JP2000209097A - Signal processor, signal processing method, signal recorder, signal reproducing device and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To superimpose digital watermark information on audio signals without lowering the quality of the audio signals while raising resistance against various signal processings. SOLUTION: Input audio signals are converted to frequency spectrum signals in an MDCT calculation part 12 by MDCT and the spectrum signals whose signal level is equal to or higher than a prescribed level obtained from the peak of the input signals are selected in an adaptive selection part 14. For 1 bit which is an n-th bit from the LSB of the successively selected spectrum signals, the digital watermark information is successively replaced in a bit operation part 15. The bits of an order lower than the n-th bit are replaced with a specified value for not making the n-th bit be influenced by an addition/ subtraction processing to the LSB. The frequency spectrum signals on which the digital watermark information generated in such a manner are returned to original digital audio signals in an IMDCT calculation part 16 and outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a signal recording apparatus which superimposes copyright protection information on an audio signal by a digital watermarking technique and records the signal, and converts a desired signal into arbitrary continuous data. Signal processing device and method for superimposing, signal recording device for recording the superimposed signal on a recording medium, recording medium on which the superimposed signal is recorded, and at least copyright information by reproducing the recording medium And a signal reproducing device for detecting a desired signal.

[0002]

2. Description of the Related Art For literary works such as music information recorded on a recording medium such as an optical disc,
There has been proposed a method of protecting the copyright by using a digital watermark technology (hereinafter, referred to as a watermark technology). In this method, data related to copyright protection is superimposed and recorded on information of a copyrighted work such as a video signal and an audio signal at a minute signal level that does not affect reproduction of the information.

[0003]

By the way, in such a watermark technique, even if the watermark signal to be superimposed is minute, if the watermark data is superimposed on an audio signal, for example, the audio signal is Deterioration of signal quality is inevitable, but in the conventional watermark technology, the original signal quality is not sufficiently maintained, and improvement has been desired. In particular, in the case of an audio signal, deterioration in quality due to the superposition of this type of data is more easily perceived than in the case of a video signal. Was.

[0004] The superimposed watermark information is used for transmission line noise, clipping, filtering and resampling in a process in which a digital audio signal in which the watermark information is embedded flows through a recording medium such as an optical disk or a communication path such as the Internet. , AD / DA conversion, compression processing, and various other processing and format conversion. However, even if such processing is performed, it must be configured to be able to appropriately demodulate.
However, with the conventional watermark technology,
There is a problem that the signal on which the watermark information is superimposed is not sufficiently resistant when subjected to the above-described various processes and format conversion, and the watermark information cannot be detected properly.

Accordingly, an object of the present invention is to convert a desired signal such as watermark information into a continuous signal such as audio data without deteriorating the quality of the continuous signal and perform various processes on the continuous signal. It is another object of the present invention to provide a signal processing apparatus and a method thereof that can appropriately superimpose the signals while having sufficient resistance.
Another object of the present invention is to appropriately demodulate watermark information from a continuous signal on which a desired signal such as watermark information is superimposed, and reproduce the original continuous signal without deterioration in quality. To provide a signal processing device and a method therefor.

Another object of the present invention is to convert a desired signal such as watermark information into a continuous signal such as audio data without deteriorating the quality of the continuous signal, and various other methods for the continuous signal. It is an object of the present invention to provide a signal recording device that appropriately superimposes a signal with sufficient resistance to processing and records a continuous signal on which the watermark information is superimposed on a recording medium. Further, another object of the present invention is to reproduce a recording signal from a recording medium on which a continuous signal having watermark information superimposed thereon is recorded, appropriately demodulate watermark information, and
An object of the present invention is to provide a signal reproducing apparatus capable of reproducing an original continuous signal without deterioration of quality.

Another object of the present invention is to convert a desired signal such as watermark information into a continuous signal such as audio data and the like, and appropriately demodulate the watermark information from a reproduced signal thereof. It is an object of the present invention to provide a recording medium on which a superimposed signal is recorded so that the signal can be reproduced without quality deterioration.

[0008]

In order to solve the above problems, a signal processing apparatus according to the present invention performs a predetermined orthogonal transform for each predetermined block of a continuous signal, and generates a frequency spectrum of the signal. And a signal superimposing means for superimposing the desired signal on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum.

In the signal processing device having such a configuration, the orthogonal transform means orthogonally transforms the continuous signal for each predetermined block to generate a frequency spectrum, and the signal level of the spectrum signal of each frequency is A desired signal such as watermark information is selectively superimposed on sufficiently large spectrum data. Therefore, a signal having a relatively large level can be superimposed on the original signal with relatively little deterioration. As a result, a signal having high resistance to various signal processing can be superimposed.

