JP3945381B2 - Modulation apparatus, modulation method, and recording medium - Google Patents

Description

[0001]
BACKGROUND 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 digital multimedia era, large-capacity digital information signals are recorded on optical disks and digital magnetic tapes.
[0003]
For example, a read-only optical disc such as a CD (Compact Disc) containing music information or a CD-ROM (CD-Read Only Memory) containing computer data is spiral or concentric on a disc-like disc substrate. The above-described various digital information signals can be recorded at a high density on the formed track, and the desired track can be accessed at a high speed during reproduction, and it is suitable for mass production and can be obtained at low cost.
[0004]
Digital magnetic tapes that record PCM music information and the like are widely used because they can be reproduced over a longer period of time than optical disks.
[0005]
In the following description, an optical disk that records and / or reproduces using an optical pickup as a recording medium for recording a digital information signal will be described. However, in the case of a digital magnetic tape, magnetic recording is performed when recording and / or reproducing. Since the only difference is that the head is used, the description of the case of the digital magnetic tape is omitted.
[0006]
The above-mentioned optical discs such as CDs and CD-ROMs convert digital information signals into digital pit rows using concave pits and convex lands, and chop the pit rows as spiral or concentric recording tracks. After mounting the stamper board on which the signal surface is recorded in the injection molding machine, the signal surface of the stamper board is made of a transparent resin material with an outer diameter of 120 mm or 80 mm, a hole diameter of the central hole of 15 mm, and a substrate thickness of 1.2 mm. The image 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 is irradiated on 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 reflective film.
[0008]
By the way, although the music information recorded on the CD and the computer data recorded on the CD-ROM are protected by the copyright law, there is no signal deterioration because they are digital information. The user can copy to a write-once optical disc such as CD-R (Compact Disc-Recordable) that can be written only once or without permission from the copyright holder, or CD-RW (Compact Disc-ReWriteable) that can be written multiple times. It is possible to do.
[0009]
The above-described write-once optical discs such as CD-R and CD-RW have substantially the same appearance as read-only optical discs such as CD and CD-ROM, but a concave groove is spirally formed on a transparent disc substrate. Alternatively, it is formed concentrically, spin coated with an organic dye serving as a recording layer on the concave groove side, and further, a reflective film and a protective film are sequentially formed on the organic dye, Moreover, it is available at a low cost.
[0010]
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 that of the CD or CD-ROM. Therefore, the copyright is infringed.
[0011]
Hereinafter, a code word string of music information recorded on a well-known CD will be described.
FIG. 1 is a diagram for explaining a signal format of music information recorded on a CD, where (a) shows music source data, (b) shows an EFM signal, and FIG. 2 shows 8-14. The figure which showed the encoding table at the time of a modulation | alteration,
3A and 3B are diagrams for explaining DSV control at the time of 8-14 modulation.
[0012]
First, the music information is recorded on the CD in a signal format conforming to the CD standard “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 to the minimum run length (minimum pit length or minimum land length) due to optical transmission characteristics of recording / reproduction and physical restrictions 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 has a low frequency component and DC component suppression characteristics. It needs to be modulated.
[0014]
Among modulation schemes that satisfy this limitation, the EFM (Eightto Four Modulation: 8-14 modulation) scheme used for CDs has a minimum run length of 3T (T = channel bit period) and a maximum run length of 11T. Is.
[0015]
That is, as shown in FIG. 1A, the music source data AD recorded on the CD is digital data, and the upper 8 bits (1 byte) + the lower 8 bits (1 byte) = 16 bits (2 bytes). A unit is constituted, and the music source data AD is constituted by a plurality of one unit.
[0016]
When the original music data AD shown in FIG. 1A is recorded on the glass master disk by laser beam at the time of mastering, the original music data AD is converted into an EFM signal format so that the signal form is suitable for recording. Then, it is recorded on the glass master disk in the form of EFM signal 1 shown in FIG. 1 (b), and thereafter, a metal master disk, a mother disk, and a stamper disk are sequentially manufactured based on the glass master disk by electroforming. Thereafter, the stamper disk is mounted in the injection molding machine, and the signal surface of the stamper disk 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.
[0017]
Here, in the format of the EFM signal 1 described above, the input music source 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 a p-bit = 8-bit input data word D, a q-bit = 14-bit run-length limited code (hereinafter referred to as “q-bit = 14-bit”) satisfying a predetermined run-length restriction rule with a minimum run length of 3T and a maximum run length of 11T. 1), and, as shown in FIG. 1B, between the converted codeword C and the codeword C, for holding a run length restriction rule and DSV (Digital Sum Value) EFM signal 1 is generated by adding a combination bit 1b of r bits = 3 bits for control and forming first and second codeword strings 1d and 1f described later. To have.
[0018]
At this time, when a predetermined run length restriction rule is satisfied, if the minimum run length is 3T, the number of “0” s between the logical values “1” and “1” in the codeword C is the smallest and d = 2 On the other hand, when the maximum run length is 11T, the maximum number of “0” is included between the logical values “1” and “1” in the codeword C = k = 10. In other words, when the run length restriction rule RLL (d, k) = RLL (2,10) is satisfied, the minimum run length is based on the run length restriction rule RLL (d, k) = RLL (2,10). (D + 1) T = 3T is set, and the maximum run length is set as (k + 1) T = 11T. The first and second codeword strings 1d and 1f, which are combined by adding a 3-bit combined 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 is satisfied, and when the NRZI conversion is performed on the first and second codeword sequences 1d and 1f as described later, the minimum run length 3T has the minimum inversion interval, while the maximum The run length 11T represents the maximum inversion interval.
[0019]
Then, the EFM signal 1 subjected to pq modulation = 8-14 modulation 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 direct current 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, and the NRZI conversion has a polarity in the bit “1” as is well known. Inverted and modulated without inverting the polarity at bit “0”, the waveform after NRZI conversion becomes the recording signal R to the glass master, and the L (low) level section in this recording signal R For example, a pit row is formed by corresponding to a concave pit (or convex land) and an H (high) level section in the recording signal R corresponding to, for example, a convex land (or concave pit).
