JP6317078B2 - Audio signal digital watermark adding apparatus and display apparatus, method thereof, and program thereof - Google Patents

Description

  The present invention relates to audio signal conversion, and more particularly to a device for adding a digital watermark, a device for displaying a digital watermark, a method thereof, and a program thereof.

  An example of the technology of a normal digital watermark adding apparatus will be described with reference to FIG.

  In order to add the digital watermark information to the audio signal, it is desirable to add the digital watermark information so as not to stand out as sound.

  In the simplest method shown in FIG. 1, an input audio signal s100 is suppressed by a low-pass filter 1000 and a high-frequency signal is suppressed, and a digital watermark signal s200 in which digital watermark information is expressed by an amplitude value of a high-frequency is used. The signal is added by the additional device 1001 to obtain the audio signal s102.

  If the digital watermark signal s200 is set to a high frequency (for example, 15 Hz or more) that is difficult for humans to listen to, the signal becomes inconspicuous as a sound and deterioration of audio quality is avoided, but an analog device that cuts the high frequency is used. When the audio content is duplicated, the digital watermark information is lost. Also, since it is easy to remove digital watermark information without degrading audio quality, it is not preferable as a digital watermark used for the purpose of copyright protection of audio contents.

  Japanese Patent Laid-Open No. 2004-151867 discloses audio data converted from a time domain signal to a frequency domain signal and subjected to quantization processing in order to realize a digital watermark insertion method suitable for digital audio data encoding processing. An electronic watermark embedding device characterized by inserting digital watermark information is disclosed. However, although a reversible replacement processing circuit having means for inserting digital watermark information into quantized audio data is described, the reversible replacement processing circuit includes a first switch circuit, The first switch circuit selects and outputs either the digital watermark information or the maximum value in the selected subband. That is, since the position where the digital watermark is embedded is the position of the frequency component that is important for human auditory characteristics among the frequency components of the audio data, it is assumed that the audio quality is greatly degraded by the insertion of the digital watermark. .

JP 11-316599 A

  Therefore, an object of the present invention is to provide a digital watermark adding apparatus, a method thereof, and a program thereof that can reduce the deterioration of audio quality of an audio signal to which digital watermark information is added.

  It is another object of the present invention to provide a digital watermark display apparatus, a method thereof, and a program thereof that make it easy to display a digital watermark.

  According to the first aspect of the present invention, an input stereo signal is converted into a frequency domain signal, and a two-axis set of a two-dimensional image using a set of a time axis and a frequency axis of the converted signal as a digital watermark. Then, a two-dimensional image as the digital watermark is added to the converted signal.

  According to the second aspect of the present invention, a stereo signal is converted into a frequency domain signal, and a set of a time axis and a frequency axis of the converted signal is converted into a two-axis set of a two-dimensional image as a digital watermark. Then, a two-dimensional image as the digital watermark added to the converted signal is detected from the stereo signal after the addition.

  Further, according to the third aspect of the present invention, a step of converting an input stereo signal into a frequency domain signal, and a set of a time axis and a frequency axis of the converted signal as a digital watermark And a step of adding a two-dimensional image as the digital watermark to the converted signal after corresponding to a set of two axes.

  In addition, according to the fourth aspect of the present invention, a step of converting a stereo signal into a frequency domain signal, and two axes of a two-dimensional image using a set of a time axis and a frequency axis of the converted signal as a digital watermark. And detecting a two-dimensional image as the digital watermark added to the converted signal from the stereo signal after the addition. Is provided.

  In addition, according to the fifth aspect of the present invention, in a program for causing a computer to function as a digital watermark adding apparatus, the computer converts an input stereo signal into a frequency domain signal, and converts the time of the converted signal. An electronic watermark characterized in that a set of an axis and a frequency axis is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and then the two-dimensional image as the digital watermark is added to the converted signal A program for adding a digital watermark for functioning as an adding device is provided.

  In addition, according to a sixth aspect of the present invention, in a program for causing a computer to function as a digital watermark detection apparatus, the computer converts a stereo signal into a frequency domain signal, and a time axis of the converted signal The frequency axis set is made to correspond to the two-axis set of the two-dimensional image as the digital watermark, and then the two-dimensional image as the digital watermark added to the converted signal is detected from the stereo signal after the addition. There is provided a digital watermark detection program for causing a digital watermark detection apparatus to function.

  According to the present invention, in the digital watermark adding apparatus, it is possible to reduce the deterioration of the audio quality of the audio signal to which the digital watermark information is added.

  In addition, according to the present invention, the digital watermark display apparatus can easily display the digital watermark.

