JP3329448B2 - Music protection system and audio data distribution system using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a music protection method for safely delivering music to subscribers, and more particularly to a distribution system for distributing audio data over a communication network such as the Internet using the same.

[0002]

2. Description of the Related Art In recent years, with the progress of digital data compression technology and digital data distribution technology represented by the Internet, a new audio content supply system that does not involve a medium such as a CD has been realized. That is, it is a net distribution system using the Internet and a compression technology such as MP3.

[0003] Thanks to the development of these digital technologies, it has become possible to store high quality music as it is,
In particular, in an audio data distribution system using the Internet, a music protection function for reliably distributing only to a contractor (purchaser) is essential.

[0004]

At present, a general method for protecting digital data is a technique called encryption. However, since audio data needs to be compressed for distribution, it is difficult to employ a method of encryption in the distribution system. That is, if the encrypted data is compressed, it cannot be restored to the original state, so that the audio data cannot be encrypted and then compressed. Also,
Artists have complained about the encryption technology that digitally processes audio data.

Accordingly, the present invention provides a highly secure music protection system in consideration of compression characteristics, and an audio data distribution system using the same. In addition, it provides a scheme in which encryption does not affect music songs.

[0006]

According to the present invention, a non-audible sound or a sound close to a non-audible region of a person, that is, a discrimination signal of a waveform which is hardly heard by a person, and a sine wave signal of an audible sound (= protection interference) We propose a protection method using sound.

A first feature of the music protection system according to the present invention is that, after an identification signal is inserted into a silent portion of an audio signal with a waveform that is hardly audible to humans, the audio signal is compressed, and after the compression, Is characterized in that only the music piece in the audio signal is encrypted in association with the identification signal. That is, the compressed file is encrypted, and the receiving side decrypts the file to restore the compressed file, and then performs compression demodulation. And
An identification signal serving as a key for the decryption (an index indicating what kind of encryption is being performed) is included in a silent portion of the audio signal, and the music is encrypted in association with the identification signal. is there. In order to make this possible, only the music piece is encrypted while avoiding the silent part where the identification signal is inserted.

As a silent part for inserting the identification signal, a headless silent part usually provided between music pieces is used. In this case, any use form of a silent part at the front of the music, a silent part at the rear, or both silent parts may be used. The identification signal to be inserted here is a signal which may be heard to some extent because it is put in a silent part which is not related to music, and is a signal having a property that only bit information needs to be transmitted even after compression processing. Therefore, the waveform that is difficult for humans to hear includes not only inaudible sound but also hard-to-hear sound near the audible sound range limit. By inserting the identification signal using the silent part in this way, it is possible to lock each song.

The above is the protection method using encryption. As described above, there are artists who dislike digital processing such as encryption. Therefore, a second feature of the music protection system according to the present invention is that a silent portion in an audio signal is
While inserting the identification signal with a waveform that is difficult for humans to hear,
A combination of different types of sine waves is superimposed on a music piece in an audio signal in association with an identification signal.

In this protection method, a key can be locked for each song by inserting an identification signal by using a silent portion in the same manner as described above. Since the interfering sound is mixed in the music,
If you can not remove the disturbing sound according to the key, it will be unbearable to hear. In other words, according to this method, strong protection can be applied to the source music itself, and there is no need for encryption. Such a sine wave is superimposed on a music piece of an audio signal in an analog manner, and even if it is digitally compressed, it can be said that there is almost no deformation due to compression. Also, since the sine waves are only superimposed, they can be removed and do not process the music itself. That is, both the identification signal and the sine wave are additions of a predetermined analog waveform, and do not process a large music piece itself, and do not need to perform data processing that the artist dislikes. Insertion of such identification signal and sine wave
It can be performed at the analog stage or at the digital stage after sampling.

The sine wave signal corresponding to such an identification signal is a sine wave combination signal obtained by combining a plurality of sine waves according to different rules. It is highly safe to use a signal that is combined with different rules for each type of identification signal. The combination can be the same or out of phase. That is, the combination associated with the first identification signal is a combination of a plurality of sine waves having the same phase and different amplitudes, and the combination associated with the second identification signal is a plurality of sine waves having the same amplitude but different phases. Various combinations such as a combination of sine waves are possible. In other words, by using a combination of sine waves that are simultaneous (different frequencies exist at the same point in time), and chronological (different frequencies exist at different points in time) , Which will further enhance safety.

