JP2000048481A - Signal processor, recording medium and signal processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a representative value correctly showing a signal level of a specified frequency band by calculating a square sum of a prescribed frequency spectrum value when an input signal is modified discrete cosine transformed to be processed. SOLUTION: An MDCT calculation part 12 MDCT transform processes a successively inputted digital audio signal DA1 to convert it to a frequency spectrum signal. A representative value calculation part 14 calculates a square of an absolute value sum of an even-th spectrum value and the square of the absolute sum of an odd-th spectrum value, and calculates a square root of its addition value, and calculates a representative value of a target frequency spectrum value to output it to an encode part 15. At this time, information DC of a copyright is modulated by a carrier wave signal SC to be superimposed on the digital audio signal DA1. Further, the information DC of the copyright is spectrum spread by the random number data PN to be superimposed. Further, an amplitude modulation part 21 multiplies an output signal of a PN spread part 20 by the detected representative value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a signal processing device, a recording medium, and a signal processing method, and can be applied to, for example, an optical disk on which an audio signal is recorded and an optical disk device for reproducing the optical disk. The present invention calculates the sum of squares of a plurality of spectrum values near a predetermined frequency spectrum when an input signal is processed by an improved discrete cosine transform (MDCT). The present invention proposes a signal processing device and a signal processing method that can be used for a digital camera, and a recording medium that records a watermark using the signal processing method.

[0002]

2. Description of the Related Art Conventionally, in an audio apparatus such as an optical disk apparatus, a digital audio signal is converted into a frequency spectrum signal by the MDCT method and processed, whereby the digital audio signal is subjected to high-efficiency encoding processing. It has been made like that.

[0003] For recording media such as optical disks,
A method of protecting copyright by a so-called watermark has been proposed. In this method, copyright-related data and the like are superimposed and recorded on an information signal such as an audio signal at a minute signal level or the like that does not affect reproduction of the audio signal.

[0004]

The digital audio signal and the like recorded on the optical disk as described above have a signal level of a predetermined frequency component (hereinafter referred to as a representative value).
If this can be detected, it is considered that this kind of watermark can be recorded by effectively utilizing the characteristics of human hearing.

At this time, in the MDCT, by converting the input signal into a frequency spectrum signal and processing it, a representative value of a predetermined frequency component is detected by effectively utilizing the frequency spectrum signal obtained by the MDCT processing. It can be considered that the watermark processing circuit can be easily added to an encoder or the like using the MDCT if the above is achieved.

In MDCT, the processing is simpler than in FFT (Fast Fourier Transform) or the like. Thus, the frequency spectrum signal obtained by the MDCT processing is effectively used to represent the representative value of a predetermined frequency component. Can be applied to the frequency analysis and the like, and the application field of the MDCT can be further expanded.

However, unlike orthogonal transform such as FFT,
In the MDCT, a phase characteristic exists in a calculation result by performing analysis without considering a phase component. That is, FIG. 7 shows an MDCT calculation result for a sine wave signal of a predetermined frequency, and FIG. 8 shows an MDCT calculation result for a signal obtained by shifting the phase of the sine wave signal by π.
The calculation result of the DCT changes depending on the phase of the input signal to be processed.

As a result, in the calculation result by the MDCT, there is a problem that the signal level of a predetermined frequency component cannot be correctly detected with respect to the input signal to be processed, thereby causing a problem that it is difficult to use the signal level for the watermark processing. Was.

The present invention has been made in consideration of the above points, and a signal processing apparatus and a signal processing method capable of using a calculation result by MDCT for processing of a watermark, and a water processing method using this method. It is intended to propose a recording medium on which marks are recorded.

[0010]

According to the present invention, there is provided a signal processing apparatus and a signal processing method, wherein a plurality of spectrums near a predetermined frequency spectrum are obtained from a frequency spectrum signal obtained by performing an improved discrete cosine transform on an input signal. Value of the spectrum and the spectrum value 2
Calculate the sum of squares.