It is a block diagram of a normal digital watermark adding apparatus. 1 is a configuration diagram of a digital watermark adding apparatus according to an embodiment of the present invention. It is a block diagram of the phase converter contained in the digital watermark adding apparatus by embodiment of this invention. It is a block diagram of the phase controller contained in the digital watermark adding apparatus by embodiment of this invention. 1 is a configuration diagram of a digital watermark display device according to an embodiment of the present invention. It is a flowchart which shows operation | movement of the digital watermark adding apparatus by embodiment of this invention. It is a table | surface which shows the control mode of the phase converter contained in the digital watermark adding apparatus by embodiment of this invention. 5 is a flowchart illustrating an operation of the digital watermark display device according to the embodiment of the present invention. It is a figure which shows the spectrogram of the pseudo stereo signal of Lch and Rch which added the digital watermark. It is a figure which shows the spectrogram of the monaural signal which converted the pseudo stereo signal to which the digital watermark was added.

(Description of configuration)
FIG. 2 is a block diagram of the digital watermark adding apparatus 1 according to the present invention. The digital watermark adding apparatus 1 includes Lch and Rch frequency analyzers 10-L and 10-R, a phase controller 20, and phase converters 30-L ₀ to 30-L _n and 30-R ₀ to 30. including a -R _n, the Lch and Rch respective frequency components synthesizer-50 L and 50-R.

Frequency analyzer 10-L inputs the Lch audio signal s1-L, Lch phase converter are each frequency component signal _s3-L 0 _{~s3-L n} of each frequency corresponding on of frequency analysis 30- L ₀ is output to to _{30-L n} and the phase shifter _30-R 0 ~30-R _n of Rch.

Similarly, the frequency analyzer 10-R inputs the Rch audio signal s1-R, the phase transformation of the Lch, each corresponding frequency component signal _s3-R 0 _{~s3-R n} for each frequency on which frequency analysis and it outputs the vessel _30-L 0 _{~30-L n} and the phase shifter _30-R 0 _{~30-R n} of Rch.

  Here, n is the number of sampling points for frequency analysis, and is an arbitrary number.

Phase controller 20 inputs the digital watermark signal s2, each control signal corresponding to the pixel of the two-dimensional image _s4-L 0 _{~s4-L n} and _s4-R 0 _{~s4-R n} of the electronic watermark to be added and each of which outputs a corresponding phase converter _30-L 0 to-to 30 _{L n} and _{30-R 0 ~30-R n} .

The phase converter 30-L _x (0 ≦ x ≦ n, where x is an integer) is a frequency component signal s3-L _x from the frequency analyzer 10-L and a frequency component from the frequency analyzer 10-R. signal _{s3-R x,} and inputs the control signal _{s4-L x} from the phase controller 20, and outputs a phase conversion output signal _{s5-L x} into a frequency component synthesizer 50-L of Lch.

Likewise, (a 0 ≦ x ≦ n, x is an integer) phase converter _30-R x is the frequency component signal _{s3-L x} and the frequency analyzer 10-R from the frequency analyzer 10-L Frequency component signal s3- _Rx and the control signal s4- _Rx from the phase controller 20 are input, and the phase conversion output signal s5- _Rx is output to the Rch frequency component synthesizer 50-R.

Frequency component synthesizer 50-L of the Lch, the phase converter _30-L 0 _{~30-L n} the phase conversion output signal _s5-L 0 _{~s5-L n} from the input, the phase conversion output signal s5 input -L _{0 ~s5-L n} watermark by combining the added digital watermark additional signal s6-L from outputs.

Similarly, the frequency component synthesizer 50-R of Rch inputs the phase conversion output signal _s5-R 0 _{~s5-R n} from the phase converter _{30-R 0 ~30-R n} , phase conversion input synthesizing an electronic watermark additional signal s6-R with the digital watermark is added from an output signal _{s5-R 0 ~s5-R n} , and outputs.

As an example of the configuration of the phase converters 30- _Lx and 30- _Rx , the configuration of the phase converter 30- _Xn is shown in FIG. Here, X is L or R, and Y is R or L. That is, Y = R when X = L, and Y = L when X = R. The phase converter 30- _Xn includes an adder 300- _Xn , a phase shift amplifier 301- _Xn, and an addition control switch 302- _Xn .

Phase converter _{30-X n} is the frequency component signals _{s3-Y n} from the frequency component signals _{s3-X n} and the frequency analyzer 10-Y from the frequency analyzer 10-X, and control signals from the phase controller 20 s4- _Xn is taken as input.

Control signal _{s4-X n,} by controlling the addition control switch _{302-X n,} in the adder _{300-X n,} whether adding the frequency component signal _{s3-Y n} in the frequency component signal _{s3-X n} To control.

