JP2004022098A - Method of preventing copying music cd, manufacturing method and system for the music cd - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of preventing copy being suitable for mass production and a manufacturing method for music CD using the method. <P>SOLUTION: The method of preventing copying a music CD is a multi-session system provided with: at least audio session constituted of audio data; and data session, in its EFM signal, pseudo information in which a sub-code channel of the audio session is changed is provided in a read-in region of the data session. The manufacturing method for the music CD is characterized in that the method of preventing copy is applied to EFM signal and a stamper is made according to the EFM signal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for preventing unauthorized copying from a CD (Compact Disc) in which music (audio) is recorded.
[0002]
[Prior art]
With the spread of personal computers (PCs) and advances in related technologies, it is now possible to record music (voice and instrumental music) with high sound quality on a large-capacity hard disk using the CD format or compression method such as MP3. ing. In addition, writable and rewritable CDs, such as CD-Rs and CD-RWs, and recording / reproducing apparatuses thereof have become widespread, and anyone can easily create a music CD.
[0003]
While such technological advances are certainly favorable, on the other hand, anyone can easily import music from a commercially available music CD directly or by converting the MP3 file to the hard disk of a personal computer. ing. Then, the file taken in from the commercial CD can be transmitted as it is on the Internet or a CD-R or a CD-RW can be easily created from the file, thereby infringing the copyright.
[0004]
[Problems to be solved by the invention]
The problem at present is that music recorded on a commercial CD can be taken into a personal computer as digital data with almost no deterioration in sound quality. Therefore, while it is possible to play back music on a general music CD player or a player (PC player) incorporated in a personal computer without any problem, an anti-PC type music having a copy protection function that cannot be imported to a personal computer (hard disk). CD development is awaited.
[0005]
As a copy protection method for such music CDs, there has been proposed a method of writing copy protection information of a new specification in subcode information or gap (pause) information between music pieces. However, this type of approach proposed to date is not easy to incorporate into a standard CD production line. In other words, in the prototype stage, it is possible to create a prototype CD by generating copy protection information using a general-purpose personal computer, incorporating this into audio data, and writing it to a CD-R or CD-RW. There are problems that need to be solved when applying this method to mass production lines.
[0006]
As shown in FIG. 1, a music CD production process starts with a process of taking data from a music source 1 such as a master disk or tape to a formatter 2. The formatter 2 composed of a computer according to a dedicated program is standardized and conforms to a globally unified standard. Through the processing by the formatter 2, a standardized EFM (Eight-to-Fourteen Modulation) signal is generated based on the data from the music source 1. This is input to the laser exposure device 3 to create a stamper 4 as a press die, and a commercial music CD is mass-produced by a press process 5 based on the stamper 4.
[0007]
The formatter 2 in such a CD production line performs a complicated process in accordance with a detailed international standard (such as IEC908 or ISO / IEC10149), and it is very difficult to modify the formatter. . However, since the above-described copy protection information is a new specification that is not included in the standard, it is necessary to change the specification of the formatter 2 when incorporating it. Many CD factories scattered around the world have a hard time responding to this, and it is not realistic. Further, even if the copy protection information is preliminarily stored in the data from the music source 1, it is considered that the signal disappears as an unnecessary signal when the signal passes through the formatter 2 and becomes an EFM signal, and does not function.
[0008]
In other words, some of the current methods are successful at the prototype stage, but are difficult to apply to production lines and are difficult to put into practical use. The present invention solves this problem and proposes a copy protection method suitable for mass production and a music CD production method using the same.
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention employs a multi-session CD system for forming at least two different sessions. That is, the music CD copy protection method according to the present invention employs a multi-session type in which at least an audio session composed of audio data and a data session are provided, and in the EFM signal, a lead-in area of the data session includes: Pseudo information obtained by changing a subcode channel of an audio session is provided. In this way, a general music CD player plays only an audio session and a personal computer reads only a data session for the reason described later, so that copy protection of audio data can be prevented. . The data session is composed of data different from the audio data of the audio session, such as a singer's profile / photo / video, a compressed file, audio data, and a program. That is, any data may be used as long as the data can be recognized by the personal computer.
[0010]
A general music CD player does not support a multi-session CD and is not expected to have a data session (only supports IEC908). Therefore, even if a data session is recorded in addition to the audio session, it is not recognized, so that only the audio data of the audio session can be reproduced without any trouble.