A signal level of a predetermined frequency is detected from an input signal to obtain a signal level detection result, and a signal level of the modulation signal of a predetermined frequency generated from predetermined serial data is changed according to the signal level detection result. To generate a reference signal, and superimpose this reference signal on the previous input signal.

After extracting a signal component of a predetermined frequency from the input signal and correcting the signal level, serial data is demodulated. At this time, a carrier signal based on the frequency of this signal component is modulated by random number data to generate a reference signal. Is generated, and the reference signal is multiplied by the previous signal component to demodulate the serial data.

In the recording medium, the signal level of a modulated signal obtained by modulating a carrier signal having substantially the same frequency as the predetermined frequency with predetermined serial data so that the signal level changes in accordance with the signal level of the predetermined frequency of the information signal. Is corrected and superimposed on the information signal and recorded.

In a frequency spectrum signal obtained by performing an improved discrete cosine transform on an input signal, the frequency spectrum signal changes according to the phase of the input signal. However, in a plurality of spectrum values near a predetermined frequency spectrum, the adjacent spectrum values are in the order of 90 degrees. It changes like a trigonometric function according to the phase of the input signal with a phase difference. By calculating the sum of squares of the spectrum value, a representative value can be detected for the predetermined frequency spectrum.

As a result, a signal level of a predetermined frequency is detected from the input signal based on the representative value or the like as necessary, a signal level detection result is obtained, and a signal level of the modulation signal of the predetermined frequency generated from predetermined serial data is obtained. Is changed according to the signal level detection result to generate a reference signal,
If this reference signal is superimposed on the previous input signal, the serial data can be superimposed as a watermark.

After extracting a signal component of a predetermined frequency from the input signal and correcting the signal level, serial data is demodulated. At this time, a carrier signal having the frequency of the signal component is modulated by random number data to obtain a reference signal. Is generated, and the reference signal is multiplied by the previous signal component to demodulate the serial data. Thus, the watermark thus superimposed can be demodulated.

In the recording medium, the signal level of a modulated signal obtained by modulating a carrier signal having substantially the same frequency as the predetermined frequency with predetermined serial data so that the signal level changes in accordance with the signal level of the predetermined frequency of the information signal. Is corrected and superimposed on the information signal and recorded,
This serial data can be recorded as a watermark.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 2 is a block diagram showing the entire system for detecting unauthorized copy according to the embodiment of the present invention. In this embodiment, when recording a digital audio signal DA1 which is an audio source, the watermark information 2 adds copyright information DC and records the digital audio signal DA1 on the optical disc 3. Here, the copyright information DC is
It is composed of information such as the copyright holder of the audio source and whether or not copying is permitted.

Further, in this system, when dubbing the optical disc 3, the watermark decoder 4 detects the copyright information DC and only the magneto-optical disc 5, digital audio tape recorder 6, Copying to CD-R7 etc. is permitted. Further, in the medium copied in this manner and distributed in the market, the copyright information DC is detected by the watermark decoder 4 from the reproduced digital audio signal, thereby detecting an illegal copy.

FIG. 1 is a block diagram showing the watermark encoder 2. In the watermark encoder 2, the MDCT calculation unit 12 performs an MDCT conversion process on the digital audio signal DA1 sequentially input, thereby converting the digital audio signal DA1 into a frequency spectrum signal. Here, the frequency spectrum signal is obtained by converting the digital audio signal DA1 to MDC.
It is a set of coefficient data obtained by the T-transform processing, and is a signal indicating the signal level of each frequency spectrum obtained by the MDCT conversion processing.

The representative value calculation section 14 repeatedly executes the processing procedure shown in FIG. 3 from the frequency spectrum signal, thereby sequentially detecting the representative value of the frequency 3 [kHz].
That is, the representative value calculator 14 proceeds from step SP1 to step SP2, and reads the frequency spectrum signal calculated by the MDCT calculator 12 for each sample block.