Further, the control signal _{s4-X n,} the phase shift amplifier _{301-X n} also controls. As a result, frequency component signal _{s3-X n} and the frequency component signal _{s3-Y n} monaural sum signal or the frequency component signal _{s3-X n} only the original signal phase, is the phase by the phase shift amplifier _{301-X n} is shifted, output from the phase converter _{30-X n} as a phase conversion output signal _{s5-X n.}

Phase converter _{30-X 0 ~30-X n} -1 is the same.

FIG. 4 shows the configuration of the phase controller 20. The phase controller 20 includes n phase determiners 200-0 to 200-n. As described above, n corresponds to the number of sampling points in the frequency analyzers 10-L and 10-R, and each phase determiner 200-x (0 ≦ x ≦ n, where x is an integer) Corresponding to the devices 30- _Lx and 30- _Rx . The digital watermark signal s2 input to the phase controller 20 is input to each phase determiner 200-0 to 200-n. As will be described later, the xy axis of the two-dimensional image as the digital watermark corresponds to the tf axis of the audio signal, but each phase determiner corresponds to each frequency.

Taking 200-n as an example among the phase determiners 200-0 to 200-n, the phase determiner 200-n adds an adder to the phase converter 30- _Xn according to the gray value of the pixel. and _{300-X n} on / off monaural addition by, outputs a control signal _{s4-X n} for controlling the amount of phase shift by the phase shift amplifier _{301-X n.} That is, the phase determiner 200-n outputs a control signal _{s4-L n} to the phase converter _{30-L n,} and outputs a control signal _{s4-Y n} to the phase converter _{30-Y n.}

  When a digital watermark is inserted, monaural addition is turned on and phase shift is performed.

  When no digital watermark is inserted, monaural addition is set to off and the phase shift amount is set to zero. As a result, the pseudo stereo signal output from the digital watermark adding apparatus 1 becomes a normal stereo signal. For example, when dealing with stereo audio signals such as music, insert a digital watermark only in the first few milliseconds and do not insert a digital watermark in the remaining time, or insert it at the end. Degradation can be avoided.

  The same applies to the phase determiners 200-0 to 200-n-1.

  The image signal of the two-dimensional image of the digital watermark is converted into a one-dimensional scanning signal and sequentially supplied to the phase controller 20, whereby each of the x-axis and y-axis of the two-dimensional image is added with the digital watermark addition signal s6- This corresponds to the time axis and frequency axis of L and s6-R. Specifically, pixels from the upper end to the lower end of a certain line in the two-dimensional image correspond to each frequency component at a certain time. The pixel signal from the upper end to the lower end of a certain line is input to the phase controller 20, and when the processing is completed, the pixel signal from the upper end to the lower end of the next line is input to the phase controller 20. The pixel signals from the upper end to the lower end of the next line correspond to each frequency component at the next time. By repeating this, the x-axis and y-axis of the two-dimensional image of the digital watermark correspond to the time axis and the frequency axis of the digital watermark addition signals s6-L and s6-R.

  Here, it has been described that the x-axis and the y-axis of the two-dimensional image correspond to the time axis and the frequency axis of the digital watermark addition signals s6-L and s6-R, but the embodiment of the present invention is not limited to this. , The x axis may correspond to the frequency axis, and the y axis may correspond to the time axis. Also, any two non-orthogonal axes of the two-dimensional image may correspond to the time axis and the frequency axis of the digital watermark addition signals s6-L and s6-R.

  FIG. 5 is a block diagram of the digital watermark display device 6 according to the present invention. The digital watermark display device 2 includes an adder 60 and a display 70, and the display 70 includes a frequency analyzer 700 and a grayscale display 701.

The adder 60 receives the digital watermark addition signals s 6 -L and s 6 -R, which are pseudo stereo audio signals, and outputs the monaural signal s 7 -M to the frequency analyzer 700 of the display 70 after monaural addition. The frequency analyzer 700, a monaural signal s7-M frequency analysis, and outputs a frequency component signal _s70-M 0 _{~s70-M n} in grayscale display 701.
(Description of operation)
The operation principle will be described using the frequency analyzers 10-L and 10-R as typical FFT calculators and the frequency synthesizers 50-L and 50-R as typical inverse FFT calculators. The aspect is not limited to this.

The Lch complex signal, which is the output of the FFT calculator, is L [x], and the Rch signal complex signal is R [x]. a _L [x] and a _R [x] are real part components, and b _L [x] and b _R [x] are imaginary part components.

(Formula 1)

(Formula 2)
x is a frequency component number and is an integer of 0, 1, 2,... n. Here, L [x] and R [x], respectively, corresponding to the frequency component signals _{s3-L x} and _{s3-R x} in FIG.

  The frequency component signal to which the digital watermark image information is added is converted into a monaural signal M [x] by Equation 3.

(Formula 3)
In the period in which the digital watermark is not inserted, the input signal is not converted into the frequency component signal, and the original signal is maintained.