According to the above-described music protection system, CD, DV
The present invention can be applied to package distribution using a recording medium such as D or MD and a compression system, and can enhance security against unauthorized use. When distributing,
A method of passing a recording medium on which a reproduction processing program for performing decryption based on the identification signal or removing the sine wave combination signal is recorded may be used. This may be a method of separately distributing an FD, a CD, or the like containing a reproduction processing program, or recording the reproduction processing program in a partial free area of a CD or DVD containing audio data, and making the program executable by a computer. You can also.

The music protection system of the present invention is most suitable for network distribution using a data communication network such as the Internet. That is, according to the present invention, after inserting an identification signal with a waveform that is difficult for humans to hear in a silent part in an audio signal, the audio signal is compressed, and only the music piece part in the compressed audio signal is replaced with Digital audio data that is encrypted in association with the identification signal is distributed via a data communication network, and further, a reproduction processing program that causes a computer to execute decryption based on the identification signal is distributed. In an audio data distribution system, or in a silent portion of an audio signal, an identification signal is inserted with a waveform that is hardly audible to humans, and in a music piece portion of the audio signal, different types of sine waves are associated with the identification signal. Digital audio data, which is a combination of superimposed signals, is distributed via a data communication network. Further, the audio data distribution system, characterized in that to distribute the reproduction processing program for executing the removal of sinusoidal combination signal based on the identification signal to the computer is provided.

In this case, it goes without saying that the server of the distribution source may be installed anywhere in Japan or overseas. The data delivery destination may be individual delivery that is directly delivered to the contractor, but a system that delivers to a predetermined base such as a convenience store and hands over what is recorded on a CD or MD is also possible.

At this time, the reproduction processing program may be transmitted via a recording medium such as an FD or a CD, but the method of distributing the data over a data communication network via the network as in the case of the audio data is troublesome. This can be omitted, and is also advantageous when performing an update. Also,
Digital audio data containing the identification signal and the sine wave combination signal is preferably distributed as compressed data compressed by a compression technique such as MP3.

In such an audio data distribution system, a key is set in a file of audio data to be distributed, and the key data is encrypted in association with an ID given to a distribution destination, and the encrypted key data is encrypted. It is preferable to use a key setting method for distribution via a data communication network. According to this, a key for preventing the distribution file from being opened is set, and the key is transmitted after being encrypted based on the ID.
Without it, even if a data file containing audio data is obtained, it cannot be opened, and the security can be further improved.

[0017]

FIG. 1 and FIG. 2 show an audio data distribution system for distributing music on a network as an example.

The distribution system S of the music transmission side (distribution company) that has set up a music distribution site is provided with a music source 1 that records an audio signal that is a source of digital audio data to be distributed. A process of inserting the identification signal 2 into a silent portion between the music pieces recorded in No. 1 (separation portion for each piece of music at the beginning or end of one piece of music) is executed.

In the first example shown in FIG. 1, when the identification signal 2 is inserted, the compression process 3 including the identification signal 2 is performed.
(For example, MP3) is executed. After the compression, encryption 4 corresponding to the identification signal 2 is performed, and the music piece is encrypted (FIG. 4). The compressed / encrypted data is stored in the server W, and the server W can be accessed as a distribution site. That is, when access is made from a contracted music receiving terminal T (such as a distribution destination personal computer or a personal computer at a convenience store) and a download of a predetermined artist album or the like is requested, the corresponding data is transmitted to the data communication network. The data is transmitted to the terminal T through the NET.

In the case of the first example, a contract is made to start music distribution, and an ID is set between the music transmitting side and the music receiving side so that the reproduction processing program 5 is distributed. ing. That is, terminal T
Is provided with an ID, so that the reproduction processing program 5 can be downloaded from the server W. Further, data of the key 6 (a combination of predetermined symbols, characters, and numbers) is also transmitted by encryption using the set ID. The key 6 serves as an opening key when opening a file to be downloaded from the server W to the terminal device T, and is sent separately from the audio data through an encryption process 7.

