WO1985002293A1

WO1985002293A1 - Antipiracy device and method for cinematographic and video carriers

Info

Publication number: WO1985002293A1
Application number: PCT/CH1984/000185
Authority: WO
Inventors: Pierre Sublet
Original assignee: Haute Securite Video Hsv S.A.
Priority date: 1983-11-21
Filing date: 1984-11-20
Publication date: 1985-05-23
Also published as: EP0162071A1; AU3613684A

Abstract

Antipiracy device comprising a detection member (180) for detecting a mark signal inscribed on a "sound" track of a video tape and which may not be eliminated during a duplication, a detection member (181) for detecting at least one digitally coded message also inscribed in said track, a retrieval member for retrieving said coded message (187) and means (183-186) for enabling or inhibiting the exploitation of the tape by a television receiver (TV) as a function of the presence or the absence of the marking signal and of the coded message or messages and/or the change of the latter resulting from a duplication.

Description

ANTI-PIRACY METHOD AND DEVICE FOR CINEMATOGRAPHIC AND VIDEO IMAGE MEDIA.

Piracy of images photographed on a cinematographic medium or recorded on a videotape and intended to be televised or reproduced by means of a video recorder can take place at any stage of the exploitation of the medium.

The most common modes of piracy are used by "professionals" and the invention proposes to produce a device which prevents them from being implemented. One of them consists of making copies of the "daughter" videotapes intended to be sold or rented and the anti-piracy device must then prevent these copies from being read.

Another common form of piracy is to obtain the mother tape from which normally available daughter tapes are made, or even to. obtain a cinematographic film and make a mother tape using an analyzer.

The subject of the invention is a method capable of prohibiting the unauthorized use of a wide range of types of image media, in order to deal with all of the situations described above, and the device for implementation of this process.

According to the invention, this method, intended to protect a complete chain of reproduction and reading of images from an original medium, comprises the recording, on the information medium, of at least one virtually indelible marking signal which cannot be eliminated during the transfer of information to another medium, this signal being arranged so as not to significantly affect the processing of the information, by detecting the presence or 'absence of this marking signal at the time of operation and by the validation or invalidation of the operation. According to a preferred embodiment, the marking signal is written on at least one "sound" track of the original medium.

Preferably, at least one coded message capable of rendering the support unusable by causing interference when it is present is also written on at least one "sound" track of the support, this message being made up of blocks distributed all along said support. track and the extraction of these blocks after detection of their presence by means of an organ suitably programmed according to the code is carried out at the time of operation, these blocks being arranged so that after their elimination the sound can be listened to from satisfactorily.

In its preferred embodiment, when the operation is carried out by means of a video recorder associated with a television receiver, said member is arranged to "self-destruct" in the event of repeated disconnections.

The invention will be better understood in the light of the description below.

In the attached drawing:

FIG. 1 represents the means of introducing a marking signal on the "sound" track of the "music" band which is used for editing a cinematographic film;

FIG. 2 represents the means of introducing a first digitally coded message, during the manufacture of a mother video tape from a marked film;

FIG. 3 represents the means of introducing a second digitally coded message, during the manufacture of a daughter tape; The latter is advantageously constituted by a programmable encoder, for example of the ED11 type sold by the company "Supertex Inc". It transmits coded signals comprising a fixed "preamble" of 46 clock periods, followed by a blank of duration equal to 18 clock periods and a digital message said, corresponding to 62 clock periods, ie 16 bits of data. The assembly formed by the preamble, the blank and the message constitutes a coded block in accordance with the code "Manchester". These blocks are recorded on the "sound" track of the film Fm with a preferably random distribution and an intensity such that the pure and simple reading of such a track would produce, when passing a block, a noise difficult to bear. hearing. In practice, the coded message will include a certain number of “primary” most significant bits which will be used for the validation of the detector (as will be seen below) and “secondary” bits of least significant used for the identification of the film. considered. The composite output signal from the mixer 6 is applied to a recording head 8 in order to obtain a mother videotape M _T on the track or tracks on which are superimposed a useful "sound" signal, the marking signal and the first coded message. Image recording was not illustrated in Figure 2.

