JPH1127695A - Copy preventing method and video signal output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a video signal not modulated from being copied by changing a plurality of color difference signals or color vectors of the color difference signals in the unit of fields regularly or irregularly and superimposing a discrimination signal denoting replacement of two color difference signals onto a horizontal synchronizing signal within a blanking period of a luminance signal. SOLUTION: A switch circuit 1 replaces color difference signals; for example, received color difference signals U, V are outputted as color difference signals V, U. The replacement of the color difference signals may be conducted regularly such as every field or at an interval of two fields or irregularly. A discrimination signal generating circuit 4 informed of a fact of replacement by a switching control signal generates a replacement discrimination signal denoting that the 1st and 2nd color difference signals are replaced with each other and gives the signal to a signal superimposing circuit 5. The signal superimposing circuit 5 superimposes the replacement discrimination signal on a horizontal synchronizing signal of the received Y signal for a blanking period of the Y signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a copy protection method,
The present invention also relates to a video signal output device that outputs a video signal to which a copy guard signal has been added so that copying is not possible.

[0002]

2. Description of the Related Art With the recent spread of magnetic recording / reproducing apparatuses (VTRs), it is extremely important to protect the copyright of video sources. For this reason, a copy guard signal is added to some software packages such as video,
The image is distorted when copying by.
Some digital broadcast receivers add a copy guard signal to a received video signal and output it.

On the other hand, with the recent advance in digital video signal compression / decompression technology, devices for handling digital video have been rapidly spreading. Since the compression / expansion technique processes a color difference signal, it is easy to output a higher quality color difference signal than conventional analog video equipment. Therefore, it is necessary to add a copy guard signal to prevent copying.

[0004]

However, the conventional copy guard signal is basically added to a carrier signal on which a chrominance signal is modulated, and is applied to a non-modulated chrominance signal. A copy guard signal could not be added. That is, there is a problem that an optimum copy guard signal does not exist for the unmodulated color difference signal and primary color signal, and these signals are easily copied.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a copy protection method capable of preventing copying of an unmodulated video signal, and a copy protection method for an unmodulated video signal. It is an object to provide a video signal output device to which a signal can be added.

[0006]

According to the present invention, there is provided a copy protection method for preventing a video signal composed of a luminance signal and two color difference signals from being copied. In the above, the two color difference signals are replaced regularly or irregularly in a field unit, or the color vectors of the two color difference signals are changed regularly or irregularly in a field unit, and the vertical return of the luminance signal is performed. A copy protection method is provided, wherein a determination signal indicating that the two color difference signals have been exchanged or a color vector of the two color difference signals has been changed is superimposed on a horizontal synchronization signal within a line erasing period. (2) In a video signal output device that outputs a video signal including a luminance signal and two color difference signals, the two color difference signals are regularly output in units of fields. Means for changing the color vectors of the two color difference signals regularly or irregularly on a field basis, and a horizontal synchronizing signal within a vertical blanking period of the luminance signal. A video signal output device comprising: means for superposing a determination signal indicating that two color difference signals have been exchanged or that the color vectors of the two color difference signals have been changed; (3) In a copy protection method for preventing copying of a video signal composed of three primary color signals, two color signals of the three primary color signals are replaced regularly or irregularly in a field unit, or the two color signals are replaced. The color vector of the signal is changed regularly or irregularly on a field-by-field basis, and horizontal synchronization of at least one of the three primary color signals within a vertical blanking period is performed. (4) providing a copy protection method characterized by superimposing a discrimination signal indicating that the two color signals have been exchanged or that the color vectors of the two color signals have been changed. In a video signal output device for outputting a video signal composed of signals, two color signals of the three primary color signals are replaced regularly or irregularly in field units, or a color vector of the two color signals is changed. Means for changing the color signals regularly or irregularly in field units, and replacing the two color signals with a horizontal synchronization signal in a vertical blanking period of at least one of the three primary color signals; or Means for superimposing a discrimination signal indicating that the color vectors of the two color signals have been changed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A copy protection method and a video signal output device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an example of a configuration for realizing a copy protection method according to the present invention. FIG. 2 is a block diagram showing an embodiment of a video signal output device according to the present invention. FIG. 4 is a waveform diagram for explaining a signal output device.

