JPH11232777A - Preventing method for data copy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent effectively copy and transfer of a voice and picture data recorded with a digital signal. SOLUTION: This method is a copy preventing method in a recording medium compressing and recording data and a data processing device compressing data and transferring it between devices. Then, a specific signal α is counted and recorded in original data of a voice or a picture of a medium being a copy origin, when the original is reproduced after compressing once, the specific signal α is emphasized and the reproduced signal is distorted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing copying of audio and image data recorded as digital signals.

[0002]

2. Description of the Related Art A music CD is most suitable as a source sound source in addition to being reproduced and enjoyed because there is no sound deterioration. In recent years, the use of MD has been remarkable, and since there is no sound deterioration similar to CD and the shape is smaller than CD,
Is often copied to an MD and used for going out. It is not illegal for individuals to copy and use them, but illegal activities such as mass-producing copies on MD and selling them without the permission of the copyright holder are increasing.

On the other hand, with the spread of personal computers, the Internet has become popular. For example, when an image such as a photograph or a picture is placed on a homepage on the Internet, the protection is carried out by designating an ID or a password, or by using a watermarking technique to display on the image that the product is a copy. ing. However, even if an ID or password is specified, even if it is illegally copied by a person who knows it, or even if watermark technology is used, the original image itself can be viewed, so it is not completely copy protected. is the current situation.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for more effectively preventing copying of audio and image data recorded by digital signals.

[0005]

First, in the present invention, a more effective copy protection signal suitable for the future technology is considered as a copy protection signal, and the output, time, and frequency of the signal are considered.
As a copy protection signal for preventing copying from a linear digital recording type recording medium (CD, magnetic disk, etc.) for recording original data indicating a reproduced waveform having elements, one waveform having the three elements in the original data is formed. A copy protection signal is formed by incorporating a digital value into the digital signal. That is, the copy protection signal is a digital value that is included in one waveform (one peak) in the waveform of the original data reproduction signal.

As a result, the copy protection signal itself is added as a digital signal having no time and frequency elements, and becomes a signal that acts only on the reproduction output value of the calculation destination data during reproduction. That is, in the case of a music CD, it becomes a signal that distorts the reproduction sound of the waveform of the calculation destination, and does not become audible when the CD containing the original data is reproduced, but is emphasized when compressed and reproduced. It can be audible and can interfere with use as a copy. In order to minimize the effect on the output during the reproduction of the original data, such a copy protection signal should be included after the peak value, preferably after 2 to 5 sampling clocks.

Further, the present invention provides a copy protection method for a recording medium for compressing and recording data such as an MD.
A specific signal is added to the original data and recorded on a copy source medium such as a CD, so that when the original data of the medium is compressed and reproduced, the specific signal is emphasized and the reproduced signal is distorted. Provide a copy protection method.
Alternatively, as a copy protection method in a data processing device such as a personal computer that compresses data and transfers the data between the devices,
A copy protection method in which a specific signal is included in original data of audio or an image as a copy source, and when the original data is once compressed and reproduced, the specific signal is emphasized so that a reproduced signal is distorted. I will provide a. As the specific signal in such a copy protection method, the above-described copy protection signal is optimal.

When the original data is digitally recorded, the specific signal is added or subtracted from 2 to 5 sampling clocks after the peak value of the original data until the data change rate becomes 0 or more. However, this is not the case when the original data is image data, and the specific signal may be added or subtracted to one of two to five pixels around the peak value of the original data.

When the original data is audio data, the specific signal is added or subtracted when the following conditions are satisfied.
That is, when the average value and the change rate of the volume of the audio data have become equal to or higher than the predetermined values. On the other hand, when the original data is image data, the conditions for adding or subtracting the specific signal are as follows. That is, when the average value and the change rate of the brightness of the image data are equal to or more than a predetermined value.

