JP2008064568A - Sound acquisition position locating method, sound acquisition position locating system, localization apparatus, and computer program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound acquisition position locating method, a sound acquisition position locating system, a localization apparatus, and a computer program which can be measures and deterrents to illegal recording and illegal distribution of works such as sound of movies by locating the acquisition position of sound. <P>SOLUTION: In a site such as a movie theater for showing a work such as a movie, a plurality of sound output devices 1, 1, 1 such as speakers are arranged at different positions, and sound is output from each of the sound output devices 1, 1, 1. On such a site, when sound is acquired and recorded by a device such as a recorder 5 provided with a sound acquisition device 4 such as a microphone, the sound output from each of the sound output devices 1, 1, 1 is recorded. Using a locating apparatus 6, time differences between each sound output from each of the sound output devices 1, 1, 1 out of the recorded sound are detected, and the acquisition position of sound is located on the basis of the detected time differences and the arrangement positions of each of the sound output devices. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention acquires a sound output from a sound output device such as a speaker by a sound acquisition device such as a microphone, and specifies a sound acquisition position specifying method for specifying the acquired position, and sound acquisition using the sound acquisition position specifying method A position identification system, a identification device used in the sound acquisition position identification system, and a computer program for realizing the identification device, and particularly a sound acquisition position identification method for identifying a recorded position from a recorded sound, The present invention relates to a sound acquisition position specifying system, a specifying device, and a computer program.

In recent years, boot leg recording that illegally records movies by bringing video cameras for recording and recording into movie theaters has become a problem. Therefore, a method of embedding information such as a movie theater and a screening time as a digital watermark in the sound of a movie so that it cannot be perceived by humans has been proposed. As a method for embedding a digital watermark into sound, the method described in Non-Patent Document 1 can be used.
R. Tachibana, 3 others, An audio watermarking method using a two-dimensional pseudo-random array, Signal Processing, Elsevier, Netherlands ( Elsevier), October 2002, Vol. 82, No. 10, p.1455-1469

  However, it is difficult to specify an unauthorized recording person simply by embedding a digital watermark in the sound, so there is a problem that the deterrence of boot leg recording is poor.

  The present invention has been made in view of such circumstances, and outputs sound from a plurality of sound output devices such as speakers arranged at different positions, and from each sound output device among recorded sounds. It is possible to estimate the recorded position by specifying the sound acquisition position based on the time difference of each output sound and the arrangement position of each sound output device. Sound acquisition position specifying method that can be used as countermeasures against deterrence and deterrence, sound acquisition position specifying system to which the sound acquisition position specifying method is applied, specifying device used in the sound acquisition position specifying system, and the specifying An object of the present invention is to provide a computer program for realizing the apparatus.

  The sound acquisition position specifying method according to the first aspect of the present invention is a sound acquisition position specifying method for acquiring sounds output from a plurality of sound output devices arranged at different positions by a sound acquisition device and specifying the acquired position. The sound output from each sound output device is acquired and recorded by the sound acquisition device, and the sound output device from which the sound is output from each sound output device is recorded. A time difference between information and each sound is detected, and a sound acquisition position is specified based on the arrangement position and time difference of each sound output device related to the detected information.

  In the present invention, the sound acquisition position can be specified based on the time difference between the sounds output from the sound output devices and the arrangement positions of the sound output devices, and thus has various effects such as estimation of the acquisition position. For example, in a venue such as a movie theater where a copyrighted work such as a movie is screened, it is possible to specify or limit the unauthorized recording person who intends to illegally record and distribute the sound of the copyrighted work. It can be used as a countermeasure and deterrent against fraud.

  The sound acquisition position specifying system according to the second aspect of the invention acquires sound output from a plurality of sound output devices disposed at different positions by a sound acquisition device and specifies the acquired position. The system includes a specifying device that specifies a position at which each sound acquisition unit acquires sound, and the specifying device outputs each sound output from each sound output unit based on the sound acquired by the sound acquisition unit. Means for detecting the information relating to the output sound source and the time difference between the sounds, and means for identifying the sound acquisition position based on the position and time difference of each sound output device relating to the detected information. It is characterized by providing.

  In the present invention, the sound acquisition position can be specified based on the time difference between the sounds output from the sound output devices and the arrangement positions of the sound output devices, and thus has various effects such as estimation of the acquisition position. For example, in a venue such as a movie theater where a copyrighted work such as a movie is screened, it is possible to specify or limit the unauthorized recording person who intends to illegally record and distribute the sound of the copyrighted work. It can be used as a countermeasure and deterrent against fraud.

  The sound acquisition position specifying system according to the third invention is arranged at different positions, respectively, and the sound output from each of the plurality of sound output devices that output sound as sound waves based on the sound signal is acquired by the sound acquisition device, A sound acquisition position specifying system for specifying an acquired position, comprising a specifying device for specifying a position at which a sound acquisition unit acquires a sound, and for each sound signal to output a sound from each sound output unit, an output source And a synthesizing unit that synthesizes a time signal indicating an output time, and the plurality of sound output devices each output a sound based on a sound signal obtained by synthesizing the time signal. The specific device calculates a time difference between each sound based on the detected time and means for detecting the time when the time signal is synthesized based on the sound acquired by the sound acquisition unit. Means for calculating the time difference calculated and Based on the arrangement position of each sound output device identified from a constant information, characterized by comprising a specifying means for specifying the acquisition position of the sound.

