtracter that takes the difference between the current sample value and the predicted value;
an adder that adds the difference sample value and the predicted value;
It is provided with a predictor that uses the addition result of the adder as a feedback input and calculates a predicted value for the next current sample value, and an output terminal that outputs the addition result of the adder.

[Effect]

Therefore, according to the present invention, it is possible to construct a predictive decoding circuit using some of the functions of the predictive encoding circuit.

〔Example〕

Hereinafter, the predictive encoding circuit according to the present invention will be explained in detail.

FIG. 1 shows an embodiment of this predictive encoding circuit, and is a block diagram showing extracted basic functions thereof.

In the figure, 1 is the first input terminal, 2 is the first output terminal, 3 is the second input terminal, 4 is the second output terminal, 5 is the subtracter, 6 is the adder, and 7 is the predictor. It is. The subtracter 5 takes the difference between the current sample value given via the input terminal 1 and the predicted value calculated by the predictor 7. The adder 6 adds the difference sample value given via the input terminal 3 (different from the current sample value given via the input terminal 1) and the predicted value calculated by the predictor 7. The result of subtraction by the subtracter 5 is sent out from the output terminal 2. The addition result in the adder 6 is given to the predictor 7 as a feedback input, and is also sent out from the output terminal 4. The predictor 7 calculates a predicted value for the next current sample value applied via the input terminal 1 based on the supplied feedback input, and supplies this predicted value to the subtracter 5 and adder 6.

FIG. 2 shows a specific example of a predictive encoding circuit constructed using some of the basic functions shown in FIG. In this figure, the same reference numerals as in FIG. 1 indicate the same constituent elements, and the explanation thereof will be omitted. In this predictive encoding circuit, the subtraction result in the subtracter 5 is given to the quantizer 8, and the quantization result in the quantizer 8 is given as a difference sample value to the adder 6.

That is, the subtracter 5 takes the difference between the current sample value given through the input terminal 1 and the predicted value calculated by the predictor 7, and the subtraction result in the subtracter 5 is sent to the quantum output terminal 2 through the output terminal 2. Send to converter 8. Then, the quantization result from the quantizer 8 is sent out from the output terminal 9 as the output of the predictive encoding circuit, and is also given to the adder 6 via the input terminal 3 as a differential sample value. The adder 6 adds the supplied difference sample value and the predicted value calculated by the predictor 7, and sends the addition result to the predictor 7 as a feedback input (past sample value). The predictor 7 calculates a predicted value for the next current sample value applied via the input terminal 1 based on the feedback input provided, and provides this predicted value to the subtractor 5 and adder 6. In the predictive encoding circuit that operates in this manner, the function of the output terminal 4 that can send out the addition result of the adder 6 is not used.

FIG. 3 shows a specific example of a predictive decoding circuit constructed using some of the basic functions shown in FIG. In this figure, the same reference numerals as in FIG. 1 indicate the same constituent elements, and the explanation thereof will be omitted. In this predictive decoding circuit, an adder 6 adds the difference sample value given via the input terminal 3 and a predicted value calculated by the predictor 7, and the result of this addition is used as a feedback input to the predictor 7. At the same time, it is sent from the output terminal 4 as the output of the predictive decoding circuit. In the predictive decoding circuit operating in this manner, the subtracter 5. It is assumed that the functions of input terminal 1 and output terminal 2 are not used.

〔Effect of the invention〕

As explained above, the predictive encoding circuit according to the present invention includes a subtracter that takes the difference between the current sample value and the predicted value;
an adder that adds the difference sample value and the predicted value;
Since it is equipped with a predictor that uses the addition result of this adder as a feedback input and calculates a predicted value for the next current sample value, and an output terminal that outputs the addition result of the adder,
It is now possible to construct a predictive decoding circuit using the functions of that part, which means that it can be shared with the predictive decoding circuit that forms the receiving part. The decoding circuit and the decoding circuit can each be constructed using the same LSI, which facilitates cost reduction.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a predictive coding circuit according to the present invention, and its basic functions are extracted, and FIG. 2 is a configuration using a part of the basic functions shown in FIG. 1. FIG. 3 is a diagram showing a specific example of a predictive decoding circuit configured using a part of the basic functions shown in FIG. 1. 1...First input terminal, 2...First output terminal, 3
...Second input terminal, 4...Second output terminal, 5.
...Subtractor, 6...Adder, 7...Predictor.

Claims (1)

[Claims] A subtracter that takes the difference between the current sample value and the predicted value, an adder that adds the difference sample value and the predicted value, and the addition result of this adder is used as a feedback input to generate the predicted value for the next current sample value. A predictive encoding circuit comprising: a predictor that calculates; and an output terminal that outputs the addition result of the adder.