[0021]
Further, as shown in FIGS. 3A and 3B, the above-described DSV has an H (high) level waveform after NRZI conversion from the start time of the code word string in the EFM signal 1 to the present time. It is an integral value that is sometimes integrated as “1” (positive polarity) and as “−1” (negative polarity) at the L (low) level. At this time, in the NRZI conversion, polarity inversion is performed with the data bit “1”. Therefore, even if the code word has the same bit pattern, it differs depending on the waveform state after the NRZI conversion just before the code word is connected. As shown in FIG. 3A, when the previous waveform state is L (low) level with respect to the input data word = 002, and immediately before the input data word = 002 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 combined via a combination bit, FIG. The absolute values of both DSVs according to FIG.
[0022]
Here, as a combined bit 1b of 3 bits between adjacent codewords C and C so that the absolute value of DSV approaches substantially zero while satisfying the run length restriction rule RLL (d, k) = RLL (2,10) , (000), (001), (010), (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 rate, so that the concave pit section and the convex land section also have approximately the same ratio. The DSV value is controlled to appear.
[0023]
Returning to FIG. 1 (b), one frame of the EFM signal 1 described above includes a synchronization signal 1a, a combined bit 1b, a subcode 1c, a combined bit 1b, a first codeword string 1d, a combined bit 1b, and a C2 error correction from the head. The code 1e, the combined bit 1b, the second codeword string 1f, the combined bit 1b, the C1 error correction code 1g, and the combined 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 with respect to each of the signals 1b to 1g as signals of 11T, 11T, and 2T in order to indicate the head of the frame using 24 bits.
[0025]
Further, the subcode 1c arranged via the combined bit 1b of 3 bits after the synchronization signal 1a is a signal for performing reproduction control to the CD.
[0026]
The first codeword string 1d arranged after the subcode 1c via the 3 bits of the combined bit 1b encodes each input data word D (each music source data) of p = 8 bits shown in FIG. By referring to the table, each code word C is converted into q = 14 bits, and a combined bit 1b of 3 bits is added between adjacent code words C and C, so that 12 code words C (12 symbols ) And 11 combined bits 1b.
[0027]
In addition, the C2 error correction code 1e arranged after the first codeword string 1d via the three combined bits 1b is converted into the first codeword string 1d and the second codeword string 1f of the EFM signal 1 during CD reproduction. In contrast, error correction is performed.
[0028]
Further, the second codeword string 1f arranged via the 3 combined bits 1b after the C2 error correction code 1e is composed of 12 codewords C (12 symbols) as in the first codeword string 1d. It consists of 11 combined bits 1b.
[0029]
Further, the C1 error correction code 1g arranged after the second codeword string 1f via the combined bit 1b of 3 bits is 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, one block as a unit of music is configured by continuing 98 (= 98 frames) recording signals after NRZI conversion for one frame of the EFM signal 1 described above. This corresponds to a period of 1/75 second.
[0031]
In the case of a CD-ROM recorded with computer data, it is only necessary to change the name of the music source data shown in FIG.
[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 code using a conventional modulation device with a combined bit added between one codeword and the next codeword while strictly adhering to a predetermined run length restriction rule. When a word string is generated, when (000), (001), (010), and (100) are temporarily added as combined bits, a state in which DSV values of a plurality of sets of code word strings are calculated is described. FIG.
[0034]
The conventional modulation apparatus 20 shown in FIG. 4 includes a glass master recording machine (not shown) for producing a CD, and a CD-R drive (for copying music information recorded on the CD to the CD-R). 8-14 modulation circuit 21, combined bit addition circuit 22, DSV value calculation circuit 23, DSV value comparison circuit / combined bit selection circuit 24, and a schematic configuration Has been.
[0035]
In the conventional modulation device 20, the 16-bit music source data AD is divided into the upper 8 bits and the lower 8 bits, and each 8-bit input data word D is converted into each 14-bit code word C. A plurality of sets of codes by temporarily adding a plurality of 3-bit combination bits 1b satisfying the run length restriction rule RLL (2, 10) between one codeword Cx and the next codeword Cy following it. A word string is generated, and one set of code word strings having the DSV absolute value closest to zero is selected from the DSV values of the plurality of sets of code word strings. The sequence is output as one determined codeword sequence that is finally determined.
[0036]
More specifically, in the conventional modulation device 20, 16-bit music source 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 source data AD is converted into the upper 8-bit input data word D and the lower 8-bit input data word D as described above with reference to FIG. When the 8-bit input data word D is sequentially converted into a 14-bit code word C based on the coding table shown in FIG. 2 by separating them in sequence order, for example, one code word Cx and one code The next code word Cy following the word Cx is sequentially read. Then, one code word Cx and the next code word Cy are input from the 8-14 modulation circuit 21 to the combined bit adding circuit 22.
[0038]
Next, the combined bit adding 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 code words C, C The combination bit adding circuit 22 has a function of adding three combined bits 1b between them, and (000), (001), (010), (100) are candidates for the three combined bits 1b in the combined bit adding circuit 22. 4 sets are prepared. Although there are 8 combinations of 3 bits 1b, two or more “1” s appear continuously in the groups (011), (101), (110), and (111) other than the above four groups, Alternatively, since “1” and “0” appear alternately, the run length restriction rule RLL (2, 10) is not satisfied, and therefore, it cannot be used.
[0039]
Then, in order to combine the code word Cx and the code word Cy sequentially input into the combined bit adding circuit 22, four sets of combined bits (000), (001), (010) between the code words 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 codeword Cx is “010” in the 12th to 14th bits, while the next codeword Cy is “00100010000010”. Since the 13th bit of one code word Cx is “1” and the 3rd bit of the next code word Cy is “1”, the first to first of the four sets of combined bits 1b described above. Although the three sets of combined bits (000), (001), and (010) can strictly comply with the run-length restriction rule RLL (2, 10), the fourth set of combined bits (100) includes the run-length restriction rule RLL (2, Since 10) is not satisfied, the addition of this combination bit (100) is stopped.
