JPH05191771A - Method for detecting presence of signal for preventing copying - Google Patents

Abstract

PURPOSE:To accurately discriminate whether or not a copy guard is inserted in a video signal by dividing a vertical blanking period of the video signal and detecting a pseudo synchronization pulse from consecutive division periods. CONSTITUTION:A video signal inputted from an input terminal 1 to a copy prevention processing presence detection circuit 100 is fed to a synchronizing separator circuit 2, from which horizontal synchronizing signal and vertical synchronizing signal H, V are obtained. Then a discrimination period signal generating circuit 3 divides the vertical blanking period into plural periods whose period is shorter than the horizontal period based on the signals H, V. When a pseudo synchronizing signal is detected for the consecutive division periods, a copy guard signal insert section synchronization detection circuit 4 discriminates the presence of a copy guard signal in the video signal. Thus, whether or not a copy guard is applied to the input video signal is accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has an inserted anti-duplication signal for preventing duplication in a recorded video signal of a recorded video tape on which video software such as a movie is recorded. The present invention relates to a method for detecting the presence / absence of a duplication prevention signal for detecting whether or not there is a signal.

[0002]

2. Description of the Related Art In order to substantially disable duplication (so-called dubbing) of a recorded tape on which video software such as a movie is recorded by a VTR for home use, some kind of copy prevention processing (hereinafter referred to as copy guard) is applied to a recorded video signal. ) Is performed.

As one of the copy guard methods, as described in Japanese Patent Laid-Open No. 288582/1986, a plurality of pairs of a pseudo sync pulse and a positive pulse are inserted in a vertical blanking interval. At the same time, there is a method of using an AGC circuit of a recording system having a predetermined characteristic as a copy guard handling process, which is often used. The copy guard signal is inserted in the vertical blanking interval because if the copy guard signal is directly inserted into the video signal portion, the content itself of the video software may be damaged.

FIG. 10 is a diagram for explaining the copy guard method described in the above publication. FIG. 10B shows a plurality of pairs of pseudo sync pulses and positive pulses for copy guard (hereinafter referred to as copy guard signals). FIG. 10A shows an example of a video signal inserted in a vertical blanking interval.
It shows a video signal without these pulses inserted. In the case of FIG. 10B, five pairs of pseudo sync pulses DP and positive pulses LP are inserted at regular intervals in each horizontal section from the 13th horizontal section to the 18th horizontal section in the vertical blanking section of the odd field. ing. In the case of this example, the 275th horizontal section to the 28th horizontal section of the even field
Similarly, a copy guard signal is also inserted in the 0 horizontal section.

In the case of this copy guard method, the number of pairs of the pseudo sync pulse and the positive pulse inserted in one horizontal section in the vertical blanking section is 5 pairs or more and 8 pairs or less, and this pseudo pulse pair is The horizontal section to be inserted is defined as five or more consecutive horizontal sections in the vertical blanking section.

In this case, if the rising edge of the pseudo sync pulse DP is continuous with the rising edge of the positive pulse LP and the copy guard signal is inserted in the video signal, V
The TR recording system AGC circuit judges that the peak value of the pseudo sync pulse DP to the peak value of the positive pulse LP is the magnitude of the sync pulse, and the level of the input video signal becomes, for example, three times or more the standard level. Gain control will be performed as if. Therefore, when this recording signal is reproduced, the recording signal has been attenuated to a level of 30% or less of the standard, so that only a low-quality and unstable image can be obtained. That is, copy protection can be substantially performed.

Incidentally, the level of the positive pulse LP is appropriately changed, and the AGC level is variously changed, so that a reproduced image of a lower quality is made.

[0008]

As described above, since the conventional copy guard correspondence processing depends on the characteristic of the AGC circuit peculiar to the external input of the VTR, there are differences in the method, characteristic, and performance of the AGC circuit. , In some cases, the copy guard function was not obtained sufficiently.

Further, the conventional method is not a method of activating the AGC circuit by discriminating whether or not the video signal is actually copy-guarded, so that, for example, the VTR causes tracking deviation or variable speed reproduction. The AGC responds to noise and other disturbance noise generated when performing as a pseudo pulse for copy guard, and the recorded video signal is reduced in quality although it is originally a normal video signal. There was a drawback that it deteriorated.

