JP2004164690A - Modulation device, modulation method and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent copying of a digital information signal on an original CD. <P>SOLUTION: A modulation device generates a number of codeword string groups from at least one codeword Cx to a following next codeword Cz by looking ahead at least a following codeword Cy following the one codeword Cx and the following next codeword Cz, and adding temporarily a plurality of joint bit groups 1b with r bits between at least one codeword Cx and the following codewords Cy and between the following codeword Cy and the following next codewords Cz, after complying with prescribed run length restrictive rules strictly. The device outputs finally one resolved codeword string resolved by choosing one codeword string group whose absolute value of a DSV value is the nearest to zero among DSV values of multiple codeword string groups, using the joint bit added between one codeword Cx and the following codeword Cy in this one codeword string group, and combining from the one codeword Cx to the following codeword Cy through the joint bit. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a modulation device, a modulation method, and a recording medium for preventing copying of a digital information signal recorded on a recording medium such as an optical disk or a digital magnetic tape.
[0002]
[Prior art]
With the advent of the age of digital multimedia, large-capacity digital information signals are recorded on optical disks or digital magnetic tapes.
[0003]
For example, a read-only optical disk such as a CD (Compact Disc) containing music information or a CD-ROM (CD-Read Only Memory) containing computer data is formed in a spiral or concentric shape on a disk-shaped disk substrate. The above-mentioned digital information signals can be recorded at high density on the tracks formed in this manner, and the desired tracks can be accessed at high speed during reproduction, and are suitable for mass production and can be obtained at low cost.
[0004]
Digital magnetic tapes containing PCM music information and the like are widely used because they can be reproduced for a longer time than optical disks.
[0005]
In the following description, an optical disk that records and / or reproduces data using an optical pickup as a recording medium for recording digital information signals will be described. However, in the case of a digital magnetic tape, when recording and / or reproducing data, The only difference is that a head is used. Therefore, a description of a digital magnetic tape will be omitted.
[0006]
Optical discs such as the CDs and CD-ROMs described above convert a digital information signal into a digital pit row with concave pits and convex lands, and carve this pit row as a spiral or concentric recording track. After the stamper board on which the signal surface has been recorded is mounted in an injection molding machine, the signal surface of the stamper board is 120 mm or 80 mm in outer diameter using a transparent resin material, the hole diameter of the center hole is 15 mm, and the substrate thickness is 1.2 mm. It is transferred to a disk-shaped transparent disk substrate, and a reflective film and a protective film are sequentially formed on the transferred signal surface to form a read-only type.
[0007]
When reproducing a read-only optical disk, a laser beam for reproduction from an optical pickup movably provided in the optical disk drive was irradiated onto the signal surface from the transparent disk substrate side to form a film on the signal surface. The signal surface is reproduced by the return light of the laser beam from the reflection film.
[0008]
By the way, music information recorded on CDs and computer data recorded on CD-ROMs are protected by copyright law, but since they are digital information, there is no signal deterioration. The user can copy to a write-once optical disc such as a CD-R (Compact Disc-Recordable) that can be written only once without permission of the copyright holder, or a CD-RW (Compact Disc-ReWritable) that can be written multiple times. It is possible to do.
[0009]
The write-once optical discs such as the CD-R and CD-RW described above have substantially the same external appearance as read-only optical discs such as CDs and CD-ROMs, but have spiral grooves formed on a transparent disc substrate. Alternatively, the recording layer is formed concentrically, an organic dye serving as a recording layer is spin-coated on the concave groove side, and a reflective film and a protective film are sequentially formed on the organic dye. Moreover, it is available at low cost.
[0010]
Then, when music information recorded on a CD or computer data recorded on a CD-ROM is copied to a CD-R or CD-RW, it is recorded in the same signal format as the CD or CD-ROM. This infringes copyright.
[0011]
Hereinafter, a code word string of music information recorded on a known CD will be described. FIGS. 1A and 1B are diagrams for explaining a signal format of music information recorded on a CD. FIG. 1A shows original music data, FIG. 1B shows an EFM signal, and FIG. A diagram showing an encoding table at the time of modulation,
FIGS. 3A and 3B are diagrams for explaining DSV control at the time of 8-14 modulation.
[0012]
First, music information is recorded on a CD in a signal format conforming to the CD standard book “Red Book” or the IEC (International Electrotechnical Commission) 908 standard.
[0013]
In this case, generally, the pit length recorded on the optical disc is limited by the minimum run length (minimum pit length or minimum land length) due to the optical transmission characteristics of recording / reproduction and physical constraints related to pit generation, clock reproduction. In order to limit the maximum run length (maximum pit length or maximum land length) from the ease of operation, and to protect the servo band, etc., the recording signal must have a low-frequency component and a DC component suppression characteristic of the recording signal. It needs to be modulated.
[0014]
Among the modulation schemes satisfying this restriction, the EFM (Eighth Fourteen Modulation: 8-14 modulation) scheme used for CDs has a minimum run length of 3T (T = cycle of channel bits) and a maximum run length of 11T. Things.
[0015]
That is, as shown in FIG. 1A, the music original data AD to be recorded on the CD is digital data, and upper 8 bits (1 byte) + lower 8 bits (1 byte) = 16 bits (2 bytes) and 1 bit. A unit is constituted, and the music original data AD is constituted by a plurality of these one units.
[0016]
When the original music data AD shown in FIG. 1A is recorded on a glass master by a laser beam at the time of mastering, the original music data AD is converted into an EFM signal format so as to have a signal form suitable for recording. Then, it is recorded on the glass master in the form of the EFM signal 1 shown in FIG. 1 (b), and thereafter, a metal master board, a mother board, and a stamper board are sequentially manufactured by electroforming based on the glass master. Thereafter, the stamper board is mounted in the injection molding machine, and the signal surface of the stamper board is transferred to the transparent disk substrate to produce a CD. Therefore, the signal surface of the CD is equivalent to the signal surface of the glass master disc.
[0017]
Here, in the format of the EFM signal 1 described above, the input music original data AD is divided into an upper 8-bit input data word D and a lower 8-bit input data word D, and the encoding table shown in FIG. Referring to the input data word D of p bits = 8 bits, a run length limited code of q bits = 14 bits (hereinafter referred to as “q bits = 14 bits”) satisfying a predetermined run length restriction rule that the minimum run length is 3T and the maximum run length is 11T. , Codeword C), and as shown in FIG. 1 (b), between the converted codeword C and the codeword C, for holding the run-length restriction rule and DSV (Digital Sum Value). The first and second code word strings 1d and 1f to be described later are generated as an EFM signal 1 by adding r bits = 3 combination bits 1b for control. To have.
[0018]
At this time, when a predetermined run length restriction rule is satisfied, the minimum run length is 3T, and the number of “0” s between the logical values “1” and “1” in the code word C is at least d = 2. On the other hand, when the maximum run length is 11T, at most k = 10 “0” s are included between logical values “1” and “1” in the code word C. In other words, when the run length restriction rule RLL (d, k) = RLL (2,10) is satisfied, the minimum run length is determined based on the run length restriction rule RLL (d, k) = RLL (2,10). (D + 1) T = 3T, and the maximum run length is set to (k + 1) T = 11T. The first and second codeword strings 1d and 1f, which are obtained by adding a 3-bit combination bit 1b between adjacent codewords C and C, have a minimum run length (d + 1) T = 3T to a maximum run length ( k + 1) T = 11T, and when the NRZI conversion is performed on the first and second codeword strings 1d and 1f as described later, the minimum run length 3T is the minimum inversion interval, while the maximum The run length 11T indicates the maximum inversion interval.
[0019]
The pfm modulation = 8-14 modulated EFM signal 1 satisfies the run length restriction rule RLL (d, k) = RLL (2,10) in which the minimum run length is 3T and the maximum run length is 11T. However, the DC component and the low frequency component of the EFM signal 1 can be reduced.
[0020]
Further, NRZI (Non Return to Zero Inverted) conversion is performed on the EFM signal 1 including the first and second codeword strings 1d and 1f. As is well known, the NRZI conversion has a polarity at bit "1". Since the modulation is performed without inverting the polarity at bit “0”, the waveform after the NRZI conversion becomes the recording signal R on the glass master, and the L (low) level section of the recording signal R is For example, a pit row is formed so as to correspond to a concave pit (or a convex land), and the H (high) level section in the recording signal R corresponds to, for example, a convex land (or a concave pit).
[0021]
As shown in FIGS. 3A and 3B, the above-mentioned DSV has a waveform of H (high) level after the NRZI conversion from the start time of the codeword string in the EFM signal 1 to the present time. This is an integrated value obtained by integrating “1” (positive polarity) at time and “−1” (negative polarity) at L (low) level. At this time, in the NRZI conversion, since the polarity inversion is performed at the data bit “1”, even if the code word has the same bit pattern, it differs depending on the waveform state after the NRZI conversion immediately before connecting the code word. As shown in FIG. 3A, when the waveform state immediately before the input data word = 002 is at the L (low) level, and as shown in FIG. The DSV value is inverted when the waveform state is at the H (high) level. For example, when the input data word = 002 and the input data word = 253 are connected via a connection bit, FIG. The absolute value of both DSVs in FIG. 3B is the same.
[0022]
Here, as a 3-bit combined bit 1b between adjacent codewords C and C such that the absolute value of the DSV approaches substantially zero while satisfying the run-length restriction rule RLL (d, k) = RLL (2, 10). , (000), (001), (010), and (100) are selected and added to reduce the DC component of the waveform of the recording signal R, resulting in recording. When the waveform of the signal R is viewed over a long period, the H (high) level section and the L (low) level section appear at substantially the same ratio, so that the concave pit section and the convex land section also have substantially the same ratio. The DSV value is controlled to appear.