It should be clearly understood, although magnetic readers and recorders have been shown in FIGS. 1 and 2, that these could be replaced by optical reading and recording devices. When preparing a copy of the original film, the procedure is the same, so that the copy also includes the marking signal and the first coded message.

The mother tape M _T is intended for the production, by authorized professionals, of a certain number of daughter tapes.

Figure 3 illustrates such an operation. FIG. 4 represents a device for extracting coded messages, connected to a television receiver and to a video recorder; and

FIG. 5 represents an alternative embodiment of the means for introducing a marking signal.

In Figure 1, there is shown a generator 1 of a sine wave of constant amplitude having a frequency of a few hertz. This is an exemplary embodiment of the aforementioned marking signal: such a signal will not disturb the reproduction of a complex microphone signal, such as those recorded on the "music" or "sound effects" tapes which are used for editing 'a cinematographic film. As editing is often done in different languages, the "dialogue" band will not be used and it has been assumed, for example, that the marking signal is written on the "music" band (and / or "sound effects"). To this end, the latter BM is introduced into a magnetic reader, the read head of which has been shown in 2. The "music" signal and the marking signal are introduced into a mixer 3 followed by a magnetic recorder 4. The latter forming a BMm band where the marking signal is superimposed on the "music" signal. This marked strip will be used for the editing of the film. This can be screened indoors without the sound reproduction being affected, the marking signal being inaudible.

As a variant, it could be envisaged to superimpose in addition to the sound the first digitally coded message which will be described later. In this case, it would obviously be necessary to equip the projection rooms with a device for extracting this first coded message. In FIG. 2, there is shown at 5 a magnetic read head on which a film Fm supposed to be marked runs as shown above and a mixer 6 which receives the "sound" signal from the film and a digitally coded message generated by a generator 7. The "sound" track of the mother band M _T is read by a magnetic head 9 and the composite "sound" signal is applied, on the one hand, to a detector 10 which indicates - for monitoring purposes - the presence of the signal marking, on the other hand, to a programmable detector 11, of the ED11 model for example. This is controlled by a clock 12 having the same frequency as the clock of the generator 7, and has inputs for programming the primary code by a member 13 which performs appropriate switching operations. This member 13 makes it possible to bring the primary code of the detector into conformity with that of the generator 7. When this conformity is achieved, the primary code appears on an output 110. The detector 11 has outputs of secondary code 111. A generator 14, of same type as generator 7, generates a second digitally coded message of the same general type as the first. This second message is defined from the first by means of a key supplied to the generator 14 by a member 15. This key can for example define the distribution of the building blocks of the second message with respect to the building blocks of the first: it is thus possible to insert a block of the second message in a well-defined position between only some of the successive blocks of the first; the "message" part of the second signal may comprise only a defined part of that of the first message, possibly with a different coding, etc.

The outputs of the members 9 and 14 are applied to a mixer 16, the output of which excites a recording head 17 of a daughter tape B _F.

Each daughter band thus comprises on its "sound" track or tracks, the marking signal and the two digitally coded messages, superimposed on the useful "sound" information. The image recording was not figured.

In Figure 4, there is shown a television receiver TV, a VCR MA and a device 18 for extracting and deleting coded messages, connected to the VCR and to the television receiver as will be indicated below. The device 18 comprises a detector 180 of the marking signal, connected to the "sound" output of the video recorder, followed by a programmable detector 181 which is represented here in the form of a single block, but which will obviously include the clock and the programming device necessary to be able to carry out the detection of the first and second digitally coded messages. Given the fact that the second coded message is, as explained above, linked to the first according to a key, the detection of the second message obviously supposes that this key is taken into account in programming of the detector.