  A phase angle φ [x] shifted by Equation 4 is obtained for the monaural frequency component.

(Formula 4)
Here, z [x] is a value indicating the luminance (or grayscale) of the digital watermark pixel to be displayed, and 0 ≦ z [x] ≦ 2. When the luminance of the pixel is maximum, it corresponds to z [x] = 0, and when the luminance of the pixel is minimum, it corresponds to z [x] = 2. In the range of 0 ≦ z [x] ≦ 2, φ [x] is a monotonically decreasing function. For example, when z [x] is “0”, it is the value that is most desired to be displayed in white, and φ [n] = π. Further, when z [x] is “2”, it is a value that is most desired to be displayed in black, and φ [n] = 0.

  Note that Expression 4 is merely an example, and may be a monotonically increasing function in the range of 0 ≦ z [x] ≦ 2 with reversed polarity.

As an example, it is assumed that the Lch signal L ′ [x] generated by the phase converter 30 -L _x outputs the monaural signal M [x] as it is.

(Formula 5)
On the other hand, the Rch signal R ′ [x] generated by the phase converter 30-Rx is obtained by shifting the phase of the L ′ [x], that is, the monaural signal M [x] by Expression 6 of the rotation calculation. And

(Formula 6)
These calculations are performed for FFT points. Thereafter, each of frequency synthesizers 50-L and 50-R, which are inverse FFT calculators, synthesizes L ′ [x] and R ′ [x], and each frequency synthesizer is a pseudo stereo signal. Certain digital watermark addition signals s6-L and s6-R are output.

In the digital watermark insertion period, both s6-L output from Lch and s6-R output from Rch are synthesized signals obtained by adding L [x] and R [x]. It becomes a monaural signal. On the other hand, since neither addition nor phase shift is performed during a period in which no digital watermark is inserted, s6-L and s6-R are stereo signals. It is recognized as a stereo signal by shortening the period for inserting the digital watermark or by setting the insertion position at the end.
In addition, since the information of the two-dimensional image of the digital watermark data is added to each unit time, the above operation is repeated.

  When the digital watermark display device 6 displays a digital watermark, the adder 60 performs monaural addition of the digital watermark addition signals s6-L and s6-R, which are pseudo stereo signals, to convert them into a monaural signal s7-M, and the frequency The analyzer 700 performs frequency analysis.

As described above, in the case of pixels to be displayed whitest, z [x] = 0 than φ [x] = π, and therefore, in equation 7, the monaural signal s70-M _x 0, and the spectral components disappear .

(Formula 7)
In the case of a pixel to be displayed the most black, since the z [x] = 2.0 than φ [x] = 0, in equation 8, monaural signal _{s70-M x} is the left monaural signal M [x] Become.

(Formula 8)
With these operation principles, the synthesized audio signal is displayed as a power spectrogram by FFT calculation, and a digital watermark can emerge as image information.

  An embodiment of the digital watermark adding apparatus 1 shown in FIG. 2 will be described with reference to the flowchart of FIG.

Frequency analyzer 10-L is to decompose the Lch signal s1-L stereo audio signal into a frequency component signal _s3-L 0 _{~s3-L n} for each frequency component. Similarly, degrade the frequency analyzer 10-R is Rch signal s1-R, the frequency component signal _s3-R 0 _{~s3-R n} for each frequency component (step S101). The output frequency component signal corresponds to Equation 1 and Equation 2.

With the frequency analyzer 10-L frequency component signals decomposed by _{s3-L 0} is frequency component signal _{s3-R 0,} which is decomposed in the frequency analyzer 10-R, are input to the phase converter _{30-L 0.} Similarly, with frequency component signal _{s3-R 0} is the frequency component signal _{s3-L 0} which is decomposed in the frequency analyzer 10-L decomposed in the frequency analyzer 10-R, the input to the phase converter _{30-R 0} Is done.

  These phase converters are provided for each L / Rch and each frequency component.

That is, 1 ≦ x ≦ n, when x is an integer, both of the frequency component signals _{s3-L x} and _{s3-R x} is input to the phase converter _{30-L x} and _{30-R x} (step S102).

The image signal s2 serving as a digital watermark is input to the phase controller 20 in FIG. 4 (step S103). Then, with respect to the frequency component at the position corresponding to the point of the pixel, the phase determiner 200-x corresponding to each frequency component from the gray value of the pixel is monaural in the phase converters 30- _Lx and 30- _Rx . The addition ON / OFF and the phase shift amount are determined (step S104). Each phase determinator 200-x outputs each control signal _{s4-L x} and _{s4-R x} that controls the mono summation and phase shift amount, the corresponding phase converter _{30-L x} and _{30-R x} ( Step S105).