[0041]
Then, after adding three sets of coupled bits (000), (001), and (010) between codewords Cx and Cy, three sets of codeword strings {Cx (000) Cy} and {Cx (001) Cy }, {Cx (010) Cy} are input to the DSV value calculation circuit 23 to calculate the DSV values of the three sets of codeword strings, as shown in case 1 shown in FIG. When a coupling bit (000) is added between Cy, the DSV value of the codeword string {Cx (000) Cy} becomes +2, and between codewords Cx and Cy as in case 2 shown in FIG. When the coupling bit (001) is added to the code word, the DSV value of the code word string {Cx (001) Cy} is −4, and between the code words Cx and Cy as in the case 3 shown in FIG. When the combined bit (010) is added, the code word string {Cx (010) Cy} SV value is -6.
[0042]
Thereafter, three sets of code word strings from the DSV value calculation circuit 23 and the corresponding DSV values are input to the DSV value comparison circuit / combination bit selection circuit 24, and the DSV value comparison circuit / combination bit selection circuit 24. And select one set of code word sequences {Cx (000) Cy} having a DSV value = + 2 so that the absolute value of the DSV approaches the most zero among the DSV values of the three sets of code word sequences. The one set of code word strings {Cx (000) Cy} is output from the DSV value comparison circuit / combined bit selection circuit 24 as one determined code word string. In other words, the DSV value comparison circuit / combination bit selection circuit 24 selects the combination bit (000) corresponding to one decision codeword string {Cx (000) Cy} whose absolute value of DSV is closest to zero. become. Thereafter, 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 codeword string {Cx (000) Cy .........} having a controlled DSV value is generated as a recording signal R (FIG. 1) suitable for recording, and a glass master disc for CD is produced by a laser beam. Or recorded on a CD-R.
[0044]
A stamper disk (not shown) is manufactured based on the glass master disk for CD, and a CD is manufactured using this stamper disk.
[0045]
From the above, the user plays 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) on a CD drive (not shown), and is output from the CD drive. The music information to be recorded on the CD-R is input to a CD-R drive (not shown), and the music information to be copied by the conventional modulation device 20 provided in the CD-R drive is obtained from the copyright holder. It is possible to copy it to the CD-R as it is.
[0046]
Therefore, when the 16-bit original music 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 form is exactly the same as the music information, the copied CD-R can be further copied, and a large number of them are circulated in the world.
[0047]
Thus, 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. Yes (for example, see Patent Document 1).
[0048]
[Patent Document 1]
JP 2001-357536 A (page 4-5, FIG. 4)
[0049]
FIG. 6 is a longitudinal sectional view showing an optical disk with copy prevention measures taken as an example of a conventional example.
[0050]
The conventional optical disc 100 shown in FIG. 6 is disclosed in the above-described Patent Document 1 (Japanese Patent Laid-Open No. 2001-357536), and will be briefly described with reference to the same publication. In a conventional optical disc 100 in which copy prevention measures are taken for an optical disc such as a DVD-ROM, it is usually based on a run-length restriction rule (described in the same publication as a run-length-suppressing encoding method). Although the concave-convex portion row having a continuous length of 3T to 14T (T is 0.133 μm) is formed, a concave portion having a continuous length shorter than the minimum run length based on the run-length restriction rule in the middle or A convex portion is recorded.
[0051]
Specifically, as shown in FIG. 6, the pit A is formed in a convex shape with a length of 1T to 2T, and the 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 pit A and pit B are values that are not based on the run length restriction rule.
[0052]
Therefore, in the conventional optical disc 100, the minimum run length 3T is not strictly observed among the run length restriction rules based on the minimum run length 3T and the maximum run length 14T, and is set to 1T to 2T which is a smaller value than this. 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, the technical idea of the above-described conventional optical disc 100 is formed by forming a concavo-convex portion row (pit row) having a continuous length of 3T to 11T based on the run length restriction rule RLL (2, 10) in the CD standard. For example, in the encoding table shown in FIG. 2, the code word C corresponding to the input data word D = 255 is “001000100010010”. However, when it is desired to form a short uneven portion row (pit row) such as 1T, a modified CD can be produced by using the code word C such as “00100110010010” instead.
[0054]
When the CD thus modified is reproduced by a commercially available optical disk drive, the proof pit consisting of 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 1T to 2T certification pit signals. Therefore, it cannot be determined whether or not the optical disc being reproduced is an original. Furthermore, when music data recorded on a modified CD is reproduced by a commercially available optical disk drive, and this reproduction data is input to the CD-R drive and copied to the CD-R, the music data is copied without any problem. .
[0055]
Therefore, copy prevention means based on the prevalence of new players capable of detecting proof pits such as the optical disc 100 is a situation where a large number of players and CD-R drives are already on the market, such as CDs. I have a problem that I cannot apply.
[0056]
Further, as in the case of an optical disk, there is a problem that a digital information signal recorded on a digital magnetic tape is also copied.
[0057]
Therefore, when a code word string is generated without strictly observing a predetermined run length restriction rule, the original recording medium on which the code word string is recorded can be surely reproduced by a commercially available player. Therefore, a modulation apparatus, modulation method, and recording medium that can prevent copying of digital information signals recorded on a recording medium such as an optical disk or a digital magnetic tape can be expected. It is rare.
[0058]
[Means for Solving the Problems]
The present invention has been made in view of the above problems, and the first invention converts a p-bit input data word into a q-bit code word, and adds r-bit combined bits between adjacent code words. In a modulation apparatus that generates a codeword string by adding and outputs the codeword string,
modulation means for prefetching at least the next code word following one code word and the next next code word when converting the p-bit input data word into the q-bit code word;
A plurality of sets of code by temporarily adding a plurality of sets of combined bits of r bits between the one codeword and the next codeword without strictly observing a predetermined run length restriction rule RLL (d, k). A word sequence is generated, and further, a plurality of sets of combined bits of the r bits are set to a predetermined run length between the next codeword in the plurality of codeword sequences and at least the next next codeword. A combined bit adding means for temporarily adding without restricting the restriction rule RLL (d, k) and generating a plurality of sets of codeword strings from at least one codeword to the next codeword;
DSV value calculation means for calculating each DSV value of a large number of codeword strings generated by the combined bit adding means;
Comparison / selection means for selecting one set of code word strings whose absolute value of DSV value is closest to zero among the DSV values of a large number of code word strings obtained by the DSV value calculation means. When,
Using the combined bits added between the one codeword and the next codeword in the one set of codeword strings selected by the comparison / selection means, the combined bits from the one codeword And a decision code word string output means for outputting one decision code word string finally determined by combining up to the next code word via the.
