MXPA99010569A - Copy protection schemes for copy protected digital material - Google Patents

Abstract

Recent copy-protection schemes for digital video copy-protection rely on a pixel-watermark together with the presence of a"ticket"to implement the"copy-once"state of content. This ticket is designed to entitle the owner of a disk/tape to making one copy of digital content. We disclose a method to pass along this ticket with the video signal after content has been converted to the analog domain. This form of the ticket is called the analog ticket. The analog signal may be recorded on a legacy device that does not comply with the copy-protection scheme (e.g. ordinary VCRs). The analog ticket is designed such that it is automatically removed in these legacy devices. Next generation copies by compliant devices are made impossible. Three possible ways of embedding the ticket signal into the analog video signal are proposed.

Description

SCHEMES OF PROTECTION AGAINST COPY FOR DIGITAL MATERIAL PROTECTED AGAINST COPY The invention relates to an apparatus for including a tag signal in an analog video signal that has been obtained from the conversion of a copy-protected digital video signal in the analog domain, with a method for including the tag signal in the analog video signal, with an analog video signal provided with the tag, so that it will be deleted or distorted when the analog video signal is recorded with the tag in a Analog VCR, and subsequently reproducing the analog video signal thereof, but does not distort the normal reproduction of the analog video signal of that analog VCR, as well as a record carrier, provided with the video signal with the tag signal included The copy protection schemes of the prior art are, for example, the protection method. :. "or. *. against well-known Macrovision copy, in which" 'a selected waveform is added' 'to the extinction range of an analog video signal, in order to avoid or prohibit registration and reproduction Subsequent in / of an analogous VCR Reference is made in this respect to EP 256,753. In addition, reference is made to EP 328,147L, which describes what is known as a "serial copy management system", which allows a restricted number of copies of the original or of a subsequent copy to be made.The original material includes _a "account value representative of the value n. During a subsequent copy made of the original or a copy, the account value included in the copied material decreases by one, until the account value reaches the value of zero, which subsequently blocks the production of additional copies. The proposed standard specifications for a new digital video medium, such as DVD-RAM (DVD = Digital Video / Versatile Disk) and possibly also a VDR (Video Disk Recorder), will be equipped with a copy protection mechanism. The schemes also implement "never copy" or "free copy" obvious, the third category of content "copy once" / "no more copy". The latter possibility allows consumers to make a single copy of the "copy once" content, for example for backup or posting purposes over time. "Copy once" / "do not copy more" is also required to comply with the legislation in "some regions of the world." The copied version receives the copy status of "do not copy anymore." The basic copyright information carries including a watermark in the content of the video (in its most basic form, slight alterations of the luminance of predetermined pixels in the video material :, invisible to the eye, but easily detectable in a reproduction device). a watermark that is different for each of the three categories of copies A watermark must be designed to be robust against a number of transformations: that is, the watermark should still be detectable after basic image processing (filtering) of opening, conversion 4: 3 &? 16? 9, NTSC *? PAL, titling, digital? analogue? digital), but also after serious attempts at piracy.The watermark is a secret, only known or by the incluor (the provider of the video material). In the event that the watermark describes the content as "copy once" / "no more copy", some additional signal in the video should indicate which of the two generations: "copy once" or "no more copy" describes the underlying video Unlike the watermark, this signal must be changed in the consumer's devices in the copying process. To accommodate this, several schemes have been proposed, introducing the concept of the so-called "tag". The tag consists of 64 bits, which indicate if a disc / tape is the original (copy once), or a record of the original (no more copy), which can not be copied anymore by the devices, which adhere to the copy protection rules. Of course, this information could be encoded in only 1 bit, as with the SCMS / CGMS copy management rules, but this would make it very easy for pirates to use it. Instead of this, one chooses to relate 64 bits cryptographically to the underlying content. The number "64" is dictated essentially by the amount of effort required to "break" the cryptographic algorithm by brute force. In addition to the players / registrars (future) that adhere to this information of rights of 'author, the so-called registrars "in compliance", are there those e? the world "not