CA2387418A1 - Digital vcr with non-standard speed playback - Google Patents

Abstract

A digital video cassette recorder records a high definition signal having an MPEG compatible structure, such as a proposed Grand Alliance signal. In the recorded format an advanced television frame occupies ten recorded tracks.
Reproduction at speeds other than the recorded speed is termed "Trick Play". Reproduction in a "Trick Play" mode necessitates a reproducing head crossing a plurality of recorded tracks.
However, since the advanced television signal is structured as groups of pictures comprising one interframe coded frame and a plurality of predicted frames, many of the recorded tracks contain data representing predicted frames. Thus an advanced television signal reproduced in "Trick Play" may represent a jumble of unrelated data segments. Operation in "Trick Play" may be facilitated by the selection of predetermined replay speeds and the allocation of specific locations within each track from which data may be reproduced. These specific track locations are utilized during recording to place advanced television image data for reproduction during "Trick Play" operation. The "Trick Play"
image data is also reproduced during normal playback but may not be utilized. The specific track locations are selected to facilitate "Trick Play" operation at a plurality of speeds in both forward and reverse directions. Since the advanced television signal comprises a plurality of predicted frames, transition from "Trick Play" to normal speed replay requires a control function which is responsive to the reproduction, at normal replay speed, of an interframe coded frame. Various methods of reproduced image transition are disclosed for selecting both to and from "Trick Play" reproduction.