Apparatus, method and storage medium for recording and/or reproducing digital data using relative position data

coded digital picture data and header data. The header data includes a sync code for the digital specific data; identification information; and relative position data associated with the intracoded digital picture data, wherein the associated relative position data is indicative of a plurality of relative positions from a current nth specific data location on the medium to each of a n+1, n+2, . . . , n+m specific data location on the medium, where m is greater than 2. The relative position data is used to reproduce the intracoded digital picture data. An apparatus and method for controlling recording and reproduction in a video cassette tape recorder are disclosed apparatus is capable of, in a recording mode, separating specific data for speed-varied reproduction from compressed digital video signals, recording them on designated tracks, recording position information of the designated tracks on a control track by an index head or recording position information of recording position-synchronized blocks at the starting portions of the designated tracks recorded with the specific data, and in a speed-varied reproduction mode, controlling a capstan servo speed so as to maintain the travel of a magnetic tape at a normal speed and periodically or non-periodically accelerate or decelerate it where specific data for varied-speed have been recorded periodically or non-periodically on predetermined portions of tracks, thereby making heads travel repeatedly at the normal speed and the high speed and thereby detect continuously the specific tracks for varied-speed. A repeatability of reproduced video at a varied speed is obtained without any deterioration in picture quality, because of recording of the specific data for speed-varied reproduction and the continuous detection of the specific data in the speed-varied reproduction. An apparatus, method and storage medium for recording and/or reproducing digital data using relative position data are discussed. According to an embodiment, the storage medium includes a plurality of specific data units, each specific data unit including digital specific data including intra---