The above-mentioned drawback is that the corresponding processing function of the copy guard is always activated regardless of whether the copy guard is applied or not. In view of this point, the present invention aims at correctly detecting whether or not the input video signal is copy guarded, that is, whether or not the copy guard signal is inserted in the video signal, and the copy guarding is applied. It is possible to prevent the processing corresponding to the copy guard from being applied to an input video signal that has not been recorded.

[0011]

In order to solve the above problems, a method for detecting the presence or absence of a copy protection signal according to the present invention is
A method for detecting the presence or absence of an anti-duplication signal in the video signal by detecting a plurality of pseudo sync pulses inserted for anti-duplication in a plurality of consecutive horizontal intervals in a vertical blanking interval of the video signal. Therefore, the vertical blanking interval of the video signal is divided into a plurality of intervals shorter than the continuous horizontal intervals in which the pseudo sync pulse is inserted, and the pseudo sync pulse is detected in the continuous divided intervals. Sometimes, it is detected that there is a copy protection signal in the video signal.

[0012]

According to the present invention having the above-described structure, only one of the horizontal sections in which the copy guide signal may be inserted in the vertical blanking section is noted, and the copy guide signal is included in the video signal. When determining whether the copy guide signal is inserted, it must be known in advance in which horizontal section the copy guide signal is inserted. However, it is not fixed in which horizontal section in the vertical blanking section the copy guide signal is inserted, and the reproduction output of the VTR is unstable, so the copy guide signal is surely inserted in the video signal. It is difficult to accurately determine whether or not there is.

According to the present invention having the above-mentioned structure, it is determined that the copy guide is present when the presence of the copy guide signal is detected in the continuous divided sections. This utilizes the property that the copy guide signal is continuously inserted in the vertical blanking interval over at least 5 horizontal intervals, and it is possible to accurately determine whether or not the copy guide is applied to the video signal. It

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for detecting the presence or absence of a copy protection signal according to the present invention will be described with reference to the drawings.

FIG. 5 is a block diagram of an embodiment of an apparatus to which the method of the present invention is applied. In FIG. 1, 10
Reference numeral 0 indicates a device for detecting the presence / absence of copy protection processing. The video signal input to the apparatus 100 through the input terminal 1 is supplied to the sync separation circuit 2, and the horizontal sync signal H and the vertical sync signal V are obtained from this. The synchronization signals H and V are supplied to the determination section signal generation circuit 3, the copy guard signal insertion section synchronization detection circuit 4, and the video section synchronization detection circuit 5, respectively.

In the judgment section signal generation circuit 3, as shown in FIG. 6, the equalization pulse section and the vertical sync pulse section of 9 horizontal sections in the vertical blanking section are excluded from the horizontal sync signal H and the vertical sync signal V. For example, a window pulse SA that becomes high level only in a section PA (this section is a section in which a copy guide signal can be inserted) and a window pulse SB that becomes high level only in the video section section PB excluding the vertical blanking section. Is generated.

For example, in the case of an odd field of an NTSC video signal, the section PA is the 10th horizontal section to the 2nd section.
One horizontal section, and the section PB is, for example, a 22nd horizontal section to a 263rd horizontal section. If it is an even field, the section PA is set to the 272nd horizontal section to the 283rd horizontal section, and the section PB is set to the 284th horizontal section to the 525th horizontal section, for example.

Then, the pulse SA is supplied to the copy guide signal insertion section synchronization detection circuit 4. The copy guard signal insertion part synchronization detection circuit 4 is a circuit to which the method of the present invention is applied, and is used in the section P as described below.
The presence or absence of the copy guard signal is detected in A.

That is, FIG. 1 is a block diagram of an example of a copy guard signal insertion section synchronization detection circuit 4 to which the present invention is applied, and FIG. 2 is a time chart for its explanation.
This example is an example of detecting whether or not a copy guard signal is inserted in each horizontal section of the section PA of the vertical blanking section, and an example in which the divided section is equal to one horizontal section.