[0011]
On the other hand, since the personal computer is compatible with the multi-session CD, when recognizing this, the sub-code channels (P to W channels) in the lead-in area of each session are read, and the start flag and the data constituting the session are read. And various settings such as TOC and TOC are stored in the storage area. At this time, the personal computer repeatedly reads the subcode in the lead-in area of each session, and overwrites the setting read once with the setting read again (rewrite function). The present invention pays attention to this rewrite function, and provides a fake subcode of the subcode of the audio session that is read first in the lead-in area of the data session that is read later, to trick the personal computer. That is, a false subcode is set for the audio session portion. Therefore, the personal computer tries to read the audio session based on the overwritten fake subcode, so that the audio data cannot be reproduced or taken into the hard disk. Thereby, copy protection of the music CD for the audio session is achieved.
[0012]
In the present invention, as one of the false sub-codes (pseudo information), a system in which identification information of digital data is set in the control unit of the Q channel can be used. In this way, the audio data of the audio session can be misidentified as digital data, so that a copy protection function can be provided. The pseudo information may be a method in which the start address of the Q channel is shifted by a predetermined value. By doing so, the start position of each track of the audio session can be misidentified, so that a copy protection function can be similarly provided.
[0013]
The copy protection function of the music CD described above only needs to process the EFM signal after passing through the formatter, so that there is no need to change the specifications of the formatter. Therefore, it can be easily adopted in an existing production line.
[0014]
The data session read by the personal computer may be composed of data obtained by compressing and encrypting audio data and software for reproducing the data. By doing so, the personal computer can reproduce the same music as that recorded in the audio session by reading out the compressed and encrypted data recorded in the data session of the multi-session CD and the reproduction software. Become like However, in the data session, the audio data is encrypted and can only be played back by the dedicated playback software that exists. Therefore, even if the compressed encrypted data is extracted and burned to a CD-R or the like, Even if it can be dropped on a hard disk in a personal computer, it cannot be converted into a file format for other playback software such as an MP3 file unless the encryption can be decrypted. Therefore, even if the compressed and encrypted data can be extracted and this portion can be copied, it cannot be reproduced after all, so that the copy protection of the music CD can be achieved even in the data session.
[0015]
The compressed encrypted data of the data session is obtained by dividing the compressed audio data in units of bytes, distributing the divided data into variable-length partitioned files, and performing exclusive OR with 8 × n encryption keys prepared for each partition. It is good that it is calculated. As described above, since the data of the data session is obtained by encrypting the compressed audio data, the data session is not easily subjected to file exchange. That is, even if the data of the data session can be taken into the hard disk of the personal computer, the compressed audio data cannot be opened unless the encryption can be decrypted. Further, since the compressed and encrypted data is encrypted so that it can be reproduced only by reproduction software capable of decrypting the data, the data cannot be reproduced by other than the exclusive reproduction software recorded on the CD.
[0016]
Variable-length segment files, the division file _{L 0} constant byte length, a division file _{L 1 ~L n-1} of greater constant byte length of the byte length than the partition file _{L 0,} this indicator file _L 1 ~L section and the file L _n even byte length is less than _n-1, may be composed of. In the present invention, since an individual encryption key is used for each section, if the byte length of a certain section file is large, the same encryption key is repeatedly used for the section file. Therefore, if each of the divided files has a variable length, the number of repetitions of the encryption key becomes irregular, which can be hidden, making it difficult to decrypt the encryption.
[0017]
Each of the 8 × n encryption keys is composed of alphanumeric characters having an 8 × n bit sequence, and one of the alphanumeric characters is cyclically shifted by a designated number of bits for each divided file. It is good. Since the encryption key has a simple structure that changes according to the cyclic shift, high-speed processing can be realized when the encryption key is decrypted by encryption or reproduction software. Note that n = 1, 2, 3,...
[0018]
By applying the above copy protection method, it is possible to generate an EFM signal from data constituting an audio session and a data session, and then perform copy protection processing on the EFM signal, and create a stamper in accordance with the EFM signal after the processing. A featured music CD production method is realized by the present invention. A multi-session compatible formatter for generating an EFM signal from data constituting an audio session and a data session; copy-protection processing means for receiving an EFM signal output from the formatter and performing copy-protection processing; The present invention proposes a music CD production system including at least a laser exposure device that creates a stamper in accordance with a processed EFM signal output from a means. Further, the music CD production system may further include an encoder that generates compressed and encrypted audio data and its reproduction software as data constituting the data session, and provides this to the formatter.
[0019]
In these production methods and production systems, the copy protection processing performed on the EFM signal can be the method according to the copy protection method of the present invention.