Subsequently, the representative value calculation unit 14 proceeds to step SP
Then, the process goes to 3 to calculate the number of the spectrum corresponding to the target frequency for the frequency spectrum calculated by the MDCT calculation unit 12. Here, the representative value calculation unit 14
A spectrum number is calculated from the frequency spectrum calculated by the MDCT calculation unit 12 so as to specify a frequency spectrum located in a narrow frequency band near a target frequency of 3 [kHz].

More specifically, the representative value calculation unit 14 calculates the frequency spectrum of the target frequency 3 [kHz] into a spectrum.
_{Let i} be the frequency spectrum sp immediately before it.
ec _i-1 , two spectra spec immediately after
Calculate the numbers specifying _{i + 1} and Spec _{i + 2} .

Subsequently, the representative value calculation unit 14 proceeds to step SP
Then, the process goes to 4 to execute the following arithmetic processing. Accordingly, the representative value calculation unit 14 adds the square of the absolute value sum of the even-numbered spectrum values and the square of the absolute value sum of the odd-numbered spectrum values, calculates the square root of the added value, and calculates the target frequency. The representative value P of the spectrum is calculated.

[0026]

(Equation 1)

That is, as described above, the calculation result of the frequency spectrum detected by the MDCT conversion has a phase characteristic, and the calculation result changes depending on the phase of the input signal even when input signals of the same frequency are processed.

This is converted to a sampling frequency of 44.1 [kHz].
z], consider a time-series sample data signal composed of 1024 data (for example, a digital audio signal). If the input signal is a single sine wave having a frequency obtained by dividing 44.1 [kHz] by an integer, 1024 Since a time waveform having the same phase is cut out every time for each data block, the same spectrum distribution is obtained for the MDCT calculation result every time (FIG. 4A).

However, when the input signal is a single sine wave having a frequency other than the integer division of 44.1 [kHz], 1
Since a time waveform having a different phase is cut out for each 024 data block, a different spectrum distribution is obtained for the MDCT calculation result every time (FIG. 4B). That is, in this case, the phase characteristics also appear in the time frame direction.

However, in the MDCT calculation result having such a relationship, when the input signal is a single sine wave, even if the phase is changed, the spectrum energy distribution is almost the theoretical value around the peak spectrum. concentrated in four, the frequency spectrum spec _i, the immediately preceding 1 the spectrum to focus these energies is intended
The frequency spectrum speci _{-1 is} immediately followed by the two spectrums speci _{+ 1} and speci _{+ 2} immediately after.

Further, regarding the spectrum in which energy is concentrated as described above, two adjacent spectrums spe
When the phase of the input signal is changed for c _n and spec _{n + 1} and the intensity is calculated, as shown in FIG. 5, these two spectra spec _n and spec _{n + 1} are π / spec _{n + 1.}
It has been found that the phase is shifted by two and changes in a trigonometric function according to the phase of the input signal. In addition, it was shown that in these two spectra, spectrum _n and spectrum _{n + 1} , the RMS (root mean square) of the spectrum value takes a constant value without depending on the phase.

Thus, in this embodiment, the four spectra spec _{n-1 to} spec _{n + 2} are:
Adding the square of the sum of absolute values of the even-numbered spectrum values and the square of the sum of absolute values of the odd-numbered spectrum values, calculating the square root of the added value, and calculating the representative value P of the target frequency spectrum. Thus, a representative value that does not depend on the phase of the target frequency spectrum is calculated.

After calculating the representative value in this way, the representative value calculating unit 14 proceeds to step SP5, outputs the calculated representative value P to the encoding unit 15, and then outputs the representative value P to step SP6.
To end the processing procedure.