[0059]
According to a second invention, in the modulation device of the first invention described above,
The adjacent code that allows the maximum run length (k + 2) T without strictly adhering to the maximum run length (k + 1) T set based on the run length restriction rule RLL (d, k) for the codeword string. The modulation apparatus is characterized by adding the r combined bits between words.
[0060]
According to a third aspect of the invention, there is provided the modulation device according to the first or second aspect of the invention described above.
The code word string output in strict adherence to the run length restriction rule RLL (d, k) is input with specific data that includes a component of a specific frequency over a predetermined period as the input data word, Further, the modulation apparatus outputs the codeword string without strictly adhering to the run length restriction rule RLL (d, k) during that period.
[0061]
Moreover, 4th invention is the modulation apparatus of 3rd invention mentioned above,
The modulation device is characterized in that the specific data is AC signal data or DC signal data that cannot be discriminated from the sense of hearing.
[0062]
Further, a fifth aspect of the invention is the modulation device according to the third aspect of the invention,
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is inserted into a silent section formed between songs. This is a modulation device.
[0063]
Further, a sixth aspect of the present invention is the modulation apparatus according to the third aspect of the present invention,
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is in a silent section formed between songs. In addition, the modulation apparatus is inserted in a section excluding the section of index number 00.
[0064]
The seventh invention converts a p-bit input data word into a q-bit code word,
In addition, in a modulation method for generating a code word string by adding r bit combination bits without adhering to adjacent code words and outputting the code word string,
when converting the p-bit input data word into the q-bit code word, a first step of prefetching at least the next code word following one code word and the next next code word;
A plurality of sets of code by temporarily adding a plurality of sets of combined bits of r bits between the one codeword and the next codeword without strictly observing a predetermined run length restriction rule RLL (d, k). A word sequence is generated, and further, a plurality of sets of combined bits of the r bits are set to a predetermined run length between the next codeword in the plurality of codeword sequences and at least the next next codeword. A second step of generating a large number of code word strings from at least the one code word to the next code word by temporarily adding the restriction rule RLL (d, k) without strictly adhering;
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 code word strings in which the absolute value of the DSV value is closest to zero among the DSV values of the plurality of code word strings obtained in the third step;
Using the combined bits added between the one codeword and the next codeword in the one set of codeword strings selected in the fourth step, the combined bits are converted from the one codeword. And a fifth step of outputting one determined codeword string finally determined by combining up to the next codeword.
[0065]
The eighth invention is the modulation method of the seventh invention, wherein
The adjacent code that allows the maximum run length (k + 2) T without strictly adhering to the maximum run length (k + 1) T set based on the run length restriction rule RLL (d, k) for the codeword string. The modulation method is characterized in that the r combined bits are added between words.
[0066]
A ninth invention is the modulation method of the seventh to eighth inventions described above,
The code word string output in strict adherence to the run length restriction rule RLL (d, k) is input with specific data that includes a component of a specific frequency over a predetermined period as the input data word, Further, the modulation method is characterized in that during the period, the codeword string is output without strictly observing the run length restriction rule RLL (d, k).
[0067]
The tenth invention is the modulation method of the ninth invention described above,
The modulation method is characterized in that the specific data is alternating current signal data or direct current signal data that cannot be discerned in terms of hearing.
[0068]
The eleventh aspect of the invention is the modulation method of the ninth aspect of the invention,
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is inserted into a silent section formed between songs. This is a modulation method characterized by the above.
[0069]
The twelfth invention is the modulation method of the ninth invention, wherein
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is in a silent section formed between songs. In addition, the modulation method is inserted in a section excluding the section of index number 00.
[0070]
A thirteenth aspect of the invention is a recording medium on which the code word string encoded by any one of the first to sixth modulation devices described above or the seventh to twelfth modulation methods described above is recorded.
[0071]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a modulation apparatus, a modulation method, and a recording medium according to the present invention will be described below in detail with reference to FIGS.
[0072]
In the modulation apparatus, modulation method, and recording medium according to the present invention, for example, when the CD standard is supported, an input data word of p bits = 8 bits is converted into a code word C of q bits = 14 bits and When the EFM signal 1 shown in FIG. 1B is generated by adding r bits = 3 combined bits 1b between the matching code words C and C, the next code word and the next code word following the one code word are generated. And the minimum run length (d + 1) T = 3T set based on the run length restriction rule RLL (d, k) = RLL (2, 10) on the CD standard. Instead of strictly observing the maximum run length (k + 1) T = 11T, the minimum run length (d + 1) T = 3T to the maximum run length (k + 2) T = 12T are allowed instead. Next through codeword at least next The combination bit 1b between one code word and the next code word is selected and added while considering the DSV value of the code word string up to the code word, and then from one code word through the combination bit 1b. The code word string up to the next code word is output as one finally determined code word string, and when the original recording medium on which the EFM signal 1 is recorded is reproduced, In particular, the first and second codeword strings 1d and 1f of the EFM signal 1 consisting of specific data described later can be reproduced without any trouble, while the copy recording medium copied from the original recording medium is reproduced. The reproduction signals of the first and second codeword strings 1d and 1f made of the copied specific data are characterized by an increase in specific frequency components, which makes reproduction impossible.
[0073]
By the way, in particular, the original recording medium on which the first and second codeword strings 1d and 1f made of specific data are recorded includes pits (or lands) formed by the maximum run length 12T that does not satisfy the conventional CD standard. However, since the code word C itself is not affected, no data reading error occurs.