  In the present invention, since the sound acquisition position can be specified based on the time difference between the sounds output from each sound output device and the arrangement position of each sound output device, it has various effects such as estimation of the recording position. For example, in a venue such as a movie theater where a copyrighted work such as a movie is screened, it is possible to specify or limit the unauthorized recording person who intends to illegally record and distribute the sound of the copyrighted work. It can be used as a countermeasure and deterrent against fraud.

  A sound acquisition position specifying system according to a fourth invention is characterized in that, in the third invention, the synthesizing means is configured to synthesize a sound signal into a frequency domain converted by using a predetermined conversion function. .

  In the present invention, by synthesizing the time signal as a digital watermark in the frequency domain, it is possible to make the listener listen without easily perceiving the sound output based on the sound signal. There is no need to make perceptible modifications.

  The sound acquisition position specifying system according to a fifth invention is the sound acquisition position specifying system according to the third or fourth invention, wherein the sound output device is three or more, and the specifying means is a sound acquisition device calculated from a time difference of sound and a sound speed; The sound acquisition position is specified based on the difference in distance between the sound output devices and the arrangement position of the sound output devices.

  In the present invention, the acquisition position can be specified using a nonlinear simultaneous equation solving algorithm such as a Gauss-Newton algorithm using parameters such as a difference in distance between the sound acquisition unit and each sound output unit.

  A specifying device according to a sixth aspect of the invention is a specifying device that specifies a position where a sound acquisition unit that acquires sound output from a sound output unit acquires sound, and a plurality of sound outputs arranged at different positions, respectively. Based on the sound output from each device and acquired by the sound acquisition device, means for detecting information related to the sound output device of the output source of each sound output from each sound output device and the time difference of each sound, and Means for specifying a sound acquisition position based on the time difference and the position of each sound output device according to the detected information.

  In the present invention, since the sound acquisition position can be specified based on the time difference between the sounds output from each sound output device and the arrangement position of each sound output device, it has various effects such as estimation of the recording position. For example, in a venue such as a movie theater where a copyrighted work such as a movie is screened, it is possible to specify or limit the unauthorized recording person who intends to illegally record and distribute the sound of the copyrighted work. It can be used as a countermeasure and deterrent against fraud.

  A computer program according to a seventh aspect of the invention is a computer program that causes a computer to specify a position where a sound acquisition unit that acquires a sound output from a sound output unit acquires a sound, and is arranged at different positions on the computer. Based on the sound output from each of the plurality of sound output devices and acquired by the sound acquisition device, the information related to the sound output device that is the output source of each sound output from each output device and the time difference between the sounds are detected. A procedure and a procedure for causing a computer to specify a sound acquisition position based on a preset arrangement position of each sound output device related to a detected time difference and detected information are characterized.

  In the present invention, when executed by a computer, the computer operates as a specifying device that specifies a sound acquisition position, and based on the time difference of the sound output from each sound output device and the arrangement position of each sound output device. Since the sound acquisition position can be specified, it has various actions such as estimation of the recording position. For example, in a venue such as a movie theater where a work such as a movie is screened, the sound that is the work is illegally Since it is possible to specify or limit the unauthorized recording person who wants to record and distribute, it is possible to provide a countermeasure and deterrent against fraudulent acts.

  The sound acquisition position specifying method, the sound acquisition position specifying system, the specifying device, and the computer program according to the present invention include a plurality of sounds such as speakers at different positions in a venue such as a movie theater where a copyrighted work such as a movie is shown. An output device is provided to output sound from each sound output device. In such a venue, when sound is acquired and recorded by a device such as a recording device equipped with a sound acquisition device such as a microphone, the sound output from each sound output device is recorded. Then, using a specific device, in the recorded sound, the time difference of each sound output from each sound output device is detected, and the sound acquisition position is determined based on the detected time difference and the arrangement position of each sound output device. Is identified.

  With this configuration, since the sound acquisition position can be specified in the present invention, it has various actions such as estimation of the recording position. For example, in a movie theater, the sound that is the copyrighted work is illegally recorded and distributed. Since it is possible to specify or limit the unauthorized record maker to be allowed to perform, it is possible to provide an excellent effect such as being able to provide a countermeasure and deterrent against fraud.

  In addition, the sound acquisition position specifying system according to the present invention, for example, a time signal using a pseudo-random number sequence in a frequency domain obtained by converting each sound signal for outputting sound from each sound output device using a predetermined conversion function. By synthesizing it as a digital watermark, it is possible to make the listener listen to the sound output based on the sound signal without making it feel uncomfortable, and it is necessary to make a perceptible modification to the work. There is an excellent effect such as not having.