The encoding section 15 modulates the copyright information DC with a carrier signal SC having a frequency of 3 [kHz] and superimposes it on the digital audio signal DA1. At this time, the copyright information DC is spectrum-spread and superimposed by the PN-sequence random number data PN, and thereby the copyright information DC is superimposed so as to be difficult to analyze. Further, at this time, the representative value calculation unit 1
By performing amplitude modulation according to the representative value of the frequency 3 [kHz] calculated in step 4, the human masking effect is effectively used, and the sound quality degradation of the digital audio signal DA1 due to the copyright information DC superimposed in this manner. To prevent

That is, in the encoding unit 15, the carrier generation unit 17 generates a carrier signal SC using a sine wave signal having a frequency of 3 [kHz]. The PSK modulator 18 repeatedly inputs the copyright information DC in the form of serial data, and inverts the phase of the carrier signal SC according to the polarity of the copyright information DC. Thereby, the PSK modulator 18
Modulates the copyright information DC with PSK.

The PN generator 19 generates PN-sequence random number data PN at a timing based on, for example, the digital audio signal DA1, and repeatedly outputs the data. PN
The spreading unit 20 converts the random number data PN of the PN sequence into PSK
The output signal of the modulation unit 18 is multiplied, whereby the PSK modulation signal based on the copyright information DC is spectrum-spread to improve confidentiality.

The amplitude modulating section 21 multiplies the output signal of the PN spreading section 20 by the representative value P detected by the representative value calculating section 14. Thereby, the amplitude modulation section 21 changes the signal level of the output signal output from the PN spreading section 20 according to the signal level of the corresponding frequency component of the digital audio signal DA1.

The adder 22 adds the output signal of the amplitude modulator 21 to the digital audio signal DA1 and outputs the digital audio signal DA1. In this embodiment, the output signal is encoded by a predetermined encoder to expose the master disk, and the optical disk 3 is mass-produced from the master disk.

FIG. 6 is a block diagram showing the watermark decoder 4. This watermark decoder 4
The copyright information DC is reproduced from the digital audio signal DA2 obtained by reproducing the optical disk 3, the magneto-optical disk 5, the digital audio tape recorder 6, and the like (FIG. 2).

In the watermark decoder 4, the MDCT calculation unit 32 performs an MDCT conversion process on the digital audio signal DA2 which is sequentially input, and thereby converts the digital audio signal DA2 into a frequency spectrum signal. The representative value calculation unit 34 repeatedly executes the processing procedure shown in FIG. 3 from the frequency spectrum signal, thereby sequentially detecting the representative value P of the frequency 3 [kHz].

The filter section 35 is constituted by a narrow band band-pass filter, and outputs a digital audio signal DA.
A signal component having a frequency of 3 [kHz] is extracted from 2 and output. The amplitude modulating unit 36 multiplies the output signal of the filter unit 35 by the reciprocal of the representative value P, thereby obtaining the copyright information DC included in the signal component of frequency 3 [kHz] extracted from the digital audio signal DA2. As for the modulation signal, the signal level of the modulation signal becomes a constant value,
The signal level of the output signal output from the filter unit 35 is corrected and output.

The PN generation unit 37 generates random number data PN of a PN series and repeatedly outputs the data. At this time, the PN generation unit 37 generates the random number data PN at a timing based on the digital audio signal DA2, thereby generating the corresponding random number data PN at the same timing as the timing for the digital audio signal DA1 in the watermark encoder 2. Generate.

The carrier generation unit 38 has a frequency of 3 [kHz].
And generates and outputs a carrier signal SC based on the sine wave signal. The multiplication unit 39 multiplies the carrier signal SC by the random number data PN to convert the carrier signal SC into the random number data P.
N and spreads the spectrum. Multiplication unit 40
Multiplies the output signal of the multiplication unit 39 by the output signal of the amplitude modulation unit 36, so that the signal level changes according to the copyright information DC and the digital audio signal DA2
And outputs a multiplied signal obtained by randomizing a signal component having a frequency of 3 [kHz].

The adder 41 accumulatively adds the output signals of the multipliers 40 in a fixed time cycle, thereby averaging the output signals of the multipliers 40 for each bit of the copyright information DC. The comparison unit 42 demodulates and outputs the copyright information DC by obtaining a comparison result between the output signal of the addition unit 41 and a predetermined reference value.