in compliance": machines modified by pirates, but also the huge existing base of analog VCRs. Because one of the requirements of the copy protection mechanism is the previous compatibility, we should allow the VCRs (which operate under the specifications of the formats such as VHS, Beta, Video-8, S-VHS, Hi-8 etc). .), are able to record "copy once" material. After copying, '1 we want the content of the video to now be "no more copy". Enforcement registrars should not be able to make a copy of a 3rd generation. Accordingly, the T tag should be designed in such a way that it is automatically taken off by these existing non-compliant registrars. c, - V The goal, therefore, is for an analog video to be recorded on tape along with the tag, on a VCR, which knows nothing about copy protection. During the playback of the tape, the analog video should reappear, but the tag should be absent in it, see figure 1. Therefore, the purpose of the invention is to propose a number of low bit rate information channels, in a signal of an analog CVBS (Extinction / Composite Video Synchronization), of either an NTSC, PAL or SECAM signature, which are automatically deleted with the registration or reproduction using consumer-grade analog VCRs. It would be desirable if the tag was not removed until the reproduction, that is, in Figure 1, the removal takes place in VCR (OUTPUT), instead of in VCR (INPUT). Otherwise, analog VCRs in future compliance would not be able to reproduce "no more copies" tapes: once they detect the watermark that indicates the state of "copy once" / "no more copy", they interpret the absence of a tag as a piracy and its reproduction is stopped. These and other aspects of the invention will be further explained hereafter, in the description of the figures. In the description of the figures, figure 1 shows the idea behind the invention, namely the recording of an analog video signal provided with a tag in an analog VCR, such that with the reproduction, the video signal is not distorts, but the tag has disappeared, figure 2, the inclusion of a tag in the form of a signal and modulated by amplitude in the analog video signal, figure 3, an apparatus for including a tag in a video signal analog of according to the first proposal, figure 4, traces of the oscilloscope of the tag, before the recording in a VCR and after the reproduction in that VCR, the labels are included according to the third proposal, and figure 5, an apparatus to include a Tag in the analog video signal according to the third proposal. It is assumed that analog video originates from the analog output of a DVD player, or arises at the end of a transmission chain. Note that the "analog label" has nothing to do with methods to prevent regular VCRs from recording analog video (such as the one that exists in Macrovision methods). Since the content provided to the VCR is copied once, the registration is explicitly allowed. What should be achieved is that the subsequent copying attempts, by the devices in compliance, are frustrated. The channels to pass along with the tag are characterized by two characteristics: (a) transmission time (for example, line 21, line 624 etc.) (b) physical carrier (eg, horizontal sync pulse, burst of color, etc.). These two points will be discussed first. With respect to (a) above: to ensure that the extra information is not visible to the viewers, but at the same time allows inexpensive implementation in consumer devices, attention will be given to two options: i. As a first option, the vertical extinction interval could be used to 'accommodate the tag. The vertical extinction range (VBI) includes lines 1-23, 311-335 and 623-625, in PAL / SECAM 50/625, and lines 1-21, 261-283, 523-525 for NTSC 60 / 525. Of these, lines 1-10, 311-321, 623-625 (PAL / SECAM) and 1-10, 261-267, 523-525 (NTSC), are reserved for receiver synchronization (equalization, synchronization line (BY) / (RY) in the SECAM, etc.), so they must remain unchanged. _.t f1.

NB In the NTSC, line 21 is not part of the VBI, .'O Petro, as it is reserved for subtitling (cióse M'i: _ captioning), and not for active video, it is previously labeled as belonging to the VBI . ii. As a second option, 3% of the active video that is not usually projected on the consumer grade screens due to overexploitation, can be used to accommodate the tag. Both choices have advantages and disadvantages: The information carried in the VBI does not "always remain in the 'video' conversion equipment (say PAL-? NTSC), which may be present in the chain of transmission for programs distributed internationally. But within a standard transmission, the VBI is a very efficient invisible channel, as demonstrated by the services of 20 years ago such as Teletext (NB) In view of this, it might seem attractive to link the tag to such an ordinary program as a NABTS / WST teletext page This seems, however, doubtful, since consumer grade VCRs with a 5 MHz bandwidth, such as S-VHS, will record and reproduce this signal intact) and Cióse Captioning, and more recently Intel's HTML-based Intertransmission technology. In addition, services such as Teletext are transmitted asynchronously, that is, it is decided on a field by field