[0010] The signal processing method of the present invention is a method of superimposing a predetermined signal related to copyright protection of a copyrighted work on a digital continuous signal related to an arbitrary copyrighted work. A predetermined orthogonal transform is performed for each block to generate a frequency spectrum of the signal, and the desired signal is superimposed on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum.

In another signal processing apparatus of the present invention, at least the above-mentioned signal is obtained by superposing a desired signal on a spectrum signal having a sufficiently large signal level in a frequency spectrum of an arbitrary digital continuous signal. What is claimed is: 1. A signal processing apparatus for reproducing a desired signal, comprising: performing orthogonal transform for each predetermined block of the arbitrary digital continuous signal to generate a frequency spectrum of the signal; And signal extracting means for extracting the desired signal from a spectrum signal having a sufficiently large signal level.

Further, another signal processing method according to the present invention relates to the copyright protection of a copyrighted work, for a spectrum signal having a sufficiently large signal level in the frequency spectrum of a digital continuous signal related to an arbitrary work. A signal processing method for reproducing at least a desired signal related to copyright protection from a signal on which a desired signal is sequentially superimposed, wherein a predetermined orthogonal transformation is performed for each predetermined block of the arbitrary digital continuous signal. Then, a frequency spectrum of the signal is generated, and the desired signal is extracted from a spectrum signal having a sufficiently large signal level in the generated frequency spectrum.

A signal recording apparatus according to the present invention is a signal recording apparatus for superimposing a desired signal on an arbitrary digital continuous signal and recording the signal on an arbitrary recording medium. An orthogonal transform unit that performs orthogonal transform and generates a frequency spectrum of the signal, and a signal superimposing unit that superimposes the desired signal on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum, Recording means for recording, on a recording medium, a signal related to the continuous signal on which the desired signal is superimposed.

Further, the signal reproducing apparatus of the present invention is a recording apparatus in which a recording signal in which a desired signal is sequentially superimposed on a spectrum signal having a sufficiently large signal level in a frequency spectrum of an arbitrary digital continuous signal is recorded. A signal reproducing apparatus for reproducing the digital continuous signal and the desired signal from a medium, wherein the level of each spectrum signal of the frequency spectrum is compared with a predetermined reference level, and the signal level is set to the predetermined reference level A level comparing unit that detects a spectrum signal whose signal level is greater than or equal to or greater than the predetermined reference level; and a signal extracting unit that extracts the desired signal from the detected spectrum signal.

Further, the recording medium of the present invention is a recording medium in which a signal is superimposed on a digital continuous signal relating to an arbitrary work and a predetermined signal relating to copyright protection of the work is superimposed, For a reproduction signal reproduced from the recording medium, the level of each spectrum signal of the frequency spectrum of the digital continuous signal obtained from the reproduction signal is compared with a predetermined reference level, and the signal level is set to the predetermined reference level. The digital continuous signal and the desired signal are reproduced by detecting the spectrum signal whose signal level is greater than or equal to or higher than the predetermined reference level and extracting the desired signal from the detected spectrum signal. This is a recording medium on which a recording signal to be recorded is recorded.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described.
This will be described with reference to FIGS. In the present embodiment, copy control of audio data is performed by superimposing digital watermark information on audio data and detecting appropriate dubbing or illegally copied audio data with reference to the digital watermark information. The present invention will be described by exemplifying a series of systems for performing the above.

First, the configuration of such a series of systems and the flow of data will be described with reference to FIG.
FIG. 1 is an overall block diagram of a series of such systems capable of detecting unauthorized copying. In this system, when a digital audio signal DA1, which is audio source data, is recorded on the optical disc 5 by the recording device 1, the watermark information 4 contained in the recording device 1 adds and records the copyright information DC. I do. Here, the copyright information DC includes information indicating a copyright holder of the audio source data, information as to whether or not copying is permitted, and the like.

When the audio data is further dubbed using the optical disk 5, the copyright information DC is detected by the watermark decoder 6 accommodated in the recording / reproducing apparatus 2, and a source for permitting copying based on the detected information. Is copied to a recording medium such as the magneto-optical disk 7, the digital audio tape recorder 8, the CD-R 9, or the like. When these media distributed in the market are reproduced by the reproducing apparatus 3, the watermark information 6 accommodated in the reproducing apparatus 3 outputs copyright information DC.
Is detected, it is determined that the data is a recording medium and audio data which are properly copied. In other words, illegal copies can be found.

Next, the recording device 1 of such a system,
The watermark encoder 4 and the watermark decoder 6 according to the present invention included in the recording / reproducing device 2 and the reproducing device 3 will be described in detail.