  Furthermore, the sound acquisition position specifying system according to the present invention includes three or more sound output devices, includes information for specifying the output sound output device, and each sound output calculated from the time difference and sound speed of the sound It is possible to specify an exact position by solving a nonlinear simultaneous equation using the difference in distance from the sound source and the position of each sound output device as a parameter using a solution algorithm such as the Gauss-Newton algorithm. It has an excellent effect.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is an explanatory diagram conceptually showing a configuration example of a sound acquisition position specifying system of the present invention. FIG. 1A illustrates a venue such as a movie theater in which a copyrighted work such as a movie is screened. In the venue, three sound output devices 1 such as speakers for outputting sound based on sound signals as sound waves. , 1, 1 are arranged at different positions in the hall.

  Each sound output device 1, 1, 1 is connected to a signal output device 2 for outputting sound signals of different channels (channel 0, channel 1 and channel 2 in FIG. 1). A video signal and a sound signal of each channel are read from a video and audio recording medium such as a DVD (Digital Versatile Disk), a video tape, and a film, and the read sound signal is output to each sound output device 1,1,1. The video signal is output to a video display unit such as a screen or a monitor (not shown).

  A signal synthesizer 3 that synthesizes (embeds) a time signal using a pseudo-random number sequence as a digital watermark is provided in the path from the signal output device 2 to each of the sound output devices 1, 1, 1. 3 synthesizes a sound signal output from the signal output device 2 to each sound output device 1, 1, 1 as a digital watermark with a time signal indicating a synchronization position of the output time.

  A sound signal obtained by synthesizing the time signal in advance is recorded in a video and audio recording medium, and the sound signal obtained by synthesizing the time signal is output from the signal output device 2 to each sound output device 1, 1, 1. Also good. In addition, the signal output device 2 and the signal synthesis device 3 may be integrated, and for example, a timing signal may be synthesized with a sound signal based on a sound collected in real time from a microphone (not shown) for a performer. It can also be applied to real-time audio output such as lectures and performances.

  In FIG. 1 (a), white circles indicate seats and listeners in the venue, and black circles indicate unauthorized persons who illegally record the sound output from each sound output device 1, 1, 1. An unauthorized person possesses a recording device 5 such as an IC recorder having a sound acquisition device 4 such as a microphone. An unauthorized person generates sound data by recording in a format such as MPEG (Motion Picture Expert Group) or MP3 (Mpeg audio layer 3) after recording by the recording device 5 having the sound acquisition unit 4. It is recorded (recorded) on a video and audio recording medium such as a DVD, or illegally distributed through a network such as the Internet.

  FIG. 1B shows a specifying device 6 that acquires sound data distributed illegally and specifies a sound acquisition position from the acquired sound data. The sound acquisition position specified by the specifying device 6 is shown in FIG. Therefore, it is possible to identify the location in the venue, and from the identified location, for example, it can be considered that there was a possibility that the person who reserved the seat arranged at the location may have illegally recorded .

  Next, the configuration of each device will be described. FIG. 2 is a functional block diagram showing a configuration example of the sound output devices 1, 1, 1, the signal output device 2, the signal synthesis device 3, and the recording device 5 used in the sound acquisition position specifying system of the present invention. The signal output device 2 outputs the sound signal of each channel to the signal synthesis device 3. When the sound signal read from the video and audio recording medium by the signal output device 2 is a compression-encoded signal, the read signal is decompressed and output to the signal synthesis device 3.

  The signal synthesizer 3 includes a signal input unit 30 that receives the sound signal of each channel output from the signal output device 2, a conversion unit 31 that converts the sound signal using a predetermined conversion function, and a human being unable to perceive. Amplitude deriving means 32 using a psychoacoustic model for deriving amplitude, watermark information generating means 33 for generating watermark information that is a source of a time signal to be synthesized as a digital watermark with a sound signal, and inverse conversion of conversion by converting means 31 And a signal output means 35 for outputting the sound signals of the respective channels to the corresponding sound output devices 1, 1, 1 respectively. The signal input means 30, the conversion means 31, the amplitude derivation means 32, the watermark information generation means 33, the inverse conversion means 34, and the signal output means 35 are provided as different circuits for each channel. Operates independently. A circuit that can perform parallel processing on signals of a plurality of channels may be used. Alternatively, the same number of signal synthesizers 3 as the number of channels may be used, and different signal synthesizers 3 may be used for each channel.

  The signal input unit 30 passes the received sound signal to the conversion unit 31 and the amplitude deriving unit 32 as a digital data sound signal (HS: Host Signal).

  The conversion means 31 multiplies the sound signal, which is digital data, by a window function, and converts the sound signal into the frequency domain by performing discrete Fourier transform (DFT) on the obtained value in a finite interval.

  The amplitude deriving means 32 derives an amplitude that cannot be perceived by a human by using a psychoacoustic model for the sound signal. That is, the lower limit of the sound intensity perceivable by humans is determined from the strength of the sound based on the sound signal, and the intensity of the timing signal embedded as a digital watermark that cannot be perceived by humans is derived as the amplitude.