In FIG. 1, 401 is an input terminal for the horizontal synchronizing signal H from the sync separation circuit 2, 402 is an input terminal for the vertical synchronizing signal V, and 403 is an input terminal for the window pulse SA from the determination section signal generating circuit 3. , 404 are output terminals.

The horizontal synchronizing signal H (FIG. 2A) including the equalized pulse from the input terminal 401 is supplied to the mask circuit 405 and the timing signal generating circuit 406. Further, the vertical synchronizing signal V from the input terminal 402 is supplied to the timing signal generating circuit 406. The reference horizontal synchronizing signal HRF (FIG. 2B) formed with the vertical synchronizing signal V as a reference is obtained from the timing signal generating circuit 406 and is supplied to the mask circuit 405.

In the mask circuit 405, the reference horizontal synchronizing signal H
The input horizontal sync signal H is masked by RF, from which an equalization pulse and, if present, a pulse SP (FIG. 2C) consisting of a copy guard signal and noise are obtained.

This pulse SP is supplied to the counter 407 and counted. The window pulse SA (FIG. 2D) from the input terminal 403 is supplied to the count enable terminal EN of the counter 407.
Is the pulse SP only in the section PA in which the copy guard signal in which the pulse SA is at the high level may be inserted.
To count. Further, the reset terminal of the counter 407 is connected to the reference horizontal synchronizing signal H from the timing signal generating circuit 406.
RF is supplied and the counter 407 is reset in the horizontal cycle. Therefore, the counter 407 counts, in each one horizontal section of the section PA, the number of pulses excluding the horizontal synchronization pulse included in the one horizontal section.

The count value of the counter 407 is input to the memory circuit 408. The memory circuit 408 is supplied from the timing signal generating circuit 406 with a write timing pulse WP having a horizontal period which is generated slightly before the reference horizontal synchronizing signal HRF. And this memory circuit 408
, The count value of each one horizontal section in the section PA from the counter 407 is written to different addresses.

The count value data stored in the memory circuit 408 is supplied to the determination circuit 409. Judgment circuit 408
Then, from the count value in each one horizontal section in the section PA,
The determination for each one horizontal section is performed based on the determination criteria as shown in the table of FIG. That is, since the copy guard signals to be inserted in one horizontal section are 5 to 8 pairs as described above, a slight margin for judgment is taken into consideration and the judgment is made as shown in FIG.

That is, when the count value in one horizontal section is 3 or less, it is determined that the one horizontal section of the input video signal does not include a copy guard signal or there is no input signal, and the determination for the one horizontal section is performed. As a result, "0" is given. If the count value in one horizontal section is 4 or more and 8 or less, it is determined that the one horizontal section of the input video signal includes the copy guard signal, and "1" is given as the determination result for the one horizontal section. If the count value in one horizontal section is 10 or more, it is determined that the one horizontal section of the input video signal contains many noises, and "2" is given as the determination result for the one horizontal section.

Further, the decision circuit 409 refers to the decision result of each horizontal section, and as described above, the copy guard signal is inserted into at least 5 consecutive horizontal sections in the vertical blanking section. In consideration of the existence, it is determined whether or not the determination result is “1” in a plurality of consecutive horizontal sections of two or more. Then, when the determination result is "1" in a plurality of continuous horizontal sections, it is determined that the copy guard signal is present in the input video signal, and the output DA is set to the high level. If there is no horizontal section in which the determination result is "1", or if there is no horizontal section that exists, it is determined that there is no copy guard signal in the input video signal, and the output DA is set to low level. ..

For example, when a copy guard signal is inserted from the 13th horizontal section to the 18th horizontal section as shown in FIG. 2A, as shown in FIG. Since the result is "1", the output DA of the copy guard signal insertion part synchronization detection circuit 4 becomes high level.

The state of the output DA of the copy guard signal insertion part synchronization detection circuit 4 is held for one field period.
Therefore, if the discriminated state in the next field is the same as the previous field, the state of the output DA continues the state at that time, and when the discriminated state is different from the previous field, the state of the output DA is inverted. To do.

