JPH0770147B2 - Digital signal duplication prohibition device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal duplication inhibiting device for inhibiting illegal duplication in a recording / reproducing system of a digitized audio / video signal.

2. Description of the Related Art In recent years, digitization of audio / video signal recording / reproducing systems is progressing rapidly. The popularization of CDs (Compact Discs) and the release of DAT (Digital Audio Tape Recorders) can be said to be remarkable manifestations. However, on the other hand, these digitized sounds /
By using a video signal recording / reproducing system, so-called digital duplication can be easily performed, and there is a risk that a large number of illegal duplications whose quality will not change from the original will be made, so from the standpoint of copyright protection. A problem has been raised. Under such circumstances, a digital signal copy prohibiting device for prohibiting illegal digital copying has become extremely important.

First, with reference to the drawings, the position and function of the above-described digital signal duplication inhibiting device will be described.

FIG. 4a shows a procedure for producing an original copy which has been subjected to copy inhibition processing. The analog signal output from the signal source 20 and to be recorded on the original recording medium is A /
The digital signal is converted into a digital signal by the D converter 21, and information for prohibiting duplication is added by the original processing unit 22 of the digital signal duplication inhibiting device, and then recorded on the original recording medium 24 by the digital recording device 23.

FIG. 4b shows the procedure for making a copy from the original, in which the digital signal recorded on the original 26 which has not been subjected to copy inhibition processing is reproduced by the digital reproducing device 27 and After passing through the copy prohibition unit 28, the digital recording device 29 makes a copy on the copy recording medium 30. However, when attempting to copy from the original 25 that has been subjected to copy prohibition processing, since the digital signal reproduced by the digital reproducing device 27 has the copy prohibition information added thereto, the copy prohibition of the digital signal copy prohibiting device is prohibited. Part 28
As a result, the digital recording device 29 is cut off by no signal, and it is impossible to make a duplicate.

Hereinafter, an example of a conventional digital signal duplication inhibiting device will be described with reference to the drawings.

FIG. 5 shows the structure of a conventional digital signal duplication prohibition apparatus. In FIG. 5, reference numeral 40 is an original processing section signal input terminal, 41 is an identification code generation circuit for generating an identification code including duplication prohibition information. , 42 is a main signal compression circuit, 43 is a mixing circuit connected to the output of the identification code generation circuit 41 and the output of the main signal compression circuit 42, and 44 is an original processing section signal output terminal.
Further, 45 is a signal input terminal of the copy prohibition section, 46 is an identification code reproducing circuit, 47 is a main signal expanding circuit, and 48 is an identification code reproducing circuit.
The gate circuit cuts off the output of the main signal expansion circuit 47 by the output of 46.

The operation of the conventional digital signal copy prohibiting apparatus configured as described above will be described below. Figure 6 shows
FIG. 1 is a diagram showing an example of a block format used in a conventional digital signal duplication prohibition apparatus, in which a main signal which is a digitized audio / video signal is temporally compressed and 256 bits are converted into 32 bits. Redundant data is added. 8 bits out of these 32 bits hold various kinds of auxiliary information called an identification code, and a part of them is information for permitting / prohibiting digital copying.

Therefore, in FIG. 5, when the original is produced, first, the digitized audio / video signal input from the original processing section signal input terminal 40 is temporally compressed by the main signal compression circuit 42, and further mixed by the mixing circuit 43. Is mixed with the identification code including the copy prohibition information generated by the identification code generation circuit 41, and after being formed into a block as shown in FIG. 6, it is output to the original processing section signal output terminal 44 and the original is output. It is recorded on the medium.

Further, during reproduction production, the signal reproduced from the original input to the duplication prohibition signal input terminal 45 is the main signal expansion circuit 47.
Then, the identification code is reproduced by the identification code reproducing circuit 46 so that the copy inhibition information is taken out and added to the control input of the gate circuit 48. If the identification code is in the duplication permitted state, the gate circuit 48 is in the passing state and a signal is output to the duplication prohibition section signal output 49.If the identification code is in the duplication prohibited state, the gate circuit 48 is in the cutoff state. Since the copy prohibition section output 49 is in a non-signal state, copying cannot be performed.

The conventional digital signal duplication prohibition device described above is a DA
It is used as a part of the T standard, and its details are described in "DIGITAL AUDIO TAPERECORDER SYSTEM RECOMMENDED DE" on April 16, 1986, "DAT Recommended Design Standards".
SIGN STANDARD APRIL 16,1986 DAT CONFERENCE).

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned configuration, since the copy inhibition information is added to the auxiliary signal of the system different from the main signal called the identification code, the circuit configuration becomes complicated and only the auxiliary signal system is provided. It is possible to break the copy prohibition relatively easily, and it depends on the recording method and format of the auxiliary signal, and therefore, when the medium is different, for example, from a digital audio disc to a digital There was a problem that it could not be applied when copying to audio tape.