[0023]
Referring back to FIG. 1B, one frame of the EFM signal 1 described above includes a synchronization signal 1a, a combination bit 1b, a subcode 1c, a combination bit 1b, a first codeword string 1d, a combination bit 1b, and a C2 error correction from the beginning. The code 1e, the combination bit 1b, the second code word string 1f, the combination bit 1b, the C1 error correction code 1g, and the combination bit 1b are arranged in this order, and are composed of 588 channel bits in total for one frame.
[0024]
Here, the synchronization signal 1a arranged at the head can be identified from the above-mentioned signals 1b to 1g as 11T, 11T, and 2T signals in order to indicate the head of the frame using 24 bits.
[0025]
The subcode 1c arranged after the synchronization signal 1a via the 3-bit combination bit 1b is a signal for controlling reproduction to a CD.
[0026]
The first code word sequence 1d arranged via the 3-bit combination bit 1b after the sub-code 1c is obtained by encoding each input data word D (each music original data) of p = 8 bits as shown in FIG. Referring to the table, the codewords are converted into codewords C of q = 14 bits, and three codewords C (12 symbols) are added between adjacent codewords C. ) And 11 combined bits 1b.
[0027]
Further, the C2 error correction code 1e arranged after the first code word string 1d via the 3-bit combination bit 1b is converted into the first code word string 1d and the second code word string 1f of the EFM signal 1 during CD reproduction. The error correction is performed for this.
[0028]
Further, the second code word sequence 1f arranged via the 3-bit combination bit 1b after the C2 error correction code 1e has 12 code words C (12 symbols) like the first code word sequence 1d described above. And 11 combined bits 1b.
[0029]
Further, the C1 error correction code 1g arranged after the second codeword string 1f via the 3-bit combination bit 1b is used to output the first codeword string 1d, the second codeword string 1f, and C2 of the EFM signal 1 during CD reproduction. Error correction is performed on the error correction code 1e.
[0030]
Then, 98 blocks (= 98 frames) of NRZI-converted recording signals after one frame of the above-mentioned EFM signal 1 are continuously formed to constitute one block which is a unit of music. This corresponds to a period of 1/75 second.
[0031]
In the case of a CD-ROM containing computer data, the description is omitted because the music original data shown in FIG. 1A only needs to be renamed to the computer original data.
[0032]
Here, a conventional modulation device will be described with reference to FIGS.
[0033]
FIG. 4 is a block diagram schematically showing a conventional modulation device,
FIGS. 5 (a) to 5 (c) show a code obtained by adding a combination bit between one code word and the next code word while strictly observing a predetermined run length restriction rule using a conventional modulator. A description will be given of a state where DSV values of a plurality of sets of code word strings are calculated when (000), (001), (010), and (100) are temporarily added as connection bits when a word string is generated. FIG.
[0034]
The conventional modulation device 20 shown in FIG. 4 includes a glass master recording machine (not shown) for producing a CD, and a CD-R drive (not shown) for copying music information recorded on a CD to a CD-R. (Not shown), and has a schematic configuration of an 8-14 modulation circuit 21, a combination bit addition circuit 22, a DSV value calculation circuit 23, and a DSV value comparison circuit / combination bit selection circuit 24. Have been.
[0035]
Then, the conventional modulation device 20 separates the 16-bit music original data AD into upper 8 bits and lower 8 bits and converts each 8-bit input data word D into each 14-bit code word C. A plurality of sets of 3-bit combination bits 1b satisfying the run-length restriction rule RLL (2, 10) are temporarily added between one code word Cx and the next code word Cy. By generating a word string and selecting one set of code word strings whose absolute value of DSV is closest to zero from among the DSV values of the plurality of code word strings, the code word of this one set is obtained. The sequence is output as one finally determined code word sequence.
[0036]
More specifically, in the conventional modulation device 20, 16-bit music original data AD is input to the 8-14 modulation circuit 21 in chronological order.
[0037]
In the 8-14 modulation circuit 21 described above, the input music original data AD is converted into the upper 8 bits of the input data word D and the lower 8 bits of the input data word D as described earlier with reference to FIG. When each input data word D of 8 bits is sequentially converted into a code word C of 14 bits based on the encoding table shown in FIG. 2, for example, one code word Cx and one code word are separated. The next code word Cy following the word Cx is sequentially read. Then, one codeword Cx and the next codeword Cy are input from the 8-14 modulation circuit 21 to the combination bit addition circuit 22.
[0038]
Next, the combined bit addition circuit 22 strictly adheres to the minimum run length 3T to the maximum run length 11T set based on the run length restriction rule RLL (2, 10) in the CD standard, and the adjacent codewords C, C It has a function of adding a 3-bit combination bit 1b between them. This combination-bit addition circuit 22 includes (000), (001), (010), and (100) as candidates for the 3-bit combination bit 1b. ) Are prepared. Note that, although there are eight 3-bit combination bits 1b, in the sets (011), (101), (110), and (111) other than the four sets described above, two or more "1" s appear continuously. Alternatively, it cannot be used because “1” and “0” appear alternately and do not satisfy the run-length restriction rule RLL (2, 10).
[0039]
Then, in order to combine the codeword Cx and the codeword Cy sequentially input into the combination bit addition circuit 22, four sets of combination bits (000), (001), and (010) are provided between the codewords Cx and Cy. , (100) are temporarily added to generate a plurality of sets of codeword strings.
[0040]
At this time, as shown in FIG. 5, for example, one code word Cx is “010” from the 12th bit to the 14th bit, while the next code word Cy is “00100010000010”. The 13th bit of one codeword Cx is “1”, and the third bit of the next codeword Cy is “1”. Although the three sets of combination bits (000), (001), and (010) can strictly adhere to the run-length restriction rule RLL (2, 10), the fourth set of combination bits (100) has the run-length restriction rule RLL (2, 10). Since the condition (10) is not satisfied, the addition of the combined bit (100) is stopped.
[0041]
Then, after adding three sets of connection bits (000), (001), and (010) between the codewords Cx and Cy, the three sets of codeword strings {Cx (000) Cy} and {Cx (001) Cy are obtained. {Cx (010) Cy} is input to the DSV value calculation circuit 23 to calculate each DSV value of the three sets of codeword strings. As a result, as shown in Case 1 of FIG. When the combination bit (000) is added between Cy, the DSV value of the code word string {Cx (000) Cy} becomes +2, and as shown in case 2 shown in FIG. When the combination bit (001) is added to the code word string {Cx (001) Cy}, the DSV value becomes -4, and as shown in Case 3 shown in FIG. 5C, between the code words Cx and Cy. When the combination bit (010) is added, the code word sequence {Cx (010) Cy} SV value is -6.
[0042]
Thereafter, the three sets of code word strings from the DSV value calculation circuit 23 and the respective DSV values corresponding thereto are input to a DSV value comparison circuit / combination bit selection circuit 24, and the DSV value comparison circuit / combination bit selection circuit 24 And selecting one set of codeword strings {Cx (000) Cy} having a DSV value = + 2 such that the absolute value of the DSV is closest to zero among the DSV values of the three sets of codeword strings. This one set of code word strings {Cx (000) Cy} is output from the DSV value comparison circuit / combination bit selection circuit 24 as one determined code word string. In other words, the DSV value comparison circuit / combined bit selection circuit 24 selects the combined bit (000) corresponding to one decision code word string {Cx (000) Cy} whose DSV absolute value is closest to zero. become. Hereinafter, the above procedure is repeated following the next code word Cy to obtain one determined code word string {Cx (000) Cy...}.
[0043]
Thereafter, one decision code word string {Cx (000) Cy...} Whose DSV value is controlled is generated as a recording signal R (FIG. 1) suitable for recording, and the laser beam is used to produce a CD glass master. Alternatively, it is recorded on a CD-R.
[0044]
Then, a stamper disk (not shown) is manufactured based on the glass master disk for the CD, and a CD is manufactured using the stamper disk.
[0045]
From the above, the user plays back a CD containing music information to be copied in accordance with copy software stored in a hard disk (not shown) in a personal computer (not shown) in a CD drive (not shown), and outputs the CD from the CD drive. Also, music information desired to be recorded on the CD-R is input to a CD-R drive (not shown), and music information desired to be copied by the conventional modulation device 20 provided in the CD-R drive is obtained with permission of the copyright holder. It is possible to copy it directly to a CD-R without using it.
[0046]
Therefore, when the 16-bit music original data AD output from the CD drive is encoded by the conventional modulation device 20 provided in the CD-R drive, the music information recorded on the CD-R is recorded on the CD. Since the EFM signal format is exactly the same as that of the music information, the copied CD-R can be further copied, and the CD-R is circulated in large quantities in the world.
[0047]
Therefore, as described above, there is an example of an optical disc that can prevent copying of music information recorded on a CD or computer data recorded on a CD-ROM to a recordable / reproducible CD-R or CD-RW. (For example, see Patent Document 1).
[0048]
[Patent Document 1]
JP-A-2001-357536 (pages 4-5, FIG. 4)
[0049]
FIG. 6 is a longitudinal sectional view showing an optical disc on which a copy protection measure is taken as an example of a conventional example.