[0074]
In this embodiment, which will be described below, an optical disk such as a CD or CD-ROM will be described as an example of a recording medium on which digital information signals are recorded. The technical idea of this embodiment can also be applied to a tape.
[0075]
<Example>
FIG. 7 is a block diagram schematically showing a modulation apparatus and a modulation method of this embodiment according to the present invention.
8 to 10 show a case where a codeword string is generated by adding a coupling bit between one codeword and the next codeword following the codeword using the modulation apparatus of this embodiment according to the present invention. While allowing the maximum run length 12T not satisfying the run length restriction rule in the CD standard, the next code word following one code word and the next next code word are pre-read, The figure for demonstrating the state which calculated each DSV value,
FIG. 11 is a diagram showing the difference in frequency spectrum accompanying the DSV value variation of the codeword string between the case of the original CD of this embodiment according to the present invention and the case of a CD-R in which the original CD is copied.
[0076]
The modulation device 30 according to the present embodiment shown in FIG. 7 is applied to a glass master recording machine (not shown) for producing a CD, and includes an 8-14 modulation circuit 31, First combined bit addition circuit 32A, first DSV value calculation circuit 33A, second combination bit addition circuit 32B, second DSV value calculation circuit 33B, DSV value comparison circuit / combined bit selection circuit 34, decision codeword string An output circuit 35 is schematically configured.
[0077]
The first and second combined bit adding circuits 32A and 32B have the same internal structure, and the first and second DSV value calculation circuits 33A and 33B have the same internal structure. Depending on the control software for operating 30, the first and second combined bit addition circuits 32A and 32B and the DSV value calculation circuits 33A and 33B are not separated separately, and the combined bit addition circuit (32 ... not shown) Although it is possible to configure as a DSV value calculation circuit (33... Not shown), here it is separated as described above for easy understanding.
[0078]
In the modulation device 30 of the present embodiment, the 16-bit music source data AD is divided into the upper 8 bits and the lower 8 bits, and each 8-bit input data word D is converted into each 14-bit code word C. For example, when the EFM signal 1 is generated by adding a 3-bit combined bit 1b between one code word Cx and the next code word Cy, the next code word following the one code word Cx is generated. Cy and the next next code word Cz are at least prefetched, and the minimum run length is not strictly observed between one code word Cx and the next code word Cy without observing the run length restriction rule RLL (2, 10). A plurality of sets of combined bits 1b are temporarily added while allowing 3T to maximum run length 12T to generate a plurality of sets of codeword strings, and the next codeword in the plurality of sets of codeword strings described above Cy and at least the next codeword A plurality of sets of combined bits 1b of 3 bits are temporarily added while allowing the minimum run length 3T to the maximum run length 12T without strictly observing the run length restriction rule RLL (2, 10) with z. A plurality of code word strings from one code word Cx to the next code word Cz through the next code word Cy are generated, and the absolute value of the DSV is the lowest among these many code word strings. One code word sequence is selected by using a combination bit 1b added between one code word Cx and the next code word Cy in one set of code word sequences. To the next code word Cy through the combined bit 1b to output one determined code word string finally determined.
[0079]
More specifically, in the modulation device 30 of the present embodiment, 16-bit music source data AD is input to the 8-14 modulation circuit 31 in chronological order.
[0080]
In the 8-14 modulation circuit 31 described above, the input music source data AD is converted into an upper 8-bit input data word D and a lower 8-bit input data word D as described above with reference to FIG. When the 8-bit input data word D is sequentially converted into the 14-bit code word C based on the encoding table shown in FIG. Differently, for example, one code word Cx is read, and at least the next code word Cy and the next next code word Cz following the one code word Cx are prefetched.
[0081]
In the following, an example in which the next code word Cy following the one code word Cx and the next code word Cz are prefetched will be described. However, the present invention is not limited to this, and the illustration is omitted here. However, it is possible to prefetch the code word further ahead of the next code word Cz.
[0082]
Then, one code word Cx and the next code word Cy are input from the 8-14 modulation circuit 31 to the first combined bit adding circuit 32A, and after the next code word Cy is output, the next next code word Cz is input from the 8-14 modulation circuit 31 to a second combined bit addition circuit 32B described later.
[0083]
Next, in the first combined bit addition circuit 32A, 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 are not strictly observed, Then, four sets of (000), (001), (010), and (100) are prepared as candidates for the combined bit 1b of 3 bits while allowing the minimum run length 3T to the maximum run length 12T. Also in this embodiment, as in the conventional example, two or more “1” appear continuously in the groups (011), (101), (110), and (111) other than the above four groups, or “ Since “1” and “0” appear alternately, they are deleted because they do not satisfy the minimum run length 3T.
[0084]
Then, in order to combine one code word Cx input into the first combined bit adding circuit 32A and the next code word Cy, four sets of combined bits (000 between the code words Cx and Cy (000) ), (001), (010), and (100) are temporarily added to generate a plurality of sets of codeword strings.
[0085]
At this time, as shown in FIGS. 8 to 10, when one code word Cx and the next code word Cy are respectively set to the same values as in the prior art for easy understanding of the gist of the present invention, one code In the word Cx, the 12th to 14th bits are “010”, while the next codeword Cy is “00100010000010”. Since the 13th bit of one code word Cx is “1” and the 3rd bit of the next code word Cy is “1”, the first to first of the four sets of combined bits 1b described above. Three sets of combined bits (000), (001), and (010) are satisfied because they satisfy the minimum run length 3T to the maximum run length 12T, and the fourth set of combined bits (100) sets the minimum run length 3T. Since it is not satisfied, addition is stopped.