The phase converter _{30-X n} of FIG. 3, and the _{s3-R n} frequency component signal _{s3-L n,} the control signal _{s4-X n} are input. Here, n is a frequency component number, and X and Y are L or R channel identification symbols. The control signal s4- _Xn controls the addition control switch 302- _Xn . Addition control switch _{302-X n} may be the mono sum (ON in step S106), the frequency component signal _{S3-Y n} is input to the adder _{300-X n} through the addition control switch _{302-X n.} In this case, the adder _{300-X n} is the frequency component signal _{S3-X n} and _{S3-Y n} monophonic sum, the addition output signal (Equation 3) to the phase shift amplifier _{301-X n} (step S107 ). If the addition control switch _{302-X n} does not mono summation, only the frequency component signal _{s3-X n} are input to the adder _{300-X n,} an adder _{300-X n} is the original signal frequency component signal s3-X _n is output to the phase shift amplifier 301- _Xn . (Step S108). Thereafter, the phase shift amplifier _{301-X n,} which is controlled by the control signal _{s4-X n} shifts the phase of the sum output signal or original signal, and outputs a phase conversion output signal _{s5-X n.} (Formula 5, Formula 6) (Step S109).

The same applies to the phase converter _{30-X 0 ~30-X n} -1.

Then, the frequency component synthesizer 50-L and 50-R are synthesized when phase conversion output signal _s5-L 1 _{~s5-L n} and _{s5-R 1 ~s5-R n} , is a pseudo-stereo audio signal The digital watermark addition signals s6-L and s6-R are output (step S110).

  Frequency analyzers 10-L and 10-R, phase controller 20, phase converters 30-Lx and 30-Rx (1 ≦ x ≦ n, x is an integer), frequency component synthesizers 50-L and 50- R repeats the above operation every unit time.

A control example of the phase converters 30-X ₀ to 30-X _n is shown in the table of FIG.

For example, for the point you want to view the most white as a pixel of the digital watermark, Lch side, i.e. in the phase converter 30-L _x, the control signal s4-L _x, 0 the phase shift amount and the mono addition switch to ON [ rad]. On the Rch side, that is, the phase converter 30- _Rx , the monaural addition switch is turned on and the phase shift amount is set to π [rad] by the control signal s4- _Rx .

Conversely, with respect to the point you want to view the most black, Lch side, i.e. in the phase converter _{30-L x,} the control signal _{s4-L x,} and the phase shift amount and the mono addition switch to ON 0 [rad] To do. Also on the Rch side, that is, on the phase converter 30- _Rx , the monaural addition switch is turned ON and the phase shift amount is set to 0 [rad] by the control signal s4- _Rx .

Incidentally, with respect to the point no pixels, Lch side, i.e. in the phase converter _{30-L x,} the control signal _{s4-L x,} the amount of phase shift to the mono addition switches to OFF and 0 [rad]. Also on the Rch side, that is, the phase converter 30- _Rx , the monaural addition switch is turned OFF and the phase shift amount is set to 0 [rad] by the control signal s4- _Rx . This means that the original signal is output as it is when there is no pixel.

  An embodiment of the digital watermark display device 6 shown in FIG. 5 will be described with reference to the flowchart of FIG.

  The adder 60 adds the Lch signal s6-L and the Rch signal s6-R of the digital watermark addition signal, which is a pseudo stereo audio signal, and outputs a monaural addition signal s7-M (step S201).

In the display device 70, a frequency analyzer 700 decomposes the monophonic sum signal s7-M, the frequency component signal _s70-M 0 _{~s70-M n} of each frequency component (step S202). The frequency analyzer 700 may be a typical FFT calculator, but the embodiment of the present invention is not limited to this.

Shading indicator 701 calculates the power of the frequency component signals _s70-M 0 _{~s70-M n} for each frequency component, each frequency is displayed as the image shading and brightness at the corresponding position (Formula 7 and Formula 8) (Step S203). The grayscale display 701 repeats frequency analysis and display for each fixed frame time (NO in step S204), and displays it as a two-dimensional screen with frequency on the vertical axis and time on the horizontal axis.

  The spectrogram of the Lch signal s-6L of the pseudo stereo audio signal added with a digital watermark according to the present invention is shown in the upper image of FIG. 9, and the spectrogram of the Rch signal s-6R is shown in the lower image of FIG.

  A signal with a strong frequency component is displayed in black and a weak signal is displayed in white, and neither of the channel signals can recognize digital watermark image data. That is, the audio signal is less deteriorated.

  Further, FIG. 10 shows a spectrogram when these pseudo-stereo audio signals to which digital watermarks are added are added and converted to a monaural signal. It can be recognized that the digital watermark image (an example of a character image) appears white as a whole in the lower part (low frequency position).

