Method for modifying a copy protected video signal with a negative amplitude pulse
First Claim
1. A method of modifying a video signal subject to copy protection to increase picture degradation where the copy protection signal causes a reduced amplitude video signal to be recorded on the copy, comprising the steps of:
- blanking a portion of the video signal at a location in the overscan portion of the video signal prior to a synchronization signal; and
adding to the blanked location a waveform for indicating a video retrace prior to occurrence of the synchronization signal.
4 Assignments
0 Petitions
Accused Products
Abstract
Enhancements to a video anticopying process that causes an abnormally low amplitude video signal to be recorded on an illegal copy. The enhancements in one version introduce into the overscan portion of the television picture, just prior to the horizontal or vertical sync signals but in active video, a negative going waveform that appears to the television receiver or videotape recorder to be a sync signal, thereby causing an early horizontal or vertical retrace. One version provides (in the right overscan portion of the picture), a checker pattern of alternating gray and black areas which causes the TV set on which the illegal copy is played to horizontally retrace earlier than normal in selected lines with a consequential horizontal shift of the picture information on those lines. This substantially degrades picture viewability. In another version a gray pattern at the bottom overscan portion of the picture causes vertical picture instability. In another version selected horizontal sync signals are narrowed, causing irregular vertical retraces. Also provided is apparatus for removing or attenuating these enhancements from the video signal, to allow copying.
20 Citations
104 Claims
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1. A method of modifying a video signal subject to copy protection to increase picture degradation where the copy protection signal causes a reduced amplitude video signal to be recorded on the copy, comprising the steps of:
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blanking a portion of the video signal at a location in the overscan portion of the video signal prior to a synchronization signal; and
adding to the blanked location a waveform for indicating a video retrace prior to occurrence of the synchronization signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of modifying a video signal subject to copy protection to increase picture degradation when a copy of the copy protected video is played, where the copy protection causes a reduced amplitude video signal to be recorded on the copy, comprising the steps of:
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providing a waveform of a type for indicating a video retrace;
substituting the waveform in at least one horizontal line of the video signal at a location prior to a synchronization signal in place of an active video signal otherwise present at that location, wherein the location is in an overscan portion of the video signal.
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22. A method of modifying a video signal subject to copy protection to increase picture degradation where the copy protection signal causes a reduced amplitude video signal to be recorded on the copy, comprising the steps of:
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providing a waveform of a type for indicating a video retrace; and
substituting the waveform in at least one horizontal line of the video signal at a location following a synchronization signal of the video signal. - View Dependent Claims (26, 27, 28, 29, 30)
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23. A method for enhancing a video copy protection process which causes a reduced amplitude video signal to be recorded on a copy of the video signal, the method comprising the steps of:
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inserting a pattern of alternating black and gray regions into an overscan portion of the active video portion of a field of the video signal; and
in successive fields shifting the locations of the rectangles, thereby causing a moving displacement in the displayed video signal.
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24. A method of modifying a video signal subject to copy protection to increase picture degradation when a copy of the copy protected video is played, where the copy protection causes a reduced amplitude video signal to be recorded on the copy, comprising the steps of:
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providing a waveform of a type for causing a television set on which the copy is being viewed to retrace horizontally prior to occurrence of the horizontal sync signal; and
substituting the waveform in at least one horizontal line of the video signal at a location prior to the horizontal sync signal in that line in place of an active video signal otherwise present at that location.
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25. An apparatus for modifying a video signal subject to copy protection, to increase picture degradation when a copy of the copy protected signal is played, where the copy protection causes a reduced amplitude video signal to be recorded on the copy, comprising:
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a blanker for blanking a portion of the active video of the video signal at a location prior to a synchronization signal in the overscan portion of the video signal;
a pulse generator for generating a predetermined waveform; and
an adder for adding the generated waveform to the blanked portion of the video signal.