[0086]
Then, after adding three sets of coupled bits (000), (001), and (010) between codewords Cx and Cy, three sets of codeword strings {Cx (000) Cy} and {Cx (001) Cy }, {Cx (010) Cy} are input to the first DSV value calculation circuit 33A to calculate the respective DSV values of the three sets of codeword strings, the codewords Cx and Cy as shown in FIGS. When the combined bit (000) is added, the DSV value of the codeword string {Cx (000) Cy} becomes +2, and when the combined bit (001) is added, the codeword string {Cx (001) Cy} DSV value of -4 becomes -4, and when the combined bit (010) is added, the DSV value of the codeword string {Cx (010) Cy} becomes -6. Up to this stage, it is the same as the conventional example described above with reference to FIGS. 4 and 5. In the conventional example, at this stage, one set of codeword strings {Cx (000 ) Cy} is selected as one finally determined codeword string, but in this embodiment, as described above, the next codeword Cy and the next next codeword Cz following one codeword Cx are selected. Therefore, one codeword Cx and the next codeword are considered in consideration of the DSV value when the codeword Cx is connected to the next codeword Cz through the next codeword Cy. After selecting and adding the combined bit 1b to Cy, the code word string from one code word Cx to the next code word Cy through the combined bit 1b is finally determined.
[0087]
Therefore, a second combination bit is added to three sets of codeword strings {Cx (000) Cy}, {Cx (001) Cy}, and {Cx (010) Cy} obtained by calculating each DSV value by the first DSV value calculation circuit 33A. The signal is input to the circuit 32B.
[0088]
Similarly to the first combined bit addition circuit 32A, the second combined bit addition circuit 32B described above can be (000), (001), (000), (001), (3) as candidates for the 3-bit combined bits 1b that satisfy the minimum run length 3T to the maximum run length 12T. Four sets of (010) and (100) are prepared.
[0089]
Then, in the second combined bit addition circuit 32B, three sets of code word sequences {Cx (000) Cy}, {Cx (001) Cy}, {Cx (010) Cy} input here are input here. From the case of the first combined bit adding circuit 32A, four sets of combined bits (000), (001), (010), and (100) are temporarily added to the next next code word Cz. Also, a large number of code word strings having a large number of sets are generated. At this time, a large number of codeword strings are encoded in a branching structure (tree structure), so that all the codeword strings are commonly shared from one codeword Cx to the next codeword Cy to the next next codeword Cz. Codeword strings up to
[0090]
Here, as shown in FIGS. 8 to 10, the next codeword Cy is “00100010000010” as described above, while the next codeword Cz is “00000001000001”. Since the 13th bit of the next code word Cy is “1” and the 8th bit of the next next code word Cz is “1”, the first of the four sets of combined bits 1b described above. Although the third set of combined bits (000), (001), and (010) satisfy the minimum run length 3T to the maximum run length 12T, the fourth set of combined bits (100) does not satisfy the minimum run length 3T. Stop adding.
[0091]
Between the three sets of codeword strings {Cx (000) Cy}, {Cx (001) Cy}, {Cx (010) Cy} and the next next codeword Cz inputted here, 3 After adding a set of combination bits (000), (001), and (010), a total of nine codeword strings {Cx (000) Cy (000) Cz}, {Cx (000) Cy (001) 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 nine sets of codes are input. When each DSV value of the word string is calculated,
In the case of the code word string {Cx (000) Cy (000) Cz} in case 11 shown in FIG. 8A, the code word Cz is transmitted from the 13th bit of the code word Cy through the combined bit (000). Since the number of “0” s up to the seventh bit is 11 consecutive, the maximum run length 12T is included, and the DSV value of the codeword string {Cx (000) Cy (000) Cz} is −3,
In the case of the codeword string {Cx (000) Cy (001) Cz} in case 12 shown in FIG. 8B, the codeword string {Cx (000) Cy (001) is not included without including the maximum run length 12T. DS value of Cz} is +3,
In the case of the codeword string {Cx (000) Cy (010) Cz} in case 13 shown in FIG. 8C, the codeword string {Cx (000) Cy (010) Cz does not include the maximum run length 12T. } DSV value is +5.
[0092]
Further, in the case of the code word string {Cx (001) Cy (000)} Cz in case 21 shown in FIG. 9A, the code word is transmitted from the 13th bit of the code word Cy through the combined bit (000). Since the number of “0” s up to the seventh bit of Cz is 11 consecutive, the maximum run length 12T is included, and the DSV value of the codeword string {Cx (001) Cy (000) Cz} is +1,
In the case of the codeword string {Cx (001) Cy (001) Cz} in case 22 shown in FIG. 9B, the codeword string {Cx (001) Cy (001) is not included without including the maximum run length 12T. DSV value of Cz} is −5,
In the case of the codeword string {Cx (001) Cy (010) Cz} in case 23 shown in FIG. 9C, the codeword string {Cx (001) Cy (010) Cz is not included without including the maximum run length 12T. } Has a DSV value of -7.
[0093]
Furthermore, in the case of the code word string {Cx (010) Cy (000) Cz} in case 31 shown in FIG. 10A, the code word is transmitted from the 13th bit of the code word Cy through the combined bit (000). Since the number of “0” s up to the seventh bit of Cz is 11 consecutive, the maximum run length 12T is included, and the DSV value of the codeword string {Cx (010) Cy (000) Cz} is −1. ,
In the case of the codeword string {Cx (010) Cy (001) Cz} in case 32 shown in FIG. 10B, the codeword string {Cx (010) Cy (001) is not included without including the maximum run length 12T. DS value of Cz} is −7,
In the case of the codeword string {Cx (010) Cy (010) Cz} in case 33 shown in FIG. 10C, the codeword string {Cx (010) Cy (010) Cz is not included without including the maximum run length 12T. } Has a DSV value of −9.
[0094]
Thereafter, nine sets of code word strings from the second DSV value calculation circuit 33B and the corresponding DSV values are input to the DSV value comparison circuit / combination bit selection circuit 34, and this DSV value comparison circuit / combination bit selection circuit. 34, among the DSV values of the nine sets of codeword strings, the codeword string {Cx (001) Cy (000) Cz} having the DSV absolute value of DSV = + 1 closest to zero, or the DSV value = One set of codeword strings {Cx (010) Cy (000) Cz} having −1 is selected and input to the determined codeword string output circuit 35. At this time, the set whose DSV absolute value is closest to zero is selected from the set including the maximum run length 12T as shown in FIGS. 8A, 9A, and 10A. it is obvious.