First, the watermark encoder 4 will be described with reference to FIGS. FIG. 2 is a block diagram showing a configuration of the watermark encoder 4. The watermark encoder 4 includes a trigger detection unit 11, an MDCT calculation unit 12, an encoding unit 13,
An MDCT calculation unit 16 is provided. Also, the encoding unit 13
Has an adaptive selection unit 14 and a bit operation unit 15.
FIG. 3 is a diagram for explaining the operation of the trigger detection unit 11 of the watermark encoder 4 and the adaptive selection unit 14 of the encoding unit 13 shown in FIG. FIG. 4 is a diagram for explaining bit operations in the bit operation unit 15 of the encoding unit 13.

First, the configuration of each part of the watermark encoder 4 will be described with reference to FIGS. As shown in FIG. 3A, the trigger detection unit 11 repeatedly detects a peak on the waveform from the sequentially input digital audio signal DA1, and determines a reference timing for embedding the copyright information DC in a certain section. Identify. Specifically, the trigger detection unit 11 compares the amplitude value of the digital audio signal DA1 sequentially input with the maximum value up to that time, and replaces the maximum value with the amplitude value when the amplitude value is larger than the maximum value. To sequentially update the maximum value. Then, when the maximum value is held without being updated for a predetermined time, the maximum value is specified as a peak value.

The MDCT calculation unit 12 includes the trigger detection unit 1
1 at predetermined timings based on the peak detected in the digital audio signal DA1.
Is transformed into a discrete cosine transform (M
DCT) to convert the digital audio signal DA1 into a frequency spectrum signal DS1. Here, the frequency spectrum signal DS1 is a set of coefficient data obtained by performing an MDCT process on the digital audio signal DA1, and is a signal indicating a signal level of each frequency spectrum obtained by the MDCT process.

The encoding unit 13 includes an MDCT calculating unit 12
The copyright information DC is embedded in the input frequency spectrum signal DS1 and output.

The adaptive selection unit 14 of the encoding unit 13
From each frequency spectrum of the frequency spectrum signal DS1 input from the DCT calculation unit 12, a spectrum whose spectrum value spectrum _i is sufficiently large is selected, and the number i of the frequency spectrum is assigned to the copyright information DC together with the frequency spectrum signal DS1. It is output to the bit operation unit 15 as a signal to be superimposed. Specifically, FIG.
As shown in (B), each frequency spectrum value spec
_{When i} is larger than the predetermined level value P1, the frequency spectrum is selected as a spectrum in which the copyright information DC is embedded.

The level value P1 is a value determined by multiplying the peak value detected by the trigger detecting section 11 by a constant coefficient, and is a specific section of the digital audio signal DA1 in which copyright information DC is to be embedded. Is a value reflecting the spectrum energy of Adaptive selection unit 14, a frequency spectrum value only if the frequency spectrum value spec _i is greater than the level value P1 spe
By so as to fill the information DC of copyright in c _i,
The processing for embedding the watermark is controlled in accordance with the energy distribution of the frequency spectrum signal DS1.

The bit operation unit 15 of the encoding unit 13
Copyright information D by adaptive selection unit 14 into a frequency spectrum value spec _i selected for each sample block
Embed C. The bit operation unit 15 includes the copyright information DC
Is repeatedly input in the form of serial data, and the polarity of each bit is written to each selected frequency spectrum value in bit units.

[0027] In the process of embedding, the bit operating unit 15, as shown in FIG. 4 (A), with respect to the frequency spectrum value spec _i the predetermined logical value is continuously,
For example, as shown in FIG. 4B, the fourth bit higher than the least significant bit is set as a logical value data corresponding to the polarity of the copyright information DC. The bit for setting the logical value data can suppress the sound quality deterioration as it is closer to the lowest order, but since the resistance to various attacks is reduced, the required sound quality and the environment to be dealt with are taken into consideration. It is selected as appropriate.

When processing the audio signal in which the copyright information DC is embedded in the manner described above to reproduce the copyright information DC, the bit operation unit 15 also performs the logical operation due to the quantization error. An offset value is set below the bit in which the logical value data is set so that the logical value can be correctly detected in the bit in which the value data is set.

Such a quantization error can be examined by, for example, addition / subtraction processing for the least significant bit. For example, as shown in FIG. 4B, when the third bit to the least significant bit are set to logical 0, in the process of adding the value 1 to the least significant bit, as shown in FIG. , No change in the logical value data is observed. However, in the process of subtracting the value 1 from the least significant bit,
As shown in FIG. 4D, a change in the logical value data is observed. Therefore, the bit operation unit 15 performs the logical value da by adding and subtracting at least the least significant bit.
As ta does not change, as shown in FIG. 4 (E), sets the logical value of the lower bits than the bit logical value data, thereby work even if not correctly reproduce the frequency spectrum value spec _i by the quantization error The right information DC can be correctly detected.

The inverse MDCT (IMDCT) calculation unit 16
The frequency spectrum signal DS1 obtained by bit manipulation in this way is subjected to inverse MDCT conversion processing, thereby outputting a digital audio signal DA2 in the same format as the original digital audio signal DA1.