[0050]
The conventional optical disc 100 shown in FIG. 6 is disclosed in Patent Document 1 described above, and will be briefly described with reference to Patent Document 1 for an optical disc such as a CD-ROM and a DVD-ROM. In the conventional optical disc 100 in which a copy protection measure is taken, 3T to 14T (T is 0.133 μm) is usually based on a run-length restriction rule (described as a run-length suppression coding scheme in the same publication). ), A concave or convex portion having a continuous length even shorter than the minimum run length based on the run length restriction rule is recorded in the middle of this process. It is a feature.
[0051]
Specifically, as shown in FIG. 6, the pit A is formed in a convex shape with a length of 1T to 2T, and a pit B is formed in a concave shape with a length of 1T to 2T at a position X away from the pit A. The lengths of the pits A and B are values that are not based on the run length restriction rule.
[0052]
Therefore, in the conventional optical disc 100, among the run length restriction rules based on the minimum run length 3T and the maximum run length 14T, the minimum run length 3T is not strictly adhered to but is set to a smaller value 1T to 2T. Thus, the minimum pit length (or minimum land length) on the optical disc 100 is formed smaller than usual.
[0053]
[Problems to be solved by the invention]
Therefore, based on the above-described technical idea of the conventional optical disc 100, an uneven portion row (pit row) having a continuous length of 3T to 11T is formed based on the run length restriction rule RLL (2, 10) in the CD standard. In order to modify a part of the signal form of the CD by applying to the well-known CD, for example, in the encoding table shown in FIG. 2, the code word C for the input data word D = 255 is “00100000010010”. However, when it is desired to form a short uneven portion row (pit row) such as 1T, a modified CD can be manufactured by using a code word C such as “00100110010010” instead.
[0054]
When the thus modified CD is reproduced by a commercially available optical disk drive, the certification pit having a short continuous length of 1T to 2T in the data is shorter than the normal pit length (land length) of 3T to 11T. The RF signal read using the optical pickup does not reach a sufficient light level or a sufficient dark level, and the binarized signal obtained from the RF signal includes a 1T to 2T certification pit signal. Therefore, it cannot be determined whether or not the optical disc being reproduced is the original. Further, when music data recorded on a modified CD is reproduced by a commercially available optical disk drive, and the reproduced data is input to a CD-R drive and copied to a CD-R, the music data is copied without any problem. .
[0055]
Therefore, the copy prevention means based on the premise of the spread of a new player capable of detecting the proof pit like the optical disk 100 is used in a situation where a large number of players and CD-R drives are already on the market such as a CD. There is a problem that it cannot be applied.
[0056]
Further, similarly to the case of the optical disk, there is a problem that the digital information signal recorded on the digital magnetic tape is also copied.
[0057]
Therefore, when a codeword string is generated while strictly observing a predetermined run-length restriction rule, the original recording medium on which the codeword string is recorded can be reliably reproduced by a commercially available player, while the original recording medium A modulation device, a modulation method, and a recording medium that can prevent copying of a digital information signal recorded on a recording medium such as an optical disk or a digital magnetic tape by causing reproduction failure in a copy recording medium on which the data is copied are desired. It is rare.
[0058]
[Means for Solving the Problems]
The present invention has been made in view of the above problems, and a first invention is to convert an input data word of p bits into a code word of q bits, and to convert r bit combination bits between adjacent code words. In a modulation device that generates a codeword string by adding the codeword string and outputs the codeword string,
when converting the p-bit input data word into the q-bit code word, a next code word that follows one code word, and a modulation unit that at least pre-reads the next next code word;
Between the one codeword and the next codeword, a plurality of sets of combined bits by the r bits are strictly adhered to a predetermined run-length restriction rule and temporarily added to generate a plurality of sets of codeword strings, Further, a plurality of sets of combination bits of the r bits are strictly adhered to a predetermined run-length restriction rule also between the next code word in the plurality of code word strings and at least the next next code word. Tentatively added, a combination bit addition means for generating a large number of sets of codeword strings from at least one codeword to the next next codeword,
DSV value calculation means for calculating each DSV value of a large number of sets of the code word strings generated by the combination bit addition means;
Comparing / selecting means for selecting one set of the codeword strings whose absolute value of the DSV value is closest to zero among the DSV values of the multiple sets of the codeword strings obtained by the DSV value calculating means; When,
Using the combination bits added between the one codeword and the next codeword in the one set of codeword strings selected by the comparison / selection means, And a decision code word string output unit that outputs one decision code word string that is finally determined by combining up to the next code word through
The input data word is AC signal data or DC signal data that cannot be discriminated perceptually, and the code word string output by the modulation device that pre-reads only the next code word includes a specific frequency component. A modulation device for inputting data over a predetermined period and encoding the input data word by pq modulation.
[0059]
According to a second aspect, in the modulation device according to the first aspect,
When the input data word is music information, and the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is inserted in a silent section formed between songs. A modulation device characterized in that:
[0060]
According to a third aspect, in the modulation device according to the first aspect,
When the input data word is music information, and when the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is included in a silent section formed between songs. In addition, the modulation device is inserted in a section excluding the section of index number 00.
[0061]
Further, the fourth invention converts a p-bit input data word into a q-bit code word, and adds r-bit combination bits between adjacent code words to generate a code word sequence. In a modulation method for outputting a word string,
when converting the p-bit input data word into the q-bit code word, a first step of at least pre-reading the next code word following one code word and the next next code word;
Between the one codeword and the next codeword, a plurality of sets of combined bits by the r bits are strictly adhered to a predetermined run-length restriction rule and temporarily added to generate a plurality of sets of codeword strings, Further, a plurality of sets of combination bits of the r bits are strictly adhered to a predetermined run-length restriction rule also between the next code word in the plurality of code word strings and at least the next next code word. A second step of generating a large number of sets of code word strings from at least one code word to the next next code word;
A third step of calculating each DSV value of the multiple sets of codeword strings generated in the second step;
A fourth step of selecting one set of the codeword strings whose absolute value of the DSV value is closest to zero among the DSV values of the multiple sets of codeword strings obtained in the third step;
Using the combination bits added between the one codeword and the next codeword in the one set of codeword strings selected in the fourth step, the combination bits from the one codeword A fifth step of combining the code words up to the next code word and outputting one finally determined code word sequence.
The input data word is AC signal data or DC signal data that cannot be discriminated perceptually, and the code word string output by the modulation device that pre-reads only the next code word includes a specific frequency component. A modulation method characterized by inputting data for a predetermined period and encoding the input data word by pq modulation.
[0062]
According to a fifth aspect, in the modulation method according to the fourth aspect,
When the input data word is music information, and the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is inserted in a silent section formed between songs. The modulation method is characterized in that:
[0063]
According to a sixth aspect, in the modulation method according to the fourth aspect,
When the input data word is music information, and when the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is included in a silent section formed between songs. In addition, the modulation method is characterized by being inserted in a section excluding the section of index number 00.
[0064]
Further, a seventh invention is a recording medium which records the code word sequence encoded by any one of the modulation devices of the above-described first to third inventions or the above-described modulation method of the fourth to sixth inventions. It is.
[0065]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present embodiment of the modulation device, the modulation method, and the recording medium according to the present invention will be described in detail with reference to FIGS.
[0066]
In the modulation device, the modulation method, and the recording medium according to the present invention, for example, in the case of conforming to the CD standard, an input data word of p bits = 8 bits is converted into a code word C of q bits = 14 bits, and an adjacent data word is converted to a code word C of q bits = 14 bits. When the EFM signal 1 shown in FIG. 1B is generated by adding r bits = 3 combination bits 1b between the matching codewords C and C, the next codeword following one codeword and the next codeword And the minimum run length (d + 1) T = 3T set based on the run length restriction rule RLL (d, k) = RLL (2, 10) according to the CD standard. Observing the maximum run length (k + 1) T = 11T, one codeword and the next codeword are taken into consideration while taking into account the DSV value of the codeword string from one codeword to the next codeword at least through the next codeword. Select the combination bit 1b with the code word And then outputting a code word sequence from one code word to the next code word via the combination bit 1b as one finally determined code word sequence, Furthermore, when the original recording medium on which the EFM signal 1 is recorded is reproduced, the first and second code word strings 1d and 1f of the EFM signal 1 composed of specific data described later can be reproduced without any trouble. On the other hand, when the copy recording medium obtained by copying the original recording medium is reproduced, the reproduction signals of the first and second codeword strings 1d and 1f composed of the copied specific data have components of specific frequencies increased, and the reproduction becomes impossible. It is characterized by falling.
[0067]
By the way, especially in the original recording medium on which the first and second code word strings 1d and 1f composed of the specific data are recorded, since the conventional CD standard is satisfied, no data reading error occurs.
[0068]
In this embodiment described below, an optical disc such as a CD or a CD-ROM will be described as an example of a recording medium on which a digital information signal is recorded. The technical idea of this embodiment can be applied to a tape.
[0069]
<Example>
FIG. 7 is a block diagram schematically illustrating a modulation device and a modulation method according to the present embodiment according to the present invention.
FIG. 8 to FIG. 10 show that using the modulator of the present embodiment according to the present invention, a combined bit is inserted between one codeword and the next codeword while strictly observing the run length restriction rule in the CD standard. When a codeword string is generated by adding, a state in which the next codeword following one codeword and the next next codeword are read ahead and each DSV value of a large number of codeword strings is calculated. Diagram for explaining,
FIG. 11 is a diagram showing a difference in the frequency spectrum between the case of the original CD of the present embodiment according to the present invention and the case of the CD-R obtained by copying the original CD due to the DSV value fluctuation of the codeword string.
