WO1986005057A1 - Methode et appareil pour la protection de signaux video - Google Patents

Methode et appareil pour la protection de signaux video Download PDF

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Publication number
WO1986005057A1
WO1986005057A1 PCT/NL1986/000006 NL8600006W WO8605057A1 WO 1986005057 A1 WO1986005057 A1 WO 1986005057A1 NL 8600006 W NL8600006 W NL 8600006W WO 8605057 A1 WO8605057 A1 WO 8605057A1
Authority
WO
WIPO (PCT)
Prior art keywords
synchronisation
tape
signals
pulses
additional
Prior art date
Application number
PCT/NL1986/000006
Other languages
English (en)
Inventor
Arie Marinus Wijnen
Original Assignee
Arie Marinus Wijnen
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Arie Marinus Wijnen filed Critical Arie Marinus Wijnen
Publication of WO1986005057A1 publication Critical patent/WO1986005057A1/fr

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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

  • a method and an apparatus for protecting video signals are described.
  • the invention provides a method for protecting video information recorded on magnetic tape against illegitimate copying, which video information is comprised in a normal composite video signal consisting of blocks of line signals having positive portions which are modulated with picture information, and negative portions serving as line synchronisation signals, said blocks being mutually separated by a portion without picture information in which a negative frame synchronisation pulse is situated, and there no line synchronisation signals are present, which frame synchronisation pulses and line synchronisation signals are fed, during recording, towards the recording heads of the recording apparatus, the frame and line synchronisation signals being, furthermore, separately derived from the video signal to be recorded and being supplied to the synchronisation circuits of the head and tape drives, said method being characterised in that, when legitimately recording the video information on a tape, in the picture signal beyond the stage from which the synchronisation signals are derived, but before the final stage connected to the recording heads, the negative frame synchronisation pulses are each replaced by two consecutive negative pulses, where the line synchronisation signals are suppressed, this in such
  • a tape recording apparatus For synchronising the transversal displacement (rotation) of the recording heads, a tape recording apparatus utilises the frame synchronisation signals,so that, when copying the signals disturbed in this manner in a second recording apparatus, the syn ⁇ chronisation in said second recording apparatus will be disturbed by repeating said pulse in a composite video signal recorded on the tape, said heads, as far as the beginning of said transversal movement is concerned, then getting confused so that recording the subsequent picture information will be considerably disturbed.
  • the synchronisation circuits of a reproduction apparatus are much simpler, and are not being disturbed by the repetition of the frame synchronisation pulse.
  • the first recording apparatus is controlled by the synchronisation signals present in the presented signal, the former being directly supplied to the respective synch-ronisation circuits so that their operation is not disturbed.
  • An improvement of such a protection by disturbing the synchronisation can be obtained by lengthening the additional negative pulse into the adjacent terminal portion of the line signal block.
  • no picture signal lines are present there, so that, during reproduction, the absence of the line signal pulses is not disturbing, but when recording again an additional disturbation in the synchronisation will produced in the recording apparatus, which will deteriorate the picture quality still further.
  • a possible removal of the disturbation by means of a suitable circuit, such as a time-base recovery circuit might be considerably hindered thereby.
  • a still further improvement can be obtained by modulating the length of the additional negative pulse, thereby still further hindering the possible recovery of the original condition, and, furthermore, disturbing the synchronisation of the reproducing apparatus to which a signal disturbed in this manner is supplied, so that the reproduction is deteriorated still further.
  • this modulation of the length of the second negative pulse is done in an arbitrary manner so as to remove any periodicity therefrom, which will make any attempt to reduce the disturbation unsuccessful.
  • the invention relates to a tape recording apparatus for executing said method, said apparatus comprising a stage for deriving the head and tape drive synchronisation signals, and a final stage connected to the recording heads, the synchroni ⁇ sation outputs of the former stage being directly connected to the synchronisation circuits of the head and tape drives, said apparatus being characterised in that in the connection between said stages an additional stage is included which is adapted to divide at least the frame synchronisation pulses of the complete video signal each into two negative pulses where no line synchronisation pulses are present.
  • said additional stage can be adapted for lengthening the additional negative pulse in such a manner that it will also suppress at least a part of the line synchronisation signals situated in the initial part of a line signal block.
  • said additional stage can be adapted for periodically, and in particular arbitrarily, modulating said additional pulses, to which end said circuit is connected to an auxiliary circuit which, in particular, can control the variation of the length of the- additional negative pulses on the basis of the line synchronisation frequency of the presented video signal which is derived from said first stage.
  • Fig. 1 a diagrammatical representation of a normal video signal suitable for being recorded on a magnetic tape
  • Figs. 2A and B a composite signal according to Fig. 1 disturbed before recording on the tape and, respectively, a portion of said disturbed signal as recorded on the tape;
  • FIG. 3 and 4 diagrammatical representations of still further disturbed video signals
  • Fig. 5 a simplified block diagram of an apparatus for executing the method of the invention.
  • Fig. 1 a composite picture (video) signal which is suitable for being recorded on magnetic tape is shown in a highly simplified manner.