[0020]
The copy protection processing means in the production system in this case includes a sub-code read unit for receiving the EFM signal and reading the sub-code, a delay unit for delaying the EFM signal after passing through the sub-code read unit for a predetermined time, A sub-code write unit for receiving the EFM signal after passing through the delay unit and rewriting the sub-code; a read processor for reading the sub-code from the sub-code read unit receiving the EFM signal and extracting the channel code; A computer that changes the corresponding part in the extracted channel code, and incorporates the channel code after the change by the computer into the subcode read by the read processor, and sends this subcode to the subcode write unit to send the subcode write unit. It can be a write processor to rewrite the subcode of the EFM signal being received, and made of a.
[0021]
The computer used for the copy protection processing means according to the present invention uses a sub-code rewriting specification (the pseudo information in which the identification information of the digital data is set in the control section of the Q channel, It is preferable that pseudo information obtained by shifting the start address of the Q channel by a predetermined value) is determined. According to this, the sub-code rewriting specifications can be changed at random for each music source, so that the most effective specifications can be determined for each music source, and it is difficult to find out.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2A shows a frame format 6 in which a subcode Q channel of an audio session is changed as pseudo information provided in a lead-in area of a data session to which the copy protection method of the present invention is applied.
[0023]
In this method, the control unit (CONTROL) of the Q channel is set to identification information “D” (01X0) indicating digital data. In other words, it is displayed that the audio session contains digital data such as a program. Then, when the music CD is to be reproduced on a personal computer, the content of the audio session is overwritten as digital data, so that the personal computer reads the audio session from the data session without reading the audio session. In other words, even if an audio session is misidentified as digital data and read according to TOC (Table Of Contents), the audio session cannot be read because the audio data is actually included.
[0024]
In the frame format 6, S0 and S1 are frame synchronization signals, CONTROL is a data type of the track (discrimination of audio data, digital data, and the like), ADR is a mode type relating to the data portion 7 in the frame format 6, and CRC is CONTROL. , ADR, and an error detection code of the data portion 7 are shown. In addition, TNO indicates a track number, MIN, SEC, and FRAME indicate a running time of one track, ZERO indicates 0, and POINT, PMIN, PSEC, and PFRAME indicate TOC (table of contents information).
[0025]
As another method, FIG. 2B shows a frame format 6 'in which the TOC of the data portion 7' is changed in the subcode Q channel. Specifically, PMIN, PSEC, and PFRAME in FIG. 2A are set to different values as PMIN ′, PSEC ′, and PFRAME ′. The values of PMIN, PSEC, and PFRAME are the start positions of the track numbers indicated by POINT, and the values indicate the start positions of the tracks on the absolute time scale (AMIN, ASEC, AFRAME) with an accuracy of ± 1 second. . Therefore, the values of PMIN ', PSEC', and PFRAME 'need only be shifted by ± 1 second or more from the values of PMIN _S1 , PSEC _S1 , and PFRAME _S1 . In this case, even if the personal computer attempts to read the audio session audio data, the personal computer reads the overwritten fake TOC, so that the reproduction becomes impossible.
[0026]
In addition to the method described above, it is also possible to use a method in which FIGS. 2A and 2B are combined. Also, as the pseudo information, the track number of the Q channel may be changed, or a channel code other than the Q channel may be changed.
[0027]
FIG. 3 shows an encoder that compresses and encrypts a music source for compressed and encrypted data recorded in a data session.
[0028]
The encoder 9 receiving the audio data from the music source 8 compresses the data to create a file 9a. The compressed file 9a is divided in units of 1 byte (8 bits) and is distributed to the variable-length sectioned file 9b. Segment _{L 0} is S bytes (fixed _length) of the file 9b, L _{1 ~L n-1} is T bytes (fixed length), _{L n} in (less than T bytes) U _bytes, L _{1 ~L n-1} > L ₀ , L _n .
[0029]
The key 9c is composed of eight alphanumeric characters A1 to A8. The alphanumeric characters A1 to A8 are each composed of an 8-bit string. Each bit string of alphanumeric characters A1~A8 is cyclic shift as shown in 9d (rotation shift), is used as a different key for each segment file _L 0 ~L _n. In the cyclic shift according to the present embodiment, one bit shifted from the right end is shifted to the left end one after another. However, it may be shifted from the left end to shift to the right end.