Next, in FIG. 5, the pulse SB from the determination section signal generation circuit 3 is supplied to the video section synchronization detection circuit 5, and the synchronization detection circuit 5 counts the number of synchronization pulses in the section PB. .. The video section synchronization detection circuit 5 can be composed of a counter and a determination section that makes a determination as described below based on the output count value of the counter.

In this case, since the section PB has a width of 241 horizontal sections, if there is no noise or dropout, normally 241 synchronization pulses are detected, but circuit error, tape damage, etc. are detected. Considering this, a margin α is set for the number of horizontal sync pulses detected. The value α of this margin is set to a dozen or more.

Then, in the video section sync detection circuit 5, the detected sync pulse number M is 241-α ≦ M ≦ 241 + α.
If so, it is determined that the input video signal does not contain noise and is normal, and the output DB of this circuit 5 is set to a high level. In addition, the number M of sync pulses detected is
If M> 241 + α or M <241−α, it is determined that the input video signal has noise and is not recognized as a normal video signal, and the output DB of this circuit 5 is set to the low level. The state of the output DB of this circuit 5 is held for one field period. Therefore, if the discrimination status in the next field is the same as the previous field, the output DB
The state of then continues the state at that time, and when the discrimination state different from the previous field is reached, the state of the output DB is inverted.

Next, the output DA of the copy guide signal insertion section synchronization detection circuit 4 and the output DB of the video section synchronization detection circuit 5
Are supplied to the AND circuit 6. Therefore, when it is determined that the input video signal has a normal video portion and the copy guard signal exists in the section PA, the output AND of the AND circuit 6 becomes high level, and is output at other times. AND goes low.

The output AND of the AND circuit 6 is supplied to the time constant circuit 7 for preventing chattering. The time constant circuit 7 is for surely detecting the presence or absence of copy guard, and the output AND of the AND circuit 6 is, for example, 30 seconds to 9 seconds.
When the high level state continues for about 0 seconds,
For example, the output DET that becomes high level is output. This output DET is the presence / absence detection device 100 of the copy prevention processing of this example.
Is the output of.

With this output DET, in this example, copy guard corresponding processing is performed on the input video signal. That is, in this example, the input video signal is supplied to the copy guard correspondence processing circuit 8 and the output DET of the copy prevention processing presence / absence detection device 100 is supplied to the copy guard correspondence processing circuit 8. The copy guard correspondence processing circuit 8 performs copy guard correspondence processing on the input video signal only when the output DET is at a high level.

In this case, as the corresponding processing, the input video signal is muted so as not to be output from the corresponding processing circuit 8, the level of the input video signal is attenuated, and the input video signal is endured by a mosaic processing or the like. There is a digital processing to prevent it.

Further, in the VTR, as a recording system AGC circuit for a video signal, it is possible to switch between a characteristic whose characteristic effectively reacts to the copy guard signal and a characteristic which is not influenced by the copy guard signal, and output DET. It is also possible to switch to a characteristic that responds effectively to the copy guard signal only when is at a high level so that the reproduced image does not endure viewing. Further, the output DET may be used to cancel the recording mode of the VTR when it is at the high level.

Further, as the corresponding processing, not only for the video signal but also for the audio signal accompanying it,
Only when the output DET is at a high level, muting processing, level attenuation, noise addition, or other processing that makes the audio unbearable may be performed.

When the output DET is at the low level, the copy guard correspondence processing circuit 8 does not carry out the above correspondence processing, and the input video signal is outputted from this circuit 8 as it is.

The video signal and the audio signal passed through the corresponding processing circuit 8 are supplied to the recording system of the VTR, for example. Thus, according to the above example, when the copy guard is applied to the input video signal by the output DET of the presence / absence detection processing apparatus 100, the video signal and / or the audio signal is not subjected to any processing. Can be prevented from being recorded.

Also, in this example, the output D of the time constant circuit 7
The FT is supplied to the alarm circuit 9, and when it is detected that the input video signal is copy guarded, it is notified to the user by, for example, lighting an alarm lamp, displaying a display, or generating an alarm sound. To be done. This can prevent the user from erroneously recognizing that the VTR is out of order.