basis, or even line by line, whether or not it is transmitted on the VBI lines. When a line is being used, a specific synchronization sequence is transmitted to the beginning of the active video of that line. If the transmitter wishes to enforce the rights of his or someone else's copy, on the transmitted content, but still allows a copy (for example, for purposes of posting with time), transmits the appropriate tag and only has to delay the transmission of a particular teletext line, a block or frame. Lines 23 (PAL) or 22 (NTSC) can be used to indicate 16: 9 mode (WSS in PAL + transmissions); Line 19 (NTSC) or 318 (PAL / SECAM) are also claimed for the cancellation of Ghosts. Care should be taken "of ß that the" 7 transmitted tag does not activate any logic associated with this functionality and vice versa. The use of line 23 in the PAL for WSS (and cannon calibration?) Can be attractive. Finally, the tags in the VBI are automatically unlinked by the digital VCRs (D-VCR), which store only the active part of the video. On the other hand, it would be expected that the 3% overexploration region would survive almost all conversions and would be transmitted universally. The "advantage of using this part of the video, is" that "" in some visual representation devices, these lines may end up being visible (depending on the temperature etc .; also the screens of the PCs when they are used as TV). In addition, the filtering of noise or other manipulations of the active video in the chain of transmission, can destroy any information of the tag contained in it. To sum up: A first proposal is to transmit during the VBI or the 3% overexploration lines, an Amplitude Modulated Y signal, with a frequency carrier of approximately 3-4 MHz, and high amplitude, with a DC level of 50% ( Gray) . For example, with an extinction level = 0%, maximum target = 100%, synchronization level = -43%: binary "0" has an amplitude of 80% and "1" an amplitude of 100%. This means that the maximum levels of these signals will be 129% resp. 150% An example of a tag, included in this way, is shown in Figure 2. This -'example shows the inclusion of a bit sequence "10110", of the tag on a line of the video signal, modulating by AM a signal And high frequency, high amplitude (not to climb). During registration, high frequencies (spatial) are amplified in the VCR (so-called pre-emphasis), to compensate for the undesirable properties of the magnetic tape. To limit the frequency excursions of the FM modulator that registers the Y signal, the preenhanced signal 'is cut off before registration. This cutoff removes any information of high amplitude in Y. Figure 3 shows an embodiment of an apparatus for including the analogous tag as shown in Figure 2, in an analog video signal. The inclusive of Figure 3 includes the analog label on line n of the video signal. The data bits are transmitted at "614 kHz using 50% DC compensation and 80% amplitudes and 100 * to represent 0 'This allows approximately 32 bits / line. The "Gateway VBI line n", is a multiple vibrator, not stable, which emits an impulse, as soon as its input sees the number n. A second proposal is to move the phase of the color burst by 180 ° in a predetermined line. At the beginning of each line, before the active part of the line, the transmitter transmits the color burst: 10 to 12 cycles of the color subcarrier frequency, fsc, which has been set to 4.433618.75 MHz (for PAL) or 3.579545 MHz (for NTCS). The receiver synchronizes an on-board oscillator in frequency and phase to this burst, and uses it to decode the resultant U, V (also called RY, BY) (PAL), or I, Q (NTCS) color signals, which have been modulated by quadrature amplitude (PAL / NTSC) on the color subcarrier. When recorded on a magnetic tape in a VCR, the color signals that modulate the color subcarrier, move down from the top of the spectrum (around fsc) to the bottom of the spectrum and centered around the fu «625 kHz (PAL), 690 kHz (NTSC). These calculations are for VHS. For Beta, Hi-8 and S-VHS, the subcarrier frequencies fall in the same interval (between 550 and 750 kHz) .- To be precise: if the analog input of the VCR sees a color signal with a burst frequency fsc and a horizontal frequency line fH »(both not necessarily equal to those specified in the standard), the burst frequency of the color ribbon should be f0 = N. fH ', N equals 40 + 1/8 for VHS and equals 47 - 1/8 for 8 mm. The fu burst phase is set to a fSc • The procedure described above is called a "low color" register. In the reproduction, the VCR electronics under color will transfer the color signal of the tape to its original interval fSc in the upper part of the spectrum, mixing it in a heterodyne mixer with the frequency sum f¿, «fsc + f0. The fsc reproduction is generated by a crystal oscillator, and fu is generated by a VCO, which is secured to the burst of color coming from the tape. There are variations in the design of the so-called subverter and the main converter, but there are always two oscillators, one of which is an oscillator with a stable X-tal reference and the other is secured to a (multiple) burst frequency (s). _. 