Thus, in this embodiment, when dubbing the optical disc 3, dubbing can be restricted based on the copyright information, and the source suspected of being illegally copied is the source. Has been made to be able to determine the source.

In the above configuration, in the optical disk manufacturing process, the digital audio signal DA1 to be recorded on the optical disk is input to the watermark encoder 2 (FIG. 1), and is sequentially converted into a frequency spectrum signal by the MDCT calculation unit 12. .

This frequency spectrum signal changes in accordance with the phase even if the frequency of the digital audio signal DA1 is constant, and adjacent spectrum values have a phase difference of 90 degrees, and correspond to the phase of the digital audio signal DA1. And changes into a trigonometric function (FIG. 5). As a result, in the frequency spectrum signal, the sum of squares of the frequency spectrum value is calculated in a narrow band including the target frequency spectrum, and a representative value that correctly represents the signal level of a specific frequency is calculated even if the phase of the digital audio signal DA1 changes. Is done.

At this time, a single frequency sine wave is
When the T-conversion is performed, the energy is concentrated in the frequency spectrum of this frequency, one frequency spectrum immediately before the frequency spectrum, and two spectrums immediately after the frequency spectrum (FIGS. 7 and 8). 3
[KHz] frequency spectrum value, this frequency 3 [k
[Hz], and the two immediately following frequency spectrum values are selected, and the sum of the absolute values of the even-numbered spectrum values from these spectrum values is calculated as 2
The power and the square of the sum of the absolute values of the odd-numbered spectrum values are added, and the representative value P of the target frequency spectrum is calculated by the square root of the added value.

Thus, the digital audio signal DA
1 indicates that a signal level of a frequency of 3 [kHz] is simply and correctly detected.

In the watermark encoder 2, a frequency 3 [k] which is a sine wave signal of the same frequency
[Hz] is generated by the carrier generation unit 17, and the carrier signal SC is PSK-modulated by serial data based on copyright information DC. Furthermore, this P
The SK modulated signal is spectrum-spread by PN sequence random number data PN, and the resulting modulated signal is amplitude-modulated according to a representative value. Accordingly, in the watermark encoder 2, the signal level of the modulation signal based on the serial data having the frequency of 3 [kHz] is changed such that the signal level of the modulation signal changes in accordance with the signal level of the frequency of 3 [kHz] in the digital audio signal DA1. The signal level is corrected to generate a reference signal indicating copyright, and this reference signal is superimposed on the digital audio signal DA1 and recorded on the optical disc 3.

As a result, in this reference signal, the signal level changes in accordance with the signal level of the digital audio signal DA1 at the same frequency. Even when the reference signal is superimposed on the digital audio signal DA1, the sound quality of the digital audio signal DA1 is degraded by the masking effect. Can be avoided. In addition, the confidentiality is improved by modulating with the PN sequence random number data PN.

The reference signal recorded in such a manner as to be superimposed on the digital audio signal DA1 is dubbed in its entirety, even in the case of dubbing in the form of a digital signal or in the form of an analog signal.

Thus, when dubbing in this manner, the dubbed source is reproduced, and the copyright information D superimposed on the digital audio signal DA1 is reproduced.
After confirming C, it is possible to take various countermeasures against illegal copying.

That is, the digital audio signal DA2 obtained from various sources in this manner is converted into a frequency spectrum signal in the MDCT calculation unit 32 of the watermark decoder 4 (FIG. 6), and then the representative value calculation unit 34 The representative value is calculated in the same manner as in the mark encoder 2. The frequency component for which the representative value is calculated in this manner is output from the filter unit 3.
At 5, the digital audio signal DA2 is extracted.

In the watermark decoder 4,
The carrier signal SC having a frequency of 3 [kHz] generated by the carrier generator 38 is spread-spectrum modulated by PN-sequence random number data PN, and the modulated signal and a signal component having a frequency of 3 [kHz] extracted from the digital audio signal DA2 are used. Is multiplied by the multiplier 40. Further, after the component of the digital audio signal DA2 mixed in the multiplication result is removed by the adder 41, the comparator 42 removes the component.
The value is identified, whereby the copyright information DC is reproduced.