[0010] By including the specific signal under such conditions, when the original data is reproduced, if the original data is voice, the specific signal is input immediately after the volume is increased, so that it is difficult for the human ear to hear the specific signal. In other words, when the original data is an image, it is difficult to distinguish the image because the specific signal enters the vicinity of a place where the original data shines. On the other hand, when reproduced after compression, it is reproduced as a very unpleasant sound, or the image is greatly deformed and cannot be used as a copied product. The effect of this specific signal is maximized when it is added or subtracted from all places in the audio or image data that satisfy the conditions of the average value of the volume and the brightness and the rate of change.

[0011]

Embodiments of the present invention will be described with reference to the accompanying drawings.

In copying from a CD to an MD or transferring data on the Internet, digital compression technology is used to reduce the amount of data to be copied or transferred. The digital compression technique will be described using FIG. 1 as an example of copying from a CD to an MD.

The data recording system of the CD is a linear digital system. When recording is performed by this method, signals in a band or a size that cannot be heard by human ears are faithfully recorded, and the reproduced output thereof is close to a linear waveform. Such a CD
In the case of digitally compressing the data recorded in the data, first, data that becomes weak voice that cannot be heard by human ears is deleted. In the case of FIG. 1, data corresponding to a portion below the dotted line 1 is deleted. Then, data such as MD-1 remains. When this MD-1 data is compressed in the time axis direction, it becomes MD-2 data, and the data compression ends. In the compression process from MD-1 to MD-2, all the portions without signals are deleted, and the signal portions are also compressed in the time axis direction, but not in the volume direction (Y axis direction). Such a compression method is called a peak sampling compression method.

When reproducing MD data compressed by such a peak sampling compression method, the compression process of FIG. 1 is reversed as shown in FIG. First, the data of MD-2 is expanded to become data like MD-1. MD
Data of each peak portion is sampled from the data of -1, and data of a portion below the dotted line 1 deleted at the time of compression is added. As a result, data restoration is completed, and an MD reproduction output is obtained.

The restored waveform shows that the rising edge of the first data starts at time 0, data with a peak below the dotted line 1 has been deleted, and the volume of the MD playback output has been reduced to 0. 3 and 4 in Fig. 2
The waveform differs from that of the CD output in that the time interval of the second peak is narrower.

Here, as shown in FIG. 3, a copy protection signal α is input to the CD output. The copy protection signal α is added or subtracted immediately after the sound volume reaches a peak so that it cannot be heard by human ears, so that it cannot be discriminated from the reproduced sound. FIG.
Here, the data when the copy protection signal α is added is represented by a solid line, and the data when the copy protection signal α is subtracted is represented by a broken line. When this is copied to an MD, the data is digitally compressed and data like MD-2 is digitally recorded.

When the MD-2 signal thus recorded is reproduced, each peak portion is reproduced with emphasis.
The added copy protection signal α is extended like the copy protection signal α ″ of the MD reproduction output. The reproduced sound becomes a sound that is delayed after the volume peaks and becomes very hard to hear. When the protection signal α is subtracted, the copy protection signal α ″ is deleted from the original playback waveform and shortened, so that the playback sound seems to be interrupted immediately after the volume peaks.

By inserting the copy protection signal α into the data a plurality of times, the audio data copied to the MD is completely different from the MD playback sound without the copy protection signal α even when the data is reproduced. And it will not be a copy product.

Next, the case where such a copy protection signal α is included in the image data will be described with reference to FIG. This image data is drawn line by line from top to bottom for simplicity, and one line is drawn from left to right. The division diagrams A and C are images before copying when the copy protection signal α is added and subtracted, respectively. At this point, the image of the copy protection signal α is sufficiently smaller than the rectangular image, and is created near a place where the brightness is strong so as not to be uncomfortable when viewed with the eyes. Here, when the data is reproduced after being once subjected to compression processing by copying or data transfer, the shapes are as shown in FIGS. The copy protection signal α ″ of the divisions B and D is once compressed and then decompressed so that the copy protection signal α is emphasized and enlarged to become the copy protection signal α ″.