[0095]
When the DSV value comparison circuit / combined bit selection circuit 34 selects the code word string, if the DSV absolute value of the code word string is the same value, 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 the code word string of the DSV value on the-side is adopted or not, the code word string on only one side of the + side or the one side can be automatically selected. In addition, the combined bit 1b corresponding to the code word string on only one side can be selected.
[0096]
Next, the decision code word string output circuit 35 adds 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 / combined bit selection circuit 34. One determined codeword string {Cx (001) Cy} finally determined by combining one codeword Cx to the next codeword Cy through the combined bit 1b using the combined bit 1b One of the decision codeword strings {Cx (010) Cy} is output. In other words, this is equivalent to a state in which the combined word 1b between the codewords Cy and Cz and the codeword Cz are removed from one set of codeword strings selected by the DSV value comparison circuit / combined bit selection circuit 34.
[0097]
That is, the codeword string {Cx (001) Cy (000) Cz} having the DSV value = + 1, which is input to the determined codeword string output circuit 35, or the codeword string {Cx (010) having the DSV value = −1. Cy (000) Cz} is a combination bit 1b added between codewords Cx and Cy is (001) or (010), and from one codeword Cx through the next codeword Cy to the next next 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 taken into consideration is closest to zero.
[0098]
On the other hand, as in the conventional example described with reference to FIG. 4, a combined bit added between codewords Cx and Cy using a conventional modulator 20 that pre-reads only one codeword Cx and the next codeword Cy. When 1b is (000), as shown in FIGS. 7 and 8 (a) to 8 (c), even if the DSV value is temporarily reduced, the first code word Cz is reached first. The DSV value becomes larger on the + side or the − side than in the case of the present embodiment that is pre-read.
[0099]
By the way, in order to generate the maximum run length 12T in the combination of the code word C and the combined bit 1b, as shown in “Cy and Cz” in FIGS. The code word C only needs to have 11 consecutive “0” s including the combined bit 1b when the combined bit 1b is added.
[0100]
Thereafter, in this embodiment, the decision codeword string {Cx (001) Cy ...} or the decision codeword string {Cx (010) Cy ...} controlled so that the DSV value becomes the best is suitable for recording. The recorded signal R is converted into a recorded signal R (FIG. 1) and recorded on a glass master (not shown) for CD by a laser beam. Then, a stamper disk (not shown) is produced on the basis of the glass master disk for CD, and this embodiment according to the present invention as shown in FIGS. 12 (a) and 12 (b) to be described later using this stamper disk. An optical disk (CD) 10 is produced as an example recording medium.
[0101]
The basic operation of the modulation apparatus and modulation method according to the present invention has been described above with specific examples. However, in order to make the explanation easier to understand, in the calculation of the DSV value, the code word string {Cx (000) Cy}, {Cx (000) Cy (000) Cz}, {Cx (000) Cy (000) ) Cz..., Such as the codeword sequence that has already been determined, is expressed so as to perform the calculation again. As a result, if all the code words Cx, Cy, Cz... Are not inputted, it is possible not only to calculate the DSV value but also to output the determined code word string. A DSV value storage circuit (not shown) is provided in the DSV value calculation circuits 33A, 33B or the DSV value comparison circuit 34 for the DSV value of the determined code word string, and at least three DSV value calculation circuits are avoided. If a code word is input, one determined code word string can be obtained.
[0102]
The modulation apparatus of the present invention capable of generating the maximum run length 12T when the codeword string is generated by adding the three combined bits 1b having the best DSV value between the adjacent codewords C and C. When 30 is used, the DSV value can take the smallest value in the codeword string including the maximum run length 12T as shown in FIGS.
[0103]
On the other hand, when the conventional modulator 20 (FIG. 4) that does not allow the maximum run length 12T is used, the DSV value is greater than when the maximum run length 12T is allowed as shown in FIGS. It is clear from the above that becomes larger. Here, the maximum run length 12T has been described as an example in which the run length restriction rule on the CD standard is not strictly observed. However, this embodiment also applies to a long run length of 13T or more, and conversely, a short run length of 2T or less. The DSV value of the codeword string can be made smaller than that when the conventional modulation device 20 is used. However, as described in the section of the prior art, it is not preferable to allow an extremely short run length or an extremely long run length from the viewpoint of transmission characteristics.
[0104]
By the way, when the above-mentioned maximum run length 12T continues for a certain period of a code word sequence, the conventional modulation device 20 has a DSV value as shown in, for example, FIGS. 8B to 8C. Since the increase occurs continuously, the DSV value of the code word string may fluctuate greatly periodically in the continuous period. 8 (b) or 8 (c) shows an example in which the DSV value rises to the right, that is, has a positive increasing tendency, but the input codewords Cx, Cy, Cz... Are the same. However, if the polarity of the determined codeword string corresponding to the first codeword Cx is reversed, the DSV value decreases downward, that is, tends to increase negatively. As a result, when a signal recorded using the conventional modulation device 20 is reproduced, a specific frequency component is increased in the reproduction signal of the codeword string, and stable reproduction is impaired. On the other hand, it is apparent that stable reproduction is maintained when the modulation device 30 of this embodiment is applied. Hereinafter, input data corresponding to a specific codeword that causes such a difference is referred to as specific data.
[0105]
By applying this technical idea, a pre-read from one code word Cx through the next code word Cy to at least the next next code word Cz is allowed, and the minimum run length 3T to the maximum run length 12T are allowed. 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. However, in the copy recording medium in which the original recording medium is copied, The reproduction data from the original recording medium is converted from the minimum run length 3T to the maximum run length 11T set by the conventional modulator 20 (FIG. 4) based on the run length restriction rule RLL (2, 10) in the CD standard. Since the code word string is recorded by adding the combined bit 1b of 3 bits between the adjacent code words C and C so as to strictly observe the Specific data portion allowing the maximum run length 12T on null recording medium, the copy recording medium it is clear that increasing the component of a particular frequency in the reproduced signal because the variation becomes large DSV value.