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31. An apparatus for modifying a video signal subject to copy protection, to increase picture degradation when a copy of the protected signal is played, where the copy protection causes a reduced amplitude video signal to be recorded on the copy, comprising:
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control circuitry for determining a portion of the active video of the video signal at a location prior to a synchronization signal in an overscan portion of the video signal;
a pulse generator for generating a predetermined waveform; and
a switch for switching the predetermined waveform into the determined portion of the active video.
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32. A method for enhancing copy protection of a video signal having a plurality of lines in each field, there being a line synchronization pulse at the beginning of each line and a field synchronization signal at the beginning of each field, the video signal being subject to a protection process which reduces the amplitude in a copy of the video signal, comprising the steps of:
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selecting at least some of the line synchronization pulses in the video signal; and
reducing a duration of the selected line synchronization pulses, thereby causing at least one spurious field synchronization pulse when a copy is made of the video signal. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. An apparatus for narrowing line synchronization pulses in a video signal having line synchronization pulses at the beginning of each line and a field synchronization pulse at the beginning of each field, comprising:
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a sync separator for providing indications of line and field synchronization pulses in the video signal;
line selector circuitry responsive to the provided indications for selecting particular lines in each field of the video signal;
a one-shot for generating a signal of predetermined length less than that of a line synchronization pulse in response to the provided indications of the line synchronization pulses; and
logic circuitry for adding the generated signals to each of the selected particular lines at a location of the line synchronization pulse in each selected line, thereby reducing a duration of the line synchronization pulse in that line.
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43. A method of defeating copy protection pulses added to a video signal, the copy protection pulses being of a type to cause a video retrace at a time other than occurrence of a video synchronization signal, and being located in an active video portion of the video signal, comprising the steps of:
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generating a signal having an amplitude about equal to an amplitude of the synchronization signal; and
modifying the video signal with the generated signa, wherein a deviation of the synchronization signal is thereby extended.
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44. A method of defeating copy protection pulses added to a video signal, the copy protection pulses being of a type to cause a video retrace at a time other than occurrence of a video synchronization signal, and being located in an active video portion of the video signal, comprising the steps of:
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generating a signal of a predetermined level; and
adding the signal to the video signal at said active video portion. - View Dependent Claims (45, 46, 47, 49, 50, 51)
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48. A method of defeating copy protection pulses added to a video signal, the copy protection pulses being of a type to cause a video retrace at a time other than occurrence of a video synchronization signal, and being located in an active video portion of the video signal comprising the steps of:
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generating a signal of a predetermined level; and
replacing the copy protection pulses with the generated signal.
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52. A method of defeating a video copy protection scheme that reduces a duration of line synchronization pulses, thereby causing a spurious field synchronization pulse in the video signal when a recording is made thereof, comprising:
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determining a location of at least some of the line synchronization pulses having reduced duration; and
modifying the line synchronization pulses to be of a longer duration. - View Dependent Claims (53, 54, 55, 57, 59, 60, 61, 62, 63, 64, 65, 66, 68, 69)
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56. An apparatus for defeat of anticopy pulses present in active video portions of a video signal, the anticopy pulses being located at the end of at least some video fields and at the end of at least some video lines in the active video portions thereof, comprising:
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a sync level restoration circuit for restoring the horizontal sync pulse tips of the video signal to a predetermined level;
circuitry for generating control signals of a first predetermined duration at the end of at least some lines of the video signal and of a second predetermined duration at the end of at least some fields of the video signal; and
switch circuitry controlled by the control pulses for switching a particular signal level into the restored video signal, thereby permitting an acceptable recording to be made thereof.
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58. An apparatus for defeat of anticopy pulses added to the active video portions of a video signal prior to synchronization pulses, comprising:
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logic circuitry for generating control signals of predetermined duration during the active video portions; and
circuitry actuated by the control pulses for combining a predetermined signal into the active video portion, thereby permitting an acceptable recording to be made of the video signal.