  Each part of the signal processing device described above can be realized by hardware, software, or a combination thereof. In addition, the signal processing method performed by the above signal processing apparatus can also be realized by hardware, software, or a combination thereof. Here, “realized by software” means realized by a computer reading and executing a program.

  The program may be stored using various types of non-transitory computer readable media and supplied to the computer. Non-transitory computer readable media include various types of tangible storage media. Examples of non-transitory computer readable media include magnetic recording media (for example, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (for example, magneto-optical disks), CD-ROMs (Read Only Memory), CD- R, CD-R / W, semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM (random access memory)). The program may also be supplied to the computer by various types of transitory computer readable media. Examples of transitory computer readable media include electrical signals, optical signals, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

  According to the present invention, in the digital watermark adding apparatus, even when audio content is copied, the digital watermark information is not lost, the audio signal to which the digital watermark information is added has little deterioration in audio quality, and the digital watermark information Removing audio can lead to significant degradation of audio quality.

  Further, according to the present invention, in the digital watermark display device, it is possible to easily display the digital watermark and to easily determine the digital watermark.

  A part or all of the above embodiment is described as in the following supplementary notes, but is not limited thereto.

(Appendix 1)
The input stereo signal is converted into a signal in the frequency domain, and a set of a time axis and a frequency axis of the converted signal is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and then the converted signal A digital watermark adding apparatus, wherein a two-dimensional image as the digital watermark is added to the digital watermark.

(Appendix 2)
The electronic watermark adding apparatus according to appendix 1, wherein
An electronic watermark adding apparatus, wherein a phase of a time / frequency component at a position corresponding to each pixel of the two-dimensional image is shifted according to a value of the pixel.

(Appendix 3)
The electronic watermark adding apparatus according to appendix 2, wherein
The input stereo signal is converted into a frequency domain signal for each channel, and the signal for each channel obtained by the conversion is generated for the number of channels, and each time / frequency component of the added signal is generated. A digital watermark adding apparatus characterized in that a shift amount corresponding to a value of a pixel located at a position corresponding to the component of the phase of the channel differs between channels.

(Appendix 4)
The electronic watermark adding apparatus according to appendix 2 or 3,
The digital watermark adding apparatus, wherein the function for calculating the shift amount is a monotonically increasing function or a monotonically decreasing function of the luminance of the pixel.

(Appendix 5)
The electronic watermark adding apparatus according to appendix 4, wherein
When the function is z [x] for the luminance of the pixel and φ [x] for the shift amount,

A digital watermark adding apparatus characterized by the above.

(Appendix 6)
A stereo signal is converted into a signal in the frequency domain, and a set of a time axis and a frequency axis of the converted signal is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and then added to the converted signal. A digital watermark detection apparatus for detecting a two-dimensional image as the digital watermark from the added stereo signal.

(Appendix 7)
The electronic watermark detection apparatus according to appendix 6, wherein
An electronic watermark detection apparatus, comprising: detecting a phase shift amount of each time / frequency component and detecting the two-dimensional image based on the phase shift amount.

(Appendix 8)
The electronic watermark detection apparatus according to appendix 6 or 7,
After adding the signals of both channels included in the stereo signal after addition, the signal is converted into a frequency component signal, and the converted frequency axis and time axis are two-dimensional two axes, and the converted signal An electronic watermark detection apparatus comprising means for two-dimensionally outputting the digital watermark.

(Appendix 9)
Converting the input stereo signal into a frequency domain signal;
A step of making a set of a time axis and a frequency axis of the converted signal correspond to a two-axis set of a two-dimensional image as a digital watermark, and then adding the two-dimensional image as the digital watermark to the converted signal When,
A method for adding a digital watermark, comprising:

(Appendix 10)
The electronic watermark adding method according to appendix 9, wherein
A method for adding a digital watermark, comprising: shifting a phase of a time / frequency component at a position corresponding to each pixel of the two-dimensional image according to a value of the pixel.

(Appendix 11)
The electronic watermark adding method according to appendix 10, wherein
The input stereo signal is converted into a frequency domain signal for each channel, and the signal for each channel obtained by the conversion is generated for the number of channels, and each time / frequency component of the added signal is generated. A digital watermark adding method characterized in that a shift amount corresponding to a value of a pixel located at a position corresponding to the component is different between channels.

(Appendix 12)
12. The digital watermark adding method according to appendix 10 or 11, wherein the function for calculating the shift amount is a monotone increasing function or a monotone decreasing function of the luminance of the pixel.

(Appendix 13)
The electronic watermark adding method according to attachment 12, comprising:
When the function is z [x] for the luminance of the pixel and φ [x] for the shift amount,

A method for adding a digital watermark.

