JPH0983936A - Video recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent unauthorized dubbing of a video information by allowing only the video recording and reproducing device recorded the video signal on a recording medium to be able to obtain a normal reproduced video signal from the recorded medium concerning the video recording and reproducing device. SOLUTION: Plural groups of scanning lines to be delayed and each delay time of them are decided by mans of a random number generated by a random number generator 5 in synchronism with the vertical synchronizing signal of the video signal to be recorded and ID information specific to the device of an ID memory 9. Based on the decision a 1H memory 11 records the video signal in the recording medium by inserting the random number in the vertical blanking period of the successively delayed video signal. At the time of reproducing, the plural groups of the scanning lines to be delayed and each delay time of them are decided by the random number separated from the reproduced video signal and ID information specific to the device and the 1H memory 11 delays the reproduced video signal based on the decision to restore to the original video signal before recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video recording / reproducing apparatus for inhibiting illegal copying of video signals.
Only in the video recording / reproducing apparatus in which the video signal is recorded on the recording medium, the normal video signal can be obtained from the recording medium.

[0002]

2. Description of the Related Art In the conventional VTR copy guard technology, copyright infringement caused by copying a large amount of sold video tapes or rented video tapes is regarded as a problem, and the image quality is significantly deteriorated during copying. Various recording methods have been proposed. This representative is the well-known macrovision method (Japanese Patent Laid-Open No. 63-107281), which is used for copying when a special signal is superimposed on a part of the video signal.
Copying is prevented by erroneously operating the C circuit and significantly degrading the image quality.

Further, in order to prevent the video tape from being rented out, it is necessary to provide a means for limiting the VTR which can record a program and a means for preventing the recorded video tape from being normally reproduced by another VTR. Of these, you can record VT
The means for limiting the R can be realized by directly connecting the scrambler used in pay broadcasting and the VTR so that the video signal output to the outside cannot be recorded by the macrovision method.

A means for preventing the recorded video tape from being normally reproduced on another VTR is that each VTR has unique information (hereinafter abbreviated as ID), and a modification according to the ID is applied to the video signal at the time of recording. , Can be realized by restoring the video by performing the reverse operation according to the ID during reproduction. I
If the deformation is performed only by D, the deformation pattern becomes constant and restoration by an illegal means becomes easy. Therefore, a random number is generated and deformed by using the random number and the ID, and the random number is recorded in the vertical blanking period to reproduce it. A method of restoring using the read random number and ID is used. In any case, if the data is reproduced by other than the recorded VTR, the normal reproduction cannot be performed because the ID information necessary for restoring the video signal is not provided, and as a result, the lending of the video tape can be prevented.

As a method of using this ID information and a random number, a method disclosed in Japanese Patent Laid-Open No. 61-201586 is considered. This method is shown in FIG.

In FIG. 4, during recording, a video signal is input from an input terminal 21 to a synchronizing circuit 23 via a switch 22, and the synchronizing circuit 23 sends a timing signal corresponding to the synchronizing signal of the video signal to a control circuit 24 and a random number generator. Output to 25. The random number generator 25 generates a random number in synchronization with the vertical synchronizing signal, and outputs it to the adder 28 via the encoder 26 and the switch 27. The encoder 26 superimposes the signal obtained by modulating the random number on the vertical blanking period of the input video signal in synchronization with the timing signal from the synchronizing circuit 23, and the input video signal on which the random number information is superposed is passed through the switch 30 to the memory circuit 31. Output to. The 29 ID memories are device-specific I
D is stored, the adder 28 adds the ID and the random number to generate scramble information, and outputs the scramble information to the control circuit 24.
The control circuit 24 sets the memory circuit 31 according to the scramble information at a predetermined time point before the start of the effective scanning line period.
Of the horizontal scanning period as a unit, and the delay time is returned to the original value after the end of the effective scanning line period. The video signal delayed by the operation of the control circuit 24 in the memory circuit 31 is input to the recording circuit 33 via the switch 32 and recorded on the video tape.

During reproduction, the reproduction video signal output from the reproduction circuit 34 is input to the decoder 35, the synchronization circuit 23 via the switch 22, and the memory circuit 31 via the switch 30. The decoder 35 reproduces the random number information superimposed in the vertical blanking period of the reproduced video signal in synchronization with the timing signal from the synchronizing circuit 23, and outputs it to the adder 28 via the switch 27. The adder 28 is ID
And a random number are added to generate scramble information, which is output to the control circuit 24. At a predetermined time point before the start of the effective scanning line period, the control circuit 24 adjusts the delay time of the memory circuit 31 in the direction opposite to the recording direction in units of the horizontal scanning cycle according to the scramble information, and delays after the end of the effective scanning line period. Reset the time to its original value. Control circuit 2 with memory circuit 31
The video signal delayed according to the operation of 4 is output from the output terminal 36 via the switch 32.

