A detector for detecting a motion vector indicating the motion of an image comprising: device for deriving corrlative values for an overall or partial screen area for the two-field image signal of a successively inputted TV signal, within an area of motion vectors to be predicted for the current field, based on the motion vectors obtained before the current field; and device for deriving, as a motion vector, an optimum value from among the correlative values, whereby the correlative values in the area of motion vectors to be predicted for the current field are derived on the basis of the motion vectors obtained before the current field, and then a motion vector is detected from among those correlative values. With the above structure, it is made possible to detect a motion vector in a larger area with a smaller amount of operation, circuit and processing time, as compared with a prior art detector.

A method for recording and/or reproducing digitally coded video signals. A frame sequence is coded in such a way that an intraframe coded picture having a fixed or variable block length is recorded at the beginning. A fixed number of interframe coded pictures follow. The block length of the interframe coded pictures can be both fixed and variable. A cutting begins with and ends before an intraframe coded picture.

Motion compensated coding of interlaced digital video signals is provided. Pixel data from successive interlaced video fields is compared to similarly situated pixel data in a plurality of previous fields to find a preferred counterpart for each current field set of pixel data. A prediction error signal is generated for each current field set of pixel data indicative of the difference between it and its preferred counterpart from a previous field. Each prediction error signal is encoded with data indicative of the previous field in which the preferred counterpart can be found. In a preferred embodiment, each set of current field pixel data is compared to a range of similarly situated pixels in each of the previous fields, and the prediction error signal is also encoded with motion vector data indicative of the location of the preferred counterpart in its previous field.

In a high-efficiency encoder which performs motion-compensation prediction, an intra-field is set every n fields. The presence of a scene change is detected. When a scene change occurs, a reference picture of motion-compensation prediction is switched, or the field immediately after the scene change is set as an intra-field.

This invention relates to a video coding decoding apparatus for effectively refreshing a video and for recovering degradation of a video caused by code error, in a short time. A video coding decoding apparatus according to the present invention comprises area shape detection (12) for dividing the picture in the single frame into a motion compensation area and the remaining area and then detecting a shape of the motion compensation area by distinguishing between the motion compensation area and the remaining area, and motion vector estimation (14) for estimating a resultant motion vector of the overall motion compensation area from a motion vector of each block in the motion compensation area. A refreshing operation is carried out from a starting point of the estimated resultant motion vector towards the direction of the estimated resultant motion vector in a motion compensation area. When a code error has occurred, code error block number informing circuit (13) informs the number of the block where the code error has occurred. The starting point of the refreshing operation is a block which, among many other adjacent blocks to the informed block, is located in an opposite direction with respect to the estimated motion vector. For this reason, a video can be refreshed effectively and degradation of a video caused by code error, can be recovered in a short time.