(Appendix 14)
Converting a stereo signal into a frequency domain signal;
The set of the time axis and the frequency axis of the converted signal is made to correspond to the two-axis set of the two-dimensional image as a digital watermark, and then the two-dimensional image as the digital watermark added to the converted signal is Detecting from the stereo signal after the addition;
A digital watermark detection method comprising:

(Appendix 15)
The electronic watermark detection method according to appendix 14,
A digital watermark detection method, comprising: detecting a phase shift amount of each time / frequency component, and detecting the two-dimensional image based on the phase shift amount.

(Appendix 16)
The electronic watermark detection method according to appendix 14 or 15,
After adding the signals of both channels included in the stereo signal after addition, the signal is converted into a frequency component signal, and the converted frequency axis and time axis are two-dimensional two axes, and the converted signal A two-dimensional output step.

(Appendix 17)
In a program for causing a computer to function as a digital watermark adding device,
Computer
The input stereo signal is converted into a signal in the frequency domain, and a set of a time axis and a frequency axis of the converted signal is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and then the converted signal An electronic watermark addition program for causing a function as an electronic watermark addition apparatus to add a two-dimensional image as the electronic watermark to the electronic watermark.

(Appendix 18)
The electronic watermark addition program according to attachment 17, wherein
A digital watermark addition program for shifting a phase of a time / frequency component at a position corresponding to each pixel of the two-dimensional image according to a value of the pixel.

(Appendix 19)
The electronic watermark adding program according to appendix 18, wherein
The input stereo signal is converted into a frequency domain signal for each channel, and the signal for each channel obtained by the conversion is generated for the number of channels, and each time / frequency component of the added signal is generated. A digital watermark addition program characterized in that a shift amount corresponding to a value of a pixel located at a position corresponding to the component of the phase of the phase differs between channels.

(Appendix 20)
20. The electronic watermark addition program according to appendix 18 or 19, wherein the function for calculating the shift amount is a monotone increase function or a monotone decrease function of the luminance of the pixel.

(Appendix 21)
The electronic watermark adding program according to attachment 20, wherein
When the function is z [x] for the luminance of the pixel and φ [x] for the shift amount,

A digital watermark adding program characterized by the above.

(Appendix 22)
In a program for causing a computer to function as a digital watermark detection device,
Computer
A stereo signal is converted into a signal in the frequency domain, and a set of a time axis and a frequency axis of the converted signal is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and then added to the converted signal. An electronic watermark detection program for causing a function of the electronic watermark detection apparatus to detect a two-dimensional image as the electronic watermark from the stereo signal after the addition.

(Appendix 23)
The electronic watermark detection program according to attachment 22,
A digital watermark detection program for detecting a phase shift amount of each time / frequency component and detecting the two-dimensional image based on the phase shift amount.

(Appendix 24)
The electronic watermark detection program according to appendix 22 or 23, wherein
After adding the signals of both channels included in the stereo signal after addition, the signal is converted into a frequency component signal, and the converted frequency axis and time axis are two-dimensional two axes, and the converted signal An electronic watermark detection program comprising means for two-dimensionally outputting.

  As an application example of the present invention, the present invention can be used as audio content creation tool software, content distribution stations, communication facilities of broadcast stations, and effectors for inserting and expressing images in the sound of musical instruments.

DESCRIPTION OF SYMBOLS 1 Digital watermark adding apparatus 6 Digital watermark display apparatus 10-L Frequency analyzer 10-R Frequency analyzer 20 Phase controller 30-L ₀ phase converter 30-L _n phase converter 30-L _x phase converter 30-R ₀ phase converter 30-R _n phase converter 30-R _x phase converter 50-L frequency component synthesizer 50-R frequency component synthesizer 60 adder 70 display 200-0 phase determiner 200-1 phase determiner 200-n phase determiner 300-X _n adder 301-X _n phase shift amplifier 302-X _n addition control switch 700 frequency analyzer 701 gray scale display 1000 low pass filter 1001 digital watermark display device s1-L audio signal s1-R audio signal s2 watermark signal _{s3-L 0} frequency component signal _{s3-L 1} frequency component signal _{s3-L n} frequency component signal _{s3-L x} Wavenumber component signals _{s3-R 0} frequency component signal _{s3-R 1} frequency component signal _{s3-R n} frequency component signal _{s3-R x} frequency component signal _{s3-X n} frequency component signal _{s3-Y n} frequency component signal _{s4-L 0} control Signal s4-L ₁ control signal s4-L _n control signal s4-L _x control signal s4-R ₀ control signal s4-R ₁ control signal s4-R _n control signal s4-R _x control signal s4-X _n control signal s5 -L ₀ phase conversion output signal s5-L ₁ phase conversion output signal s5-L _n phase conversion output signal s5-L _x phase conversion output signal s5-R ₀ phase conversion output signal s5-R ₁ phase conversion output signal s5-R _n phase conversion output signal _{s5-R x} phase conversion output signal _{s5-X n} phase conversion output signal s6-L watermarking additional signal s6-R watermarking additional signal s7-M monaural sum signal _{s70-M 0} frequency Min signal _{s70-M 1} frequency component signal _{s70-M n} frequency component signal s100 audio signal s101 audio signal s102 audio signal s200 watermark signal