'o The instabilities of the. synchronization (fluctuation) in the conveyor system of the tape, have a disastrous influence on the subcarrier phase, and therefore, on the quality of the color. Two phase comparison cycles, a coarse control cycle and a fine control cycle, quickly compensate for these instabilities by adjusting the frequency of the heterodyne mixer to produce a burst that is outside the standard of 4.433618.75 or 3.579545 MHz. will lose some of the intentional modulation of the burst phase / frequency in the input signal to the VCR, at the output, by this assurance of the output burst to a reference crystal. The fine control cycle "slowly" adjusts the frequency of the heterodyne mixer f? comparing the phase difference of the reference crystal oscillator and the converted burst of the ribbon, averaged over a few lines. The coarse control cycle responds "quickly" to the large phase difference. To understand their work, one should know that in VHS and its descendants, the phase of the color subcarrier, and therefore, the burst, as recorded by a head A (one of the two heads of record present in the VCR), it has been programmed to go 90 ° for the hori zon ta l, for the PAL this happens in addition to the alternation of the + 135 ° standard burst. For head B (the other head of record in the VCR), no extra phase is introduced. This is done to reduce chromium-crosstalk between adjacent tracks. It should be noted here that in the 8 mm system, the roles of heads A and B are exchanged. Now in playback, when the comparator in the coarse control cycle in the color synchronization circuit notices a large phase difference, it can respond in two ways: the phase difference is large because (a) a large error has occurred; in that case, the coarse control cycle interrupts the burst and the color signal for that line. (b) the oscillator is in the wrong phase of the set of jumps 0 ° - »90 ° - 180 ° -270 ° - 0 °; in that case, the coarse control cycle advances the oscillator on board to fu in steps of 180 ° (or sometimes 90 °), until the assurance occurs. This is called the 4f selector. To transmit a "0", advance the burst 180 ° on a fixed line n (say n = 18). To transmit a "1", advance the burst 180 ° on the line n + l.

This "0" or "1" is detected by the measurement of the phase of the burst on line n + 1. There are two ways in which this information is distorted in reproduction: 1. The coarse control cycle sees an error-fsc phase of 180 °, and responds by advancing the heterodyne frequency fu 90 ° or 180 °. 2. Even if the coarse control cycle does not respond, there is a color comb filter, present in each VCR, to reduce crosstalk between the tracks. This comb filter 2H, takes the average of the line n and n-2 (for the PAL, for the NTCS: ÍH, average of the lines n and n-l). If the burst on line n is advanced 180 °, this will give an average of 0 with the burst on line n-2. In this way, one or two bits per frame can be transmitted. This number of bits is limited because the coarse control cycle takes several lines (typically 5-8) to recover, and obviously, this recovery needs to take place before the video lines are transmitted, which are visible in the screen . The following table shows that the amplitude A and the phase f of the burst in the line n + 1, will be after the reproduction from a VCR with and without a coarse control cycle that responds.

The table above shows the amplitude and phase shift of the burst on the line n + l after transmitting a bit "0" or "1", after registering and playing the bits in an analog VCR, with several PLL configurations. In this table, c is the normal burst amplitude (approximately 43%). The last column (pathological case) shows what is measured on line n + l without going through a VCR (ie, directly on the output of a DVD player). Note that in none of the VCR configurations, both "0" and "1" can be detected reliably with playback. An example: transmit a "0" to a VCR with a comb filter ÍH and a 4f selector that advances in steps of 180 °. Due to "0", the burst on line n is 180 ° forward and the burst on line n + l is 0 ° forward. In the reproduction, the selector 4f advances the burst in the line n + l 180 ° with the detection of the "bad" burst in the line n. Next, the comb filter ÍH averaged this with the 'o line (n + l) -l = n, which was already 180 ° ahead, -so that the result is a burst with a normal amplitude and a displacement of 180 ° phase. A third proposal is based on the relationship that normally exists between the line frequency fH and the subcarrier frequency fsc. In a particular line in the VBI or the 3% overexploration region, a signal _is transmitted with approximately the same frequency "as the color subcarrier, fsc, which is" modulated in phase with the bits of the tag That is, 0 'correspond to two colors, let's say at 0 ° and 90 ° in the UV space. The signal frequency of the tag should be very close to (284-1 / 4) fH + 25 Hz (PAL) or (455/2) x f¿ (NTSC). However, the following rules should be taken into account: For PAL: '-_.