FIG. 7 is a block diagram of an example of the copy guard signal insertion section synchronization detection circuit 4 to which another example of the method of the present invention is applied, and FIG. 8 is a time chart for its explanation. In FIG. 7, 411 is an input terminal for the horizontal synchronizing signal H from the sync separation circuit 2, 412 is an input terminal for the vertical synchronizing signal V, 413 is an input terminal for the window pulse SA from the determination section signal generating circuit 3, and 414 is It is an output terminal.

The horizontal synchronizing signal H from the input terminal 411 is supplied to the clock terminal of the counter 415. Further, the window pulse SA (FIG. 8B) from the input terminal 413 is supplied to the count enable terminal EN of the counter 415,
In the counter 415, the horizontal synchronizing signal H as an input clock is counted in the section PA.

Further, the horizontal synchronizing signal H from the input terminal 411
The vertical synchronizing signal V from the input terminal 412 is supplied to the timing signal generating circuit 416. In this timing signal generation circuit 416, as shown in FIGS.
A section having a length shorter than the minimum continuous insertion section of the copy guard signal (as described above, the copy guard signal is inserted into at least 5 consecutive horizontal sections in the vertical blanking section), for example, 3 Divide into horizontal sections,
A reset pulse RS (FIG. 8G) is generated at the leading edge and the trailing edge of each divided section Pa, Pb, Pc, Pd. At the time immediately before the reset pulse except the first reset pulse, the latch pulses La, Lb, Lc, and Ld are respectively generated.
(FIGS. 8H-K).

Then, the reset pulse RS from the timing signal generating circuit 416 is supplied to the reset terminal of the counter 415. Therefore, the counter 415 counts the sync pulse, pseudo sync pulse, and noise included in each of the divided sections Pa, Pb, Pc, and Pd.

The count value output of the counter 415 is supplied to the latch circuits 417, 418, 419 and 420. And
The count value of the division section Pa is latched by the latch circuit 417 by the latch pulse La, the count value of the division section Pb is latched by the latch circuit 418 by the latch pulse Lb, and the count value of the division section Pc is the latch pulse Lc.
Is latched by the latch circuit 419, and the count value of the divided section Pd is latched by the latch circuit 420 by the latch pulse Ld.

The latch circuits 417, 418, 41
The count value data latched by the 9 and 420 is the judgment circuit 42
Supplied to 1. In this determination circuit 421, from the count value in each divided section, the determination about the divided section is performed.
The determination criteria shown in the table of FIG. 4 are used. That is, the copy guard signals inserted in one horizontal section are, as described above, 5 to 8 pairs, and based on the number of pulses including this and the horizontal synchronization pulse, a slight margin for determination is taken into consideration, and The determination is made as shown in 4.

That is, if the count value in one divided section is 7 or less,
It is determined that the divided section of the input video signal does not include the copy guard signal or that there is no input signal, and "0" is given as the determination result for the divided section. If the count value in one divided section is 8 or more and 29 or less, it is determined that the divided section of the input video signal includes the copy guard signal, and "1" is given as the determination result for the divided section. If the count value in one divided section is 30 or more, it is determined that the divided section of the input video signal contains many noises, and "2" is given as the determination result for the divided section.

Further, in the decision circuit 421, the decision result of each divided section is referred to, and as described above, the copy guard signal is inserted into at least 5 consecutive horizontal sections in the vertical blanking section. With that in mind,
It is determined whether or not the determination result is "1" in a plurality of continuous two or more divided sections. Then, when the determination result is "1" in a plurality of continuous divided sections, it is determined that the copy guard signal is present in the input video signal, and the output DA is set to the high level. Further, when there is no divided section in which the determination result is "1", or when there are continuous sections that do not exist, it is determined that there is no copy guard signal in the input video signal, and the output DA is set to low level. ..

For example, as shown in FIG. 2A, when the copy guard signal is inserted from the 13th horizontal section to the 18th horizontal section, the determination result is "1" in the continuous divided sections Lb and Lc. Therefore, the output DA of the copy guard signal insertion section synchronization detection circuit 4 becomes high level.