In the recording apparatus 1 of the present embodiment, the output signal is encoded by a predetermined encoder to expose the master disk, and the optical disk 5 is mass-produced from the master disk.

Next, the flow of processing in the watermark encoder 4 will be described with reference to FIG. FIG. 5 is a flowchart showing the flow of the process of the watermark encoder 4. In the watermark encoder 4, when the process is first started (step SP1), it is determined whether or not a peak on the waveform is detected by the trigger detection unit 11, that is, a timing serving as a reference for embedding the copyright information DC in a certain section. Is determined (step SP2). If the timing is not specified in step SP2, the process waits until the timing is specified.

If the timing has been specified in step SP2, the digital audio signal DA1
Are sequentially read for each sample block (step SP
3) The MDCT calculation is performed in the MDCT calculation unit 12 to calculate the frequency spectrum signal DS1 (step SP4), and then the frequency spectrum in which the copyright information DC is embedded by comparing the frequency spectrum signal DS1 with the level value P1. The value _i of the frequency spectrum in which the value spec _i is adaptively selected and the copyright information DC is embedded
Is specified (step SP5).

[0034] Then, set to a logical value corresponding to the polarity of the copyright information DC predetermined bits of the selected frequency spectrum value spec _i (step SP6), the lower bits than the bits set information DC copyright Is set to logic 0, and a predetermined offset value is further added, so that the copyright information DC can be correctly reproduced even by a quantization error (step SP7). Then, the inverse MDCT is calculated on the bit spectrum of the frequency spectrum signal DS1, and the digital audio signal DA2 is output in the same format as the original digital audio signal DA1 (step SP8).

Then, it is determined whether or not the section in which the copyright information DC is to be embedded has been completed (step SP9). If not completed, the procedure returns to step SP3 to sequentially execute steps SP3 to SP3 for the subsequent range of sample blocks. Step S
The process of P8 is repeated. If the section in which the copyright information DC is embedded in step SP9 ends, it is determined whether the processing of the digital audio signal DA1 has been completed (step SP10). If not completed, the process returns to step SP2. The section in which the next copyright information DC is to be embedded is detected, and the processing from step SP3 to step SP9 is performed on the section. In step SP10,
When the processing of the digital audio signal DA1 is completed, a series of processing ends (step SP11).

Finally, the operation of the watermark encoder 4 and the effect of each processing / operation will be described together. For example, in a manufacturing process of an optical disk, a digital audio signal DA1 to be recorded on the optical disk is input to the watermark encoder 4,
The trigger detector 11 repeatedly detects peaks on the waveform of the digital audio signal DA1 and specifies a reference timing for embedding copyright information DC in a certain section. Thereby, the digital audio signal DA
1 as compared with the case where this type of data is always embedded, the digital audio signal DA in which the copyright information DC is embedded.
One location can be reduced and effectively hidden from view. That is, it is possible to embed the copyright information DC such that sound quality deterioration is prevented and analysis is difficult.

Next, the digital audio signal DA1
Is sequentially converted into a frequency spectrum signal DS1 by MDCT conversion processing in an MDCT calculation unit 12, and copyright information DC is embedded in the frequency spectrum signal DS1 and output in a subsequent encoding unit 13. This makes it possible to prevent sound quality deterioration and to make analysis difficult, as compared to a case where this kind of data is directly embedded in the digital audio signal DA1 or a case where a PCM audio signal is superimposed by operating with this kind of data. Can be embedded.

[0038] In the watermark encoder 4, in this case the frequency spectrum values spec _i of the frequency spectrum signal DS1 is larger than the level value P1 that is adaptively determined according to the peak value only, the frequency spectrum embedding information DC of copyright with respect to the value spec _i. This makes it possible to selectively embed this type of data in a frequency spectrum value having a large energy as compared with a case where the copyright information DC is always embedded in a specific frequency spectrum value, thereby improving resistance to attacks such as compression. In addition, it is possible to effectively avoid the deterioration of the sound quality of the digital audio signal DA1 and to conceal the copyright information DC so as to be difficult to find.

Specifically, the level value P1 is a value adaptively determined according to the peak value of the input digital audio signal, and is a specific section of the digital audio signal DA1 in which the copyright information DC is to be embedded. It reflects the spectrum energy of Thereby, the watermark encoder 4 converts the frequency spectrum signal DS
1 is adaptively controlled to embed a watermark according to the energy distribution of the frequency spectrum value 1 and the frequency spectrum value spe
When c _i is relatively large, control can be performed such that copyright information DC is embedded, and when frequency spectrum value spectrum _i is relatively small, copyright information DC is not embedded.