According to the above configuration, the sum of the squares of a plurality of spectrum values near the frequency of 3 [kHz] is calculated from the frequency spectrum signal obtained by subjecting the digital audio signal to the MDCT conversion. Even if the phase changes, a representative value that correctly represents the signal level in a specific frequency band can be detected. As a result, the copyright information DC can be superimposed on the digital audio signal using the watermark by using the representative value to cope with illegal copying.

Further, at this time, by modulating and recording the copyright information DC with the frequency at which the representative value is detected in this way, it is possible to effectively utilize the masking effect and reduce the sound quality deterioration.

Since the spectrum is spread by the PN series random number data PN, the confidentiality of the copyright information can be improved.

In the above embodiment, the case where the representative value is calculated by calculating the square root of the sum of squares calculated from the four spectrum values has been described. However, the present invention is not limited to this, and the present invention is not limited to this. In a sufficient range, the sum of squares may be used as a representative value. By doing so, the overall configuration can be simplified accordingly.

In the above-described embodiment, the square value of the sum of the absolute values of the even-numbered spectrum values and the square value of the sum of the absolute values of the odd-numbered spectrum values are added from the four spectrum values. However, the present invention is not limited to this, and the present invention is not limited to this, and when sufficient accuracy for practical use can be ensured, the representative value is calculated from the target frequency spectrum value and the adjacent spectrum value. Alternatively, when further accuracy is required, a representative value may be calculated from five or more spectrum values.

In the above-described embodiment, a case has been described in which a representative value is calculated for a frequency spectrum of frequency 3 [kHz], and copyright information is superimposed by a modulation signal of frequency 3 [kHz]. However, the present invention is not limited to this, and can be widely applied to a case where a representative value is calculated for various frequency spectrums and a case where copyright information is superimposed.

Further, in the above-described embodiment, the case where the copyright information is superimposed has been described. However, the present invention is not limited to this, and can be widely applied to the case where various information is superimposed as necessary. it can.

In the above-described embodiment, the case where a digital audio signal is recorded on an optical disk and reproduced is described. However, the present invention is not limited to this case. For example, when various information is transmitted via the Internet. Etc. can be widely applied.

Further, in the above-described embodiment, the case where the representative value is calculated and the modulation signal is amplitude-modulated by the serial data has been described. However, the present invention is not limited to this. However, the present invention can be widely applied to applications such as waveform analysis for observing a temporal change of a specific frequency component in real time. Also, the present invention can be applied to a watermark encoding system in which desired data is directly embedded in a frequency spectrum obtained by performing an MDCT calculation on an input signal.

[0065]

As described above, according to the present invention, when an input signal is processed by performing an improved discrete cosine transform, a sum of squares of a plurality of spectrum values near a predetermined frequency spectrum is calculated. Signal processing apparatus and signal processing method capable of detecting a representative value that correctly represents a signal level in a specific frequency band even if the phase of the signal changes, and thereby using a calculation result by MDCT for watermark processing or the like By using this signal processing method, a recording medium on which a watermark is recorded can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a watermark encoder according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an unauthorized copy processing system to which the watermark encoder of FIG. 1 is applied;

FIG. 3 is a flowchart illustrating a processing procedure of a representative value calculation unit of the watermark encoder of FIG. 1;

FIG. 4 is a signal waveform chart for explaining a process of a representative value calculation unit in FIG. 1;

FIG. 5 is a characteristic curve diagram for explaining a process of a representative value calculation unit in FIG. 1;

FIG. 6 is a block diagram illustrating the watermark decoder of FIG. 2;

FIG. 7 is a characteristic curve diagram showing an MDCT calculation result.

8 is a characteristic curve diagram showing an MDCT calculation result when the phase of the input signal in FIG. 7 is changed.