In view of the above problems, the present invention provides a digital signal duplication inhibiting device that inhibits digital duplication without using an auxiliary signal such as an identification code.

Means for Solving the Problems In order to solve the above problems, the digital signal duplication prohibiting apparatus of the present invention comprises a signal section detecting means for detecting a start point of a digital signal to be recorded on an original recording medium. ,
From the starting point of the digital signal detected by the signal section detecting means, the first gate means for fixing the least significant bit of the digital signal to a state of 0 or 1 for every constant number of sample data, Means for generating a state in which sample data whose least significant bit is fixed to 0 or 1 repeatedly appears at a fixed interval in the digital signal recorded on a recording medium, and another recording medium from the original. A signal section detecting means for detecting the start point of the digital signal emitted from the original when performing the duplication,
It is detected that the least significant bit of the sample data forming the digital signal is fixed to 0 or 1.
The 0/1 state detecting means detects, by the 0/1 state detecting means, that the sample data whose least significant bit is fixed to 0 or 1 repeatedly appears at regular intervals in the digital signal read from the original. When the prohibition state detecting means detects that the sample data whose least significant bit is fixed to 0 or 1 repeatedly appears at a fixed interval in the digital signal, the digital signal is cut off. It is provided with a second gate means for prohibiting copying.

Operation According to the present invention, by adopting the above-mentioned configuration, it is possible to add the copy inhibition information to the digital signal itself without deteriorating its quality and using a special auxiliary signal.

Embodiment Hereinafter, a digital signal duplication prohibiting apparatus according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the configuration of a digital signal duplication inhibiting device according to an embodiment of the present invention. In FIG. 1, 1 is an original processing section signal input terminal, 2 is a signal section detection circuit connected to the original processing section signal input terminal, 3 is an amplitude detection circuit connected in parallel to the signal section detection circuit 2, 4 Is a control circuit connected to the output of the signal section detection circuit 2 and the output of the amplitude detection circuit 3, 5 is a first gate circuit for fixing the least significant bit of the signal to 0 under the control of the control circuit 4, and 6 is original processing This is a partial signal output terminal.

Further, 7 is a copy prohibition section signal input terminal, 8 is a signal section detection circuit connected to the copy prohibition section signal input terminal 7, 9 is a zero detection circuit connected to the least significant bit of the signal, and 10 is a signal section detection circuit. A prohibition state detection circuit connected to the output of 8 and the output of the zero detection circuit 9, a second gate circuit 11 connected to the copy prohibition section signal input terminal 7 and controlled by the output of the prohibition state detection circuit 12, Is a signal output terminal for the copy inhibition portion.

The operation of the digital signal duplication prohibiting device configured as described above will be described below. In the present embodiment, the case of application to a DAT that records a music signal sampled at 48 KHz and quantized at 16 bits will be taken up.

First, in the production of an original, a music signal to be recorded on the original is converted into a digital signal and then input from the original processing section signal input terminal 1. The signal section detection circuit 2 has a function of discriminating between a silent section of the input digital signal and a section of the music signal, and the amplitude detection circuit 3 has a function of detecting the magnitude of the amplitude of the input digital signal. Is. Each of these detection signals is input to the control circuit 4, and the operation of the control circuit 4 detects a section in which the music signal is included in the input digital signal and has a large amplitude. Further, the control circuit 4 outputs a control signal for causing the gate circuit 5 to be in the cutoff state and outputting 0 for a time corresponding to 200 sample data in this section. As described above, the original processing section signal output terminal 6 is
For the duration of 200 sampling hours, a signal that has been subjected to copy inhibition processing with its least significant bit fixed to 0 is output and recorded on the original medium. FIG. 2 shows an example of 16-bit data before the copy inhibition process and 16-bit data after the copy inhibition process.

Next, in the copy production, the digital signal reproduced from the original is input from the copy prohibition section signal input terminal 7, and the signal section detection circuit 8 detects the section in which the music signal is present, and at the same time, the lowest level of the digital signal is detected. The zero detection circuit 9 connected to the bit detects a state in which zeros continue in the least significant bit. These detection signals are sent to the prohibition state detection circuit 10, respectively, in the section where there is a music signal,
It is determined whether or not there is a state in which the least significant bit of the digital signal is continuously 0 for 200 sampling times. If such a state exists, the original that you are currently trying to duplicate is
Since the copy inhibition processing has been performed, the gate circuit 11
Is cut off, and only the signal in the silent state is output to the duplication prohibition signal output terminal 12, and duplication is prohibited. FIG. 3 shows a state in which duplication is prohibited when a duplication is illegally produced in a system using the digital signal duplication inhibiting device according to the present embodiment as described above. Copying is prohibited except for a part of the music signal section between the copy prohibition processing sections, and a silent state is recorded on the copy medium.