Then, in the watermark encoder 4, the selected frequency spectrum value speci is _specified.
Is set to a logical value corresponding to the copyright information DC, and the frequency spectrum signal DS1 is operated, and the operated frequency spectrum signal DS1 is inverted MDC.
T conversion processing is performed, whereby copyright information DC is embedded in the digital audio signal DA1.

At this time, a predetermined offset value is added below the bit whose logical value is set by the copyright information DC so that the logical value by the copyright information DC does not change by addition and subtraction to at least the least significant bit. Thus, when reproducing the copyright information DC, the copyright information DC can be correctly reproduced even if the frequency spectrum value changes due to a quantization error.

In the copyright information DC recorded in a manner superimposed on the digital audio signal DA1 in this manner, even when dubbing is performed in the form of a digital signal or in the form of an analog signal, the dubbing is performed as it is. Become. Thus, when dubbing, the dubbed source is reproduced, the copyright information DC superimposed on the digital audio signal DA1 is confirmed, and various countermeasures against illegal copying can be implemented.

Next, the watermark decoder 6 will be described with reference to FIGS. As described above, the watermark decoder 6 is accommodated in the recording / reproducing device 2 and the reproducing device 3 of the system shown in FIG. 1, and includes, for example, an optical disk 5, a magneto-optical disk 7, a digital audio tape recorder 8, a CD-ROM. The copyright information DC is reproduced from the digital audio signal DA2 obtained by reproducing R9 and the like. FIG. 6 is a block diagram showing a configuration of the watermark decoder 6. The watermark decoder 6 includes a trigger detection unit 21, an MD
It has a CT calculator 22 and a decoder 23. Also,
The decoding unit 23 has an adaptive selection unit 24 and a bit detection unit 25. First, the configuration of each unit of the watermark decoder 6 will be described.

The trigger detecting section 21 repeatedly detects a peak on the waveform of the digital audio signal DA2 sequentially inputted, and detects a reference timing for reproducing the copyright information DC for a certain section.

The MDCT calculation unit 22 includes the trigger detection unit 2
By the timing based on the peak detected in step 1,
The digital audio signal DA2 sequentially input is subjected to MDCT processing in the same manner as the above-mentioned MDCT calculation unit 12, and is converted into a frequency spectrum signal DS2. Here, the frequency spectrum signal DS2 is a set of coefficient data obtained by performing the MDCT processing on the digital audio signal DA2, and is a signal indicating the signal level of each frequency spectrum obtained by the MDCT processing.

The decoding unit 23 reproduces and outputs copyright information DC from the frequency spectrum signal DS2 obtained by the MDCT calculation unit 22.

The adaptive selection of the decoding unit 23 24, the level value the value spec _i of i-th frequency spectrum of the frequency spectrum signal DS2 is adaptively determined according to the detected peak value in a trigger detection unit 21 If it is larger than P2, its frequency spectrum value spec _i
Is selected as the spectrum signal in which the copyright information DC is embedded, and the frequency spectrum number i is output to the bit detection unit 25 together with the frequency spectrum signal DS2.

The bit detector 25 of the decoding unit 23, from the frequency spectrum value spec _i chosen for each sample block in the adaptive selector 24 as described above, to reproduce the information DC of copyright. That is, the bit detector 25
Is selected read a predetermined bit frequency spectrum value spec _i selective, sequential copyright data by bit strings detected in each sample block information DC
Output as

In the recording / reproducing apparatus 2 and the reproducing apparatus 3 of the present embodiment, when dubbing the optical disc 5,
Dubbing can be restricted based on this copyright information. It is also possible to determine the source of a source suspected of being illegally copied.

Next, the processing flow in the watermark decoder 6 will be described with reference to FIG. FIG. 7 is a flowchart showing the flow of the process of the watermark decoder 6. In the watermark decoder 6, first, when the process is started (step SP21), it is determined whether or not a peak on the waveform is detected by the trigger detecting unit 21, that is, a reference for reproducing the copyright information DC for a certain section. It is determined whether a certain timing has been detected (step SP22). Step SP22
In, if no peak is detected, the process waits until a peak is detected.

In step SP22, when the reference timing for reproducing the copyright information DC for a certain section is detected, the digital audio signal DA2 is sequentially read for each sample block (step SP2).
3) The MDCT calculation section 22 executes the MDCT calculation to calculate the frequency spectrum signal DS2 (step SP24). Then, the frequency spectrum signal DS2
And the level value P2 to select a frequency spectrum value spectrum _{i in} which the copyright information DC is embedded, specify the number i of the frequency spectrum for reproducing the copyright information DC (step SP25), and select the selected frequency. reads the predetermined bit of the spectrum values spec _i, demodulates the information DC copyright (step SP26).