[Explanation of symbols]

2 ... watermark encoder, 4 ... watermark decoder, 12, 32 ... MDCT calculation unit, 1
4, 34 ... Representative value calculation unit, 17, 38 ... Carrier wave generation unit, 19, 37 ... PN generation unit

Claims (38)

[Claims] An improved discrete cosine transform means for performing an improved discrete cosine transform process on an input signal to generate a frequency spectrum signal; detecting a plurality of spectrum values near a predetermined frequency spectrum from the frequency spectrum signal; A signal processing apparatus comprising: a calculating means for calculating a sum of squares. 2. The method according to claim 1, wherein the calculating means calculates a square value of a sum of absolute values of even-numbered spectrum values and a square value of a sum of absolute values of odd-numbered spectrum values from a plurality of spectrum values near the predetermined frequency spectrum. The signal processing device according to claim 1, wherein the sum of squares is calculated by adding 3. The signal processing apparatus according to claim 1, wherein said calculating means calculates a square root of said sum of squares. 4. A reference signal generating means for generating a reference signal by changing a signal level of a modulation signal generated from predetermined serial data in accordance with the sum of squares or the value of the square root of the sum of squares. The signal processing device according to claim 1, further comprising a signal superimposing unit configured to superimpose a signal on the input signal. 5. The reference signal generating means, after phase-modulating a carrier signal having a frequency corresponding to the predetermined frequency spectrum with the serial data,
The signal processing device according to claim 4, wherein the modulation signal is generated by modulating the modulated signal with random number data. 6. The signal processing apparatus according to claim 4, wherein an output signal of said signal superimposing means is recorded on a predetermined recording medium. 7. The signal processing device according to claim 4, wherein the serial data is information about a copyright. 8. A signal level detecting means for detecting a signal level of a predetermined frequency from an input signal and outputting a signal level detection result, and converting the signal level of the modulation signal of the predetermined frequency generated from predetermined serial data into the signal level. A signal processing device comprising: a signal generation unit that generates a reference signal by changing the reference signal in accordance with a detection result; and a signal superimposition unit that superimposes the reference signal on the input signal. 9. The signal generator according to claim 8, wherein the signal generation unit generates the modulated signal by modulating the carrier signal of the predetermined frequency with the serial data and then modulating the carrier signal with random number data. Signal processing device. 10. The signal processing apparatus according to claim 8, wherein an output signal of said signal superimposing means is recorded on a predetermined recording medium. 11. The signal processing apparatus according to claim 8, wherein the serial data is information about a copyright. 12. A signal extracting means for extracting a signal component corresponding to the predetermined frequency spectrum from the input signal, wherein a signal level of the signal component is determined according to a reciprocal of the sum of squares or a reciprocal of the square root of the sum of squares. Signal level correcting means for correcting the signal level of the signal component by changing the signal level, and data demodulating means for demodulating serial data from the signal component whose signal level has been corrected by the signal level correcting means. The signal processing device according to claim 1. 13. The data demodulating unit modulates a carrier signal having a frequency of the signal component with random number data to generate a reference signal, and multiplies the signal component by the reference signal to demodulate the serial data. The signal processing device according to claim 12, wherein: 14. The input signal according to claim 1, wherein the input signal is a reproduced signal obtained by reproducing a predetermined recording medium.
3. The signal processing device according to 2. 15. The signal processing device according to claim 12, wherein the serial data is information about a copyright. 16. A signal extracting means for extracting a signal component of a predetermined frequency from an input signal, a signal level detecting means for detecting a signal level of the signal component and outputting a signal level detection result, and a signal level of the signal component And a data demodulator for demodulating serial data superimposed on the input signal and transmitted from the signal component whose signal level has been corrected by the signal level corrector. The data demodulation unit modulates a carrier signal at a frequency of the signal component with random number data to generate a reference signal, and multiplies the reference signal by the signal component to demodulate the serial data. A signal processing device characterized by the above-mentioned. 17. The apparatus according to claim 1, wherein the input signal is a reproduced signal obtained by reproducing a predetermined recording medium.