[0070]
The modulation device 30 according to the present embodiment shown in FIG. 7 is applied to a glass master recording device (not shown) for producing a CD, and includes an 8-14 modulation circuit 31 and A first combination bit addition circuit 32A, a first DSV value calculation circuit 33A, a second combination bit addition circuit 32B, a second DSV value calculation circuit 33B, a DSV value comparison circuit / combination bit selection circuit 34, The output circuit 35 is roughly configured.
[0071]
The first and second combined bit addition circuits 32A and 32B have the same internal structure, and the first and second DSV value calculation circuits 33A and 33B also have the same internal structure. The first and second combined bit adding circuits 32A and 32B and the DSV value calculating circuits 33A and 33B are not separated from each other depending on the control software for operating the 30 and the combined bit adding circuit (32 ... not shown). Although it can be configured as a DSV value calculation circuit (33... Not shown), it is separated as described above to make the description easy to understand.
[0072]
In the modulation device 30 of the present embodiment, the 16-bit music original data AD is divided into upper 8 bits and lower 8 bits, and each 8-bit input data word D is converted into each 14-bit code word C. For example, when an EFM signal 1 is generated by adding a 3-bit combination bit 1b between one code word Cx and the next code word Cy, the next code word following the one code word Cx Cy and the next next code word Cz are at least read ahead, and a plurality of three-bit codes are placed between one code word Cx and the next code word Cy while strictly complying with the run-length restriction rule RLL (2, 10). A plurality of sets of combined bits 1b are temporarily added to generate a plurality of sets of codeword strings, and further, between the next codeword Cy and at least the next next codeword Cz in the plurality of sets of codeword strings. Also strictly enforces the run-length restriction rule RLL (2, 10). While a plurality of combined bits 1b of 3 bits are temporarily added, a large number of sets of codeword strings from one codeword Cx to at least the next next codeword Cz through the next codeword Cy are generated. One set of codeword strings whose absolute value of DSV is closest to zero is selected from the multiple codeword strings, and one codeword Cx and the next codeword in this one set of codeword strings are selected. Using a combination bit 1b added between the first code word Cy and the next code word Cy from one code word Cx to the next code word Cy via the combination bit 1b, a final determined code word sequence is output. ing.
[0073]
More specifically, in the modulation device 30 of the present embodiment, the 16-bit music original data AD is input to the 8-14 modulation circuit 31 in chronological order.
[0074]
In the 8-14 modulation circuit 31, the input music original data AD is converted into the upper 8 bits of the input data word D and the lower 8 bits of the input data word D as described earlier with reference to FIG. When sequentially separating each 8-bit input data word D into a 14-bit code word C based on the encoding table shown in FIG. Differently, for example, one codeword Cx is read, and at least the next codeword Cy following the one codeword Cx and the next codeword Cz are prefetched.
[0075]
Note that, in the following, an embodiment will be described in which prefetching is performed up to the next codeword Cy and the next codeword Cz following one codeword Cx, but the present invention is not limited to this and illustration is omitted here. However, it is also possible to pre-read a codeword further ahead than the next codeword Cz.
[0076]
Then, one codeword Cx and the next codeword Cy are input from the 8-14 modulation circuit 31 to the first combination bit addition circuit 32A, and the next codeword Cy is output after the next codeword Cy is output. Cz is input from the 8-14 modulation circuit 31 to a second combined bit addition circuit 32B described later.
[0077]
Next, in the first combined bit addition circuit 32A, a 3-bit minimum run length 3T to a maximum run length 11T set based on the run length restriction rule RLL (2, 10) in the CD standard are strictly adhered to. Four sets of (000), (001), (010), and (100) are prepared as candidates for the combination bit 1b. Also in this embodiment, as in the conventional example, in the sets (011), (101), (110), and (111) other than the four sets described above, two or more “1” s appear continuously or “ Since “1” and “0” appear alternately and do not satisfy the minimum run length 3T, they are deleted.
[0078]
Then, in order to combine one code word Cx input into the first combined bit addition circuit 32A and the next code word Cy, four sets of combined bits (000) are interposed between the code words Cx and Cy. ), (001), (010), and (100) are temporarily added to generate a plurality of sets of codeword strings.
[0079]
At this time, as shown in FIGS. 8 to 10, when one code word Cx and the next code word Cy are set to the same value as the conventional one in order to easily explain the gist of the present invention, one code The twelfth to fourteenth bits of the word Cx are “010”, while the next code word Cy is “00100010000010”. The 13th bit of one codeword Cx is “1”, and the third bit of the next codeword Cy is “1”. The three coupled bits (000), (001), and (010) are satisfied because they satisfy the minimum run length 3T to the maximum run length 11T, and the fourth coupled bit (100) has the minimum run length 3T. Stop adding because you are not satisfied.
[0080]
Then, three sets of connection bits (000), (001),
After adding (010), the three sets of codeword strings {Cx (000) Cy}, {Cx (001) Cy}, and {Cx (010) Cy} are input to the first DSV value calculation circuit 33A, and three sets When the DSV values of the code word string are calculated, the code word string {Cx (000) Cy} when the coupling bit (000) is added between the code words Cx and Cy as shown in FIGS. Is +2, the DSV value of the code word string {Cx (001) Cy} is -4 when the combination bit (001) is added, and the code word string is added when the combination bit (010) is added. The DSV value of {Cx (010) Cy} is -6. Up to this stage, it is the same as the conventional example described earlier with reference to FIGS. 4 and 5. In the conventional example, at this stage, a set of code word strings {Cx (000) whose absolute value of DSV is closest to zero at this stage. ) Cy} is selected as one finally determined code word sequence, but in the present embodiment, as described above, the next code word Cy following the one code word Cx and the next next code word Cz Is read ahead, one code word Cx and the next code word are considered in consideration of the DSV value obtained when one code word Cx is connected to the next code word Cz via the next code word Cy. After selecting and adding the combination bit 1b between the code word and Cy, a code word sequence from one code word Cx to the next code word Cy via the combination bit 1b is finally determined.
[0081]
Therefore, the three sets of code word strings {Cx (000) Cy}, {Cx (001) Cy}, and {Cx (010) Cy} obtained by calculating each DSV value in the first DSV value calculation circuit 33A are added with second combined bits. The signal is input to the circuit 32B.
[0082]
Similarly to the first combined bit addition circuit 32A, the second combined bit addition circuit 32B described above (000), (001), (001), as a candidate of the 3-bit combination bit 1b that satisfies the minimum run length 3T to the maximum run length 11T. Four sets of (010) and (100) are prepared.
[0083]
Then, in the second combined bit addition circuit 32B, the three sets of codeword strings {Cx (000) Cy}, {Cx (001) Cy}, {Cx (010) Cy} input here are input here. The four combined bits (000), (001), (010), and (100) are tentatively added to the next code word Cz, which is the same as that of the first combined bit addition circuit 32A. Also generates a large number of sets of codeword strings. At this time, a large number of sets of codeword strings are encoded in a branching structure (tree structure), so that one codeword Cx passes through the next codeword Cy and the next codeword Cz in common. Up to the code word string.
[0084]
Here, as shown in FIGS. 8 to 10, the next codeword Cy is “00100010000010” as described above, while the next codeword Cz is “00100010000010”. The 13th bit of the next codeword Cy is “1”, and the third bit of the next codeword Cz is “1”. The third combination bit (000), (001), (010) satisfies the minimum run length 3T to the maximum run length 11T, but the fourth combination bit (100) does not satisfy the minimum run length 3T. Stop adding.
[0085]
Then, between the three sets of codeword strings {Cx (000) Cy}, {Cx (001) Cy}, {Cx (010) Cy} and the next codeword Cz input here, 3 After adding the combination bits (000), (001), and (010), nine code word strings {Cx (000) Cy (000) Cz} and {Cx (000) Cy (001) in total Cz}, {Cx (000) Cy (010) Cz}, {Cx (001) Cy (000) Cz}, {Cx (001) Cy (001) Cz}, {Cx (001) Cy (010) Cz} , Cx (010) Cy (000) Cz}, {Cx (010) Cy (001) Cz}, {Cx (010) Cy (010) Cz} are input to the second DSV value calculation circuit 33B, and 9 codes are set. Each DSV value of the word string is calculated.
[0086]
Here, the DSV value of the codeword string {Cx (000) Cy (000) Cz} becomes -3 as in Case 11 shown in FIG.
As in case 12 shown in FIG. 8B, the DSV value of the codeword string {Cx (000) Cy (001) Cz} is +3,
As in case 13 shown in FIG. 8C, the DSV value of the codeword string {Cx (000) Cy (010) Cz} is +5.
[0087]
Also, the DSV value of the code word string {Cx (001) Cy (000) Cz} becomes +1 as in case 21 shown in FIG.
As in case 22 shown in FIG. 9B, the DSV value of the codeword string {Cx (001) Cy (001) Cz} becomes -5,
The DSV value of the codeword string {Cx (001) Cy (010) Cz} becomes -7 as in the case 23 shown in FIG. 9C.
[0088]
Further, the DSV value of the codeword string {Cx (010) Cy (000) Cz} becomes −1 as in the case 31 shown in FIG.
As in case 32 shown in FIG. 10B, the DSV value of the codeword string {Cx (010) Cy (001) Cz} becomes -7,
As in the case 33 shown in FIG. 10C, the DSV value of the codeword string {Cx (010) Cy (010) Cz} is -9.