Then, it is determined whether or not the section for reproducing the copyright information DC has ended (step SP27). If the section for reproducing the copyright information DC has not ended, the process returns to step SP23, and The processing of step SP23 to step SP26 is repeated for the sample block of. In step SP27, if the section for reproducing the copyright information DC has ended, it is determined whether or not the processing of the digital audio signal DA2 has been completed (step SP28).
2, the process from step SP23 to step SP27 is repeated for the next section, and the next copyright information DC
Is performed. If the processing of the digital audio signal DA2 has been completed in step SP28, a series of processing ends (step SP29).

Finally, the operation of the watermark decoder 6 and the effect of each processing / operation will be described together. The various digital audio signals DA2 generated by the water mark encoder 4 as described above are input to the watermark decoder 6, and the trigger detecting section 21 repeatedly detects the peaks on the waveform of the digital audio signal DA2. The reference timing for reproducing the copyright information DC in a certain section is specified. Thereby, the digital audio signal DA
1 at the same timing as when the copyright information DC is embedded.
The copyright information DC can be reproduced from A2. When reproducing this type of data, even if the digital audio signal DA2 is deformed by various attacks such as transmission path noise, clipping, filtering, resampling, AD / DA conversion, and compression processing, the copyright is protected. Can be correctly reproduced.

Here, the digital audio signal DA2
Are sequentially converted into a frequency spectrum signal DS2 by an MDCT conversion process in an MDCT calculation unit 22, and a decoding unit 23 reproduces and outputs copyright information DC from the frequency spectrum signal DS2. In the watermark decoder 6, each frequency spectrum value sp of the frequency spectrum signal DS2 is
If ec _i is greater than the level value P2 determined adaptively in accordance with the peak value only, to reproduce the information DC copyright than the frequency spectrum value spec _i. Therefore, the watermark decoder 6 can correctly select the frequency spectrum value spectrum _{i in} which the copyright information DC is embedded in the watermark encoder 4, and the selected frequency spectrum value spectrum
c _i given bit is detected from which the information DC copyright are reproduced.

The present invention is not limited only to the present embodiment, and various suitable modifications are possible. For example, in the above-described embodiment, a case has been described in which a peak on a waveform is used as a reference timing for embedding copyright information. For example, a zero-cross point, a gap portion having continuous zero values, and an audio signal Various triggers, such as a rapidly changing attack portion, can be used as reference timing.

In the above-described embodiment, when the frequency spectrum value is larger than the predetermined level value, the frequency spectrum value is bit-operated to directly embed the copyright data. Calculate some representative value for the frequency spectrum value,
Copyright data may be embedded indirectly via this representative value. By doing so, the confidentiality of the embedded data can be increased accordingly.

Further, in the above-described embodiment, when the frequency spectrum value is larger than the predetermined level value, one bit of the copyright data is embedded in each sample block, but a plurality of bits are embedded in each sample block. The copyright data may be embedded for each block length different from the sample block.

Further, in the above-described embodiment, the level value is determined according to the peak value on the waveform of the digital audio signal. However, for example, various indices such as the average spectrum energy for each sample block are used. The level value may be determined according to.

In the above-described embodiment, the digital audio signal is converted into a frequency spectrum signal by the MDCT transform which is one of the orthogonal transforms. However, the digital audio signal is converted into the digital signal by various orthogonal transform methods such as a fast Fourier transform. The audio signal may be converted into a frequency spectrum signal.

Further, in the above-described embodiment,
Although the case where the copyright information is superimposed has been described, any suitable various information may be superimposed. Further, 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 may be applied to a case where various information is transmitted via the Internet, for example.

[0061]

As described above, according to the present invention,
A desired signal such as watermark information can be converted into a continuous signal such as audio data without deteriorating the quality of the continuous signal and having sufficient resistance to various processes on the continuous signal. , A signal processing device capable of appropriately superimposing the signal and a method thereof can be provided. Further, a signal processing device capable of appropriately demodulating watermark information from a continuous signal on which a desired signal such as watermark information is superimposed and reproducing the original continuous signal without deterioration in quality, A method can be provided.

A desired signal such as watermark information is converted into a continuous signal such as audio data.
Appropriate superimposition without deteriorating the quality of the continuous signal and with sufficient resistance to various processes on the continuous signal, and printing the continuous signal on which the water mark information is superimposed on a recording medium. A signal recording device for recording can be provided. In addition, a recording signal is reproduced from a recording medium on which a continuous signal on which the watermark information is superimposed is recorded, the watermark information is appropriately demodulated, and the original continuous signal is reproduced without deterioration in quality. And a signal reproducing apparatus capable of performing the above.

Furthermore, a desired signal such as watermark information can be converted into a continuous signal such as audio data, for example, and the watermark information can be appropriately demodulated from the reproduced signal so that the continuous signal can be reproduced without deterioration in quality. It is possible to provide a recording medium on which a superimposed signal is recorded.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a series of systems according to an embodiment of the present invention in which digital watermark information is superimposed on audio data and copy control is performed on the digital watermark information.