At the end of each of the interleaved blocks which constitute the first and second coded messages, the detector 181 provides a validation signal on an output 1810 and the primary codes of the two messages on a group of outputs 1811. These primary codes are put in memory at 182 and sent, at the same time as the marking signal, to a microprocessor 183 associated with programming members 184. The program supplied by the members 184 determines, as will be explained below, in which situations the microprocessor will send, by means of an “input-output” member 185, an order of inhibition (output 1850) of the correct reproduction of the tape or, on the contrary, an order of correct reproduction (output 1851). These orders are applied to an organ 186 which mixes and transmits to TV the "video" signal coming from MA, the composite "sound" signal coming from MA and the "sound" signal, cleared of the two coded messages, supplied by an extracting organ 187. The member 186 can, for example, be arranged, when it has received an inhibition order, to transmit the composite "sound" signal affected by the interference consisting of at least one of the two digitally coded messages and which makes it inaudible. It can also, in the event that the "sound" signal originating from MA only comprises the marking signal, introduce an interference signal into the video signal, or even trigger the stopping of the motor for driving the tape of MA or interruption of transmission, etc. When it receives a correct reproduction order, the member 186 on the other hand transmits the normal "video" signal and the "sound" signal from the extractor member 187.

This is advantageously of the type described in French patent application No. 83 02355 filed on February 9, 1983. Such an organ, when it receives a validation signal from the output 1810, and for a duration greater than the duration d 'a block of coded messages, interrupts the transmission of the composite "sound" signal and fills the white intervals thus created by delayed portions of the composite "sound" signal in which no coded message is present. The "sound" signal from device 187 is thus freed from interference and practically indistinguishable by the ear of the original "sound" signal. The practical realization of the circuits of the device 18 is within the reach of the skilled person. Advantageously, a P channel CMOS or N channel MOS technology will be used, which results in very low consumption. It is then possible to supply these circuits from the "audio" output of the television receiver, on which signals will be present during the operation of the receiver. There is shown in the drawing a converter 188, powered by this audio output and capable of charging a micro-battery which will supply energy to the circuits of the device 18. A power supply unit by the sector can however be provided.

As will be explained below, the device 18 should normally be permanently connected to the TV receiver while the latter is in service and any disconnection can be considered as an attempt at fraud. To thwart such attempts, there is provided in device 18 a circuit 189 for measuring the impedance of the line connecting to the TV receiver. Such a measurement circuit, in the event of disconnection, notes the presence of an infinite impedance and sends a signal to the microprocessor. The latter can then for example command the erasure of a memory 1852 having a capacity of a few bits, positioned at 1 at the origin. Thus, after a determined number of disconnections, this memory will be completely erased. The program can be arranged so that, with each new commissioning of the assembly of FIG. 4, the microprocessor tests the presence of at least one "1" bit in the memory and, if this presence is not observed, sends an inhibition order. The return to service of the device 18 will then require that the memory be recharged by an authorized person. It is also possible, in the case where the device is powered by a micro-battery charged by the converter 188, to provide that the microprocessor proceeds, in the absence of several bits "1" in the memory 1852, to discharge of the battery, which will constitute a warning for the fraudster, who must wait a certain time for the commissioning of the device.

We will now examine the various possible "piracy" attempts and the way in which the device described makes it possible to thwart them.

We will first consider the case of a "video" tape which reproduces a film. In the event of theft of the original film, if "video" tapes are made from it, only the marking signal will be present in the "sound" tracks. The absence of the first and second coded messages will cause the microprocessor to transmit the inhibition signal. In the event of theft of a copy of the film or of the parent "video" tape, a "video" tape made from this copy will only carry the marking signal and the first coded message, hence the transmission of 'an inhibition signal. In the event of theft of a daughter "video" tape, a "video" tape made from it will carry both the marking signal and the two coded messages. However, since it is a copy of a copy, the first coded message will have undergone two successive alterations on reading (flanks of the distorted rectangular signals) and the second will have undergone one. It is then easy to arrange the detector circuit 181 so that it does not detect altered messages, or else the program so that the microprocessor identifies such altered messages and sends an inhibition signal. Anyone with an authorized daughter tape and a VCR equipped with the device in Figure 4, can obviously, with a second VCR, make a duplication of this tape. It will be noted that the coded messages will have disappeared on the copy, but the marking signal, which is not eliminated by the detector 180, will remain, so that such a copy cannot be used with the assembly of FIG. 4 It will therefore not be marketable in practice. It will be noted that a "video" tape made from an amateur film, or an old "video" tape, will not be provided with either the marking signal or the digitally coded messages. Such a band will normally pass through the apparatus of FIG. 4, the microprocessor being programmed to send a correct reproduction signal when it does not receive a marking signal.