  The watermark information generating means 33 includes a pseudo random array (PRA) recorded in advance in a recording means 33a such as a hard disk or RAM, information for specifying a venue such as a movie theater, information for specifying a screening time, The watermark information is generated by turbo-coding specific information such as information specifying the sound output device 1. The pseudo random number sequence and the specific information are, for example, data input by the operator operating the signal synthesizer 3 in advance to the signal synthesizer 3 and recorded in the recording unit 33a. Different pseudo-random number sequences are used for each channel, and the channel, that is, the sound output device 1 can be specified by the pseudo-random number sequence. The pseudo-random number sequence recorded in the recording means 33a is a number sequence composed of “+1” and “−1”. For example, a digit of the sequence is generated by a random number function in which 100 numbers from 0 to 99 are generated uniformly. A random number corresponding to the number is generated, and when the generated numerical value is a value from 0 to 49, it is “+1”, and when it is a value from 50 to 99, it is “−1”, “+1” and It is generated by arranging “−1”. Alternatively, the pseudo-random number sequence may be generated by converting the specific information with a predetermined function. In this case, the pseudo-random number sequence can be used as the specific information.

  Then, the signal synthesizer 3 modulates the amplitude derived by the amplitude deriving unit 32 with the watermark information generated by the watermark information generating unit 33, and converts the modulated amplitude and the sound signal converted into the frequency domain by the converting unit 31. The phase signal is multiplied by the window signal by the inverse transform means 34, and an inverse discrete Fourier transform (IDFT) is performed to generate a time signal that becomes a watermark signal (WS).

  Then, the signal synthesizer 3 synthesizes the time signal generated by the inverse conversion means 34 with a sound signal to generate a sound signal (WHS: Watermarked Host Signal) in which the time signal is combined as a digital watermark. The signal is output from the signal output means 35 to the output devices 1, 1, 1. The signal synthesizer 3 synthesizes a time signal including each specific information for each channel sound signal received from the signal output device 3, and a sound output device corresponding to each sound signal obtained by synthesizing each time signal. Output to 1,1,1. Note that the timing signal is synthesized at the same position in time with respect to the sound signals corresponding to the respective channels. Accordingly, when sounds based on the respective sound signals are output from the sound output devices 1, 1, 1, the portions where the timing signals are synthesized are output simultaneously. However, a timing signal may be synthesized with a predetermined time difference in advance. In this case, when a sound based on each sound signal is output from each sound output device 1, 1, 1, the timing signal is synthesized. The output will be output with a certain time difference. That is, the time signal is a signal indicating the output time as a synchronization position or as a time difference, and is a signal including specific information for specifying the output sound generator 1.

  The signal synthesizer 3 illustrated in FIG. 2 is configured as a functional block diagram, but each function may be configured as hardware or software. In addition, here, the signal synthesizer 3 that performs various processes by applying the method described in Non-Patent Document 1 in the background art is illustrated, but the present invention is not limited to this, and the sound signal is watermarked as a time signal. Various methods of embedding information can be used.

  The recording device 5 having the sound acquisition unit 4 encodes the sound acquired by the sound acquisition unit 4 to generate sound data which is digital data, and records the sound data generated by the encoding unit 50. Recording means 51 for connecting, and connection means 52 for connecting to an external device for distributing sound data. Instead of using the recording device 5 having the sound acquisition device 4, the sound acquisition device 4 may be connected to the recording device 5 by wire or wirelessly.

  FIG. 3 is a block diagram showing a hardware configuration example of the specifying device 6 used in the sound acquisition position specifying system of the present invention. The specific device 6 is a CD that reads various information from a control unit 60 such as a CPU (Central Processing Unit) that controls the entire device, and a recording medium such as a CD-ROM that records information such as the computer program 100 and data of the present invention. Auxiliary storage means 61 such as a ROM drive, a recording means 62 such as a hard disk for recording various information read by the auxiliary storage means 61, and a temporary generated when the computer program 100 of the present invention recorded in the recording means 62 is executed. Storage means 63 such as a RAM for storing typical data. Then, by executing the computer program 100 of the present invention stored in the storage unit 63 under the control of the control unit 60, the computer operates as the specifying device 6 of the present invention. Further, the specifying device 6 includes a communication connector for acquiring sound data from an external device, a communication port for acquiring sound data from a communication network, an acquisition means 64 such as a medium reading drive for reading sound data from various information recording media, and a monitor. The display means 65 is provided.

  FIG. 4 is a functional block diagram showing a functional configuration example of the specifying device 6 used in the sound acquisition position specifying system of the present invention. The specifying device 6 that has executed the computer program 100 under the control of the control unit 60 converts the sound signal based on the sound data acquired by the acquisition unit 64 into a conversion unit 66 that converts the sound signal using a predetermined conversion function. Normalization means 67 that normalizes the sound signal, synchronization detection means 68 that attempts to detect the synchronization and specific information of the pseudorandom number sequence related to the time signal, and the sound acquisition position based on the processing result of the synchronization detection means 68 An acquisition position specifying means 69 for specifying is realized.