[0008]

However, the above-mentioned conventional structure has a drawback that the cost of the apparatus is increased because a large capacity memory is required. That is, although the vertical synchronization is disturbed to cause so-called V-dancing to display an abnormal screen, the V-dancing amount must be increased to obtain a sufficient effect, and for that purpose, a large-capacity memory circuit is required. 31 must be built in.

The present invention solves the above-mentioned conventional problems, and an object thereof is to realize a sufficient lending prevention effect with a small capacity memory.

[0010]

In order to achieve the above object, the video recording / reproducing apparatus of the present invention generates a random number in synchronization with a vertical synchronizing signal of a video signal to be recorded at the time of recording, and the random number is generated. Is inserted in the vertical blanking period of the video signal to be recorded, and the random number and a predetermined value peculiar to the device are calculated based on a predetermined calculation formula, and according to the calculated value. A horizontal scanning line group to be delayed and a delay time of the video signal are determined, and a predetermined horizontal scanning line group of the video signal is selectively and sequentially delayed based on the determination, and then the video signal is recorded on a recording medium. At the time of recording and reproducing, the random number separated from the reproduced video signal and the value peculiar to the device are calculated based on the calculation formula, and the horizontal scanning line to delay the reproduced video signal according to the calculated value. Determining the group and the delay time, sequentially brought delays a predetermined horizontal scanning line groups of the reproduced video signal based on the determination, and has a structure to be restored to the original recording the video signal before.

[0011]

In the image recording apparatus of the present invention, the scanning line group specified by using the random number and the ID unique to the apparatus is delayed on the recording medium by the delay amount specified by the random number and the unique ID. The recording medium has the same ID for recording.
Although an image recording / reproducing apparatus having the above can correct the added skew, an apparatus having a different ID will output an image that is skewed and is unattractive, so that the lending of the video tape can be prevented.

[0012]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is an input terminal,
2, 7, 10, 12 are switches, 3 is a synchronization circuit, 4 is a control circuit, 5 is a random number generator, 6 is an encoder, 8 is an adder, 9 is an ID memory, 11 is a 1H memory, 13 is a recording circuit, Reference numeral 14 is a reproducing circuit, 15 is a decoder, and 16 is an output terminal.

With respect to the video recording / reproducing apparatus configured as described above, the operation at the time of recording will be described first. During recording, all the four switches 2, 7, 10, 12 are tilted to the R side, and the video signal is input from the input terminal 1 to the encoder 6 and the synchronizing circuit 3 via the switch 2. The synchronizing circuit 3 outputs a timing signal corresponding to the synchronizing signal of the video signal to the control circuit 4 and the random number generator 5. The random number generator 5 generates a 22-bit long random number in synchronization with the vertical synchronizing signal, and outputs it to the adder 8 via the encoder 6 and the switch 7.
The encoder 6 adds 10 bits of check bits for error correction to a random number of 22 bits to make it 32 bits long and then modulates it, synchronizing with the timing signal from the synchronizing circuit 3 and vertically blanking period of the input video signal. Superimpose on. I of 9
The D memory stores a 22-bit long ID, and the adder 8 performs an exclusive OR operation for each bit of the 22-bit long ID and the 22-bit long random number, and outputs the 22-bit long operation result to the control circuit. Output to 4. The control circuit 4 decomposes the 22-bit data into one 2-bit data and four 5-bit data, and the operation pattern of the delay time with the 2-bit data is shown in Table 1.
, The four 5-bit data respectively indicate the position of the operation line group for performing the delay operation.

[0014]

[Table 1]

For example, if the n-th 5-bit data value out of the four 5-bit data is m, then 64 + 32 × (n
-1) Perform a delay operation from the + m line. The line group in which the delay operation may start is n is an integer from 1 to 4,
Since m is an integer from 0 to 31, the horizontal scanning line specified is 64H to 191H, which is an effective scanning line 20.
Although it is biased upward from the center of the range from H to 262H,
In TV programs, the eyes are concentrated because the faces of the characters are located in this range, and due to the nature of the skew that draws a downward tail on the screen, it is effective to block the object slightly above the center of the screen. Target.

In Table 1, t1, t2, t3, and t4 indicate delay times of four scanning line groups to be delay-operated, which are defined by four 5-bit data. That is,
When the 2-bit data is 00, the delay time t1 of the first scanning line group is 0.2H, the delay time t2 of the second scanning line group is 0.2H, and the delay time t2 of the third scanning line group is Delay time t
3 indicates 0.3H, and the delay time t4 of the fourth scanning line group is 0.3H.