[0030]
There is shown a variation of the key _K 0 ~K _n to 9e. The key _K 0 ~K _n as shown in 9e is a structure in which cyclic shift of any one of bit strings of alphanumeric characters A1 to A8. For example, 'becomes a (key _K 1), next, A2 is cyclically shifted A2' A1 is cyclic shifted A1 becomes (key _K 2). The key K ₀ ~K _n is employed in different combinations for each audio CD, this and dedicated playback software to know the change in the same combination and the key, that is, if a playback software with a common key (secret key) Play Can not do it. Examples of the combination of the key _K 0 ~K _n, or adopts the K 0 ~K _8, or employs a K 5 ~K _n. Copy protection is enhanced by the complexity of the decryption by the change of the combination and a key K ₀ ~K _n increases.
[0031]
The encryption is performed by the exclusive OR operation unit 9f. Here, division file _L 0 ~L _n and the key _K 0 ~K _n is an exclusive OR operation (EXOR). For example, the encryption is performed by changing the key for each section, such as L ₀ and K ₀ , L ₁ and K ₁ , L ₂ and K ₂ ... L _n and K _n . The result of the exclusive OR operation unit 9f becomes the compressed and encrypted data. The encoder 9 outputs the compressed and encrypted data and dedicated reproduction software having a common key capable of reproducing the data as data 10.
[0032]
FIG. 4 shows an outline of a music CD production line using the above copy protection method.
[0033]
The formatter 11 which receives the audio data and the data 10 from the music source 8 and generates the EFM signal has the same specification as the conventional one. In the production line of the present embodiment, the EFM signal output from the formatter 11 is received by the copy protection processing means 12, where the copy protection processing of FIG. 2 is performed. The processed EFM signal output from the copy prevention processing means 12 is input to the laser exposure unit 13 to form a stamper 14. Music CDs are mass-produced by a pressing step 15 using the stamper 14 as a mold.
[0034]
A copy protection processing unit 12 reads a subcode of an audio session and a data session from the EFM signal, extracts a channel code, for example, a Q channel code, and executes a subcode rewriting of the EFM signal. And a computer 30 that takes in the extracted Q-channel code and changes a necessary portion.
[0035]
As shown in FIG. 5, the processor 20 receives the EFM signal and reads the subcode, and the EFM signal after passing through the subcode read unit 21 for a predetermined time (= at least Q channel). A delay unit 22 for delaying a code change, a subcode write unit 23 for receiving an EFM signal after passing through the delay unit 22 and rewriting a subcode, and a subcode read unit for receiving an EFM signal A read processor 24 for reading a sub-code from the sub-code 21 to extract a Q-channel code; incorporating a Q-channel code after being changed by the computer 30 into the sub-code read by the read processor 24; To the sub Comprising a write processor 25 to rewrite the subcode of the EFM signal being received to de light unit 23, a.
[0036]
The read processor 24 and the write processor 25 have a common memory 26, and the subcode read by the read processor 24 is stored in the memory 26 and overwritten by the write processor 25. The overwritten subcode is sent to the subcode write unit 23 by the write processor 25.
[0037]
The sub-code read unit 21 and the sub-code write unit 23 have the same configuration, and include a shift register that measures the sub-code read timing. That is, when the EFM synchronization is detected and the EFM signal is started to be captured, and when the subcode synchronization patterns S0 and S1 are detected, the read processor 24 reads the data or the write processor 25 after shifting by at least the number of bits of the subcode. Is written.
[0038]
The sub-code read into the memory 26 by the read processor 24 is divided into each channel, and the computer 30 fetches the Q channel code and changes the corresponding portion. The location to be changed is determined according to the subcode rewriting specification, and this specification is determined by the flexible disk 31. This subcode rewriting specification describes how to change the Q channel of an audio session provided in a data session.
[0039]
The Q channel thus set by the computer 30 is overwritten by the write processor 25 with the data session currently stored in the memory 26. Then, the sub-code whose Q channel has been updated is sent to the sub-code write unit 23, and is written at a sub-code equivalent position of the EFM signal which enters the shift register after being delayed by the delay unit 22 for the processing time described above. Is executed.
[0040]
【The invention's effect】
According to the present invention, a music CD copy protection method which can be applied to a production line without any modification to an existing formatter is provided, thereby providing a music CD production method having a practical copy protection processing step. And a system is provided. That is, the formatter generates an EFM signal composed of each session in accordance with the conventional standard, and processes the EFM signal output from the formatter. Just add them. Therefore, the production line can be switched without extra cost.