In the terminal T, when desired data is sent from the server W, the reproduction processing program 5 is executed using the identification signal 2 and the key 6. The identification signal 2 is necessary for decrypting the encryption 4 of the music piece by the distribution system S, and the key 6 is required for opening the file. The identification signal 2 is obtained by compressing and demodulating the download data (this will be described later).
Is transmitted by encryption 7, and is obtained by performing decryption 8 using its own ID.

When the reproduction processing program 5 is executed, a file is opened by the key 6 and the type of encryption is specified based on the identification signal 2. For example, what kind of processing is performed on the encryption 4 corresponding to the first identification signal 2, and the encryption 4 and the third encryption also corresponding to the second identification signal 2?
... Corresponding to the identification signal 2 of FIG. Thus, the type of the encryption 4 indicated by the identification signal 2 is analyzed,
Decryption 9 is executed according to the analysis result.

When the decryption 9 is performed, the compressed data obtained by the compression process 3 is restored, and the compressed demodulation 10 is performed on the compressed data. That is, in the case of this example, the compression failure process 10 is performed twice, ie, temporary compression demodulation for the identification signal 2 and actual compression demodulation for the music. Then, in the compression demodulation process 10 for extracting the identification signal 2, a copy of the compressed file sent from the server W is used, and the original compressed file is left as it is. Decrypt 9 for this original compressed file
Is performed, and after the encryption of the compressed data of the music piece is decrypted, the compression demodulation 10 is performed.

The data after the decryption 9 and the compression / demodulation 10 is an audio signal 11 of the same quality as the original music in the music source 1 and can be used within the contract.

Next, the second example shown in FIG. 2 will be described.
In this example, in the distribution system S, a process of superimposing the sine wave combination signal 12 on the music piece (that is, in the piece) is executed in association with the identification signal 2 inserted in the same manner as described above. Then, the identification signal 2 and the sine wave combination signal 1
The process of compressing the audio signal into which the audio signal 2 has been input by the digital compression process 3 is executed. The compressed data is stored in the server W, and this server W can be accessed from the contracted music receiving terminal T, and the corresponding data is transmitted to the terminal T via the data communication network NET in response to the download request. Sent.

As in the first example, the reproduction processing program 5 is distributed by setting an ID between the music transmitting side and the music receiving side, and further uses the set ID. The data of the key 7 is also transmitted by the encryption 8.

In the terminal T, when desired data is sent from the server W, a key 6 is first required to open the file. The key 6 is obtained by performing a decryption 8 using an ID on the one transmitted by the encryption 7. Key 6 obtained by this
When the file is opened, the compression demodulation 10 can be performed, and the identification signal 2 inserted in the distribution system S is obtained by the reproduction processing program 5 downloaded in the terminal T. The identification signal 2 is necessary for removing the sine wave combination signal 12 of the data received from the server W.

When the reproduction processing program 5 is executed, the type of the sine wave combination signal 12 is specified based on the identification signal 2. For example, what kind of combination of sine waves is the sine wave combination signal 12 corresponding to the first identification signal 2, and the sine wave combination signal 12 also corresponding to the second identification signal 2, The sine wave combination signals 12... Corresponding to the identification signal 2 are grasped. As described above, the type of the sine wave combination signal 12 indicated by the identification signal 2 is analyzed, and the sine wave combination signal removal 13 is executed so as to remove the sine wave combination signal 12 according to the analysis result. That is, when the sine wave combination signal removing step 13 is executed, the sine wave combination signal 12 is removed from the music based on the identification signal 2.

The data after the sine wave combination signal removal 13 is performed is an audio signal 11 having the same quality as the original music in the music source 1 and can be used within the contract.

FIG. 3 shows an example of an audio signal containing the identification signal 2. Generally, before or after one song (between songs)
Are formed with silence portions F and R of about one second, and are used for cueing a music piece. In this example, the silent portions F, R
The identification signal 2 is inserted into the. Silence F,
Although R is provided before and after the music piece, the identification signal 2 may be inserted in only the front silence part F, only the rear silence part R, or in any form of both the front F and the rear R.