As described above, since the image is shifted due to the enlargement of the copy protection signal α, the image subsequent to the copy protection signal α ″ is drawn at a position shifted by the copy protection signal α ″. Because of this, the original rectangular image is transformed into a wedge shape. By placing a large number of such copy protection signals α in an image, a large number of images can be misaligned. As a result, the image data once compressed and copied or transferred can be reproduced. Will be a completely different image.

The user must not realize that the copy protection signal α required for such a copy protection method exists in the original data (CD output in FIG. 3 and divisional diagrams A and C in FIG. 4). The condition and method for inserting the copy protection signal α for that purpose will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 5 shows an input buffer 10 for separating input audio data into three types of signals, a clock signal, an L / R timer signal, and source data, and a peak value and an average value of the volume of the source data. A peak / average value detection circuit 12 input to the CPU 15 and a change rate detection circuit 13 for obtaining a change rate of the volume of the source data and inputting the change rate to the CPU 15
And a clock timer circuit 14 for inputting a clock signal to the CPU 15, and a mixer circuit 16 for delaying source data.
, A CPU 15 that outputs an addition / subtraction command to the mixer circuit 16, a mixer circuit 16 that adds or subtracts the copy protection signal α to or from the source data, and a source data to which the copy protection signal α is added or subtracted. 1 shows an output buffer 18 for outputting, and a RAM 17 for temporarily holding a copy protection signal α input from an input device.

The input audio data is input to an input buffer 10.
The signal is separated into three digital signals of a clock signal, an L / R timer signal, and source data. Clock signal and L /
The R timer signal is sent to the CPU via the clock timer circuit 14.
15 is input. The source data is input to the peak value / average value detection circuit 12 and the change rate detection circuit 13. The source data input to the peak value / average value detection circuit 12 is subjected to D / A conversion to become analog source data. From the analog source data, the peak value of the sound volume and the average value of the sound volume within an arbitrary time are obtained, and the obtained peak value and average value are sent to the CPU 15. The source data input to the change rate detection circuit 13 is also first D / A converted into analog source data. The change rate detection circuit 13 obtains the change rate of the volume of the analog source data within an arbitrary time, and sends the obtained change rate to the CPU 15.

The CPU 15 includes a peak / average value detection circuit 1
2 and whether the average value and the change rate of the source data sent from the change rate detection circuit 13 are larger than the set values, and if they are larger, only when the peak value of the source data at that time is larger than the average value. , An add / subtract instruction is transmitted to the mixer circuit 16, and at the same time, the copy protection signal α input from the RAM 17 is input to the mixer circuit 16. At this time, after the copy protection signal α detects the first peak value after satisfying the conditions of the average value, the change rate, and the peak value of the audio data,
It is input to the mixer circuit 16 after 5 clocks until the volume change rate becomes 0 or more.

The mixer circuit 16 includes a delay circuit 11 and a peak / average value detection circuit 12 (or a change rate detection circuit 13).
+ Source data delayed by the same time as the delay time of the CPU 15 and a copy protection signal α sent from the CPU 15
Is added or subtracted, and the source data processed by the copy protection signal α is output. The source data is output to the outside by the output buffer 18 and recorded on a CD or the like as original data.

The copy protection signal α is input from the input device and temporarily stored in the RAM 17. The stored copy protection signal α is input to the CPU 15 when the RAM 17 is called from the CPU 15. The copy protection signal α input to the CPU 15 is input to the mixer circuit 16 after being synchronized with the source data by the clock signal. The addition and subtraction performed in the mixer circuit 16 are performed according to an equation as shown in FIG. 6, resulting in an output waveform as shown in FIG.

The original audio data thus created is
When reproduced, the result is as shown in FIG. The copy protection signal α adds or subtracts source data when the conditions for addition and subtraction are met, but addition and subtraction are performed on one waveform as shown in FIG.
If there are other places in one packet where the conditions for addition and subtraction are satisfied, the addition and subtraction are performed each time.