  • This signal comprises a zero level 1 on which, at the beginning of a picture frame, a negative frame synchronisation pulse 2 appears. Thereafter follows a block 3 of line signals shown as lines.
  • Each block 3 comprises a plurality of picture lines 4 in which the picture information is contained, and the portion 4' thereof below the zero level serves for line synchronisation.
  • portions 5 are situated which, during reproduction, lie outside the limits of the screen, and which, when recording on a tape, need not to contain picture information, as is shown in the drawing by the absence of the positive line portions.
  • the corresponding line syn ⁇ chronisation portions 5' are present, which are also present in the interspaces between the blocks 3 with the exception of the location of the pulses 2.
  • the pulse 2 is split into two pulses 2a and 2b. If, now, these pulses are pre ⁇ sented to a synchronisation circuit of a recording apparatus, the first one will synchronise the frame synchronisation, i.e. the be ⁇ ginning of the recording head displacement. The second pulse 2b will, again, result in a head synchronisation. The head will, then, have the tendency to return to the initial position, and will get out of step thereby.
  • Fig. 2B it is diagram atically shown what happens when recording on a tape.
  • a reproducing apparatus with simpler synchronisation cir ⁇ cuits has, in this respect, a certain -inertia, and. will not react to this repetition; this circuit will only react in the correct manner to the first pulse 2a.
  • the absence of the signals 5' in the part outside the block 3 is not disturbing for the reproduction either, since, in the reproduction apparatus, the signals 4' are sufficient for the line synchronisation.
  • the additional pulse 2b is lengthened in such a manner that it extends into at least a portion of the signals 5' within the block 3.
  • this will lead to suppressing the signals 5' in the manner shown at 2b 1 in Fig. 2B, and to a more serious disturbation of the synchro ⁇ nisation when recording the signal thus disturbed.
  • the reproduction apparatus will not be hindered by the absence of the pulses 5' as long as the suppression has not reached the region 4' .
  • the synchronisation is dis ⁇ turbed in such a manner that a picture of an unsaleable quality is obtained.
  • the lengthening of the pulse 2b should, of course, not extend farther than the portion 5', since by suppressing the signals 4' the line synchronisation in the reproducing apparatus will be disturbed.
  • the lengthenin of the pulses 2b near the various blocks 3 can be modulated in the manner shown in Fig. 4 so that such a recovery will become virtually impossible. This will be the case indeed if such a modulation is not periodical, but is made at random. This can be obtained by means of control circuits operating according to a random function, which can, for instance, make use of a basic frequency contained in the video signal. Apart from the fact that, thereby, a recovery of the line synchronisation can be completely avoided, this has also a disturbing influence on the line synchronisation in the reproduction apparatus so that the quality of the reproduced picture will be made still worse.
  • Fig. 5 shows in a diagrammatical way the structure of a recording apparatus according to the invention.
  • the video signal to be recorded is supplied at 3 to a normal control circuit 7.
  • the signals for synchronising the drive 8 for the tape 9 and for controlling the heads 10 are derived at 11 and 12 respectively. This synchronisation can, therefore, take place in the normal manner.
  • the complete video signal at the output 13 is led towards a circuit 14 wherein the splitting of the frame synchronisation signal 2 and, as the case may be, the suppression of the synchroni ⁇ sation signals 5' takes place.
  • the output 15 thereof is connected to the normal frequency modulation circuit 16, and the output 17 thereof is connected to the heads 10.
  • the picture signal sent towards the heads 10 is disturbed in the manner described above, but this will not influence the synchronisation of the drive 8 of the tape 9 and of the heads 10, so that a normal recording of the disturbed signal on the tape 9 takes place .
  • an auxiliary stage 18 is used which is adapted to control the stage 14 in such a manner that the length of the pulses 2b is modulated in the desired manner.
  • This stage 18 can comprise an associated oscillator, but can also be connected to an additional output 19 of the stage 7, from which a frequency present in the video signal, e.g. that of the line synchronisation signals 4' and 5', can be derived, which frequency can be lowered in a suitable manner by means of frequency sealers.
  • This stage can also be con ⁇ structed in such a manner that the scaling factor is modulated in turnfoli and this, as the case may be, in a completely arbitrary way.

Abstract

Methode et appareil pour la protection de signaux vidéo enregistrés sur des bandes magnétiques, permettant d'empêcher de faire des copies de ces bandes. Lors de l'enregistrement légitime sur une cassette, dans le signal vidéo, au delà de l'étage (13) à partir duquel les signaux de synchronisation sont dérivés, mais avant l'étage final (16) relié aux têtes d'enregistrement (10), les impulsions négatives (2) de synchronisation d'image sont remplacées chacune par deux impulsions négatives consécutives (2a, 2b) dans lesquelles les signaux de synchronisation de ligne (5') sont supprimés, cela de sorte que la bande et les entraînements de la tête dudit appareil ne subissent aucune influence et que, lors de la copie sur une autre bande, les signaux de synchronisation perturbés de l'appareil d'enregistrement soient envoyés vers la tête et les circuits de synchronisation de la bande (11, 12), ce qui entraîne une perturbation de la synchronisation. En particulier les impulsions négatives additionnelles (2b) peuvent être amenées jusqu'à la partie terminale adjacente (5) d'un bloc de signaux de ligne (3), et la longueur d'une telle impulsion additionnelle (2b) peut être modulée, cela, si on le désire, d'une façon aléatoire, afin d'obtenir une protection complémentaire.
PCT/NL1986/000006 1985-02-22 1986-02-24 Methode et appareil pour la protection de signaux video WO1986005057A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL8500515 1985-02-22
NL8500515A NL8500515A (nl) 1985-02-22 1985-02-22 Werkwijze en toestel voor het beveiligen van beeldsignalen.