In the first example, the audio signal containing the identification signal 2 is compressed and then encrypted 4. As shown in FIG. 4, the encryption 4 is performed only on a music piece (compressed music piece). At the time of such encryption processing, the identification signal (compressed identification signal) is
By setting aside for about seconds (unencrypted portion: white in the figure), it is possible to reliably prevent the encryption from reaching the identification number. That is, the encryption need not be over the entire music tune, but may be narrower and partial than the music tune.

FIG. 5 shows an example of an audio signal including the identification signal 2 and the sine wave combination signal 12 according to the second example. The identification signal 2 is the same as in the first example, except that the sine wave combination signal 12 is superimposed on the middle of the music piece to be a disturbing sound. In the case of this example, for a predetermined duration of 1 to 10 seconds (which may be constant or random), a plurality of frequency components (1 to 5
A sine wave A (oblique line) formed by combining the sine waves A (oblique lines) is superimposed, and for the next predetermined duration of 1 to 10 seconds, a sine wave B (solid) having a combination of frequency components different from the combined sine wave A is obtained. It is superimposed. Thereafter, the sine waves A and B may be repeated, or different types of combined sine waves may be superimposed. More specifically, the music tune is divided every second, and the first section has X
A composite wave of 1, X2, X3, X4 cycles is superimposed, a composite wave of Y1, Y2, Y3, Y4 cycles is superimposed in the next second section, and a Z1, Z2, Z3, Z4 cycle is performed in the third section. Sine wave combination signal 4 such that the composite wave of In this way, when viewed within each section (that is, within 1 second) (simultaneously), the frequencies X1 to X4 for the first section, Y1 to Y4 for the second section, and Z1 to Z4 for the third section. Are different from each other, and when different sections, for example, the first section and the second section are compared (with time), waveforms having different frequencies of X cycle and Y cycle exist. Therefore, it is possible to generate various and complicated combinations.

FIG. 6 shows an example of the identification signal 2. The condition of the identification signal 2 is that it is hard for humans to hear: a waveform in a sound range outside the audible sound, a waveform close to the audible limit in the audible sound range, and a general length of a silent period serving as a break between music pieces. That is, a sufficient signal can be put as identification information within about one second. The identification signal 2 does not pose a problem because bit information only needs to be transmitted, even if there is some deformation due to compression. Even if the identification signal 2 can be heard by human ears, there is no problem because it is put into a silent part. In the example of FIG. 6, a pair of very high-pitched burst signals is repeatedly used. By giving 16 degrees of freedom to the interval d between the pair of bursts, 4-bit digital information can be expressed. Thus, for example, a 160-bit digital number can be created using 40 pairs of bursts. It should be noted that the higher the frequency of the identification signal 2 is, the more difficult it is to hear and the more preferable it is.
In the case of 3, it is preferable that the frequency be around 16 kHz.

FIG. 7 illustrates one optimal sine wave component for the sine wave combination signal 12. The characteristic of the sine wave in this example is that the characteristics of the compression are taken into consideration.

That is, it is required that the disturbing sound does not change even after undergoing a compression process when applied to Internet distribution, and that it can be completely removed. For this purpose, a sine wave in the audible sound range is used, and in the example shown in FIG. 7, the rise and fall are made slow (smooth), and 0.1 second or more is secured. Also, the duration can be reliably determined as 1 second or longer as a whole. If these frequency components are used in combination of about 1 to 6 types, the degree of freedom can be given to the amplitude, the duration, the phase, etc., so that various kinds of combined sine waves can be generated, and the safety can be improved. Can be enhanced.

In the above method, if the music receiver had the same music as the original music included in the music source 1, if the original music was compared with the downloaded and demodulated music, it would be added. It is possible to remove a certain sine wave. If this should be considered, it is desired that some original sound deformation be performed before the sine wave combination signal 4 is superimposed. One of the means is a sample point moving method. This means that, for example, three sample points each having a value of zero are added between the original sample points, and after smoothing the signal with a low-pass filter, an appropriate fourth sample point is selected and the other three sample points are discarded. Means. By doing so, it is possible to change the value of digital data without deforming the music in an analog manner.