[0089]
Thereafter, the nine sets of codeword strings from the second DSV value calculation circuit 33B and the respective DSV values corresponding thereto are input to the DSV value comparison circuit / combination bit selection circuit 34, and the DSV value comparison circuit / combination bit selection circuit At 34, a codeword string {Cx (001) Cy (000) Cz} having a DSV value = + 1 whose absolute value of DSV is closest to zero among the DSV values of the nine codeword strings, or a DSV value = One of the sets of the code word string {Cx (010) Cy (000) Cz} having −1 is selected and input to the decision code word string output circuit 35.
[0090]
When the code word string is selected by the DSV value comparison circuit / combined bit selection circuit 34, if the absolute value of the DSV of the code word string is the same, the code word string of the DSV value on the + side is adopted. If it is determined in advance in the modulation device 30 whether to use the code word string of the DSV value on the minus side or the code word string on only one of the + side and one side, it can be automatically selected. Further, it is possible to select the combination bit 1b corresponding to the code word string on only one side.
[0091]
Next, the decision code word string output circuit 35 adds a code word between one code word Cx and the next code word Cy in one set of code word strings selected by the DSV value comparison circuit / combination bit selection circuit 34. One determined code word sequence {Cx (001) Cy} finally determined by combining one code word Cx to the next code word Cy via the combined bit 1b using the combined bit 1b thus obtained, or One of the determined code word strings {Cx (010) Cy} is output. In other words, this is equivalent to a state where the combination bit 1b between the code words Cy and Cz and the code word Cz are removed from one set of code word strings selected by the DSV value comparison circuit / combination bit selection circuit 34.
[0092]
That is, the code word string {Cx (001) Cy (000) Cz} having the DSV value = + 1 input to the decision code word string output circuit 35 or the code word string {Cx (010) having the DSV value = −1 Cy (000) Cz} is that the combination bit 1b added between the code words Cx and Cy is (001) or (010), and one code word Cx passes through the next code word Cy and the next next bit. The combination bit 1b added between the code words Cx and Cy is selected so that the absolute value of the DSV when the DSV value of the code word string up to the code word Cz is considered is closest to zero.
[0093]
On the other hand, as in the conventional example described with reference to FIG. 4, using the conventional modulation device 20 that pre-reads only one codeword Cx and the next codeword Cy, the coupling bit 1b is generated between the codewords Cx and Cy. In the case of the addition, one decision code word string {Cx (010) Cy} having a DSV value of +2 is obtained as shown in FIG. 4, and then one decision code word string {Cx (010) 8) When a code word Cz is connected to Cy}, the results are as shown in FIGS. 8A to 8C, and the DSV values in FIGS. 8A to 8C are obtained by pre-reading the next next code word Cz. The DSV value obtained when the DSV value obtained at that time is greater than the code word sequence {Cx (001) Cy (000) Cz} of +1 or the code word sequence {Cx (010) Cy (000) Cz} of which the DSV value is −1. It becomes larger on the + side or-side.
[0094]
Thereafter, in this embodiment, the determined code word sequence {Cx (001) Cy...} Or the determined code word sequence {Cx (010) Cy...} Controlled so that the DSV value is the best is suitable for recording. The recording signal R is converted into a recording signal R (FIG. 1), and is recorded on a glass master disk for CD (not shown) by a laser beam. Then, a stamper disk (not shown) is manufactured based on the glass master disk for CD, and the present embodiment according to the present invention as shown in FIGS. An optical disk (CD) 10 serving as a recording medium of an example is manufactured.
[0095]
The basic operation of the modulation device and the modulation method according to the present invention has been described with reference to specific examples. However, for the sake of simplicity of description, in calculating the DSV value, codeword strings {Cx (000) Cy}, {Cx (000) Cy (000) Cz}, and {Cx (000) Cy (000) ) Cz...｝, Such that the already calculated code word string is again subjected to the calculation. As a result, unless all the code words Cx, Cy, Cz... Are input, not only the DSV value cannot be calculated, but also the determined code word string can be output. For the determined DSV value of the code word string, a DSV value storage circuit (not shown) is provided in the DSV value calculation circuits 33A and 33B or the DSV value comparison circuit 34 to avoid duplication of DSV value calculation and at least three DSV value calculations. When a codeword is input, one determined codeword string can be obtained.
[0096]
From the above, when generating a codeword string by adding a 3-bit combination bit 1b such that the DSV value becomes the best between adjacent codewords C and C, the next codeword Cy following one codeword Cx and the next codeword Cy When the modulator 30 of the present invention that generates a code word sequence by at least pre-reading the next next code word Cz is used, as shown in FIGS. Can take the smallest value.
[0097]
On the other hand, when the conventional modulation device 20 (FIG. 4) that does not prefetch the next codeword Cz is used, the next codeword Cz is prefetched as shown in FIGS. It is clear from the above that the DSV value becomes larger than the case where the modulation device 30 of the present embodiment is applied, and the DSV value of the codeword string generated by applying the modulation device 30 of the present embodiment is smaller than the case where the conventional modulation device 20 is used. It can be a value.
[0098]
By the way, when the codeword string is continuously increased for a certain period when the codeword string is encoded using the conventional modulation device 20, the DSV value of the codeword string may periodically fluctuate greatly. This is because the decision codeword corresponding to the first codeword Cx is the same as when the DSV value rises to the right, that is, when the input codewords Cx, Cy, Cz. If the polarity of the column is reversed, the DSV value may decrease to the right, that is, may have a negative increasing tendency. As a result, when a signal recorded using the conventional modulation device 20 is reproduced, a component of a specific frequency is increased in a reproduced signal of a codeword string, and stable reproduction is impaired. On the other hand, when the modulation device 30 of this embodiment is applied, it is clear that stable reproduction is maintained. Hereinafter, input data corresponding to a specific codeword that causes such a difference is referred to as specific data.
[0099]
Applying this technical idea, it pre-reads from one codeword Cx to at least the next next codeword Cz via the next codeword Cy, and strictly observes the minimum run length 3T to the maximum runlength 11T. When the code word string generated from the specific data is recorded on the original recording medium, the DSV value of the recorded code word string is extremely small, so that reproduction failure does not occur. It is apparent that the variation of the DSV value of the specific data portion on the original recording medium is large, so that the component of the specific frequency increases in the reproduced signal.
[0100]
This is shown in FIG. As shown in FIG. 11, the reproduction frequency spectrum of the code word string of the specific data part recorded on the original recording medium (CD) is gradually attenuated in the low-frequency part, whereas When a copy recording medium (CD-R) copied by the conventional modulation device 20 is reproduced by the conventional CD (CD), the reproduction frequency spectrum of the code word string of the specific data portion is such that the component of the specific frequency increases in the low-frequency portion. Therefore, reproduction of the copy recording medium (CD-R) becomes unstable.
[0101]
When the technical idea of the present embodiment is applied to a CD-ROM containing computer data, it is only necessary to change the music original data AD shown in FIG. 7 to the computer original data. Description is omitted.
[0102]
Next, an optical disc serving as a recording medium of the present embodiment according to the present invention will be described with reference to FIG. FIGS. 12 (a) and 12 (b) are a perspective view and a longitudinal section for explaining an optical disc which is a recording medium of the present embodiment according to the present invention.
[0103]
As shown in FIGS. 12A and 12B, an optical disk (hereinafter, referred to as an original CD) 10 serving as a recording medium of the present embodiment according to the present invention includes a CD (Compact Disc) containing music information, It is applied to a read-only optical disc such as a CD-ROM (CD-Read Only Memory) containing computer data, and a digital information signal recorded on this original CD 10 is EFM (Eight to Fourteen Modulation: 8-14 modulation). According to the method, encoding is performed using the modulation device 30 of the present embodiment described above so that the minimum run length satisfies 3T and the maximum run length satisfies 11T as the highest priority.
[0104]
The above-mentioned original CD 10 is composed of a disc-shaped transparent disk substrate 11 having an outer diameter of 120 mm or 80 mm, a center hole diameter of 15 mm, and a substrate thickness of 1.2 mm. The pit sequence is converted into a digital pit sequence, and this pit sequence is carved as a spiral or concentric recording track 12 to record a signal surface.
[0105]
Here, the recording track 12 strictly adheres to the minimum run length 3T to the maximum run length 11T among the code words Cx, Cy, Cz... Using the modulation device 30 of the present embodiment described above, and , At least the next code word Cy and the next code word Cz following one code word Cx are read ahead, and a combination bit 1b is added to optimize the DSV value to generate one decision code word sequence. An uneven pit array is formed in advance over the entire surface corresponding to this one determined code word array. Further, a metal reflective film 14 and a protective film 15 are sequentially formed on the signal surface of the original CD 10, so that the original CD 10 is formed in a read-only type. The surface 11b of the transparent disk substrate 11 opposite to the one surface 11a is the side on which the reproduction laser beam Lp is irradiated.
[0106]
When the recording track 12 recorded on the original CD 10 is reproduced by a commercially available CD player or CD-ROM drive, the specific data portion has a small DSV value and strictly adheres to a predetermined run-length restriction rule. No error occurs. On the other hand, as shown in FIGS. 8A to 8C, 9B, 9C, 10B, and 10C, specific data that generates a large DSV value is the input data word D. In the case where a period occurs, the DSV value of the code word string in the optical disc manufactured by the conventional modulation device 20 has a large amount of fluctuation, and fluctuates in a cycle based on the length of one or two frames of the code word string. Therefore, a reproduction failure occurs.