In the above embodiment, the scanning line groups to be delayed are four groups, but other numbers may be used, and the arithmetic expressions for determining the groups may be located above the center of the screen except 64H to 191H. Almost the same effect can be obtained if it is skewed to generate skew.

The input video signal on which the random number information is superimposed by the encoder 6 is input to the 1H memory 11 via the switch 10. The video signal delayed by the operation of the control circuit 4 in the 1H memory 11 is passed through the switch 12 to the recording circuit 1
3 and is recorded on a video tape. The delay operation in the 1H memory 11 will be described in detail later.

Next, the operation during reproduction will be described. 4 during playback
All the switches 2, 7, 10, 12 are tilted to the P side, and the reproduced video signal output from the reproducing circuit 14 is input to the 1H memory 11 via the switch 10 and the 1H memory according to the operation of the control circuit 4. The reproduced video signal delayed by 11 is input to the decoder 15 via the switch 12 and to the synchronizing circuit 3 via the switch 12 and the switch 2. The synchronizing circuit 3 outputs a timing signal corresponding to the synchronizing signal of the video signal to the control circuit 4 and the decoder 15. The decoder 15 reproduces the 32-bit length data superimposed in the vertical blanking period of the reproduced video signal in synchronization with the timing signal from the synchronizing circuit 3 and performs error correction 22.
The bit-length data is output to the adder 8 via the switch 7.

The adder 8 performs an exclusive OR operation for each bit of the 22-bit length ID stored in the ID memory 9 and the 22-bit length data read by the decoder, and outputs the 22-bit length operation result to the control circuit 4. Output to. Control circuit is 2
The 2-bit data is divided into one 2-bit data and four 5-bit data, and the operation pattern of the delay time is specified by the 2-bit data and the position of the scanning line group on which the 5-bit data is operated is specified. Correspondence between the data and the delay time or the position of the scanning line group is matched at the time of recording, and the extra delay time inserted at the time of recording is removed.

The information used for the operation at the time of recording is an ID and a random number. If the same information is obtained at the time of reproduction, the original video signal can be restored by performing the operation reverse to that at the time of recording, but the random number is recorded via the encoder. The ID is recorded and reproduced through the decoder, whereas the ID is neither recorded nor reproduced. ID
There are 2 to the 22nd power combinations, and each unit has different I
Since it has D, other than the device used for recording, that is,
A normal reproduced image cannot be obtained unless the ID memory of the device used for recording is read.

2 and 3 in addition to FIG. 1 will be used for explaining the delay operation performed in the line memory in detail. FIG. 2A shows the input and output of the 1H memory operated during recording. The control circuit 4 resets the delay time to 0H every V synchronization. When the delay time is increased from 0H to 0.3H at the position of the front porch of the first line to be delayed, the horizontal synchronizing signal is output after the copy of the immediately preceding 0.3H video signal is output. FIG.
(B) shows another operation example at the time of recording. The delay time is changed from 0H to 0.3H after 0.3H from the position of the front porch.
When it is increased to H, the video signal from the position of the front porch is output again, and the H synchronization becomes continuous. One of the points of operation during recording is to place the seam of the doubled part and the part that follows it in front of the horizontal sync signal.
This consideration is necessary to maintain the relative time relationship between the horizontal sync signal and the video signal. The other is to operate to increase the delay time without fail. If the delay time is reduced, a part of the 1H memory is skipped without being read, and the image cannot be restored.
When the operation to insert the skew is performed several times, the operation in the direction of increasing the delay time is repeated. Therefore, when the sum of the operated delay times reaches the maximum delay time of the memory, the new skew cannot be inserted. In the case of the present embodiment using, the delay time is 0H → t1 → (t1 + t2) → (t
1 + t2 + t3) → (t1 + t2 + t3 + t4 = 1H)
And change.

Next, the operation during reproduction will be described. As a premise, it is assumed that the self-recording reproduction is performed by the same device used for recording. FIG. 3 is a waveform diagram for explaining the operation of the line memory during reproduction. The control circuit 4 resets the delay time to 1H for each V synchronization. When the delay time is reduced from 1H to 0.7H at the position corresponding to the front porch of the first line group to be operated, the video signal of 0.3H immediately after is skipped and the horizontal synchronizing signal is output following the front porch. . 3A and 3B are respectively shown in FIG.
It is an explanatory view of the processing at the time of reproduction corresponding to the explanatory view of the processing at the time of recording of (a) and (b), but in both cases, since the repeated portion due to the increase of the delay time is skipped at the time of reproduction, it is normal. There is no difference in the output of the horizontal synchronizing part when reproduced at. The delay time due to the memory at the time of reproduction changes only in the decreasing direction, and in the case of this embodiment using the 1H memory,
The delay time of each line group is 1H → (1H-t1) → (1H
-T1-t2) → (1H-t1-t2-t3) → (1H
-T1-t2-t3-t4 = 0H).

