| 摘要 |
An apparatus for modifying a video signal to protect the unauthorized recording and reproduction thereof is disclosed. In accordance with the invention, the video signal is modified in such a manner that insufficient vertical synchronization information is contained in some, but not all, of the vertical blanking intervals. Particularly, insufficient vertical synchronization information is contained in a sequence of vertical blanking intervals which will cause the rotational velocity of the tape head of the VTR to constantly vary.
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