[0107]
Similarly, when the user copies the original CD 10 on which the music original data AD (FIG. 7) including the specific data described above is recorded to a copy recording medium (CD-R) using a CD-R drive (not shown). As described above, since the conventional modulation device 20 (FIG. 4) is provided in the CD-R drive, the original music data AD (FIG. 7) obtained by reproducing the original CD 10 is converted to the CD-R drive. When input to the drive, only one codeword Cx and the next codeword Cy are read ahead in the conventional modulation device 20 (FIG. 4), and a combination bit 1b is added to generate a codeword string. The DSV value of the copied code word sequence has a larger variation than that in the case of using the modulation device 30 (FIG. 7) of the present embodiment, and has a period based on the length of one or two frames of the code word sequence. Fluctuating. Therefore, when this copy recording medium (CD-R) is reproduced by a commercially available CD player or CD-ROM drive, the reproduced signal has a specific effect that adversely affects the operation of the binarization circuit, tracking or focus servo, and the like. The frequency component increases, and the reproduction becomes unstable or cannot be reproduced. Thus, when the original CD 10 is copied onto a copy recording medium (CD-R), it is possible to prevent copyright infringement on the digital information signal. It is known that a large variation in the DSV value of the above-mentioned code word string adversely affects the stability of the reproducing apparatus, as described in the section of the prior art in JP-A-6-197024. Details are omitted here.
[0108]
Next, encoding and using specific data of an AC signal or a DC signal which cannot be discriminated in terms of audibility as the music original data AD is more effective for copy prevention measures, and this case will be described with reference to FIGS. 13 and 14. I do.
[0109]
FIG. 13 (a) shows a case where the original CD of the present invention produced by encoding specific data of an AC signal which cannot be discerned as perceived as music original data AD is reproduced, and FIG. 13 (b) shows a copy of the original CD of the present invention. FIG. 14 (a) shows a case where a CD-R is reproduced, and FIG. 14 (a) shows a case where an original CD of the present invention produced by encoding specific data of a DC signal which cannot be discriminated perceptually as music original data AD is reproduced; (B) is a diagram showing a case where a CD-R obtained by copying the original CD of the present invention is reproduced.
[0110]
First, as shown in FIG. 13 (a), a signal which cannot be discriminated from the ear as the music original data AD, for example, specific data composed of an AC signal of about 22.05 KHz is applied to the present embodiment shown in FIG. The signal is input to an 8-14 modulation circuit 31 provided in the example modulation device 30. For example, when the specific data composed of an AC signal of about 22.05 KHz is converted into a 14-bit code word C, the minimum run length 3T to the maximum run length 11T are strictly observed, and the next run time following one code word Cx is followed. At least the code word Cy and the next code word Cz are read ahead at least, and a combination bit 1b that gives the best DSV value is added to generate one decision code word sequence. This is applied to an original CD 10 (FIG. 12) serving as a recording medium according to the present invention. When the original CD 10 is reproduced, the reproduced signal of the code word string does not increase the component of the specific frequency, so that it is reproduced as AC signal data which does not cause any trouble and cannot be discriminated in terms of audibility. So the user does not notice at all. It is to be noted that, as shown in FIG. 13A, the specific data composed of the AC signal is subjected to a fade-in / fade-out process before and after a predetermined period as shown in FIG. Is also one of the features. Also, as the predetermined period in which the specific data of the AC signal is inserted, in the case of music data, a silent period between songs is suitable.
[0111]
On the other hand, as shown in FIG. 13 (b), when the original CD 10 on which specific data composed of an AC signal is recorded is copied to a CD-R and the CD-R is reproduced, the code word over the predetermined period described above is reproduced. Since a specific frequency component is increased in the reproduced signal of the column, an unreadable section occurs, and noise of a low frequency component is generated by data interpolation in the reproducing apparatus. The user can hear that the CD-R is an abnormal optical disk because the user can hear an unpleasant sound such as "sound" and prevent copyright infringement of the digital information signal on the copied CD-R. be able to.
[0112]
Next, FIG. 14A is an example in which the AC signal data of FIG. 13A is replaced with specific data composed of a DC signal that cannot be discriminated from the ears as the music original data AD, and is produced by applying this data. When the original CD 10 (FIG. 12) serving as the recording medium according to the present invention is reproduced, the reproduction signal of the code word string does not increase the component of the specific frequency, so that there is no problem and the audibility is not increased. Since it is reproduced as DC signal data which cannot be distinguished above, the user does not notice at all. It should be noted that, as shown in FIG. 14A, the specific data composed of a DC signal is subjected to fade-in and fade-out processing before and after a predetermined period as shown in FIG. Is also one of the features. Also, as the predetermined period in which the specific data of the DC signal is inserted, in the case of music data, a silent period between songs is suitable.
[0113]
On the other hand, as shown in FIG. 14B, even when the original CD 10 on which the specific data including the DC signal is recorded is copied to the CD-R, an unreadable section occurs during the predetermined period as described above. I will. Therefore, even in this case, since the copied CD-R cannot be reproduced, copyright infringement of the digital information signal on the copied CD-R can be prevented.
[0114]
Here, when the input data word D to be p-q modulated is music information, and the p-bit input data word D is converted into a q-bit code word C, as described above, it is converted into one code word Cx. When at least the next code word Cy and the next next code word Cz are read ahead and a code word string is generated, the specific data of the AC signal or the DC signal which cannot be discriminated by the above-described audibility is included in the music information. The case of inserting a music piece into a silent section formed between music pieces will be described more specifically with reference to FIGS.
[0115]
FIG. 15 is a schematic diagram for explaining a silent section between music pieces on a general CD.
FIG. 16 is a schematic diagram for explaining a specific data insertion mode 1 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between songs in the recording medium according to the present invention;
FIG. 17 is a schematic diagram for explaining a specific data insertion mode 2 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between music pieces in the recording medium according to the present invention;
FIG. 18 is a schematic diagram for explaining a specific data insertion mode 3 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between music pieces on the recording medium according to the present invention;
FIG. 19 is a schematic diagram for explaining a specific data insertion mode 4 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between songs in the recording medium according to the present invention.
[0116]
Here, a case will be described in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section formed between songs on the original CD 10 (FIG. 12) serving as a recording medium according to the present invention and recorded. First, a silent section in the case of a general CD (Compact Disc) in which music information is recorded as reference data for this will be described first.
[0117]
That is, as shown in FIG. 15, in the case of a general CD containing music information, the TOC (not shown) in the lead-in area (not shown) formed on the inner peripheral side according to the CD standard book “Red Book”. In the Table of Contents, the start address of each music piece is recorded in advance as the index information of the music information. Further, a plurality of songs recorded in the data area on the CD track also have a song number, an index number, an address and the like recorded for each song as shown.
[0118]
More specifically, when a plurality of songs recorded on a CD are generalized and displayed using n (where n is a natural number of 2 or more), for example, among the plurality of songs, for example, an (n−1) th song And the nth tune, a silent section is formed.
[0119]
Also, the song number n-1 corresponding to the (n-1) th song is the n-1th song from the performance end position (not shown) immediately after the performance of the (n-2) th song (not shown) has ended. The performance end position of the music number n-1 corresponding to the (n-1) -th song is recorded up to the performance end position immediately after the end of the performance, and the n-th song and the n-th song It is set in a silent section formed between them. Further, a music number n corresponding to the n-th music is recorded after the performance end position of the music number n-1 corresponding to the n-th music.
[0120]
Also, the index numbers for indicating the order of the movements in the respective songs can be assigned to the (n-1) th song and the nth song from 01 to 99 at the maximum. Are recorded from the position of the start address (not shown) of the (n-1) th music to the end of the performance of the music number n-1 of this music. The index number 01 (-99) in the tune is recorded from the position of the start address of the tune to the performance end position (not shown) of the tune number n of the tune. At this time, the start address (not shown) of the (n-1) th tune and the start address of the nth tune are located in a silent section between the tunes and located before the leading end at which the performance of each tune starts. It is recorded in.
[0121]
Further, in a silent section formed between the (n-1) th song and the nth song, there is a section in which an index number 00 that is not related to each song is recorded. Is set between the performance end position of the music number n-1 of the (n-1) th music and the position of the start address of the nth music.
[0122]
As described above, the (n-1) -th song ends at the performance end position of the song number n-1 of the song. On the other hand, the n-th song starts from the position of the start address of the song.
[0123]
Here, when a song number, an index number, and a start address are recorded for each song corresponding to a plurality of songs recorded in a data area on a track as in the above-described CD, the recording according to the present invention is performed. In the original CD 10 (FIG. 12) serving as a medium, for example, specific data of an AC signal or a DC signal, which cannot be discriminated by hearing, is shown in a silent section formed between the (n-1) th song and the nth song. The data is inserted and recorded based on one of the specific data insertion modes 1 to 4 shown in FIGS.
[0124]
First, as shown in FIG. 16, in the case of the specific data insertion mode 1 in the recording medium according to the present invention, for example, between the (n−1) -th song and the n-th song on the original CD 10 (FIG. 12). The specific data described above is inserted and recorded in the silent section formed in the section No. 1 and in the section of index number 00 assigned to the position as described above.
[0125]
As a result, when the original CD 10 in which the specific data is inserted and recorded in the section of index number 00 is entirely copied onto a CD-R (copy recording medium), the copied CD-R also has the (n-1) th tune. When the copied CD-R is played back, the specific data is recorded in the silent section formed between the song and the n-th song, and the specific data is recorded in the section with index number 00. In the same manner as described above, an unreadable section occurs due to the copied specific data and the CD-R becomes unreproducible, so that copyright infringement of the digital information signal on the copied CD-R can be prevented beforehand. .