It goes without saying that various modifications may be made to the devices described and shown, without departing from the spirit of the invention.

The marking signal could be made more complex, in order to make it more difficult to eliminate it, during a copy of the medium, by sophisticated electronic means.

A particularly interesting variant would consist in constituting said signal of calibrated holes in the signal modulated at audible frequencies corresponding to the "sound" information.

FIG. 5 represents a device making it possible to introduce such holes on the "music" tape B _M which is used for mounting a film. This strip is read by a head 2 and the corresponding modulated signal is applied to a member 100 for detecting and counting "natural holes" that inevitably comprises said signal (these holes correspond to intervals, of short duration and of irregular distribution, Advantageously, the devices of FIGS. 1 and 2 will be used both, that is to say that the band B _{Mm will} comprise both the very low frequency signal mentioned with reference to FIG. 1 and the "artificial holes" . If these are partially filled during the superposition of the "dialogue" signal on the "music" signal, it will thus be certain that at least one marking signal remains. With regard to the coded messages No 1 and No 2 mentioned above, the duration of the blocks which compose them may not exceed 10 to 15 ms and in this case, it may be sufficient to simply eliminate said blocks, without replace with delayed portions of the "sound" signal, the "whites" thus created being practically invisible to the ear. We could even consider introducing the blocks of said messages at the place of "natural" or "artificial" holes in the "sound" signal, in order to further reduce the effect on the ear of their elimination. These solutions will simplify the production of the extractor member.

Various means of complicating the unauthorized detection of digital coded messages could be envisaged. For example, it is possible to make the code of message No 1 include an indication of a predetermined time interval which will identify each block of an "artificial hole"; the detector unit will then have to note that the blocks actually appear at the end of this time interval after each "artificial hole".

It is also possible to provide an indirect addressing of the positions of the blocks of message No 2 with respect to those of message No 1, a first block of message No 2 indicating for example the number of blocks of message No 2, a second block, the distances between the blocks, etc. To make coded message No 2 more annoying on hearing, it is still possible to make it include analog blocks, constituted by a very annoying frequency modulation, for example 2000 Hz, and whose position will be during which no noise emission of a level higher than a predetermined low threshold was made). The realization of the member 100 is within the reach of ordinary skill in the art. Each time it has counted a predetermined number N of natural holes calibrated in threshold and in width, the member 100 will send a control signal to a member 101 which directly receives the modulated signal. This member 101 is arranged to introduce an "artificial hole", of calibrated threshold and width, into the modulated signal. Its realization is also within the reach of those skilled in the art. The modulated signal interrupted by the "artificial holes" thus introduced is applied to a recording head 4 which produces a "music" band marked 4.

The "artificial holes" thus introduced on the "music" band, for example around a "natural hole" and all the N "natural holes", have a duration short enough not to be perceptible to the ear, for example 5 ms. The elimination of such a marking signal is practically impossible. The detection of its presence or absence by the member 180 of FIG. 4 does not, however, present any difficulty. The "artificial holes" are in fact easily recognizable by electronic means programmed according to their threshold and width calibration and their distribution on the support (detection of an "artificial hole" after a number N of "natural holes" "for example, or using any other means of coding the distribution of holes).

According to a more particular embodiment, a generator 103, controlled by the member 100, superimposes on the modulated signal, during the duration of each "artificial hole", a single period of a signal whose frequency corresponds to the duration of the "artificial hole", ie a frequency of 200 Hz for a duration of 5 ms. This audible frequency is applied with a sufficiently low level not to, given its short duration, disturb the normal hearing of the modulated signal.