7. The signal processing device according to 6. 18. The signal processing device according to claim 16, wherein the serial data is information about a copyright. 19. A recording medium on which a predetermined information signal is recorded, wherein a carrier signal having substantially the same frequency as the predetermined frequency is converted into a predetermined signal so that the signal level changes according to the signal level of the predetermined frequency of the information signal. A recording medium, wherein a signal level of a modulation signal modulated by serial data is corrected and superimposed on the information signal and recorded. 20. The recording medium according to claim 19, wherein said serial data is information about a copyright. 21. An improved discrete cosine transform processing of an input signal to generate a frequency spectrum signal, detecting a plurality of spectrum values near a predetermined frequency spectrum from the frequency spectrum signal, and calculating a sum of squares of the spectrum value. A signal processing method characterized by the above-mentioned. 22. From a plurality of spectrum values near the predetermined frequency spectrum, a square value of a sum of absolute values of even-numbered spectrum values and a square value of a sum of absolute values of odd-numbered spectrum values are added. The signal processing method according to claim 21, wherein the sum of squares is calculated. 23. The signal processing method according to claim 21, wherein a square root of the sum of squares is calculated. 24. A reference signal is generated by changing a signal level of a modulation signal generated from predetermined serial data in accordance with the sum of squares or the value of the square root of the sum of squares. 22. The signal processing method according to claim 21, wherein the signal is superimposed on and output. 25. The signal according to claim 24, wherein a carrier signal of a frequency corresponding to the predetermined frequency spectrum is phase-modulated by the serial data, and then modulated by random number data to generate the modulated signal. Processing method. 26. The input signal on which the reference signal is superimposed is recorded on a predetermined recording medium.
5. The signal processing method according to 4. 27. The signal processing method according to claim 24, wherein the serial data is information about a copyright. 28. A method for detecting a signal level of a predetermined frequency from an input signal to obtain a signal level detection result, and changing a signal level of a modulation signal generated from predetermined serial data according to the signal level detection result. And superimposing the reference signal on the input signal. 29. The signal processing method according to claim 28, wherein the carrier signal of the predetermined frequency is phase-modulated by the serial data, and then modulated by random number data to generate the modulated signal. 30. The apparatus according to claim 2, wherein the input signal on which the reference signal is superimposed is recorded on a predetermined recording medium.
9. The signal processing method according to 8. 31. The signal processing method according to claim 28, wherein the serial data is information about a copyright. 32. A signal component corresponding to the predetermined frequency spectrum is extracted from the input signal, and the signal level of the signal component is changed according to the reciprocal of the sum of squares or the reciprocal of the square root of the sum of squares. 22. The signal processing method according to claim 21, wherein after correcting the signal level of the signal component, serial data is demodulated. 33. A method according to claim 31, wherein a carrier signal based on the frequency of the signal component is modulated by random number data to generate a reference signal, and the serial signal is demodulated by multiplying the reference signal by the signal component. 33. The signal processing method according to 32. 34. The input signal is a reproduced signal obtained by reproducing a predetermined recording medium.
3. The signal processing method according to 2. 35. The signal processing method according to claim 32, wherein the serial data is information about a copyright. 36. A signal component of a predetermined frequency is extracted from an input signal, a signal level of the signal component is detected, a signal level detection result is obtained, and a signal level of the signal component is corrected based on the signal level detection result. A signal processing method for demodulating serial data, wherein a carrier signal at a frequency of the signal component is modulated with random number data to generate a reference signal, and the reference signal is multiplied by the signal component to demodulate the serial data. A signal processing method. 37. The apparatus according to claim 3, wherein the input signal is a reproduced signal obtained by reproducing a predetermined recording medium.
7. The signal processing method according to 6. 38. The signal processing method according to claim 36, wherein the serial data is information about a copyright.