  The acquisition unit 64 performs expansion processing on the acquired sound data as necessary, and passes the sound signal, which is digital data, to the conversion unit 66.

  The transforming means 66 multiplies the sound signal, which is digital data, by a window function, and transforms the sound signal into the frequency domain by performing a discrete Fourier transform (DFT) on the obtained value in a finite interval.

  The normalizing means 67 performs normalization processing on the sound signal converted by the converting means 66 so that the synchronization signal to be detected has a predetermined intensity.

  The synchronization detecting means 68 synchronizes the reference pseudo-random number sequence recorded in advance in the recording means 62 with the pseudo-random number sequence included as watermark information in the time signal synthesized with the sound signal, and also to the sound signal. Specific information included as watermark information in the synthesized time signal is detected.

  The acquisition position specifying unit 69 calculates the time difference at which the sound is acquired based on the synchronization result of the synchronization detecting unit 68, and the sound output device 1 that is the output source of each sound specified based on the calculated time difference and the specific information, respectively. , 1, 1 to specify the sound acquisition position. The specified acquisition position is displayed on the display means 65. The specified acquisition position may be output by a method such as output to another device or recording on an information recording medium.

  The specific device 6 illustrated in FIG. 4 is configured as a functional block diagram realized as software, but each function may be configured as hardware, and in that case, a device dedicated to the specific device 6 You may make it implement | achieve as. In addition, here, the specific device 6 that performs the process of detecting the watermark information by applying the method described in Non-Patent Document 1 in the background art is illustrated, but the present invention is not limited to this, and the timing is determined from the sound signal. Various methods for detecting watermark information embedded as a signal can be used.

  Next, the synthesis and detection of timing signals in the sound acquisition position specifying method of the present invention will be described. FIG. 5 is an explanatory diagram conceptually showing the synthesis of a pseudo random number sequence as a time signal in the sound acquisition position specifying method of the present invention. In FIG. 5, a number sequence composed of “+1” and “−1” is a pseudo-random number sequence synthesized with a sound signal as a time signal. The pseudo random number sequence is synthesized as shown in FIG. 5 on a virtual plane represented by a time-frequency coordinate system obtained by discrete Fourier transform of the sound signal. By synthesizing in this way, it is possible to utilize the characteristic that sound of a certain frequency changes relatively slowly. Therefore, by taking the difference between adjacent DFT frames, the influence of the sound signal is reduced. There is an effect of increasing resistance to noise.

  FIG. 6 is an explanatory view conceptually showing the synchronization of the pseudo random number sequence synthesized with the sound signal and the pseudo random number sequence in the sound acquisition position specifying method of the present invention. FIG. 6A shows a state in which the sound data acquired by the specifying device 6 of the present invention from the acquisition unit 64 is subjected to windowed discrete Fourier transform by the conversion unit 66 and normalized by the normalization unit 67. A pseudo-random number sequence synthesized with a sound signal based on sound data is shown in a time-frequency coordinate system. The sound that is the source of the acquired sound data is a sound in which the sounds output from the three sound output devices 1, 1, 1 arranged at different positions are superimposed on each other. Recording is performed with a time difference based on the difference in distance between the sound acquisition unit 4 and each of the sound output units 1, 1, 1. Accordingly, there is a difference in the temporal recording positions of the pseudo random number sequences output simultaneously from the sound output devices 1, 1, 1, and in FIG. 6 (a), the pseudo random number sequence PRA0 indicated by a solid line, and indicated by a broken line. The positions on the time axis are different from each other as indicated by the pseudo random number sequence PRA1 and the pseudo random number sequence PRA2 indicated by the one-dot chain line.

  FIG. 6B shows a pre-recorded pseudo-random number sequence PRA-REF for reference that is used for synchronization by the synchronization detection means 68 by the specifying device 6 of the present invention. FIG. 6C shows a method of detecting the synchronization position by the synchronization detection means 68 in the identification device 6 of the present invention. The inner product value of the sound data indicating the synchronization state and the reference pseudo-random number sequence PRA-REF. Is shown as a graph with respect to the time axis. The synchronization detection unit 68 shifts the reference pseudo-random number sequence PRA-REF shown in FIG. 6B little by little in the time axis direction as shown by the arrows in the figure, and the sound data shown in FIG. The graph shown in FIG. 6C can be obtained. As shown in FIG. 6C, the inner product value takes a maximum value at a position where the pseudo random number sequences PRA0, PRA1, and PRA2 synthesized with the sound data are synchronized with the reference pseudo random number sequence PRA-REF. Since the pseudo-random number sequences PRA0, PRA1, and PRA2 are different numbers for the sound output devices 1, 1, and 1, the pseudo-random number sequences PRA-REF corresponding to the respective pseudo-random number sequences PRA0, PRA1, and PRA2 are used. It is possible to specify which sound output device 1, 1, 1 corresponds to each local maximum value. In FIG. 6C, the inner product value with the pseudo random number sequence PRA0 is indicated by a solid line, the inner product value with the pseudo random number sequence PRA1 is indicated by a broken line, and the inner product value with the pseudo random number sequence PRA2 is indicated by a one-dot chain line. The pseudo-random number sequence is synthesized at the same time for the sounds output from the sound output devices 1, 1, 1, but the arrangement positions of the sound output devices 1, 1, 1 and the sound acquisition device 4 respectively. Depending on the difference in distance, a time difference occurs in the arrival of the sound in which the pseudorandom number sequence is synthesized. This time difference appears in FIG. 6C as a difference in position on the time axis of the maximum value of each inner product value.

