| 摘要 |
<p>A system for scrambling a video signal having a plurality of horizontal lines, each of which includes a video information portion (A, B, C) and a non-video information portion (48). The scrambling system includes a memory (10) means (12) for storing the video information portion of each video signal line in the memory; and means (12) for forming scrambled horizontal lines by retrieving each of a plurality of said stored video information lines in a plurality of segments (A1, A2; B1, B2; C1, C2) preceded by a non-video segment (42) and separated by non-video segment(s) (44). The retrieval means include means for varying the respective durations of the retrieved video information segments in individual scrambled horizontal lines in accordance with an encryption keystream (46); and means for varying the total duration of the non-video segments for (42, 44) for individual scrambled horizontal lines in accordance with a predetermined timing pattern. A complementary descrambling system also is disclosed.</p> |