The effect of starting the delay operation at the position of the front porch is that the skew is caused by the horizontal synchronizing pull-in operation of the TV receiver by operating while maintaining the positional relationship between the horizontal synchronizing signal and the video section. Even if it remains, it will not be noticeable. Since the horizontal position on the TV screen is determined by the time relationship with the fall of the H pulse, if a time shift occurs between the fall of H and the video section, it will appear as a video position shift on the screen as it is, and within the video section. When you operate the memory delay time with, there is a possibility that you can see the seam on the screen.

Finally, let us consider a playback video in the case of not self-recording playback. When reproduced by an ordinary device not according to the present invention, the skewed video signal shown in FIG. 2A or 2B is output to the TV, and T
The V horizontal sync circuit attempts to follow changes in the horizontal sync phase. From the scanning line with skew to the PL of the horizontal synchronization circuit
The time until the L operation converges is determined by the amount of skew and the time constant of the PLL, but with a normal TV, it takes several tens of H to pull in a large skew such as 0.2 H, and the image of that part It is a very unsightly screen with undulations. In the embodiment of the present invention, 0.2H to 0.3 is centered on the portion where the line of sight is slightly above the center of the screen.
A large amount of skew corresponding to H is generated at four locations, and the position and size are randomly changed for each field. Therefore, the number of skews visually synthesized on the screen by the afterimage effect is about eight. , The screen is unbearable for viewing. When reproduced by another device according to the present invention, the information regarding the skew is misinterpreted because the ID is different,
Since a phenomenon in which skew is added due to the correction operation occurs, the deterioration of the image quality is larger than that when the image is reproduced by a normal device.

By skewing the image so that it is biased upward from the center of the screen, the line of sight is concentrated because the person's face is located at the top, and the skew disturbance can be increased visually, and the deterioration of image quality is felt to a greater extent. Can be made.

[0027]

As described above, according to the present invention, in the horizontal synchronizing signal portion of a specific scanning line within the effective scanning period, recording is performed through the delay means for increasing the delay time by a specific amount, and at the time of reproduction,
By providing means for reducing the delay time of the delay means by a specific amount in the front porch portion of the horizontal synchronizing signal,
It is possible to realize a video recording / reproducing apparatus capable of generating a sufficient amount of skew with a small capacity of the line memory of about 1H, and having a scramble effect with little image quality deterioration during self-recording / reproduction at low cost.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a video recording / reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a signal waveform diagram in the same embodiment.

FIG. 3 is a signal waveform diagram in the example.

FIG. 4 is a block diagram of a conventional video recording / reproducing apparatus.

[Explanation of symbols]

1, 21 Input terminal 2, 7, 10, 12, 22, 27, 30, 32 Switch 3, 23 Synchronous circuit 4, 24 Control circuit 5, 25 Random number generator 6, 26 Encoder 8, 28 Adder 9, 29 ID Memory 11 1H memory 13, 33 Recording circuit 14, 34 Playback circuit 15, 35 Decoder 16, 36 Output terminal 31 Memory circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H04N 7/167

Claims (2)

[Claims] 1. A random number is generated in synchronization with a vertical synchronizing signal of a video signal to be recorded, the random number is inserted into a vertical blanking period of the video signal to be recorded, and the random number and a predetermined number thereof are set. A value peculiar to the device is calculated based on a predetermined calculation formula, a horizontal scanning line group to be delayed and the delay time of the video signal are determined according to the calculated value, and the video is determined based on the determination. After selectively delaying a predetermined horizontal scanning line group of the signal sequentially, the video signal is recorded on a recording medium, and at the time of reproduction, the random number separated from the reproduced video signal and the value peculiar to the device, A horizontal scanning line group to be delayed and a delay time of the reproduced video signal are determined according to the calculated value, and a predetermined horizontal scanning line group of the reproduced video signal is determined based on the determination. And allowed to sequentially delay, video recording and reproducing apparatus characterized by restoring the original recording the video signal before. 2. The random number and the device-specific value are each a binary signal of a plurality of bits, and a predetermined plurality of bits among a plurality of bits of the operation value determine a horizontal scanning line to be delayed, 2. The video recording / reproducing apparatus according to claim 1, wherein the delay time of the horizontal scanning line to be delayed is determined by other plural bits.