Next, in the sound acquisition position specifying method of the present invention, a method for specifying the sound acquisition position will be described. FIG. 7 is an explanatory diagram showing the arrangement of the sound output devices 1, 1, 1 and the sound acquisition device 4 in the sound acquisition position specifying system of the present invention. In FIG. 7, the positions of the sound output devices 1, 1, 1 and the sound acquisition device 4 are shown on a two-dimensional plane indicated by xy coordinates. Of the plurality of sound output devices 1, 1, 1, for example, the sound output device 1 that outputs the sound of channel 0 is used as a reference, and the coordinates of the position are set to s ₀ = (0, 0). Further, the coordinate of the position of the sound output device 1 of the i-th channel (i = 1, 2,..., N) is s _i (i = 1, 2,..., N), and the coordinate of the position of the sound acquisition device 4 is m. And And the distance between the position m of the position S ₀ and the sound acquisition unit 4 of the sound output device 1 of the channel 0, the distance between the position m of the i position of the sound output unit 1 of the channel s _i and the sound acquisition unit 4 When the difference is d _i0 , the relationship of the following formula 1 is established.

|| s _i || ² −d _i0 ² −2 || m || d _i0 −2s _i ^T m = 0 Equation 1
Where m = (x _m , y _m )
s ₀ = (0,0)
s _i = (x _i , y _i ) (i = 1, 2,..., N)
s _i ^T is the transpose of s _i
|| V || is the norm of vector V

In Equation 1, d _i0 can be calculated by multiplying the time difference between the synchronization positions described with reference to FIG. 6 by the speed of sound. Therefore, Equation 1 is a simultaneous nonlinear equation for the unknown m, and the coordinates of the position of the sound acquirer 4 can be specified by solving the equation 1 for m by an algorithm such as the Gauss-Newton algorithm. Note that the method for specifying the sound acquisition position is not necessarily limited to the method using the Gauss-Newton algorithm, and is based on the difference in arrival times of the sounds output from the plurality of sound output devices 1, 1, 1. Various methods for specifying the position can be used. For example, the first arrival direction of the sound relative to the acquisition position is obtained from the arrival time difference between the sounds output from the arbitrary two sound acquisition devices 1 and 1 and the arrangement position of the sound output devices 1 and 1, and other combinations A method in which the second arrival direction of the sound is obtained from the sounds related to the second sound acquisition devices 1 and 1, and the geometric intersection of the first arrival direction and the second arrival direction is specified as the sound acquisition position. It is possible to use.

  Next, processing of various devices used in the sound acquisition position specifying system of the present invention will be described. FIG. 8 is a flowchart showing an example of processing of the signal synthesizer 3 used in the sound acquisition position specifying system of the present invention. The signal synthesizer 3 receives the sound signal of each channel output from the signal output device 2 by the signal input means 30 (S101), and converts the received sound signal into a conversion means 31, an amplitude derivation means 32, a watermark. By the processing of the information generation means 33 and the inverse conversion means 34, time signals including specific signals corresponding to each are synthesized (S102), and each sound signal obtained by synthesizing the time signals is sent from the signal output means 35 to the corresponding sound output device 1. , 1, 1 (S103).

  Each sound output device 1, 1, 1 outputs a sound as a sound wave in the hall based on the sound signal. When the output sound is illegally recorded and distributed, for example, as sound data, processing for acquiring the sound based on the distributed sound data and specifying the recorded position is performed.

  FIG. 9 is a flowchart showing an example of processing of the specifying device 6 used in the sound acquisition position specifying system of the present invention. The specifying device 6 acquires sound data by the acquisition unit 64 under the control of the control unit 60 that executes the computer program 100 (S201). The sound data acquired in step S201 is sound data suspected of boot leg recording that is illegally distributed through a network such as the Internet. If the sound data is compressed in a format such as MP3, decompression processing is performed.

  The specifying device 6 performs a discrete Fourier transform on the sound signal, which is digital data based on the acquired sound data, by performing a process of the conversion unit 66 based on the control of the control unit 60, and performs a discrete Fourier transform (S202). Normalization processing is performed by the processing of the normalizing means 67 (S203).

