Abstract: In an apparatus for detecting amounts of relative motion of a picture expressed by a digital video signal, between successive fields of the signal, a fixed set of picture element positions are designated as respective representative points in each field of the video signal. For each representative point, the signal level value for that point during a preceding field is compared with each of a successive of picture element values in the current field, within a corresponding comparison interval which extends prior to and subsequent to the position of that representative point in the field.

Abstract: In apparatus for recording/reproducing a composite video signal on and from a rotary recording medium (1), the field of the composite video signal is detected and only odd or even field signal is delayed by one half (H/2) a horizontal scanning period so that the composite video signal is changed to a modified composite video signal which is recorded on the rotary recording medium (1) together with a field distinguishing signal (Sf) produced using the result of the field detection. The field distinguishing signal (Sf) is arranged to be located at a given time position with respect to a predetermined vertical sync signal of every one frame period of the recording signal on a rotary recording medium (1) driven and rotated at a rotational period equal to the vertical scanning period of the composite video signal.