In FIG. 1, a switch circuit 1 includes a first
And the second color difference signal are input. The first color difference signal is, for example, a signal of U, Pb, and Cb. The second color difference signal is, for example, a signal of V, Pr, and Cr. That is, in the switch circuit 1, one set of U and V, P
One set of color difference signals b and Pr and one set of color difference signals Cb and Cr are input.

The first color difference signal is branched to terminals a and d.
, And the second color difference signal is branched to terminals b and c.
Is input to The switch circuit 1 has switches 1A and 1B, and the switches 1A and 1B are connected to terminals a and c or terminals b and d.
Connect to one of Switches 1A and 1B are connected to terminals a,
c, the input first and second color difference signals are output as they are. When the switches 1A and 1B are connected to the terminals b and d, the input first and second color difference signals are , And the signals are interchanged and output. That is, the switch circuit 1 operates as a switching unit that switches the two input color difference signals.

The luminance (Y) signal is input to a synchronization detection circuit 2 and a signal superposition circuit 5. The synchronization detection circuit 2 generates a horizontal synchronization signal and a vertical synchronization signal from the Y signal,
To enter. The control circuit 3 supplies a switching control signal for switching the switches 1A and 1B of the switch circuit 1 to a vertical blanking period (VBI) obtained from the horizontal synchronization signal and the vertical synchronization signal.
And is supplied to the switch circuit 1. The control circuit 3 also outputs a switching control signal to the determination signal generation circuit 4.
To supply. The switching control signal is, for example, an H level signal when switching is performed, and an L level signal when switching is not performed. Note that the switching control signal input to the switch circuit 1 and the switching control signal input to the discrimination signal generation circuit 4 are:
The same signal or different signals may be used. Also, if the timings of both are within the VBI of the same field,
The timing may or may not be the same.

[0011] The discrimination signal generation circuit 4 generates an exchange discrimination signal indicating that the first and second color difference signals have been exchanged, and inputs the signal to the signal superimposition circuit 5 when the switching is performed by the switching control signal. . The signal superimposition circuit 5 receives the input Y
The switching determination signal is superimposed on the signal at the timing of the horizontal synchronization signal in VBI. The replacement determination signal is a horizontal synchronization signal having a much larger amplitude value, for example, about 100 IRE, than the amplitude value 40 IRE of a normal horizontal synchronization signal. That is, the replacement determination signal generated by the determination signal generation circuit 4 may be a signal for setting the amplitude value of the horizontal synchronization signal to, for example, about 100 IRE as a result.

In FIG. 2, (A) shows a Y signal when two input color difference signals are not exchanged, and (B) shows a Y signal when two input color difference signals are exchanged. . As shown in FIG. 2A, when the two color difference signals are not exchanged, no exchange determination signal is superimposed on the horizontal synchronization signal in VBI, and the amplitude value of the horizontal synchronization signal is a normal 40 IRE. It is. As shown in FIG. 2B, when two color difference signals are exchanged, V
The replacement determination signal is superimposed on at least one horizontal synchronization signal in BI, and the amplitude value of the horizontal synchronization signal is, for example, 1
00IRE.

As described above, when the color difference signals U and V are inputted by the exchange of the color difference signals by the switch circuit 1, the color difference signals V and U or the color difference signals Pb and P are used.
When r is input, the signals are output as color difference signals Pr and Pb, and when the color difference signals Cb and Cr are input, they are output as color difference signals Cr and Cb. The replacement of the color difference signals may be regular such as every one field or every two fields, or may be irregular. In other words, it is sufficient if it is a field unit. Even if it is irregular, the presence or absence of the replacement can be identified by the presence of the replacement determination signal.