- - H "(a) this signal of the tag is transmitted only during even frames, not during" odd "frames, and (b) the signal of the tag it is reversed every 2nd, 4th, 6th, frame, etc. For NTCS: (a) this signal from the tag is transmitted during all frames, and (b) the signal from the tag is reversed every 2nd 4-f, 6, frame, etc. The inversion of the tag of the tag corresponds to the assignment of two new colors to "0" and "1", which are offset 180 ° forward. As a result of the fact that the tag of the tag is secured to fH, the signal of the tag has a fixed phase with respect to the horizontal synchronization pulse, in that line: that is, in an oscilloscope that uses this horizontal synchronization pulse as an activator, the signal of the tag is fixed. If the investment in step b were not made, the tag of the tag would appear together with its version displaced 180 °, due to the fractional relation between fsc "and ÍH- (for" PAL, after two blocks, the color subcarrier in the same line has picked up a phase delay of 180 °, while for the NTSC, after a frame, the color subpoftadora on the same line has picked up a phase delay of 180 °). The sign of the tag is detected by averaging this line over a number of frames. The signal of the tag is removed with the record as follows: the frequency at which the tag is modulated in phase, is basically the subcarrier of the color. The VCR will interpret the tag of the tag as a sequence of colors. During playback, the VCR 'will ensure this "color signal" to a reference crystal oscillator in fsc- The frequency of the horizontal line fH, however, is not stable, due to the fluctuation in the mechanism of the transport system of the tape. Therefore, with the reproduction, the tag of the tag no longer supports any fixed phase relation to fH and when it is added over several frames, it will average 0. Figure 4 shows the oscilloscope traces of the tag before registration in a VCR and after playing from that VCR. In Figure 4, the modulation parameter is "1", it is + 45 °, "0" is -45 ° '. In 'the top: before registering in a' VCR; in the bottom part: after playing from that VCR. Vertical dotted lines indicate the limits of the bit: the places where the carrier phase can be changed to encode a bit. It is clear from the graph at the top, that all the strokes fall on the top of each, while on the graph at the bottom, the carrier fluctuates backwards and forwards, and averages away. Figure 5 shows a modality of an apparatus for including the tag as in the third proposal, in the analog video signal. With the inclusion of Figure 5, the data bits are transmitted at 614 kHz using 0 ° and 180 ° to represent "0" and "1". This allows approximately 32 bits / line. The block "+2" in figure 5 is for NTSC, and should become a "+4" block for the PAL. The "VBI Gateway n-line" block in Figure 5 is a non-stable multiple vibrator, which emits an impulse, as soon as its input sees the number n. For the transmission of the tag according to the second and third proposals, it is recommended to adjust the luminance signal Y in the resulting line to zero. If the luminance signal on the line is equal to zero, it will not impede the methods but taking the luminance signal equal to zero will simply mask any potential artifacts. The following table summarizes and lists the advantages and disadvantages of the three proposals described above.

. PSK fsc + inversion in the fluctuations in R / D (?) -SET successive frames the transport of the mechanical tape, ie fH where R means "eliminated" and D means 'distorted' ' + + - - Luma high • Simple / cheap • Cutting can be frequency and • Works with high volume SECAM device dependent. • High bit rate With respect to security, the following comments will be made. The tag could be divided into the analog signal with the reproduction by pirates. This could be avoided by relating the tag with specific properties of the active video of the box in which it is included. With playback, the analog video is mutilated (for example, high-frequency colors are corrupted, but also-a loss of resolution Y might work), and the illegally inserted tag would no longer correspond to the underlying video. The requirements in an analogous label can now be summarized as follows. The tags should not be recognizable by compliant DVD recorders, after registration and the subsequent playback step in / from the analog VCR, as described in figure 1. The tags may become unreadable by the VCR "(ENTRY) ( during registration) or on the VCR (EXIT) '(during playback) In addition, the tag could be completely deleted, or simply distorted (eg, shifted by frequency) In order of preference: Complete elimination overcomes the distortion, to make it more difficult for pirates to reset the tag manually. Deletion in VCR (OUTPUT) instead of in VCR (INPUT), is preferable, since a compliant DVD recorder, or a future VCR, will not play the material once copied (otherwise illegal), without a tag . The tag consists of 64 bits, which should be transmitted approximately once every 10 seconds. Due to the analogous nature of the channel, ECC should be applied and the number of bits approximately doubled to 128. It should be difficult to reinsert the tag (cryptographically / computationally) into the analog video. The transmission of the tag in the analog video, should require as little physical equipment as possible, apart from the one already in place, to convert the MPEG to CVBS.

