Trick play method for digital VCRs

Abstract

In digital VCRs for home use, the video signal for each field is recorded on multiple tracks. Thus, it is difficult to reproduce the video signal smoothly in high‐speed trick playback, where the signal is restored by scanning across the tracks. This paper intends to realize a satisfactory high‐speed reproduction, and discusses the improvement of the head scanning trajectory, a high‐speed trick playback error‐control method, and a data coding method for the high‐speed trick playback. In the base‐band recording VCR, there is a problem that the fixed position of the image frame cannot be restored in integer‐multiple speed playback. In order to cope with this problem, a method to adjust the drum rotation speed is considered, and the relation between the variation of the drum rotation and the period of the image presentation is derived. In the high‐speed playback, only the C1 code can be restored among the error‐correcting codes. For this problem, it is shown that the C3 code can be added and the error‐correcting capability can be improved when a data area for high‐speed trick playback is provided as in the bit‐stream recording VCR. The requantization coding and the data‐division coding methods are proposed as data coding methods for the high‐speed trick playback. The effectiveness of those methods is demonstrated by image simulation. © 1997 Scripta Technica, Inc. Electron Comm Jpn Pt 3, 80(12): 65–81, 1997