Video scrambling by segmenting video information lines

• US 4,736,420 A
• Filed: 09/19/1986
• Issued: 04/05/1988
• Est. Priority Date: 09/19/1986
• Status: Expired due to Term

• Current Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Original Assignee: Cable/Home Communication Corporation, MACOM Technology Solutions Holdings, Inc.
• Inventors: Moroney, Paul, Walker, Gordon K., Katznelson, Ron D.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/909,763
• Time in Patent Office: 564 Days
• Field of Search: 380/10, 380/11, 380/20, 380/14
• US Class Current: 380/215
• CPC Class Codes: H04N 7/1696 by changing or reversing the order of active picture signal portions

Abstract

A system for scrambling a video signal having a plurality of horizontal lines, each of which includes a video information portion and a non-video information portion. The scrambling system includes a memory; means for storing the video information portion of each video signal line in the memory; and means for forming scrambled horizontal lines by retrieving each of a plurality of said stored video information lines in a plurality of segments preceded by a non-video segment and separated by non-video segment(s). 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; and means for varying the total duration of the non-video segments for individual scrambled horizontal lines in accordance with a predetermined timing pattern. A complementary descrambling system also is disclosed.

Claims

1. A system for scrambling a video signal having a plurality of horizontal lines, each of which includes a video information portion and a non-video information portion, comprising

a memory;

means for storing the video information portion of each video signal line in the memory; and

means for forming scrambled horizontal lines by retrieving each of a plurality of said stored video information lines in a plurality of segments preceded by a non-video segment and separated by non-video segment(s);

wherein the retrieval means include

means for varying the respective durations of the retrieved video information segments in individual scrambled horizontal lines; and

means for varying the total duration of the non-video segments for individual scrambled horizontal lines.

2. A system according to claim 1 wherein the retrieval means vary the respective durations of the retrieved video information segments in accordance with an encryption keystream.

3. A system according to claim 2, wherein the retrieval means vary the total duration of the non-video segments in individual scrambled lines in accordance with a predetermined pattern.

11. A system according to claim 1,

wherein the video information portion of each horizontal line includes m blocks of video information;

wherein the means for storing said video information portions of each horizontal line in the memory includes means for providing a scrambler store address pointer value for sequentially addressing n consecutive storage locations in the memory for sequentially storing the m individual blocks of the video information portion of each horizontal line; and

wherein the means for retrieving said video information portions of each horizontal line includes means for providing a scrambler retrieve address pointer value for sequentially addressing the n storage locations in the memory for sequentially retrieving the m individual blocks of the video information portion of each horizontal line.

12. A system according to claim 11, wherein the retrieving means commences said retrieval of information portions of a given horizontal line before the storage means completes storing the information portions of said given horizontal line.

13. A system according to claim 12, wherein the memory is a FIFO buffer memory, thereby enabling the number of storage locations n to be less than the number of individual blocks of video information m that are stored for each horizontal line.

14. A system according to claim 11, wherein the memory is a FIFO buffer memory, thereby enabling the number of storage locations n to be less than the number of individual blocks of video information m that are stored for each horizontal line.

4. A system for descrambling a scrambled video signal having a plurality of horizontal lines, each of which includes a segmented video information portion preceded by a non-video segment, with the video information segments in an individual scrambled horizontal line being separated by non-video segment(s), and with the respective durations of the video information segments in an individual scrambled horizontal line being different for different individual scrambled lines, and with the total duration of the plurality of non-video segments in an individual scrambled horizontal line being different for different individual scrambled lines, the system comprising

a memory;

means for storing the video information segments of each scrambled horizontal line in the memory; and

means for forming descrambled horizontal lines by retrieving the stored video information segments of each line in a nonsegmented format;

wherein the storage means include means for storing the video information segments in accordance with the variation in the respective durations of the video information segments in different individual scrambled horizontal lines and the variation in the total duration of the plurality of non-video segments in different individual scrambled lines.

5. A system according to claim 4 wherein

the variation in the respective durations of the video information segments in different individual scrambled horizontal lines is in accordance with an encryption keystream,

the storage means store the video information segments in accordance with the encryption keystream.

6. A system according to claim 5, wherein

the variation in the total duration of the non-video segments in different individual scrambled lines is in accordance with a predetermined pattern;

and

the storage means further store the video line segments in accordance with said predetermined pattern.

7. A system according to claim 4,

wherein the video information portion of each horizontal line includes m blocks of video information;

wherein the means for storing said video information portions of each horizontal line in the memory includes means for providing a descrambler store address pointer value for sequentially addressing n consecutive storage locations in the memory for sequentially storing the m individual blocks of the video information portion of each horizontal line; and

wherein the means for retrieving said video information portions of each horizontal line includes means for providing a descrambler retrieve address pointer value for sequentially addressing the n storage locations in the memory for sequentially retrieving the m individual blocks of the video information portion of each horizontal line.

8. A system according to claim 7, wherein the retrieving means commences said retrieval of information portions of a given horizontal line before the storage means completes storing the information portions of said given horizontal line.

9. A system according to claim 8, wherein the memory is a FIFO buffer memory, thereby enabling the number of storage locations n to be less than the number of individual blocks of video information m that are stored for each horizontal line.

10. A system according to claim 7, wherein the memory is a FIFO buffer memory, thereby enabling the number of storage locations n to be less than the number of individual blocks of video information m that are stored for each horizontal line.

15. A system comprising

a scrambler for scrambling a video signal to provide a scrambled video signal having a plurality of horizontal lines, each of which includes a segmented video information portion preceded by a non-video segment, with the video information segments in an individual scrambled horizontal line being separated by non-video segment(s), and with the respective durations of the video information segments in an individual scrambled horizontal line being different for different individual scrambled lines, and with the total duration of the plurality of non-video segments in an individual scrambled horizontal line being different for different individual scrambled lines;

and

a descrambler for descrambling said scrambled video signal, the descrambler comprising

a memory;

means for storing the video information segments of each scrambled horizontal line in the memory; and

means for forming descrambled horizontal lines by retrieving the stored video information segments of each line in a nonsegmented format;

wherein the storage means include means for storing the video information segments in accordance with the variation in the respective durations of the video information segments in different individual scrambled horizontal lines and the variation in the total duration of the plurality of non-video segments in different individual scrambled lines.

16. A system according to claim 15, wherein

the variation in the respective durations of the video information segments in different individual scrambled horizontal lines is in accordance with an encryption keystream;

and

the storage means store the video information segments in accordance with the encryption keystream.

17. A system according to claim 16, wherein

the variation in the total duration of the non-video segments in different scrambled lines is in accordance with a predetermined pattern;

and

the storage means further store the video line segments in accordance with said predetermined pattern.

18. A system according to claim 15,

wherein the video information portion of each horizontal line includes m blocks of video information:

wherein the means for storing said video information portions of each horizontal line in the memory includes means for providing a descrambler store address pointer value for sequentially addressing n consecutive storage locations in the memory for sequentially storing the m individual blocks of the video information portion of each horizontal line; and

wherein the means for retrieving said video information portions of each horizontal line includes means for providing a descrambler retrieve address pointer value for sequentially addressing the n storage locations in the memory for sequentially retrieving the m individual blocks of the video information portion of each horizontal line.

19. A system according to claim 18, wherein the retrieving means commences said retrieval of information portions of a given horizontal line before the storage means completes storing the information portions of said given horizontal line.

20. A system according to claim 18, wherein the memory is a FIFO buffer memory, thereby enabling the number of storage locations n to be less than the number of individual blocks of video information m that are stored for each horizontal line.