[0041]
In particular, the copy protection method of the present invention is an anti-personal computer specification which has copy resistance to a personal computer that is rapidly improving in performance. According to the music CD to which the copy protection method of the present invention is applied, the personal computer is designed to read only data sessions. In addition, since the audio data recorded in this data session is compressed and encrypted, if it cannot be decrypted, it cannot be converted to a file of another format, and can be reproduced only by special reproduction software. Therefore, a more reliable copy protection function is provided.
[0042]
Furthermore, in the present invention, since only the subcode channel portion is to be changed without changing the audio data, a copy protection method without changing the sound quality of the audio data can be provided.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a conventional music CD production line.
FIG. 2 is a frame format in which a subcode Q channel of an audio session to which the copy protection method of the present invention is applied is changed.
FIG. 3 is an explanatory diagram of an encoder that performs a copy protection method according to the present invention.
FIG. 4 is an explanatory diagram of a music CD production line according to the present invention.
FIG. 5 is a block diagram showing a specific example of copy protection processing means.
[Explanation of symbols]
6, 6 'frame format 7, 7' data portion in frame format 8 music source 9 encoder 10 data (compressed and encrypted data and its reproduction software)
DESCRIPTION OF SYMBOLS 11 Formatter 12 Copy prevention processing means 13 Laser exposure device 14 Stamper 15 CD press

Claims (14)

A multi-session type having at least an audio session composed of audio data and a data session is provided, and in the EFM signal, pseudo information obtained by changing a subcode channel of the audio session is provided in a lead-in area of the data session. A copy protection method for music CDs, comprising: 2. The method according to claim 1, wherein the pseudo information is obtained by setting identification information of digital data in a Q channel control unit. 3. The music CD copy protection method according to claim 1, wherein the pseudo information is obtained by shifting a start address of the Q channel by a predetermined value. The music CD copy protection method according to any one of claims 1 to 3, wherein the data session is composed of data obtained by compressing and encrypting audio data and software for reproducing the data. Compressed encrypted data is obtained by dividing compressed audio data in units of bytes, distributing the divided data into variable-length partitioned files, and performing an exclusive OR operation using 8 × n encryption keys prepared for each partition. 5. The method according to claim 4, wherein the music CD is protected from being copied. Variable-length segments file, the classification file _{L 0} of fixed-byte length, the division file _{L 1 ~L n-1} of the larger fixed length in bytes of the byte length than the said section file _{L 0,} said section file _L 1 ~L copy protection method of claim 5, wherein the music CD that is composed of a divided file L _n bytes length is smaller than _n-1. The 8 × n encryption keys are composed of alphanumeric characters having 8 × n bit strings, and are obtained by cyclically shifting any one of the alphanumeric characters by a designated number of bits for each divided file. 6. The method for preventing copying of a music CD according to claim 5. A method for producing a music CD, comprising: generating an EFM signal from data constituting an audio session and a data session, performing copy protection processing on the EFM signal, and creating a stamper in accordance with the processed EFM signal. 9. The production method according to claim 8, wherein the EFM signal is subjected to copy protection processing according to the copy protection method according to any one of claims 1 to 7. A multi-session compatible formatter for generating an EFM signal from data forming an audio session and a data session, copy protection processing means for receiving an EFM signal output from the formatter and performing copy protection processing, A music CD production system, comprising: at least a laser exposure device that creates a stamper in accordance with an output EFM signal after processing. 11. The music according to claim 10, further comprising: an encoder that generates compressed and encrypted data of audio data and reproduction software thereof according to the copy protection method according to any one of claims 4 to 7, and provides the generated software to a formatter. CD production system. 12. The production system according to claim 10, wherein the copy protection processing means performs copy protection processing on the EFM signal according to the copy protection method according to any one of claims 1 to 7. The copy protection processing means includes a sub-code read unit for receiving the EFM signal and reading the sub-code, a delay unit for delaying the EFM signal after passing through the sub-code read unit for a predetermined time, and a delay unit after passing through the delay unit. Sub-code write unit for receiving the EFM signal and rewriting the sub-code, a read processor for reading the sub-code from the sub-code read unit receiving the EFM signal and extracting the channel code, and the extracted channel code And a computer for changing the corresponding portion in the sub-code, and incorporating the channel code after the change by the computer into the sub-code read by the read processor, sending the sub-code to the sub-code write unit and receiving the sub-code write unit Have been Production system and light processor to rewrite the subcode of the FM signal, consisting claim 12. 14. The production system according to claim 13, wherein the computer of the copy protection processing means determines a subcode rewriting specification according to a replaceable recording medium.

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