Publications (1)

Publication Number Publication Date
WO1986005057A1 true WO1986005057A1 (fr) 1986-08-28

Family

ID=19845579

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NL1986/000006 WO1986005057A1 (fr) 1985-02-22 1986-02-24 Methode et appareil pour la protection de signaux video

Country Status (3)

Country Link
EP (1) EP0214267A1 (fr)
NL (1) NL8500515A (fr)
WO (1) WO1986005057A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0364047A1 (fr) * 1988-10-11 1990-04-18 Copyguard Enterprises S.A. Méthode pour empêcher l'enregistrement non autorisé sur bandes de programmes vidéo
EP0416663A2 (fr) * 1989-09-08 1991-03-13 Matsushita Electric Industrial Co., Ltd. Appareil d'enregistrement de données
WO1991016791A1 (fr) * 1990-04-20 1991-10-31 Copyguard Enterprises S.A. Procede et appareil destines a empecher la copie non autorisee de signaux video sur une bande
WO1996031878A1 (fr) * 1995-04-07 1996-10-10 Trevor Franklin Procede et appareil de traitement d'un signal video
US5673356A (en) * 1988-10-11 1997-09-30 Copyguard Enterprises S.A. Method and an apparatus for preventing unauthorized recording on tapes on video programs

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963865A (en) * 1975-06-04 1976-06-15 Trans-American Video, Inc. Anti-piracy method and system
US4100575A (en) * 1976-03-22 1978-07-11 Sony Corporation Method of and apparatus for modifying a video signal to prevent unauthorized recording and reproduction thereof
GB1571386A (en) * 1977-03-09 1980-07-16 Ivs Ltd Video tape recording apparatus
GB2050675A (en) * 1979-04-11 1981-01-07 Dimmers J A Video Copying and Transmission Inhibitor
GB2055501A (en) * 1979-08-03 1981-03-04 Ivs Uk Ltd Video tape recording apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3963865A (en) * 1975-06-04 1976-06-15 Trans-American Video, Inc. Anti-piracy method and system
US4100575A (en) * 1976-03-22 1978-07-11 Sony Corporation Method of and apparatus for modifying a video signal to prevent unauthorized recording and reproduction thereof
GB1571386A (en) * 1977-03-09 1980-07-16 Ivs Ltd Video tape recording apparatus
GB2050675A (en) * 1979-04-11 1981-01-07 Dimmers J A Video Copying and Transmission Inhibitor
GB2055501A (en) * 1979-08-03 1981-03-04 Ivs Uk Ltd Video tape recording apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0364047A1 (fr) * 1988-10-11 1990-04-18 Copyguard Enterprises S.A. Méthode pour empêcher l'enregistrement non autorisé sur bandes de programmes vidéo
WO1990004305A1 (fr) * 1988-10-11 1990-04-19 Copyguard Enterprises S.A. Procede et appareil servant a empecher l'enregistrement non autorise de programmes video sur bandes
AU634502B2 (en) * 1988-10-11 1993-02-25 Copyguard Enterprises S.A. An apparatus for preventing unauthorised recording on tapes of video programmes
US5673356A (en) * 1988-10-11 1997-09-30 Copyguard Enterprises S.A. Method and an apparatus for preventing unauthorized recording on tapes on video programs
EP0416663A2 (fr) * 1989-09-08 1991-03-13 Matsushita Electric Industrial Co., Ltd. Appareil d'enregistrement de données
EP0416663A3 (en) * 1989-09-08 1992-02-26 Matsushita Electric Industrial Co., Ltd. Data recording apparatus
US5159502A (en) * 1989-09-08 1992-10-27 Matsushita Electric Industrial Co., Ltd. Data recording apparatus
WO1991016791A1 (fr) * 1990-04-20 1991-10-31 Copyguard Enterprises S.A. Procede et appareil destines a empecher la copie non autorisee de signaux video sur une bande
US5481608A (en) * 1990-04-20 1996-01-02 Copyguard Enterprises Method and an apparatus for preventing unauthorized copying of video signals on tape
WO1996031878A1 (fr) * 1995-04-07 1996-10-10 Trevor Franklin Procede et appareil de traitement d'un signal video

Also Published As

Publication number Publication date
NL8500515A (nl) 1986-09-16
EP0214267A1 (fr) 1987-03-18

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