No Title

The delay time is dependent on the variety of picture elements included within a block. The video signal is provided from the delay circuit 2a to a subtractor 2b. Here the distinction between the image sign, and the prediction signal equipped by way of a line 105a branching from an output line a hundred and five of a prediction signal generator 5, is produced, and the difference, i.e. the prediction error signal, is then provided to a quantizer three which capabilities to limit the number of attainable levels.

A controller 301 is provided for control of coding in accordance with occupancy of the buffer reminiscence 300. Included in the coding control are number of quantizing characteristics, sub-sample or thin-out of image components in horizontal direction, and sub-line or thin-out of image elements in vertical path. Through the coding management, coding effectivity can always be optimized in any management mode. DESCRIPTION OF PREFERRED EMBODIMENTS Referring to FIG. 1, there is proven an overall scheme of a coded video signal transmitting and receiving system. One method of utilization of a coded video sign is such that, as shown at stable line, an output code from an encoder incorporated in a transmitter is transmitted by way of a transmission path to a decoder included in a receiver and decoded thereat.

One of four parallel image factor outputs is equipped via line 108-6a to a subtractor 8-12a, proven in FIG. The position of an image component processed by the arithmetic unit 8-1 might be known as hereinafter image element point D1 as shown in FIG. 3A. Similarly, other arithmetic units 8-2 by way of 8-4 are used for computing image factor factors D2 through D4, and 4 arithmetic units in whole are used in parallel for concurrent computations for one block. Line reminiscence pair 1-1 and 1-2 and another line reminiscence pair 1-3 and 1-4 are saved and skim out alternately, in order that the video signal which is rendered scan conversion i.e. transformed into two-dimensional blocks, is output in a string of image parts. One of two outputs from a line memory pair in studying operation is selectively output via the multiplexor 1-5. The block-formation video sign on a line 101 from the multiplexor 1-5 branches to the strains 101a and 101b, then is provided to the delay circuit 2a and optimum prediction detector eight, respectively. The above-mentioned scan conversion is advantageous for the reason that predictive coding circuit using the two-dimensional blocks is straightforward.

9 is a block diagram displaying intimately the prediction sign generator 5 in FIG. 4A. In the determine, a two-dimensional memory 5-1 has substantially the same construction as that of the two-dimensional memory 8-11 included in the arithmetic unit 8-1.

This value was obtained when the sampling frequency was 8 MHz, so that data of about zero.8M bits/sec. Was dedicated to the movement vector info alone. Accordingly, the place a tv sign is transmitted at a transmission velocity of 1.5M bits/sec., the motion vector info would occupy slightly greater than 50% of everything of data transmitted. A predictive coding methods operates primarily based on a precept that a distinction between a sign to be transmitted and a prediction sign is transmitted in order to lower the quantity of transmission info. This invention contemplates an adaptive predictive coding system whereby a plurality of prediction features that give the prediction signals are used and an optimum one of many prediction functions is used for performing a prediction coding operation. Thus, the controller 301 receives a sign representative of the occupancy of the buffer memory 300 via a line one hundred ten, and designates the quantizer 3, optimum prediction detector 8 and code compressor 7 through line 111, and designates the quantizer three, the optimum prediction detector eight, the code compressor 7 and the interpolator 302 via line 112.

The sum of these two code lengths is considered to be an amount of knowledge generated when the actual prediction function is used. With regard to the opposite prediction functions, the sum of two code lengths is equally determined. A prediction perform which is obtained when the results of comparison of the sum of the 2 code lengths reveals a minimum is set as an optimum prediction function, that is, a movement vector. It is feasible to make smaller the amount of the transmission info when the movement vector is set in this manner than when the motion vector is decided by utilizing only the prediction error data as in the prior art. The percentage of the codes necessary to represent this movement vector with respect to all the transmission info varies significantly relying upon the transmission velocity at the transmission path used.

For the predictive coding system utilizing motion compensation, the vary of correction, i.e., the variety of vectors N, should ideally be as massive as potential and the variety of picture components in a block be as small as potential. From this viewpoint, the method of in which needed hardware is determined by the worth of N and a broad variety of movement compensation disadvantageously needs an increased hardware. In contrast, the method of primarily makes use of M arithmetic models repeatedly for N occasions, and the hardware requirement is just about decided by the worth of M. Thus, it can be seen that the tactic of is more advantageous. The tackle of the prediction sign generator memory 8-11a for writing the above-mentioned supplementary picture parts is preferably next to the addresses for storing picture parts which are needed for figuring out the optimum prediction operate for the current block, for facilitating read/write management. For this purpose, A1 via A8 are written following the addresses for storing x1 through x16 as proven in FIG. The needed storage capability of the prediction sign generator memory 8-11a is expressed, utilizing symbols k, L, m and n, as (2m+k)×(2n+L) for figuring out the optimum prediction operate of the present block, k×(2n+L) for supplementary image elements for determining the optimum prediction function of the following block, amounting to 2(m+k)×(2n+L) in whole.