It cannot be envisaged by a fraudster to filter it, because that would have the effect of completely removing the 200 Hz from the modulated signal, which is obviously unacceptable. given by information contained in the digital blocks. The extractor unit will then operate as indicated with reference to FIG. 4 (removal of the analog blocks and replacement by a delayed portion of the "sound" information), but by positioning itself by means of the address information, analog blocks contained in digital blocks.

It will be noted that the key mentioned above, which defines the generation of message No 2 from message No 1, may include an algorithm that varies from one batch of videograms to another. The packaging of each cassette in this batch will then be provided with a detachable label on which the key or the variable algorithm will be coded in the form of a magnetic code or a bar code for example. The introduction of this label into the detection and extraction unit will allow the latter to process a videogram of the batch in question, to the exclusion of all others.

Although the invention has been described with reference to the use, which is very advantageous in practice, of “sound” tracks for entering the marking signals and, one or, preferably, two coded messages, it can be envisaged to 'write such signals and messages on "video" tracks, without departing from the scope of the invention.

Claims

1. Anti-piracy process, characterized by writing, on an information medium, at least one marking signal which is practically indelible and cannot be eliminated during a transfer from. the information on another medium, this signal being arranged so as not to substantially harm the exploitation of the information, by detecting the presence or absence of this marking signal at the time of exploitation and by validation or invalidation of the operation.

2. Method according to claim 1, characterized by the additional recording on the information medium of at least one coded message capable of rendering the medium unusable by causing an unacceptable disturbance when it is present, this message being composed of blocks distributed all along the support, these blocks being arranged so that their elimination does not appreciably deteriorate the quality of the information during operation and by detecting the presence of these blocks and extracting them at the time of operation.

3. Method according to claim 2, characterized in that the marking signal and the coded message are written on at least one "sound" track of the support.

4. Method according to claim 2, characterized in that the marking signal is written on one of the "sound" bands used in the editing of a cinematographic film.

5. Method according to claim 4, characterized in that a coded message is superimposed on said "sound" tape at the latest at the time of the production of a "mother" video tape.

6. Method according to claim 5, characterized by the superimposition on said "sound" tape of a second coded message at the time of the production of a "daughter" video tape.

7. Method according to one of claims 1 to 6, characterized in that the marking signal comprises at least artificial modulation holes having a calibrated width and amplitude.

8. Method according to claim 7, characterized in that said artificial modulation holes are calibrated on natural holes of predetermined rank of the "sound" signal.

9. Method according to one of claims 1 to 8, characterized in that the marking signal comprises at least one inaudible frequency written all along the support.

10. The method of claim 7 or 8, characterized by the superimposition, on each artificial hole, of an audible frequency of period substantially equal to the duration of said hole.

11. Method according to claim 6, characterized in that the second coded message is generated from the first using a key.

12. Method according to claim 11, characterized in that said key is variable and written on a coded label associated with the packaging of the support and the information.

13. Method according to claims 5 to 10, characterized in that at least one of the coded messages includes information which defines the position of its blocks relative to the artificial holes.

14. Method according to one of claims 5 to 10, characterized in that said coded messages consist of blocks of insufficient duration so that after their elimination, the information remains exploitable.

15. Method according to one of claims 5 to 10, characterized in that said coded messages consist of blocks wedged on the natural and / or artificial holes.

16. Device for implementing the method according to one of claims 1 to 15, connected to a video recorder associated with a television receiver, characterized in that it is arranged so that its return to service is no longer possible when '' he suffered a predetermined number of disconnections.

17. Device according to claim 16, characterized by means of detecting each disconnection and by a memory whose content is modified on each detection of a disconnection.

18. Device for implementing the method according to one of claims 4 to 15, characterized in that it includes means for validating or inhibiting the operation as a function of the presence or absence of the signal marking and coded message (s) and / or alteration thereof resulting from the transfer of information to another medium.

19. Device according to claim 18, characterized by means of validating the operation by eliminating the coded message or messages.

20. Device according to claim 19, characterized in that said means interpose, in the intervals left free after elimination of the building blocks of the coded message or messages, delayed portions of useful information.

21. Device according to one of claims 16 to 20, characterized in that it comprises means for its supply from the "audio" output of the television receiver.