[0126]
However, when copying the original CD10 recorded by inserting the specific data into the section of index number 00 to a CD-R, the user avoids the silent section between the songs by random access to the original CD10. It is also conceivable to copy a plurality of songs from the start address position to the CD-R. In this case, since the silent section between the songs is not copied on the CD-R, the The specific data recorded in the section of each index number 00 set in the... Are not copied, so that even if the copied CD-R is reproduced, the unreadable section does not occur, and the specification on the original CD 10 is not performed. The data copy protection function will not work on the copied CD-R. In order to avoid this, according to the present invention, even when the user collects a plurality of songs from the position of the start address of each song on the original CD 10 and copies them to a CD-R, each recorded in the silent section between the songs. By adopting any of the specific data insertion modes 2 to 4 shown in FIGS. 17 to 19 described below so that the specific data is always copied, the copy protection function of the original CD 10 can be further improved. Things.
[0127]
That is, as shown in FIG. 17, in the case of the specific data insertion mode 2 in the recording medium according to the present invention, for example, on the original CD 10, it is formed between the (n-1) th music and the nth music. The performance end position of the music number n-1 of the (n-1) th music set in the silent section is set to the start address of the nth music from the performance end position of the music number n-1 in the case shown in FIG. The specific data described above is inserted and recorded between the end of the (n-1) th tune and the performance end position of the tune number n-1 extended here. Accordingly, the section in which the index number 00 is recorded is shortened.
[0128]
Although illustration is omitted here, the performance end position of the music number n-1 of the (n-1) th music is extended until it coincides with the position of the start address of the nth music, and the (n-1) th music is played. Specific data may be inserted and recorded between the end of the music and the performance end position of the music number n-1 extended to the position of the start address. In this case, the index number 00 is recorded. Although the section is deleted, the (n-1) th song ends at the performance end position of the song number n-1, and the nth song starts from the start address position of the nth song which is the same position as this position. It does not cause any trouble.
[0129]
Therefore, when the original CD 10 is manufactured by adopting the technical idea of the specific data insertion mode 2 as shown in FIG. 17, the specific data that cannot be discriminated in terms of audibility is in a silent section formed between music pieces. In addition, the original CD 10 is inserted and recorded in a section other than the section of the index number 00, and the user copies a plurality of songs from the start address of each song to the CD-R with respect to the original CD10. Even in this case, for example, since the (n-1) th song is always copied to the performance end position of the song number n-1, the end of the (n-1) th song on the original CD 10 and the song number n- Since the specific data recorded between the end of the performance 1 is always copied onto the CD-R, if the copied CD-R is reproduced, the CD-R cannot be reproduced due to the specific data. It is as described above. Of course, even if the original CD 10 adopting the technical idea of the specific data insertion mode 2 as shown in FIG. 17 is entirely copied to the CD-R, the specific data is copied following the end of the (n-1) th music piece. It is obvious.
[0130]
Next, as shown in FIG. 18, in the case of the specific data insertion mode 3 in the recording medium according to the present invention, for example, the original data is formed between the (n-1) th music and the nth music on the original CD10. The position of the start address of the n-th song set in the silence section is set to the music number n-1 of the (n-1) -th song from the start address position of the n-th song in the case shown in FIG. After moving to the end position side, the above-described specific data is inserted and recorded between the position of the start address of the n-th song and the leading end of the song. Accordingly, the section in which the index number 00 is recorded is shortened. Further, in this case, the position of the start address of the n-th song is moved to the (n-1) -th song side, so that the position from the start address of the n-th song to the head of the n-th song is shifted. Although the silent state tends to last a little longer, the section from the start address of the nth song to the beginning of the nth song is set within the time range in which the user can accept the silent state. It will not cause any trouble.
[0131]
Although not shown here, the start address of the n-th song is matched with the performance end position of the song number n-1 of the n-1th song, and the performance of the song number n-1 is ended. Specific data may be inserted and recorded between the start address position of the n-th song matched with the position and the leading end of the n-th song. In this case as well, a section in which index number 00 is recorded Is deleted, but the (n-1) -th song ends at the performance end position of the song number n-1, and the n-th song starts from the position of the start address of the n-th song which is the same position as this position. So there is no trouble.
[0132]
Therefore, when the original CD 10 is manufactured by adopting the technical idea of the specific data insertion mode 3 as shown in FIG. 18, the specific data that cannot be discriminated in terms of audibility is in a silent section formed between music pieces. In addition, the original CD 10 is inserted and recorded in a section other than the section of the index number 00, and the user copies a plurality of songs from the start address of each song to the CD-R with respect to the original CD10. Even in this case, for example, since the data is always copied from the position of the start address of the n-th song, the specific data recorded between the start address of the n-th song and the leading end of the song on the original CD 10 is also a CD. As described above, if the copied CD-R is reproduced, the CD-R cannot be reproduced due to the specific data if the copied CD-R is reproduced. Of course, even if the original CD 10 adopting the technical idea of the specific data insertion mode 3 as shown in FIG. 18 is entirely copied to the CD-R, the specific data is copied following the start address of the n-th song. Is obvious.
[0133]
Next, as shown in FIG. 19, in the case of the specific data insertion mode 4 in the recording medium according to the present invention, the specific data insertion mode 1 shown in FIG. 16, the specific data insertion mode 2 shown in FIG. The original CD 10 is produced by combining with the specific data insertion form 3 shown in FIG. 18, and for example, between the end of the (n-1) th music and the performance end position of the music number n-1 of this music. The above-mentioned specific data is inserted and recorded, and the specific data is also inserted and recorded in the section of index number 00, and further, between the position of the start address of the n-th song and the leading end of the song. The specific data is inserted and recorded.
[0134]
Although FIG. 19 illustrates a case where the three sets of the specific data insertion modes 1 to 3 described above are combined, the present invention is not limited to this, and at least two or more of the specific data insertion modes 1 to 3 are combined. Alternatively, an original CD 10 may be manufactured.
[0135]
Therefore, the original CD 10 produced by combining at least two or more of the above-mentioned specific data insertion modes 1 to 3 can be entirely copied to a CD-R, or the user can record a plurality of songs from the start address of each song. Even if the data is copied onto a CD-R, at least one or more specific data is always copied between the songs on the CD-R. Therefore, when the copied CD-R is reproduced, at least one or more specific data is reproduced. As described above, the CD-R falls into an unreproducible state.
[0136]
In the modulation device, the modulation method, and the recording medium according to the present invention described in detail above, the case of the EFM modulation (8-14 modulation) system used for the CD has been described, but the invention is not limited to the CD standard. , P-bit input data word D is converted into a q-bit code word C, at least the next code word Cy and the next next code word Cz following one code word Cx are read ahead, and Strictly adheres to the minimum run length (d + 1) T to the maximum run length (k + 1) T set based on the run length restriction rule RLL (d, k) of The above-mentioned technical idea can be applied to any pq modulation that generates a codeword string by adding such r-bit combination bits 1b.
[0137]
Further, when the input data word D to be pq modulated is music information and the p-bit input data word D is converted into a q-bit code word C, the next code following one code word Cx is used. At least the word Cy and the next code word Cz are read ahead, and a minimum run length (d + 1) T to a maximum run length (k + 1) set based on a predetermined run length restriction rule RLL (d, k). T is strictly adhered to, and an r-bit combination bit 1b is added between adjacent codewords C and C so that the DSV value becomes the best, thereby generating a codeword string. At the time of recording in FIG. 12, specific data of an AC signal or a DC signal which cannot be discriminated in terms of audibility may be inserted and recorded in a silent section formed between music pieces in music information. Improve the performance of the copy protection function To increase the be in a silent section formed between tracks specific data as described above, and, in which may be recorded by being inserted into a section except the section index number 00.
[0138]
【The invention's effect】
According to the modulation device, the modulation method, and the recording medium of the present invention described in detail above, a p-bit input data word is converted into a q-bit code word, and an r-bit combination bit is inserted between adjacent code words. In addition, when generating a codeword string, in particular, at least look ahead to the next codeword following the one codeword and the next codeword, and combine the one codeword with the next codeword. A plurality of sets of combined bits of r bits are tentatively added while strictly observing a predetermined run-length restriction rule to generate a plurality of sets of codeword strings, and further, a next codeword in the plurality of sets of codeword strings is generated. And at least the next code word, tentatively adding a plurality of sets of combination bits of r bits while strictly observing a predetermined run-length restriction rule, and at least one code word from the next code word Up to a number of codeword strings up to A set of codeword strings whose absolute value of the DSV value is closest to zero is selected from each DSV value of the string, and one codeword and the next codeword in this set of codeword strings are selected. Is used to combine the one codeword and the next codeword via the combining bit to output a final determined codeword string. A recording medium in which a number of code word strings are recorded in succession can be normally reproduced without any trouble, and when a copy recording medium in which this recording medium is copied is reproduced, a decision code word string in which a number of code words are continuously copied is reproduced. Since a specific frequency component is increased in the signal and the DSV value is destroyed and cannot be reproduced, copyright infringement of the digital information signal on the copied copy recording medium can be prevented beforehand.