[0037]

According to the music protection system of the present invention, the identification signal + encryption after compression or the identification signal + sine-wave signal is adopted, so that if the identification signal is not deciphered, it is associated with this. The encryption and sine wave signal cannot be decrypted, and the security is very high. In addition, especially in the latter method, sine wave = disturbing sound can be distributed in a distorted state by superimposing it, so that safety can be improved, and music is not digitally processed, so it is a reminder to the artist Good,

Further, since the processing process and the signal in consideration of the compression characteristics are used, it is most suitable for audio data distribution via the Internet using MP3, and the security is remarkably enhanced by applying to an existing network distribution system. be able to. Further, according to the present invention, it is only necessary to manage the source itself before the compression processing, so that the management of the music source in the Internet distribution is easy.

In addition, when the system is broken, the system can be changed simply by replacing the reproduction processing program. When more security is required, the reproduction processing program is periodically replaced. It is possible. For example, by changing the playback processing program,
Since the correspondence between the identification signal and the encryption signal or the identification signal and the sine wave can be changed, even if the system is broken once, the reconstruction is easy.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first example of an audio data distribution system according to the present invention.

FIG. 2 is a schematic diagram showing a second example of the audio data distribution system according to the present invention.

FIG. 3 is an exemplary diagram of an audio signal including an identification signal.

FIG. 4 is an explanatory diagram in the case where an audio signal containing an identification signal is compressed and encrypted.

FIG. 5 is an exemplary diagram of an audio signal including an identification signal and a sine wave combination signal.

FIG. 6 is a waveform chart showing an example of an identification signal.

FIG. 7 is a waveform chart showing an example of a sine wave signal.

[Explanation of symbols]

 Reference Signs List 1 music source 2 identification signal 3 compression process 4 encryption process 5 reproduction processing program 6 key 7 encryption process (for key) 8 decryption process (for key) 9 decryption process 10 compression demodulation process 12 sine wave combination signal 13 sine Wave combination signal removal process S distribution system W server T terminal NET Internet

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁷ identification code FI G11B 20/10 G10L 9/00 E 9/18 M (58) Field surveyed (Int.Cl. ⁷ , DB name) G10L 19 / 00 G09C 1/00 660

Claims (8)

(57) [Claims] After inserting an identification signal into a silent part of an audio signal with a waveform that is hardly audible to humans, the audio signal is compressed, and only the music piece part of the compressed audio signal is converted to the identification signal. A music protection method characterized in that the data is encrypted in association with. 2. A combination of different types of sine waves in a silent part of an audio signal with a waveform that is hardly audible to humans, and in a music piece part of the audio signal in association with the identification signal. A music protection system characterized by overlapping signals. 3. A recording medium recording music according to the music protection method according to claim 1. 4. After inserting an identification signal in a silent part in an audio signal with a waveform that is hardly audible to humans, the audio signal is compressed, and only a music piece in the compressed audio signal is converted into the identification signal. Audio data characterized by distributing, via a data communication network, digital audio data that has been encrypted in association with the digital audio data, and further distributing a reproduction processing program for causing a computer to execute decryption based on the identification signal. Delivery system. 5. A combination of different types of sine waves in a silent part of an audio signal with a waveform that is hardly heard by humans, and in a music piece part of the audio signal in association with the identification signal. An audio system, comprising: distributing digital audio data obtained by superimposing signals via a data communication network; and further distributing a reproduction processing program for causing a computer to remove a sine wave combination signal based on the identification signal. Data distribution system. 6. The audio data distribution system according to claim 5, wherein the digital audio data is compressed and distributed. 7. The audio data distribution system according to claim 4, wherein the reproduction processing program is also distributed via a data communication network. 8. A key is set for a digital audio data file to be distributed, and the key data is
8. An encryption method in accordance with an ID assigned to a distribution destination, and distributing the encrypted key data through a data communication network.
An audio data distribution system according to any one of the preceding claims.