The audio data for adding or subtracting the copy protection signal α has a waveform having three elements of volume (output), time, and frequency. The digital signal acts only on the (output value) and has no time and frequency components. When the audio data at the destination is reproduced, the reproduced waveform is distorted. In other words, it is not an independent signal that has three elements of volume, time, and frequency in the original data, as is the case with the reproduction noise of “bottoms,” but a predetermined waveform in the original data without the elements of time and frequency. It is a parasitic signal that is parasitic inside and acts only on its volume. This is the same even if the original data is changed to digital image data.

In the case of an image, the conditions for inserting the copy protection signal α as described above are as follows. First, an average value, a peak value, and a change rate of brightness in an image are obtained. When the calculated average value and the change rate are equal to or greater than a preset value and the peak value is equal to or greater than the average value, a location is determined.
The copy protection signal α is added to or subtracted from the data of the portion of ５5 pixels.

As described above, immediately after the peak of the volume, the copy protection signal α is added or subtracted around the brightness peak of the image, so that the user of the original data does not realize that the copy protection signal α exists. Can be implemented.

[0031]

According to the copy protection method of the present invention, if compression processing is performed when copying or transferring data, the copied or transferred data is completely different from the original data, so that the copied or transferred data can be copied and used. It becomes impossible and illegal copy use can be prevented.

[Brief description of the drawings]

FIG. 1 is a waveform diagram when data is compressed from a CD to an MD and copied.

FIG. 2 is a waveform diagram when data is restored from an MD.

FIG. 3 is a waveform diagram from data copy to restoration when a copy protection signal according to the present invention is added.

FIG. 4 is an explanatory diagram when the present invention is used for image data.

FIG. 5 is a circuit diagram for creating data of the present invention.

FIG. 6 is a data waveform diagram generated by the circuit of FIG. 5;

[Explanation of symbols]

 α, α ′, α ″ copy prevention signal 10 input buffer 11 delay circuit 12 peak / average value detection circuit 13 change rate detection circuit 14 clock timer circuit 15 CPU 16 mixer circuit 17 RAM 18 output buffer

Claims (8)

[Claims] 1. A copy protection signal added to a recording medium of a linear digital recording system for recording original data indicating a reproduced waveform having three elements of output, time, and frequency, wherein the three elements in the original data are A copy protection signal formed by adding a digital value to a digital signal having one waveform. 2. A copy protection method for a recording medium on which data is compressed and recorded, wherein a specific signal is added to original data on a copy source medium and recorded.
A copy protection method in which when the original data of the medium is once compressed and then reproduced, the specific signal is emphasized and the reproduced signal is distorted. 3. A copy protection method in a data processing apparatus for compressing data and transferring the data between apparatuses, wherein a specific signal is included in original audio or image data to be copied. A copy protection method wherein the specific signal is emphasized when compressed and then reproduced, so that the reproduced signal is distorted. 4. When the original data is digitally recorded, the specific signal is added or subtracted from 2 to 5 sampling clocks after the peak value of the original data until the data change rate becomes 0 or more. The copy protection method according to claim 1. 5. The method according to claim 1, wherein when the original data is audio data, the specific signal is added or subtracted when an average value and a change rate of the volume of the audio data are equal to or more than a predetermined value. Copy protection method described in 1. 6. The method according to claim 1, wherein when the original data is image data, the specific signal is added to or subtracted from a portion of 2 to 5 pixels around the peak of brightness of the image data. Copy protection method described in 1. 7. A method according to claim 1, wherein when the original data is image data, the specific signal is added or subtracted when an average value and a change rate of brightness of the image data become equal to or more than a predetermined value.
7. The copy protection method according to claim 4 or claim 6. 8. The copy protection method according to claim 2, wherein the specific signal is the copy protection signal according to claim 1.