Claims (18)

1. CHAPTER CLAIMEDICATORÍO Having described the invention, it is considered as a novelty and, therefore, the content is claimed in the following CLAIMS: 1. An apparatus for including a tag signal in one or more lines of an analog video signal, the apparatus comprising: first input means for receiving the analog video signal, second input means for receiving. the signal of the tag, - means for including the signal of the tag in one or more lines of the video signal, characterized in that the means for 'including are adapted to include a tag signal by adding an amplitude-modulated signal with a carrier frequency r predetermined, in one or more lines, a bit in the tag of the tag of a first binary value is represented by a first predetermined amplitude in the amplitude-modulated signal, a bit in the tag of the tag of a second binary value is represented by a second predetermined amplitude in the signal modulated by ampli ud. The apparatus according to claim 1, characterized in that the predetermined carrier frequency has a value between 3 and 4 MHz. The apparatus according to claim 1 or 2, characterized in that the first predetermined amplitude is substantially equal to the 200% peak to peak and the second predetermined amplitude is substantially equal to 160% peak to peak, where 100% peak to peak is equivalent to the distance value between the extinction level and the peak or maximum target in the luminance signal. 4. An apparatus for including a tag signal in one or more lines of an analog video signal, the apparatus comprises: - first input means for receiving the analog video signal, second input means for receiving the signal of the tag, means for including the tag of the tag in one or more lines of the video signal, characterized by the means to include are adapted to include a tag signal by changing the phase of the bursts of color in one of two subsequent lines in the signal of video, a bit in the tag of the tag of a first binary value is represented by the burst of color in the first of the two subsequent lines in the video signal changed in phase, one bit in the tag of the tag of a second binary value it is represented by the burst of color__in the second of the two subsequent lines in the video signal changed in phase. The apparatus according to claim 4, characterized in that the means for including are adapted to change the phase of the color burst by 180 °. 6. An apparatus for including a tag signal in one or more lines of an analog video signal, the apparatus comprising: - first input means for receiving the analog video signal, second input means for receiving the tag of the tag, means for including the tag of the tag in one or more lines of the video signal, characterized in that the means for including are adapted to include a tag signal by adding a predetermined carrier frequency that is modulated by phase with the bits in the tag of the tag in one or more lines of the analog video signal, one bit of the tag of the tag of a first binary value is represented by the carrier frequency modulated in phase by a first phase angle, one bit of the signal of the tag of one second Binary value is represented by the carrier frequency modulated in phase by a second phase angle. The apparatus according to claim 6, characterized in that the predetermined carrier frequency is substantially equal to the color subcarrier frequency. The apparatus according to claim 6 or 7, characterized in that the first phase angle i i is substantially equal to 0 ° and the second phase angle is substantially equal to 90 °. The apparatus according to claim 6, 7 or 8, characterized in that the means for including are adapted to add the signal of the tag to one or more lines of even frames in only the video signal. 10. The apparatus according to claim 6, 7 or 8, characterized in that the means for including are adapted to invert the signal of the tag included in each nth frame of the video signal, where m is an integer equal to 2. The device according to claim 6, 7 or 8, characterized in that the means to include are adapted to invert the signal of the tag included in the (2 + m) th box of the video signal, where m is an integer equal to 0, 4, 8, 12, 12 The apparatus according to any of the preceding claims, characterized in that one or more lines are lines included in the vertical extinction ranges of the video signal. The apparatus according to any of claims 1 to 11, characterized in that one or more lines are lines in the over-scan portion of the active lines in the video signal. The apparatus according to any of the preceding claims, characterized in that it also comprises writing means for writing the video signal with the tag of the tag included in a record carrier. 15. The method for including a video signal in one or more lines of an analog video signal, characterized in that it is carried out in accordance with claim 1, 4 or 6. 16. The method according to the claim 15, characterized in that it also comprises the step of registering the video signal with the signal of the tag included in a record carrier. 17. The record carrier obtained with the method according to claim 16, characterized in that it has the video signal with the tag of the included tag, registered therein. 18. The analog video signal obtained with the method according to claim 15, characterized in that it has the signal of the tag included in it.