Method and apparatus to synthesize and defeat video copy protection signals
First Claim
1. A method of defeating copy protection signals in one or more selected video lines of a video signal being supplied to a VCR and/or TV set, wherein the copy protection signals include sync and/or pseudo sync and AGC pulses, with the AGC pulses having a given small position separation, including zero separation, from the sync/pseudo sync pulses, comprising:
- providing the AGC pulses with the leading edge thereof having the small position separation from the trailing edge of respective sync/pseudo sync pulses wherein the small position separation maintains the copy protection effect; and
shifting the relative position of either the leading edge of the AGC pulses or the trailing edge of the respective sync/pseudo sync pulses with respect to each other to provide a further position separation therebetween sufficient to reduce the effects of the copy protection signals in the VCR and/or TV set and allow the recording of a viewable copy.
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Abstract
A method and apparatus for defeating copy protection signals in a video signal, and also for providing copy protection signals for a video signal, is disclosed. The defeat technique generally utilizes a particular pulse position shifting, modulation, etc., of AGC, normal sync and/or pseudo sync pulses to increase the separation between the pulses. Various embodiments are disclosed including selective shifting of the relative positions of either the sync/pseudo sync or AGC pulses, trimming portions of the sync/pseudo sync and/or the AGC pulses and narrowing of either the sync/pseudo sync and/or the AGC pulses, all to provide the selective position separation between the sync/pseudo sync and AGC pulses. The copy protection technique includes various embodiments for dynamically varying the sync/pseudo sync and AGC pulse separation by applying a modulation of the above position shifting, trimming and/or narrowing techniques over selected time periods to cycle from the copy protection condition to the copy protection defeat condition, back to the copy protection condition.
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Citations
36 Claims
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1. A method of defeating copy protection signals in one or more selected video lines of a video signal being supplied to a VCR and/or TV set, wherein the copy protection signals include sync and/or pseudo sync and AGC pulses, with the AGC pulses having a given small position separation, including zero separation, from the sync/pseudo sync pulses, comprising:
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providing the AGC pulses with the leading edge thereof having the small position separation from the trailing edge of respective sync/pseudo sync pulses wherein the small position separation maintains the copy protection effect; and
shifting the relative position of either the leading edge of the AGC pulses or the trailing edge of the respective sync/pseudo sync pulses with respect to each other to provide a further position separation therebetween sufficient to reduce the effects of the copy protection signals in the VCR and/or TV set and allow the recording of a viewable copy. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for defeating copy protection signals in one or more selected video lines of a video signal being supplied to a VCR and/or TV set, wherein the copy protection signals include sync and/or pseudo sync pulses and AGC pulses, with the AGC pulses having a given small position separation, including zero separation, from the sync and/or pseudo sync pulses, comprising:
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input means for supplying the copy protected video signal with the AGC pulses and the respective sync/pseudo sync pulses with the given small position separation which maintains the copy protection effect;
timing circuitry for providing timing signals indicative of one or more video lines containing sync/pseudo sync and AGC pulses; and
circuit means responsive to the timing circuitry for shifting the relative edges and/or positions of the AGC pulses and of the sync/pseudo sync pulses with respect to each other so as to provide a further position separation there between which is of sufficient separation to reduce or defeat the effects of the copy protection signals in the VCR and/or TV set and allow the recording of a viewable copy of the video signal. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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24. A method of providing copy protection signals in a video signal employing sync or pseudo sync pulses followed by AGC pulses, comprising:
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providing the AGC pulses with the leading edges thereof generally coincident with the trailing edges of respective sync/pseudo sync pulses thereby having essentially small to zero position separation consistent with maintaining copy protection;
dynamically increasing over time the position separation between the sync/pseudo sync pulses and the respective AGC pulses so as to reduce or defeat the effects of the copy protection signals; and
dynamically decreasing over time the position separation between the sync/pseudo sync pulses and the respective AGC pulses to return to the essentially small to zero position separation that maintains copy protection. - View Dependent Claims (25, 26, 27, 28, 29, 30)
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31. Apparatus for providing copy protection signals in a video signal employing sync and pseudo sync pulses followed by AGC pulses, comprising:
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timing circuitry for providing timing signals indicative of video lines which are to contain the copy protection signals, and of the location in the video lines of selected copy protection signals;
circuit means responsive to the timing circuitry for generating modulated inverted pseudo sync pulses, and for generating AGC pulses that vary in width and position delay in response to the modulated inverted pseudo sync pulses; and
summing means receiving the video signal and responsive to the circuit means and the timing circuitry for adding to the video signal a dynamic copy protection signal formed of position modulated AGC pulses relative to the pseudo sync pulses. - View Dependent Claims (32, 33, 34, 35)
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36. A method of providing copy protection signals in a video signal and for defeating the copy protection signals when desired, wherein the copy protection signals include sync and/or pseudo sync pulses and AGC pulses, comprising:
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providing the AGC pulses with the leading edges thereof coincident with, or separated by less than 1.0 microsecond from, the trailing edges of respective sync/pseudo sync pulses to provide the copy protection signals; and
position separating relative to time the AGC pulses and/or the respective sync/pseudo sync pulses an amount of 1.5 or more microseconds sufficient to defeat the copy protection effect of the copy protection signals.
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Specification