FIG. 2 is a block diagram showing a configuration of a watermark encoder of the system shown in FIG. 1;

FIG. 3 is a diagram for explaining an operation of a trigger detection unit and an adaptive selection unit of an encoding unit of the watermark encoder shown in FIG. 2;

FIG. 4 is a diagram for explaining a bit operation in a bit operation unit of an encoding unit of the watermark encoder shown in FIG. 2;

FIG. 5 is a flowchart illustrating a flow of a process in the watermark encoder illustrated in FIG. 2;

FIG. 6 is a block diagram showing a configuration of a watermark decoder of the system shown in FIG. 1;

FIG. 7 is a flowchart illustrating a processing flow in the watermark decoder shown in FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording device, 2 ... Recording / reproducing device, 3 ... Reproducing device, 4 ...
Watermark encoder, 5 optical disk, 6 watermark decoder, 7 magneto-optical disk, 8 digital audio tape recorder, 9 CD-R,
11: trigger detection unit, 12: MDCT calculation unit, 13:
Encoding unit, 14 adaptive selection unit, 15 bit operation unit, 16 IMDCT unit, 21 trigger detection unit, 22
... MDCT calculation unit, 23 ... decoding unit, 24 ... adaptive selection unit, 25 ... bit detection unit

Claims (25)