This example does not determine whether or not the copy guard signal is inserted in one horizontal section, but counts the sync signal and the pseudo sync pulse of the copy guard signal included in a plurality of horizontal sections. , And whether or not there is a copy guard signal. Therefore, since it is possible to make a determination including the horizontal synchronization pulse, the reference horizontal synchronization signal as in the example of FIG. 1 is not required, and the determination timing can be set easily.

Next, an example of use of the copy prevention processing presence / absence detection apparatus 100 of FIG. 5 described above will be described. The use example of FIG. 9 is applied to a so-called double deck VTR system having a function of combining two VTRs.

That is, reference numeral 11 is a first VTR unit, which is compatible with, for example, the so-called VHS system. Reference numeral 21 denotes a second VTR section, which is compatible with, for example, an 8 mm video.

Reference numeral 31 denotes a mode switching signal generating circuit, to which the operation input decoding signal from the operation input decoding circuit 33 is supplied. The operation input decoding circuit 33 is supplied with a remote control signal from the commander 34 for remote control and a key input operation signal from the key input operation section 35. Therefore, the mode switching signal generation circuit 3
From 1 are obtained various mode switching signals for setting the mode according to the remote control input from the commander 34 or the key input operation at the key input operation section 35.

An output video signal of the first VTR section 11,
The output video signal of the second VTR section 21 is supplied to one and the other input ends a and b of the switch circuit 30.
The switch circuit 30 is selectively switched to one of the input terminals a and b by the switching signal SW from the mode switching signal generation circuit 31, and one output of the first VTR section 11 or the second VTR section 21. The video signal is obtained from this switch circuit 30. And this switch circuit 3
The video signal obtained from 0 is output to the monitor output terminal 32. This monitor output terminal 32 has a monitor T
The video input terminal of the V receiver is connected.

12 and 22 are input select circuits for the first and second VTR units 11 and 21. The video signal from the tuner 36, the external input video signal from the line input terminal 37, and the output video signal of the second VTR unit 21 are input to the input select circuit 12. Further, the input select circuit 22 includes a tuner 3
6, the video signal from the external input video signal from the line input terminal 37, and the output video signal from the first VTR unit 11 are input. 38 is a TV antenna.

The input select circuits 12 and 22 are brought into the input selected state according to the mode set by the select signal from the mode switching signal generating circuit 31.

The output signals of the input select circuits 12 and 22 pass through the copy guard corresponding processing circuits 13 and 23 corresponding to the circuit 8 in the example of FIG. 1 described above, respectively, and the recording system of the first VTR unit 11 and the output signals. 2 VTR section 21
Input to the recording system of. In the case of this example, a muting process is performed as the copy guard handling process.

The output video signals of the input select circuits 12 and 22 are also supplied to the presence / absence detection circuits 14 and 24 of the anti-duplication processing having the configuration shown in FIG. 1 as an example of the present invention. Therefore, the input select circuit 12,
When the video signal from 22 is copy guarded, it is detected by the detection circuits 14 and 24, and the detection output DET is used by the corresponding processing circuits 13 and 23 to cope with copy guard such as muting described above. Processing is performed. Then, the video signal subjected to the copy guard corresponding processing is supplied to the recording system of the VTR units 11 and 21. Therefore, the copy guard works effectively. That is, the video signals from the input select circuits 12 and 22 are muted and are not supplied to the VTR units 11 and 21 and cannot be dubbed.

In the double deck VTR system having the above configuration, the first VTR section 11 is set to the reproduction state and the second VTR section 11 is set to the second state.
When the so-called dubbing is performed with the VTR unit 21 in the recording state, or when the second VTR unit 21 is in the reproducing state and the first VTR unit 11 is in the recording state and dubbing is performed, an external VTR is used. In either case of supplying the video signal obtained by reproduction to the line input terminal and performing dubbing for recording in the first VTR section 11 or the second VTR section 21, the reproduction video signal is obtained. The detection circuit 14, 2 determines whether or not the copy guard is applied.
In 4 it is possible to detect reliably and accurately. Then, based on the detected output, copy guard corresponding processing such as muting, recording level attenuation, recording stoppage, and digital mosaic processing is appropriately performed.