  Further, the identifying device 6 reads the reference pseudo-random number sequence recorded in advance in the recording unit 62 by the processing of the synchronization detecting unit 68 based on the control of the control unit 60, and synthesizes the read pseudo-random number sequence and the sound signal. By synchronizing with the pseudo-random number sequence included as watermark information in the generated time signal, and detecting specific information included in the watermark information in the time signal synthesized with the sound signal, each sound output device 1, 1, The time when the time signal is combined with each sound related to 1 is detected (S204). If the timing signal cannot be detected in step S204, the subsequent processing is not performed.

  Then, the specifying device 6 calculates the time difference between the sounds related to the sound output devices 1, 1, 1 based on the detected time by the processing of the acquisition position specifying means 69 based on the control of the control means 60 (S205). ), The difference between the distances of the sound acquisition device 4 and the sound output devices 1, 1, 1 calculated from the calculated sound time difference and sound speed, and the arrangement of the sound output devices 1, 1, 1 recorded in advance. By solving the nonlinear simultaneous equations with the installation position as a parameter by a solution algorithm such as Gauss-Newton algorithm, the sound acquisition position by the sound acquisition device 4 is specified (S206), and the acquired acquisition position is displayed on the display means 65. (S207). For example, when the relationship between the seat and the seated person in the venue in the situation where bootleg recording is suspected is known, the outflow route of the sound data is estimated from the acquisition position specified in step S206 and the seated person in the vicinity thereof. can do.

  Next, an experimental result by the sound acquisition position specifying method of the present invention will be described. FIG. 10 is an arrangement diagram showing the arrangement positions of the sound output devices and the sound acquisition positions in the experiment of the sound acquisition position specifying system of the present invention. FIG. 10 shows the arrangement position and the sound acquisition position of the sound output device on the plane indicated by the x-coordinate and the y-coordinate, and three sound output devices are used to output three-channel sound. . The sound output devices are arranged at S0 (0,0), S1 (0,3) and S2 (3,0), and the sound acquisition devices are indicated by test locations (TL: Test Location) indicated by TL1 to TL10 in the drawing. ), And obtain and record the sound output from each sound output device.

  FIG. 11 is a distribution diagram showing the results of a simulation experiment of the sound acquisition position specifying system of the present invention. FIG. 11 shows an experimental result in the case of simulating the situation where the sound output device and the sound acquisition device are arranged at the position shown in FIG. Based on the distance between each sound output device and the sound acquisition device, the simulation experiment calculates each delay time until the sound output from the position of each sound output device reaches the sound acquisition position, and calculates each delay obtained. The timing signal was embedded in the sound signal as a digital watermark based on time, and the acquisition position was specified based on the sound signal embedded with the timing signal. As shown in FIG. 11, in most of the results of the simulation experiment, the acquisition position is specified with an error of 1 m or less. However, as the acquisition position is farther from the sound output device, the error increases. . Since the error in the time difference of the synchronization position at a specific time hardly changes in any TL, this error is considered to be due to the position of the sound output device and the nature of the simultaneous nonlinear equations.

  FIG. 12 is a distribution diagram showing the results of an experiment in a real environment of the sound acquisition position specifying system of the present invention. FIG. 12 shows the experimental results when the sound output device and the sound acquisition device are actually arranged at the positions shown in FIG. As a result of the experiment in the actual environment, the timing signal may not be detected, and even if it could be detected, the error was larger than in the simulation experiment. This is due to factors such as the effect of the SN ratio between the acquired and recorded sound signal and the environmental noise being as small as 6 dB, and the effect of the difference in the sound attenuation rate of each channel depending on the position of the sound output device. Conceivable.

  The average value of the difference in the distance between the specified position and the actual position was calculated for six TLs excluding the TL on x = 4 where the error was large, and it was 0.21 m in the simulation experiment. It was 0.39 m in the experiment in. When only the average value is taken into consideration, it is considered possible to limit the number of fraudulent candidates to a few, for example, in a movie theater, including the position specified from the result of the experiment in the actual environment and the position in the vicinity thereof. However, in practical use, it is desirable to consider not only the average value but also the variance of the error, so it is desirable to further reduce the error. The error can be reduced by examining the conditions according to the implementation environment. Specifically, various conditions such as the strength of the digital watermark, the length of the pseudo-random number sequence, and the placement of the sound output device will be examined according to the implementation environment such as the venue where the sound is output and the field of the output sound. Then, it is considered that the position specifying accuracy can be improved by adjusting.

  In the above-described embodiment, the form used as a boot leg recording measure has been described. However, the present invention is not limited to this, and in various environments where sound is output from a plurality of sound sources, various positions for specifying the sound are identified. In addition to the form, it is possible to develop into various forms such as a form in which the position is specified by acquiring a sound. In addition, when applied to such a form, it is not always necessary to synthesize a time signal as a digital watermark into a sound signal, and an acquisition position may be specified based on a perceptible sound output from a sound output device.

  Moreover, although the form using three sound output devices was shown in the said embodiment, this invention is not limited to this, The form using four or more sound output devices may be sufficient.