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67. An apparatus for defeat of an anticopy modification to a video signal, the anticopy modification including reducing a duration of at least some of the horizontal synchronization pulses in the video signal so as to be less than a standard duration, the apparatus comprising:
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logic circuitry for determining a location of the horizontal blanking interval in at least certain lines of the video signal and generating a control signal in response;
a pulse generator for generating a horizontal synchronization pulse of predetermined duration; and
switch circuitry for adding the generated horizontal synchronization pulse to the video signal, the switch circuitry so adding in response to the control signal.
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70. An apparatus for defeat by level shifting of anticopy pulses present in the active video portions of a video signal, the anticopy pulses being located at the end of at least some video lines in the active portion thereof, comprising:
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a timing circuit for generating a control signal at a start of the anticopy pulses-at the end of at least some video lines;
a pulse generator for generating a pulse having a particular level above a blanking level of the video signal at the end of each video line, in response to the control signal; and
means for adding the generated pulse to the video signal, thereby increasing a level of the end of each video line. - View Dependent Claims (71, 72, 73)
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74. A method of defeating copy protection pulses added to a video signal, the copy protection pulses being of a type to cause a video retrace other than at occurrence of a video synchronization signal, and being located in an active video portion of the video signal, comprising the steps of:
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determining a location of the video synchronization signal;
generating a pulse of an amplitude approximately that of the video synchronization signal; and
adding the generated pulse to the video signal immediately prior to occurrence of the video synchronization signal. - View Dependent Claims (75, 76, 77, 78, 80, 81, 82, 83, 84, 85)
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79. A method of defeating a video copy protection process, the process being of a type to cause a video retrace at a time other than occurrence of a video synchronization signal in a video signal and being located in an active video portion of the video signal, and also including added pulses extending below a blanking level of the video signal, the added pulses being located in selected horizontal video lines of the video signal between the horizontal sync pulse and about at the beginning of active video in each video line, the method comprising the steps of:
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generating a control signal at locations of the added pulses; and
attenuating the added pulses in response to the control signals.
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86. A method of defeating a copy protection process that adds pulses to a video signal, the method comprising the steps of:
reducing an amplitude of at least a portion of an active video part of the video signal; and
increasing an amplitude of a synchronization pulse of the video signal.
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87. An apparatus for defeating a video copy protection process, the process being of a type to cause a video retrace at a time other than occurrence of a video synchronization signal in a video signal and being located in an active video portion of the video signal, and also including added pulses extending below a blanking level of the video signal, the added pulses being located in selected horizontal video lines of the video signal between the horizontal sync pulse and the beginning of active video in each horizontal video line, the apparatus comprising:
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logic circuitry for generating control signals at locations of the added pulses; and
an attenuator for attenuating the added pulses in response to the control signals. - View Dependent Claims (88, 89, 90, 91, 92)
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- 93. A method of defeating the effects of a video anti-copy process that adds pulses to blanking intervals of a video signal, comprising replacing a back porch portion of the video signal having an amplitude at blanking level with a signal having an amplitude below the blanking level.
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98. A method of defeating a video copy protection process that adds paired negative and positive going pulses to blanking intervals of a video signal, the method thereby enabling recording a viewable copy of the video signal, comprising the steps of:
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determining a particular portion of at least some video lines of the video signal, the added pulses being present in the particular portion; and
reducing a level of the particular portion to below a blanking level of the video signal. - View Dependent Claims (99, 100, 101)
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102. An apparatus for defeat of an anti-copy process that adds paired negative-going and positive-going pulses to blanking intervals of a video signal, comprising:
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means for determining a back porch portion of the video signal, the back porch having an amplitude of a blanking level of the video signal; and
means for replacing the back porch portion with a signal having an amplitude below the blanking level. - View Dependent Claims (103)
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104. An apparatus for defeat of a video copy protection process that adds pulses to blanking intervals of a video signal, comprising:
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a generator for generating a signal below a blanking level of the video signal;
timing circuitry for determining durations of particular portions of at least some lines of the video signal, the added pulses being present in the particular portions; and
an adding circuit for adding the generated signal to the video signals at the determined duration.
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Specification