Cryptography – Key management – Having particular key generator
Patent
1991-11-08
1993-08-24
Cain, David
Cryptography
Key management
Having particular key generator
380 17, 380 10, H04N 7167
Patent
active
052395820
ABSTRACT:
A method and apparatus for generating a ramp at cutpoints in a cut and rotate video line scrambling system. The undesirable shortening of the active portion of the video line which typically occurs in cut and rotate scrambling to overcome the problem of abrupt transitions at the cutpoints is eliminated by providing a synthesized ramp between the video amplitude level at the cutpoint and the blanking level at each of the cutpoints. This synthesized ramp is calculated by digital logic in conjunction with a delay line for inserting the ramp at its proper temporal position in the video signal. The ramp approximates a sine.sup.2 function and is formed of three consecutive pixels, each pixel having an associated calculated video amplitude.
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Cain David
Macrovision Corporation
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