It is explanatory drawing which shows notionally the structural example of the sound acquisition position specific system of this invention. It is a functional block diagram which shows the structural example of the sound output device used in the sound acquisition position specific system of this invention, a signal output device, a signal synthesis device, and a recording device. It is a block diagram which shows the structural example of the hardware of the specific apparatus used with the sound acquisition position specific system of this invention. It is a functional block diagram which shows the function structural example of the specific apparatus used with the sound acquisition position specific system of this invention. It is explanatory drawing which shows notionally the synthesis | combination of the pseudorandom number sequence as a time signal in the sound acquisition position specific method of this invention. It is explanatory drawing which shows notionally the synchronization of the pseudorandom number sequence synthesize | combined with the sound signal and the pseudorandom number sequence in the sound acquisition position specifying method of this invention. It is explanatory drawing which shows arrangement | positioning of a sound output device and a sound acquisition device in the sound acquisition position specific system of this invention. It is a flowchart which shows an example of a process of the signal synthesizer used in the sound acquisition position specification system of this invention. It is a flowchart which shows an example of the process of the specific apparatus used with the sound acquisition position specific system of this invention. FIG. 5 is a layout diagram showing the position of each sound output device and the sound acquisition position in an experiment of the sound acquisition position specifying system of the present invention. It is a distribution map which shows the result of the simulation experiment of the sound acquisition position specific system of this invention. It is a distribution map which shows the result of the experiment in the real environment of the sound acquisition position specific system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sound output device 2 Signal output device 3 Signal synthesizer 31 Conversion means 32 Amplitude derivation means 33 Watermark information generation means 34 Inverse conversion means 4 Sound acquisition device 5 Recording apparatus 6 Identification apparatus 66 Conversion means 67 Normalization means 68 Synchronization detection means 69 Acquisition position specifying means 100 Computer program

Claims (7)

A sound acquisition position specifying method for acquiring sounds output from a plurality of sound output devices arranged at different positions by a sound acquisition device and specifying the acquired position,
The sound output from each sound output device is acquired and recorded by the sound acquisition device,
From the recorded sound, detect information related to the sound output device of each sound output from each sound output device and the time difference of each sound,
A sound acquisition position specifying method, characterized in that a sound acquisition position is specified based on an arrangement position and a time difference of each sound output device related to the detected information. A sound acquisition position specifying system for acquiring sounds output from a plurality of sound output devices respectively arranged at different positions by a sound acquisition device and specifying the acquired position;
Each sound acquisition device has a specific device that identifies the position where the sound was acquired,
The specific device is:
Based on the sound acquired by the sound acquirer, means for detecting information related to the sound output device of each sound output from each sound output device and the time difference of each sound;
A sound acquisition position specifying system comprising: means for specifying a sound acquisition position based on the arrangement position and time difference of each sound output device related to the detected information. A sound acquisition position specifying system that acquires sound output from a plurality of sound output devices that are arranged at different positions and outputs sound as sound waves based on sound signals, and that acquires the acquired position. There,
A specific device that identifies the position where the sound acquisition unit has acquired the sound,
For each sound signal that outputs sound from each sound output device, including specific information for specifying the output sound output device, comprising a synthesis means for synthesizing a time signal indicating the output time,
The plurality of sound output units are configured to output sounds based on sound signals obtained by synthesizing time signals, respectively.
The specific device is:
Means for detecting when the timing signal is synthesized based on the sound acquired by the sound acquisition device;
Means for calculating the time difference between the sounds based on the detected time;
A sound acquisition position specifying system comprising: specifying means for specifying a sound acquisition position based on the calculated time difference and the arrangement position of each sound output device specified from the specific information.   4. The sound acquisition position specifying system according to claim 3, wherein the synthesizing unit is configured to synthesize a sound signal into a frequency domain converted by using a predetermined conversion function. The sound output device is three or more,
The specifying means specifies a sound acquisition position based on a difference in distance between the sound acquisition device and each sound output device calculated from a sound time difference and a sound speed, and an arrangement position of each sound output device. The sound acquisition position specifying system according to claim 3 or 4, wherein the sound acquisition position specifying system is configured. A sound acquisition device that acquires the sound output from the sound output device is a specific device that identifies the position where the sound is acquired,
Information related to the sound output device that is the output source of each sound output from each sound output device based on the sound that is output from each of the plurality of sound output devices arranged at different positions and acquired by the sound acquisition device, and Means for detecting the time difference of each sound;
A specifying device comprising: means for specifying a sound acquisition position based on a detected time difference and an arrangement position of each sound output device related to the detected information. A computer program that causes a computer to specify a position where a sound acquisition unit that acquires sound output from a sound output unit acquires sound,
According to the sound output device that is the output source of each sound output from each output device, based on the sound that is output from each of the plurality of sound output devices arranged at different positions on the computer and acquired by the sound acquisition device A procedure for detecting the time difference between information and each sound;
A computer program for causing a computer to execute a procedure for specifying a sound acquisition position based on a preset arrangement position of each sound output device related to a detected time difference and detected information.

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