Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/76—Television signal recording
  • H04N5/91—Television signal processing therefor
  • H04N5/913—Television signal processing therefor for scrambling ; for copy protection
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N5/00—Details of television systems
  • H04N5/76—Television signal recording
  • H04N5/91—Television signal processing therefor
  • H04N5/913—Television signal processing therefor for scrambling ; for copy protection
  • H04N2005/91307—Television signal processing therefor for scrambling ; for copy protection by adding a copy protection signal to the video signal
  • H04N2005/91314—Television signal processing therefor for scrambling ; for copy protection by adding a copy protection signal to the video signal the copy protection signal being a pulse signal inserted in blanking intervals of the video signal, e.g. pseudo-AGC pulses, pseudo-sync pulses

Definitions

• This invention relates to a method of preventing unauthorized copying of video tape cassette recordings and an apparatus for executing the method.
• the method is based on a procedure by which, when producing video cassettes intended to be held for sale or lease by copying (dubbing) an original video tape recording, strong signal components are introduced into the video signal to be recorded, which signal components modify the recorded signal in such a manner that, should the video tape thus produced be unduly copied, a satisfactory video picture of such "pirate” video tape would not be reproduceable, while, however, the authorized "original copies” produced by means of the method according to the invention are reproduceable in conventional video tape recorders (VTR:s) without the modifying signal recorded thereon adversely influending the reproduction quality of the video picture.
• VTR video tape recorders
• the modification signal applied to it will have an influence on the recording signal of the copying VTR that such copies of the "original” copy, when played back, will give rise to inacceptable pictures: The picture rolls, loses colors and synchronization.
• the modification signal acts as an interference signal which effectively destructs the entire picture content of the video tape.
• This invention relates to a method of this kind which is particular ⁇ ly suited to be used for producing, by simultaneous copying, a plurality of video tape cassettes intended to be held for sale or let out on hire and each containing a copy of a video signal recording on an original video tape, a 1"- tape for instance, comprising vertical and horizontal synchronizing signal, color signal, and picture signal portions, and in which the recorded signal has been modified in accordance with the invention to make difficult or prevent production of useable copies by copying the cassettes thus produced.
• Figure 1 shows a block diagram of an apparatus for simultaneous production of a plurality of copies of an original video tape, said copies being modified according to the invention
• FIG. 3 illustrates an implementation of the method according to the invention
• -said means comprise a pulse train generator unit 4 for generating signals in the form of a pulse train required for modifying the video signal and comprising means for setting duration, position in time, and amplitude of the pulses of said pulse train, a detector unit 5 for detecting the time of appearance of the interval (vs + ihs) of the video signal intended for implementation of the modification signal, and a pulse implementation unit 6 for superpositioning the modification signal pulses on the video signal within said interval (vs + ihs) thereof.
• the video signal On its way from the master 1 to the booster amplifier 2, the video signal passes the detector unit 5.
• the detector unit 5 delivers a trigger signal to pulse train generator 4, causing this unit in dependence of choice of pulse position and pulse train duration within the synchronization interval (vs + ihs) for each picture to deliver a pulse burst to pulse implementation unit 6, in which unit said pulse burst is superimposed on the video signal within the time interval determined by means of said pulse duration setting means of the pulse train generating unit 4, e.g., as shown in Fig. 2, a pulse train with the duration p_.
• a video cassette tape having a recorded signal generally corresponding to the ones shown in Figs. 2 and 3 was copied in a video recording machine delivering a highest peak-to-peak-voltage of 1 volt in accordance with known standard.
• the values of the characters pulse amplitude, pulse duration, pulse position, and pulse frequency were varied from part to part of copies thus produced. Subsequently, such copies were copied in a conventional video machine equipped with tape copying facilities, whereafter the signal obtained from such "pirate copies" was measured in the same manner as the signal obtained from the original.
• circuits which constitute components of the pulse train generator unit 4 of an apparatus according to the invention and which determine the characters frequency, amplitude, duration, and position of the modification signals, whether said circuits are arranged for having an invariable or a variable influence on the signal may be arranged on the basis of well known technique and, of course, in the latter case the control of the variation, at random for instance, of one or more of said characters may. be provided for by means of computer.

Landscapes

• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Television Signal Processing For Recording (AREA)
• Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
• Management Or Editing Of Information On Record Carriers (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20365686

Family Applications (1)

Country Status (6)

Cited By (7)

Citations (2)

• 1986
  • 1986-09-24 SE SE8604024A patent/SE458081B/xx not_active IP Right Cessation
• 1987
  • 1987-09-22 JP JP50564387A patent/JPH02500709A/ja active Pending
  • 1987-09-22 AU AU79627/87A patent/AU7962787A/en not_active Abandoned
  • 1987-09-22 EP EP19870906123 patent/EP0324755A1/de not_active Ceased
  • 1987-09-22 WO PCT/SE1987/000426 patent/WO1988002588A1/en not_active Application Discontinuation
• 1988
  • 1988-05-24 DK DK283688A patent/DK283688D0/da not_active Application Discontinuation

Patent Citations (2)

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