If the video signal output from the video signal output device shown in FIG. 1 is displayed as it is on a display means such as a cathode ray tube, the quality of the video is significantly impaired. However, a display device such as a television receiver detects the replacement determination signal and restores the two color difference signals, whereby the image can be displayed without disturbing the image quality.

In a recording apparatus such as a VTR, if the horizontal synchronizing signal exceeds a certain level, it is difficult to record a video signal due to a dynamic range. Therefore, it is impossible to record the Y signal on which the replacement determination signal is superimposed, and even if the Y signal can be recorded, the replacement determination signal disappears. Therefore, the two color difference signals are returned to the normal state. It becomes impossible. Thereby, copying of the video signal can be prevented.

In this embodiment, an example in which two color difference signals are exchanged has been described, but a method of changing a color vector by changing the amplitude of the color difference signal is also effective. Further, the present invention is also applicable to three primary color signals of R, G, and B. In the case of the three primary color signals of R, G, and B, two predetermined color signals among the three primary color signals may be replaced or the color vector may be changed. The replacement determination signal may be superimposed on at least one of the three color signals (for example, the remaining one color signal).

[0017]

As described in detail above, the copy protection method and the video signal output device of the present invention can be used to replace two color difference signals regularly or irregularly in field units, or to change the two color difference signals. The color vector of a signal is changed regularly or irregularly on a field basis, and two color difference signals are replaced with a horizontal synchronization signal within a vertical blanking period of a luminance signal, or the color vector of two color difference signals Are superimposed, and two color signals of the three primary color signals are regularly or irregularly replaced in units of fields, or the color vectors of the two color signals are changed. The two color signals are changed to a horizontal synchronizing signal within a vertical blanking period of at least one of the three primary color signals, which is changed regularly or irregularly in field units. Since the discrimination signal indicating that the color vector has been changed or the color vector of the two color signals has been changed is superimposed, it is possible to prevent copying of the unmodulated video signal, A copy guard signal can be added to the signal.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example configuration for realizing a copy protection method according to the present invention, and is a block diagram illustrating an embodiment of a video signal output device according to the present invention.

FIG. 2 is a waveform diagram illustrating a copy protection method and a video signal output device according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 switch circuit 2 synchronization detection circuit 3 control circuit 4 determination signal generation circuit 5 signal superposition circuit

Claims (4)

[Claims] 1. A copy protection method for preventing a video signal consisting of a luminance signal and two color difference signals from being copied, wherein the two color difference signals are replaced regularly or irregularly in field units, or The color vectors of the two color difference signals are changed regularly or irregularly on a field basis, and a horizontal synchronization signal in a vertical blanking period of the luminance signal is
A copy protection method comprising superposing a discrimination signal indicating that the two color difference signals have been exchanged or that the color vectors of the two color difference signals have been changed. 2. A video signal output device for outputting a video signal composed of a luminance signal and two color difference signals, wherein said two color difference signals are replaced regularly or irregularly in a field unit, or Means for changing the color vector of the color difference signal regularly or irregularly in field units; and a horizontal synchronizing signal within a vertical blanking period of the luminance signal,
A video signal output device comprising: means for superposing a discrimination signal indicating that the two color difference signals have been exchanged or that the color vectors of the two color difference signals have been changed. 3. A copy protection method for preventing copying of a video signal composed of three primary color signals, wherein two color signals of the three primary color signals are replaced regularly or irregularly in field units, or Changing the color vectors of the two color signals regularly or irregularly on a field basis; and adding the two color signals to the horizontal synchronization signal within the vertical blanking period of at least one of the three primary color signals. A copy protection method characterized by superimposing a determination signal indicating that color signals have been exchanged or that the color vectors of the two color signals have been changed. 4. A video signal output device for outputting a video signal composed of three primary color signals, wherein two of the three primary color signals are replaced regularly or irregularly in a field unit, or Means for changing the color vectors of the three color signals regularly or irregularly on a field basis; and applying the two colors to a horizontal synchronizing signal within a vertical blanking period of at least one of the three primary color signals. Means for superposing a determination signal indicating that the signals have been exchanged or that the color vectors of the two color signals have been changed.