Then, whether or not the video signal is subjected to the anti-duplication process is detected only by detecting the presence of the pseudo sync pulse in the vertical blanking section, and the number of sync pulses in the video section section is also checked. Then, the pseudo sync pulse in the vertical blanking interval of the video signal becomes V
Since it is detected whether or not the noise is generated at the time of variable speed reproduction of TR, the presence or absence of the copy prevention processing can be accurately detected.

In the double deck VTR system of the above example, the presence / absence detection circuit and the copy guard correspondence processing circuit of the copy prevention processing are provided at the input stage of the recording system of each VTR section. An anti-duplication detection circuit and a copy guard processing circuit are provided in the output stage, and when the dubbing is performed between the first VTR section and the second VTR section, the VTR section side that is in a reproduction state is prevented. The processing presence / absence detection circuit may be made operable.

The above example is an example in which a pair of a pseudo sync pulse and a positive pulse is inserted as a copy guard signal in the vertical blanking interval to perform copy protection processing on a video signal. The target anti-duplication process is not limited to this, and can be applied as long as it includes pseudo sync pulses in successive horizontal intervals in the vertical blanking interval.

[0064]

As described above, according to the present invention, by detecting the presence of the pseudo sync pulse for the copy guard inserted in the vertical blanking interval, the duplication prevention signal is detected in the video signal. Whether it is inserted,
That is, since it is detected whether or not the anti-duplication process is applied, the detection output can be used to perform an appropriate anti-duplication process on the video signal and the audio signal accompanying it.

In addition, in the present invention, the copy guard signal is normally inserted continuously in a plurality of horizontal intervals in the vertical blanking interval, so that the copy guard signal is continuously inserted in successive horizontal intervals in the vertical blanking interval. Then, when it is determined that the copy guard signal is inserted, or for each section having a length shorter than the length of the minimum continuous insertion section of the copy guard signal, it is determined whether or not the copy guard signal is inserted, When the copy guard signal insertion is detected in the continuous section, it is determined that the input video signal is copy guarded. Therefore, it is possible to accurately detect whether or not the input video signal is copy guarded.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a detection apparatus for carrying out an example of a method for detecting the presence or absence of a copy protection signal according to the present invention.

FIG. 2 is a diagram for explaining the operation of the example of FIG.

FIG. 3 is a diagram for explaining the operation of the example of FIG.

FIG. 4 is a diagram for explaining the operation of another example of the method of the present invention.

FIG. 5 is a block diagram of an embodiment of an apparatus for detecting the presence / absence of copy protection processing to which the method of the present invention is applied.

FIG. 6 is a diagram for explaining the operation of the example of FIG.

FIG. 7 is a block diagram of an embodiment of a detection circuit for carrying out another example of the presence / absence detection method of the copy protection signal according to the present invention.

8 is a diagram for explaining the operation of the example in FIG. 7. FIG.

FIG. 9 is a block diagram of an example of use of the copy prevention processing presence / absence detection apparatus according to the present invention.

FIG. 10 is a video signal waveform diagram for explaining an example of a signal for anti-duplication processing.

[Explanation of symbols]

 2 Sync separation circuit 3 Judgment section signal generation circuit 4 Copy guard signal insertion part synchronization detection circuit 5 Video part synchronization detection circuit 6 AND circuit 7 Time constant circuit 8 Copy guard compatible processing circuit 9 Warning circuit 13 Copy guard compatible processing circuit 14 Copy protection Processing presence / absence detection circuit 23 Copy guard correspondence processing circuit 24 Duplication prevention processing presence / absence detection circuit 407, 415 Counter 406, 416 Timing signal generation circuit 409, 421 Judgment circuit Pa, Pb, Pc, Pd Division section

Claims (1)

[Claims] 1. The presence / absence of an anti-duplication signal in the video signal by detecting a plurality of pseudo sync pulses inserted for anti-duplication in a plurality of consecutive horizontal intervals within a vertical blanking interval of the video signal. A vertical blanking interval of the video signal is divided into a plurality of intervals having a shorter interval width than a plurality of continuous horizontal intervals in which the pseudo sync pulse is inserted, and A method for detecting the presence / absence of an anti-duplication signal, wherein the anti-duplication signal is detected to be present in the video signal when the pseudo sync pulse is detected.