As described above, according to this embodiment, the least significant bit is reset to 0 for 200 sampling times, that is, about 4 milliseconds only in the section where the amplitude of the digital signal detected by the amplitude detection circuit 3 is large. By doing so, the copy inhibition information can be added to the main signal without impairing the audible quality.

In the present embodiment, the signal interval detection circuits 2 and 8 distinguish between the silent interval and the signal interval in that in the silent interval, the state in which the least significant bit is 0 is 200 sampling time before the prohibition process is performed. This is because there is a possibility that it will continue for a long time. Furthermore, in the music signal section, the probability that the least significant bit is 0 for more than 200 sample times in a section other than the inhibition-processed section is 1/200 of 2 or 10 Since it is less than 1 / 60th power, there is almost no risk of malfunction.

Further, although the case where the least significant bit is fixed to 0 has been shown in this embodiment, there is no problem even if the least significant bit is fixed to 1. Further, the length of the processing section of 200 sample times may be changed as appropriate. Further, the application is not limited to the digital audio field.

EFFECTS OF THE INVENTION As described above, according to the present invention, a signal section detecting unit that detects a starting point of a digital signal to be recorded on an original recording medium, and a starting point of the digital signal detected by the signal section detecting unit. From the first gate means for fixing the least significant bit of the digital signal to the state of 0 or 1 for every fixed number of sample data, the least significant bit is recorded in the digital signal recorded on the original recording medium. Means for generating a state in which sample data whose lower bits are fixed to 0 or 1 repeatedly appear at regular intervals, and the digital data read from the original when the original is copied to another recording medium. A signal section detecting means for detecting the start point of the signal, and detecting that the least significant bit of the sample data constituting the digital signal is fixed to 0 or 1. The 0/1 state detecting means for outputting the least significant bit to 0 in the digital signal read from the original.
Alternatively, a prohibition state detecting means for detecting that the sample data fixed to 1 repeatedly appears at a constant interval, and a sample whose least significant bit is fixed to 0 or 1 in the digital signal by the prohibition state detecting means. A second gate means for blocking the digital signal and prohibiting duplication when it is detected that the data repeatedly appears at a certain interval is eliminated. Also, since the copy prohibition information can be added to the digital signal itself without impairing its quality, the circuit configuration is relatively simple, and it becomes difficult to break the copy prohibition by integrating the circuit into an IC. Further, it is possible to realize an excellent digital signal duplication inhibiting device that does not depend on the recording method or format of the auxiliary signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a digital signal duplication prohibition apparatus according to an embodiment of the present invention, FIG. 2 is a state diagram showing an example of sample data before duplication prohibition processing and after duplication prohibition processing, and FIG. Fig. 4 is a data array diagram showing how copying is prohibited on the medium. Fig. 4 is a block diagram showing the procedure for making an original that has been subjected to copy inhibition processing and the procedure for making a copy from the original. Fig. 5 is a conventional method. FIG. 6 is a block diagram showing the configuration of the digital signal duplication prohibiting device, and FIG. 6 is a data array diagram showing an example of a block format used in the conventional digital signal duplication inhibiting device. 2,8 ... Signal section detection circuit, 3 ... Amplitude detection circuit, 4 ...
… Control circuit, 5 …… Gate circuit, 9 …… Zero detection circuit,
10 …… Inhibited state detection circuit, 11 …… Gate circuit, 41 …… Identification code generation circuit, 42 …… Main signal compression circuit, 43 …… Mixed circuit, 46 …… Identification code reproduction circuit, 47 …… Main signal expansion Circuit, 48 ... Gate circuit.

Claims (1)

[Claims] 1. A signal section detecting means for detecting a starting point of a digital signal to be recorded on an original recording medium, and constant sample data from the starting point of the digital signal detected by the signal section detecting means. By the first gate means for fixing the least significant bit of the digital signal to the state of 0 or 1 for each number, the least significant bit is 0 or 1 in the digital signal recorded on the original recording medium. Means for generating a state in which the sample data fixed to the recording medium repeatedly appears at regular intervals, and detecting the start point of the digital signal read from the original when the original is copied to another recording medium. Signal section detecting means and 0/1 state detecting means for detecting that the least significant bit of the sample data forming the digital signal is fixed to 0 or 1. By means of an inhibition state detection means for detecting that the sample data whose least significant bit is fixed to 0 or 1 repeatedly appears at a fixed interval in the digital signal read from the original, and the inhibition state detection means. When the sample data whose least significant bit is fixed to 0 or 1 repeatedly appears in the digital signal at regular intervals, the digital signal is blocked to prohibit duplication. A digital signal duplication inhibiting device comprising a second gate means.