Claims (8)

The input stereo signal is converted into a frequency domain signal for each channel, and a signal obtained by adding the signals for each channel obtained by the conversion is generated for the number of channels, and the time axis and frequency axis of the added signal are calculated. A set is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and a shift amount corresponding to a value of a pixel at a position corresponding to the phase of each time / frequency component of the added signal is set. The digital watermark adding apparatus adding a two-dimensional image as the digital watermark to the added signal by changing the phase according to the shift amount and making the phase different for each channel . The digital watermark adding apparatus according to claim 1 ,
The digital watermark adding apparatus, wherein the function for calculating the shift amount is a monotonically increasing function or a monotonically decreasing function of the luminance of the pixel. The digital watermark adding apparatus according to claim 2 ,
When the function is z [x] for the luminance of the pixel and φ [x] for the shift amount,
A digital watermark adding apparatus characterized by the above. Converting a stereo signal into a mono signal, the converting the monaural signal into a frequency domain signal, a to that electronic watermark detecting device detects a two-dimensional image as a digital watermark from said converted signal,
The two-dimensional image as the digital watermark is
The stereo signal is converted into a frequency domain signal for each channel, a signal obtained by adding the signals for each channel obtained by the conversion is generated for the number of channels, and a set of time axis and frequency axis of the added signal is set. Corresponding to the two-axis set of the two-dimensional image as a digital watermark, and the shift amount according to the value of the pixel at the position corresponding to the phase of each time / frequency component of the added signal, It is a two-dimensional image added to the added signal by shifting the phase according to the shift amount by making it different between channels.
An electronic watermark detection apparatus characterized by the above. Converting an input stereo signal into a frequency domain signal for each channel ;
Generating a signal by the number of channels by adding the signals for each channel obtained by the conversion; and
A set of the time axis and frequency axis of the added combined signal to correspond to a set of two axes of the two-dimensional image as a digital watermark, corresponding to a phase ingredients of each time and each frequency component of the sum combined signal Changing the shift amount according to the value of the pixel at the position to be different between channels;
Adding a two-dimensional image as the digital watermark to the added signal by shifting the phase according to the shift amount ;
A method for adding a digital watermark, comprising: Converting a stereo signal to a monaural signal ;
Converting the monaural signal into a frequency domain signal;
Detecting the two-dimensional image as a digital watermark from said converted signal, an that electronic watermark detecting method having a,
The two-dimensional image as the digital watermark is
The stereo signal is converted into a frequency domain signal for each channel, a signal obtained by adding the signals for each channel obtained by the conversion is generated for the number of channels, and a set of time axis and frequency axis of the added signal is set. Corresponding to the two-axis set of the two-dimensional image as a digital watermark, and the shift amount according to the value of the pixel at the position corresponding to the phase of each time / frequency component of the added signal, It is a two-dimensional image added to the added signal by shifting the phase according to the shift amount by making it different between channels.
A digital watermark detection method characterized by the above. In a program for causing a computer to function as a digital watermark adding device,
Computer
The input stereo signal is converted into a frequency domain signal for each channel, and a signal obtained by adding the signals for each channel obtained by the conversion is generated for the number of channels, and the time axis and frequency axis of the added signal are calculated. A set is made to correspond to a two-axis set of a two-dimensional image as a digital watermark, and a shift amount corresponding to a value of a pixel at a position corresponding to the phase of each time / frequency component of the added signal is set. A digital watermark adding apparatus that adds a two-dimensional image as the digital watermark to the summed signal by shifting the phase in accordance with the shift amount and making the phase different depending on the channel A program for adding digital watermarks to function. In a program for causing a computer to function as a digital watermark detection device,
Computer
Converting a stereo signal into a mono signal, the converting the monaural signal into a frequency domain signal, digital watermark for functioning as a detection to that electronic watermark detecting device a two-dimensional image as a digital watermark from the converted signal A detection program ,
The two-dimensional image as the digital watermark is
The stereo signal is converted into a frequency domain signal for each channel, a signal obtained by adding the signals for each channel obtained by the conversion is generated for the number of channels, and a set of time axis and frequency axis of the added signal is set. Corresponding to the two-axis set of the two-dimensional image as a digital watermark, and the shift amount according to the value of the pixel at the position corresponding to the phase of each time / frequency component of the added signal, It is a two-dimensional image added to the added signal by shifting the phase according to the shift amount by making it different between channels.
A digital watermark detection program characterized by the above.