[0139]
Further, by the modulation device and the modulation method according to the present invention, AC signal data or DC signal data that cannot be discriminated perceptually as input data words are input for a predetermined period, and the input data words are encoded by pq modulation. If the recorded recording medium is copied and reproduced on a recording medium, a harsh sound such as a "geek sound" or a "gear sound" is generated during an unreadable section due to DSV control failure. In addition, it is possible to notify the user that the copy recording medium is an abnormal recording medium, and to prevent copyright infringement on the digital information signal on the copy recording medium.
[0140]
Further, according to the modulation device, the modulation method, and the recording medium of the present invention, when the input data word is music information and specific data of an AC signal or a DC signal that cannot be discriminated from perception is input over a predetermined period. The specific data may be inserted into a silent section formed between songs and / or the specific data may be inserted into a silent section formed between songs and an index By inserting the data into a section excluding the section of the number 00 and recording it on the recording medium, when the copy recording medium obtained by copying this recording medium is reproduced, an unreadable section occurs due to the copied specific data and the copy recording medium is generated. Therefore, it is possible to prevent copyright infringement on the digital information signal on the copy recording medium.
[Brief description of the drawings]
1A and 1B are diagrams for explaining a signal format of music information recorded on a CD, wherein FIG. 1A shows music original data, and FIG. 1B shows an EFM signal.
FIG. 2 is a diagram showing an encoding table at the time of 8-14 modulation.
FIGS. 3A and 3B are diagrams for explaining DSV control during 8-14 modulation.
FIG. 4 is a block diagram schematically illustrating a conventional modulation device.
FIGS. 5 (a) to 5 (c) show a conventional modulator in which a combined bit is added between one code word and the next code word while strictly observing a predetermined run-length restriction rule. FIG. 7 is a diagram for explaining a state in which DSV values of a plurality of sets of code word strings are calculated when (000), (001), and (010) are temporarily added as connection bits when a code word string is generated. is there.
FIG. 6 is a longitudinal sectional view showing an optical disk on which a copy protection measure is taken as an example of a conventional example.
FIG. 7 is a block diagram schematically illustrating a modulation device and a modulation method of the present embodiment according to the present invention.
8 (a) to 8 (c) show the relationship between one code word and the next code word following the run length restriction rule in the CD standard using the modulator of the present embodiment. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next codeword are read ahead, and a codeword is interposed between one codeword and the next codeword. And one set of combined bits (000), and three sets of combined bits (000), (001), and (010) are tentatively added between the next codeword and the next codeword. It is a figure for explaining the state where each DSV value of many code word strings was computed at the time.
9 (a) to 9 (c) show the relationship between one codeword and the next codeword following the run length restriction rule in the CD standard using the modulator of the present embodiment. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next codeword are read ahead, and a codeword is interposed between one codeword and the next codeword. Is temporarily added with one set of combination bits (001), and three sets of combination bits (000), (001), and (010) are tentatively added between the next codeword and the next codeword. It is a figure for explaining the state where each DSV value of many code word strings was computed at the time.
FIGS. 10 (a) to (c) show the relationship between one code word and the next code word following the run length restriction rule in the CD standard using the modulator of the present embodiment. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next codeword are read ahead, and a codeword is interposed between one codeword and the next codeword. Is temporarily added with one set of combination bits (010), and three sets of combination bits (000), (001), and (010) are tentatively added between the next codeword and the next codeword. It is a figure for explaining the state where each DSV value of many code word strings was computed at the time.
FIG. 11 is a diagram illustrating a difference in a frequency spectrum caused by a change in a DSV value of a codeword string between the case of the original CD according to the embodiment of the present invention and the case of a CD-R obtained by copying the original CD. .
FIGS. 12A and 12B are a perspective view and a longitudinal section for explaining an optical disc serving as a recording medium of the present embodiment according to the present invention.
13 (a) shows a case where an original CD of the present invention produced by encoding specific data of an AC signal which cannot be discriminated in terms of perception as music original data AD is reproduced, and FIG. 13 (b) shows a case where the original CD of the present invention is reproduced. FIG. 11 is a diagram showing a case where a copied CD-R is reproduced.
14 (a) shows a case where an original CD of the present invention produced by encoding specific data of a DC signal which cannot be discriminated in terms of listening as music original data AD is reproduced, and FIG. 14 (b) shows a case where the original CD of the present invention is reproduced. FIG. 11 is a diagram showing a case where a copied CD-R is reproduced.
FIG. 15 is a schematic diagram for explaining a silent section between music pieces on a general CD.
FIG. 16 is a schematic diagram for explaining a specific data insertion mode 1 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between songs in the recording medium according to the present invention.
FIG. 17 is a schematic diagram for explaining a specific data insertion mode 2 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between music pieces in the recording medium according to the present invention.
FIG. 18 is a schematic diagram for explaining a case of a specific data insertion mode 3 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between songs in the recording medium according to the present invention.
FIG. 19 is a schematic diagram for explaining a specific data insertion mode 4 in which specific data that cannot be discriminated in terms of audibility is inserted into a silent section between music pieces in the recording medium according to the present invention.
[Explanation of symbols]
1 ... EFM signal,
1a: synchronization signal, 1b: combination bit, 1c: subcode,
1d: first code word sequence, 1e: C2 error correction code,
1f: second code word string, 1g: C1 error correction code,
10 ... an optical disc serving as a recording medium of the present embodiment according to the present invention;
11: transparent disk substrate, 12: recording track,
20: a conventional modulation device,
21 ... 8-14 modulation circuit, 22 ... combined bit addition circuit,
23 ... DSV value calculation circuit, 24 ... DSV value comparison circuit / coupled bit selection circuit,
30... The modulation device of the present embodiment,
31 ... 8-14 modulation circuit,
32A: a first combined bit adding circuit; 32B: a second combined bit adding circuit;
33A: first DSV value calculation circuit, 33B: second DSV value calculation circuit,
34 DSV value comparison circuit / coupling bit selection circuit
35 ... decision code word string output circuit.

Claims (7)

A modulation device that converts a p-bit input data word into a q-bit code word, adds a r-bit combination bit between adjacent code words, generates a code word sequence, and outputs this code word sequence ,
when converting the p-bit input data word into the q-bit code word, a next code word that follows one code word, and a modulation unit that at least pre-reads the next next code word;
Between the one codeword and the next codeword, a plurality of sets of combined bits by the r bits are strictly adhered to a predetermined run-length restriction rule and temporarily added to generate a plurality of sets of codeword strings, Further, a plurality of sets of combination bits of the r bits are strictly adhered to a predetermined run-length restriction rule also between the next code word in the plurality of code word strings and at least the next next code word. Tentatively added, a combination bit addition means for generating a large number of sets of codeword strings from at least one codeword to the next next codeword,
DSV value calculation means for calculating each DSV value of a large number of sets of the code word strings generated by the combination bit addition means;
Comparing / selecting means for selecting one set of the codeword strings whose absolute value of the DSV value is closest to zero among the DSV values of the multiple sets of the codeword strings obtained by the DSV value calculating means; When,
Using the combination bits added between the one codeword and the next codeword in the one set of codeword strings selected by the comparison / selection means, And a decision code word string output unit that outputs one decision code word string that is finally determined by combining up to the next code word through
The input data word is AC signal data or DC signal data that cannot be discriminated perceptually, and a code word string output by a modulation device that pre-reads only the next code word contains a specific frequency component. A modulation device, comprising: inputting data over a predetermined period; and encoding the input data word by pq modulation. The modulation device according to claim 1,
When the input data word is music information, and when the specific data which cannot be distinguished in terms of audibility is input for a predetermined period, the specific data is inserted into a silent section formed between songs. A modulation device characterized by the above-mentioned. The modulation device according to claim 1,
When the input data word is music information, and when the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is included in a silent section formed between songs. And a modulator inserted in a section excluding the section of index number 00. A modulation method for converting a p-bit input data word into a q-bit code word, adding a r-bit combination bit between adjacent code words to generate a code word sequence, and outputting the code word sequence. ,
when converting the p-bit input data word into the q-bit code word, a first step of at least pre-reading the next code word following one code word and the next next code word;
Between the one codeword and the next codeword, a plurality of sets of combined bits by the r bits are strictly adhered to a predetermined run-length restriction rule and temporarily added to generate a plurality of sets of codeword strings, Further, a plurality of sets of combination bits of the r bits are strictly adhered to a predetermined run-length restriction rule also between the next code word in the plurality of code word strings and at least the next next code word. A second step of generating a large number of sets of code word strings from at least one code word to the next next code word;
A third step of calculating each DSV value of the multiple sets of codeword strings generated in the second step;
A fourth step of selecting one set of the codeword strings whose absolute value of the DSV value is closest to zero among the DSV values of the multiple sets of codeword strings obtained in the third step;
Using the combination bits added between the one codeword and the next codeword in the one set of codeword strings selected in the fourth step, the combination bits from the one codeword A fifth step of combining the code words up to the next code word and outputting one finally determined code word sequence.
The input data word is AC signal data or DC signal data that cannot be discriminated perceptually, and a code word string output by a modulation device that pre-reads only the next code word contains a specific frequency component. A modulation method comprising: inputting data over a predetermined period; and encoding the input data word by pq modulation. In the modulation method according to claim 4,
When the input data word is music information, and the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is inserted into a silent section formed between songs. A modulation method, comprising: In the modulation method according to claim 4,
When the input data word is music information, and the specific data which cannot be discriminated in terms of audibility is input for a predetermined period, the specific data is included in a silent section formed between songs. A modulation method characterized by being inserted in a section excluding the section of index number 00. A recording medium on which the codeword string encoded by any one of the modulation device according to claim 1 and the modulation method according to claim 4 is recorded.

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