[Claims] 1. A signal processing apparatus for superimposing a desired signal on an arbitrary digital continuous signal, comprising: performing a predetermined orthogonal transform for each predetermined block of the continuous signal to generate a frequency spectrum of the signal. And a signal superimposing means for superimposing the desired signal on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum. 2. The signal superimposing means compares the level of each spectrum signal of the generated frequency spectrum with a predetermined reference level, and based on a result of the comparison, sets the signal level to be lower than the predetermined reference level. The signal processing device according to claim 1, wherein the desired signal is superimposed on the spectrum signal whose signal level is higher or equal to or higher than the predetermined reference level. 3. The signal processing apparatus according to claim 2, wherein said signal superimposing means detects a maximum value of an amplitude of said continuous signal, and determines said predetermined reference level based on said maximum value of said amplitude. 4. A range for detecting a maximum value of the amplitude of the continuous signal and determining a range serving as a unit of processing for superimposing the desired signal on the continuous signal based on the detected maximum value of the amplitude. Determining means for detecting the maximum value of the amplitude of the continuous signal for each of the determined ranges, determining the predetermined reference level, and determining at least one or more in the range. The signal processing device according to claim 3, wherein the desired signal is superimposed so that the desired signal is included. 5. The signal superimposing means superimposes the desired signal by sequentially replacing predetermined bit data of the spectrum signal data having a sufficiently high signal level with the desired signal data. The signal processing device according to claim 1. 6. The signal superimposing means, wherein when the continuous signal is output in a predetermined form based on the type of the signal, the data indicating the level of the signal in the data of the spectrum signal is output. 6. The signal according to claim 5, wherein predetermined data of predetermined one or a plurality of bits having such a low weight that a change in the continuous signal due to superimposition of the continuous signal cannot be observed is sequentially replaced with data of the desired signal. Processing equipment. 7. The signal superimposing means converts the one or more predetermined bits to be replaced with data of the desired signal,
The low weight bits not including the predetermined number of bits from the least significant bit of the spectrum signal data, the predetermined number of bits from the least significant, by addition and subtraction to the least significant bit of the spectrum signal data, 7. The signal processing apparatus according to claim 6, wherein predetermined data is set such that data of the predetermined bit replaced with data of the desired signal is not affected. 8. The signal processing apparatus according to claim 1, wherein said orthogonal transform means performs discrete cosine transform (DCT) on said continuous signal and detects a frequency spectrum of said continuous signal. 9. The signal processing apparatus according to claim 1, further comprising an inverse orthogonal transform means for performing an inverse orthogonal transform on the frequency spectrum on which the desired signal is superimposed, and generating a digital continuous signal on which the desired signal is superimposed. apparatus 10. The inverse orthogonal transform means according to claim 9, wherein said frequency spectrum on which said desired signal is superimposed is subjected to inverse discrete cosine transform (IDCT) to generate a digital continuous signal on which said desired signal is superimposed. A signal processing device according to claim 1. 11. The continuous signal is a signal relating to a desired work, and the desired signal superimposed on the continuous signal is a signal of information relating to copyright protection of the work. The signal processing device according to claim 1. 12. A method for superimposing a predetermined signal related to copyright protection of a work on a digital continuous signal related to an arbitrary work, wherein a predetermined orthogonal transform is performed for each predetermined block of the continuous signal. And generating a frequency spectrum of the signal, and superimposing the desired signal on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum. 13. A signal in which a desired signal is sequentially superimposed on a spectrum signal having a sufficiently large signal level in a frequency spectrum of an arbitrary digital continuous signal.
A signal processing device for reproducing at least the desired signal, wherein the orthogonal processing unit performs a predetermined orthogonal transform for each predetermined block of the arbitrary digital continuous signal, and generates a frequency spectrum of the signal. A signal extraction unit for extracting the desired signal from a spectrum signal having a sufficiently large signal level in a frequency spectrum. 14. The signal extracting means compares the level of each spectrum signal of the generated frequency spectrum with a predetermined reference level, and based on the result of the comparison, sets the signal level to be lower than the predetermined reference level. 14. The signal processing device according to claim 13, wherein the desired signal is extracted from the spectrum signal having a higher level or a signal level equal to or higher than the predetermined reference level. 15. The signal processing apparatus according to claim 14, wherein said signal extracting means detects a maximum value of an amplitude of said continuous signal and determines said predetermined reference level based on said maximum value of said amplitude. 16. A maximum value of the amplitude of the continuous signal is detected,
The apparatus further includes a range determination unit that determines a range that is a unit in which the desired signal is superimposed on the continuous signal based on the detected maximum value of the amplitude. The signal processing device according to claim 15, wherein a maximum value of the amplitude of the continuous signal is detected for each range, the predetermined reference level is determined, and the desired signal is extracted. 17. The signal processing apparatus according to claim 13, wherein said signal extracting means sequentially extracts predetermined bit data of the spectrum signal data having a sufficiently large signal level as said desired signal data. 18. The signal processing apparatus according to claim 13, wherein said orthogonal transform means performs discrete cosine transform (DCT) on said continuous signal and detects a frequency spectrum of said continuous signal. 19. The continuous signal is a signal related to a desired work, and the desired signal superimposed on the continuous signal is a signal of information related to copyright protection of the work. The signal processing device according to claim 1. 20. A signal in which a desired signal related to copyright protection of a copyrighted work is sequentially superimposed on a spectrum signal having a sufficiently large signal level in a frequency spectrum of a digital continuous signal related to an arbitrary copyrighted work. Thus, at least a signal processing method for reproducing a desired signal related to copyright protection, performing a predetermined orthogonal transformation for each predetermined block of the arbitrary digital continuous signal, generating a frequency spectrum of the signal, A signal processing method for extracting the desired signal from a spectrum signal having a sufficiently large signal level in the generated frequency spectrum. 21. A signal recording apparatus for superposing a desired signal on an arbitrary digital continuous signal and recording the signal on an arbitrary recording medium, performing a predetermined orthogonal transformation for each predetermined block of the continuous signal, and Orthogonal transform means for generating a frequency spectrum; signal superimposing means for superimposing the desired signal on a spectrum signal having a sufficiently large signal level in the generated frequency spectrum; and the desired signal being superimposed. Recording means for recording a signal relating to the continuous signal on a recording medium. 22. An orthogonal transform unit for inversely transforming the frequency spectrum on which the desired signal is superimposed to generate a digital continuous signal on which the desired signal is superimposed. 22. The signal recording apparatus according to claim 21, wherein the digital continuous signal on which a desired signal is superimposed is recorded on the recording medium. 23. A recording medium in which a recording signal in which a desired signal is sequentially superimposed on a spectrum signal having a sufficiently large signal level in a frequency spectrum of an arbitrary digital continuous signal is recorded from a recording medium. A signal reproducing apparatus that reproduces the desired signal, comprising: a level of each spectrum signal of the frequency spectrum;
Level comparing means for comparing a signal level with the predetermined reference level and detecting a spectrum signal whose signal level is higher than the predetermined reference level or whose signal level is equal to or higher than the predetermined reference level; A signal reproducing device comprising: signal extracting means for extracting a desired signal. 24. The recording signal is a digital continuous signal obtained by inverse orthogonally transforming a frequency spectrum on which the desired signal is superimposed, performing a predetermined orthogonal transformation on the recording signal, and converting a frequency spectrum of the signal. 24. The signal reproducing apparatus according to claim 23, further comprising an orthogonal transform unit for generating, wherein the level comparing unit performs the comparison on each of the spectrum signals of the generated frequency spectrum. 25. A recording medium in which a signal is superimposed on a digital continuous signal relating to an arbitrary work and a predetermined signal relating to copyright protection of the work is recorded. For the signal, the level of each spectrum signal of the frequency spectrum of the digital continuous signal obtained from the reproduction signal is compared with a predetermined reference level, and the signal level is higher than the predetermined reference level or the signal level is higher than the predetermined reference level. The digital continuous signal and the recording signal from which the desired signal is reproduced are recorded by detecting the spectrum signal that is equal to or higher than a predetermined reference level and extracting the desired signal from the detected spectrum signal. Recording media.