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US 5,673,356 AGranted
Method and an apparatus for preventing unauthorized recording on tapes on video programs
AssigneeCopyguard Enterprises S.A.
InventorArie Marinus Wijnen
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AssigneeCopyguard Enterprises S.A.
InventorArie Marinus Wijnen
Estimating the term…
A method and apparatus are provided for preventing unauthorized recording of video programs on tape, in which the frame repetition frequency of the signals to be transmitted is changed in such a manner that, on the one hand, the operation of a television apparatus used for reproducing said signals will not be disturbed, but that, on the other hand, the cooperation between the driving means for the tape and the recording head displacement in the tape recording apparatus will be disturbed. The apparatus comprises an input stage (4) for digitalizing the video signals, a shift memory (5), an output stage (8) for converting the video signals to be used into analog form, an input control stage (6) for the memory (5) and an output control stage (7) for the memory (5). The control frequency of the input control stage (6) is adapted to the frame repetition frequency of the digitalized video signals to be stored in the memory (5). The control frequency of the output control stage (7) is different from the control frequency of the input control stage (6), and the capacity of the memory (5) is sufficient to compensate the differences between the signal input and output.
An apparatus for processing video signals so as to prevent unauthorized recording thereof on tape, said apparatus including an apparatus output and comprising an input stage, connected to an input of the apparatus, for receiving video signals to be processed and including means for separating synchronization signals from the video signals to be processed to produce separated synchronization signals at an output of said input stage, an A/D converter for receiving said video signals from a first output of said input stage and for producing corresponding digitized video signals, a digital memory for receiving the digitized video signals from said A/D converter, a A/D converter, connected to an output of said memory and having an output connected to said apparatus output, a first control stage for controlling writing of said video signals in said memory under control of said separated synchronization signals at said output of said input stage, and a second control stage for controlling reading out of said stored signals from said memory, said memory comprising a digital shift memory means for expanding and compressing signals in a frame area without adding lines or suppressing lines from the frames of said signals, and said second control stage providing a reading frequency which is different from the writing frequency of said first control stage, the capacity of said digital shift memory means being sufficient to compensate for differences between the video signal input and output, said video signals comprising picture lines each comprising a color burst and a horizontal synchronization pulse in advance of said color burst and said apparatus further comprising an additional means for introducing an additional horizontal line synchronization pulse into the video signal after said color burst.
A method for preventing unauthorized recording of composite video signals of video programs on tape wherein the frame lengths of the composite video signals of such programs are varied in order to disturb the operation of a tape recording apparatus used to record said signals, said method comprising the steps of storing said signals in a digital memory with a different frame length, and recovering said signals from said memory, signals in a frame area being expanded and compressed respectively without adding lines to or suppressing lines from the frames of said signals, and said video signals being read out of said memory at a different frequency which is different from that at which the signals are written into said memory, said video signals each including a color burst preceded by a line synchronization signal and the method further comprising the step of adding a further line synchronization signal after the color burst so as to disturb synchronization of a time based corrector used in attempting to cancel the frequency change to said different frequency.
An apparatus for processing video signals so as to prevent unauthorized recording thereof on tape, said video signals comprising a color burst and a horizontal synchronization pulse in advance of said color burst, said apparatus including an apparatus output and comprising an input stage, connected to an input of the apparatus, for receiving video signals to be processed and including means for separating synchronization signals from the video signals to be processed to produce separated synchronization signals at an output of said input stage, an A/D converter for receiving said video signals from a first output of said input stage and for producing corresponding digitized video signals, a digital memory for receiving the digitized video signals from said A/D converter, a D/A converter, connected to an output of said memory and having an output connected to said apparatus output, a first control stage for controlling writing of said video signals in said memory under control of said separated synchronization signals at said output of said input stage, and a second control stage for controlling reading out of said stored signals from said memory, said memory comprising a digital shift memory, said second control stage providing a reading frequency which is different from the writing frequency of said first control stage, the capacity of said digital shift memory being sufficient to compensate for differences between the video signal input and output, and said apparatus further comprising an additional means for introducing an additional horizontal line synchronization pulse into the video signals after said color pulse.
A method for preventing unauthorized recording of composite video signals of video programs on tape wherein the frame lengths of the composite video signals of such programs are varied in order to disturb the operation of a tape recording apparatus used to record said signals, said method comprising the steps of digitizing said signals, storing said signals in a digital memory with a different frame length, and recovering said signals from said memory in analog form, said video signals being read out of said memory at a different frequency which is different from that at which the signals are written into said memory, the video signals each including a color burst preceded by a line synchronization signal, and the method further comprising the step of adding a further line synchronization signal after the color synchronization burst so as to disturb synchronization of a time-base corrector used in attempting to cancel the frequency change to said different frequency.
In a method for preventing unauthorized recording of video programs on tape, said video programs comprising video signals including synchronizing signals comprising a line synchronizing signal preceding a color burst, said method comprising changing the frame repetition frequency of the video signals for the video program in such a manner that the operation of a tape recording apparatus for recording thereof will be disturbed, the frame repetition frequency of the signals to be transmitted being changed in a manner such that the operation of a television apparatus used for reproducing said video signals will not be disturbed but such that cooperation between the driving means for the tape and recording head displacement in the tape recording apparatus will be disturbed, the improvement wherein the method further comprises the step of adding, to the video signals, a further line synchronization signal after each color burst so as to disturb the synchronization of a time-base corrector used for cancelling the change in the frame repetition frequency.
A method for preventing unauthorized recording of composite video signals on tape wherein, said method comprising receiving video signals comprising a picture line comprising a color burst and a horizontal synchronization pulse in advance of said color burst, and adding to each video signal an additional horizontal synchronization pulse, each additional horizontal synchronization pulse being added after the color burst of each composite video signal so as to disturb synchronization of a device used in attempting unauthorized copying of the video signals.
Dependencies are inferred from the claim text.