[0106]
This is shown in FIG. As shown in FIG. 11, the reproduction frequency spectrum of the code word string of the specific data part allowing the maximum run length 12T recorded on the original recording medium (CD) is gently attenuated in the low frequency part. On the other hand, when the copy recording medium (CD-R) copied by the conventional modulation device 20 is reproduced from the original recording medium (CD), the reproduction frequency spectrum of the code word string of the specific data portion is specified in the low frequency portion. The frequency component is increasing, and reproduction of the copy recording medium (CD-R) becomes unstable.
[0107]
When the technical idea of this embodiment is applied to a CD-ROM containing computer data, it is only necessary to change the name of the music source data AD shown in FIG. 7 to the computer source data. Description is omitted.
[0108]
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. 12A and 12B are a perspective view and a vertical cross-sectional view for explaining an optical disc that is a recording medium of the present embodiment according to the present invention.
[0109]
As shown in FIGS. 12 (a) and 12 (b), an optical disc (hereinafter referred to as an original CD) 10 serving as a recording medium of the present embodiment according to the present invention is a CD (Compact Disc) containing music information, It is applied to read-only optical discs such as CD-ROM (CD-Read Only Memory) containing computer data, and the digital information signal recorded on this original CD 10 is EFM (Eight to Fourteen Modulation: 8-14 modulation). ) Method, the minimum run length is 3T and the maximum run length is 12T, so that the highest priority is satisfied.
[0110]
The above-described original CD 10 has a digital information signal on one surface 11a of a disk-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. Are converted into digital pit rows, and the signal surfaces are recorded by cutting the pit rows as spiral or concentric recording tracks 12.
[0111]
Here, the recording track 12 satisfies the minimum run length 3T to the maximum run length 12T among the code words Cx, Cy, Cz... Using the modulation device 30 of the present embodiment described above, and Then, at least prefetching the next codeword Cy and the next next codeword Cz following one codeword Cx, and adding a combination bit 1b that gives the best DSV value, generates one decision codeword string A concave-convex pit row is formed in advance over the entire surface corresponding to this one determination code word row. Further, a metal reflective film 14 and a protective film 15 are sequentially formed on the signal surface of the original CD 10 to form the original CD 10 in a reproduction-only type. The surface 11b side opposite to the one surface 11a of the transparent disk substrate 11 is the side that irradiates the reproduction laser beam Lp.
[0112]
When the recording track 12 recorded on the original CD 10 is reproduced by a commercially available CD player or CD-ROM drive, even if the run length 12T outside the CD standard is included, the 14-bit code word C itself satisfies the standard. Therefore, no error occurs in the reproduction data. On the other hand, a large DSV value is obtained if the run length restriction rules in the CD standard as shown in FIGS. 8B and 8C and FIGS. 9B and 10C and FIGS. 10B and 10C are observed. In the optical disk manufactured by the conventional modulation device 20, the DSV value of the code word string has a large amount of fluctuation and the length of one frame of the code word string or In this embodiment, however, the maximum run length 12T outside the CD standard is allowed, so that the DSV value of the codeword sequence changes. Improved and stable reproduction is obtained.
[0113]
Similarly, when the user copies the original CD 10 on which the original music data AD (FIG. 7) including the specific data described above is recorded onto 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 music source data AD (FIG. 7) obtained by reproducing the original CD 10 is stored in the CD-R. If input to the drive, the minimum run length (d + 1) set based on the run length restriction rule RLL (d, k) = RLL (2, 10) in the CD standard in the conventional modulator 20 (FIG. 4). Since the code word string is generated by adding the combined bit 1b of 3 bits while strictly observing T = 3T to the maximum run length (k + 1) T = 11T, the DSV value of the copied code word string is the present embodiment. Modulation Larger amount of change than with the location 30 (FIG. 7), which vary basis the period and one frame length or 2 frame length of the codeword sequence. Therefore, when this copy recording medium (CD-R) is reproduced by a commercially available CD player or CD-ROM drive, the reproduction signal has a specific effect that adversely affects the operation of the binarization circuit, tracking or focus servo, etc. The frequency component increases and the reproduction becomes unstable or cannot be reproduced. Thereby, when the original CD 10 is copied to a copy recording medium (CD-R), copyright infringement on the digital information signal can be prevented. As described in the prior art section of Japanese Patent Laid-Open No. Hei 6-197024, it is known that a large amount of variation in the DSV value of the code word string described above adversely affects the stability of the regenerator. The details are omitted.
[0114]
Next, if the AC data or the specific data of the DC signal that cannot be discerned in terms of the audibility is encoded and used as the music source data AD, it is further effective for copy prevention measures, and this case will be described with reference to FIGS. To do.
[0115]
FIG. 13 (a) shows a case where the original CD of the present invention produced by encoding specific data of an AC signal that cannot be discriminated as music source data AD is reproduced, and (b) is 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 that cannot be discerned as audible music data AD is reproduced, (B) is the figure which showed the case where CD-R which copied the original CD of this invention was reproduced | regenerated.
[0116]
First, as shown in FIG. 13 (a), a signal that cannot be discriminated as music source data AD, for example, specific data consisting of an AC signal of about 22.05 KHz, is shown in FIG. 7 over a predetermined period. This is input to an 8-14 modulation circuit 31 provided in the modulation device 30 of the example. For example, when converting specific data consisting of an AC signal of about 22.05 KHz into a 14-bit codeword C, the minimum run length 3T to the maximum run length 12T are allowed without strictly observing the run length restriction rule, and The next codeword Cy and the next next codeword Cz following one codeword Cx are at least prefetched, and a combined bit 1b that provides the best DSV value is added to generate one decision codeword string. The single determination code word string is applied to the original CD 10 (FIG. 12) which is a recording medium according to the present invention. When this original CD 10 is reproduced, the reproduced signal of the code word string does not increase the specific frequency component, so that it is reproduced as AC signal data without any trouble and inaudible discrimination. So the user is completely unaware. Note that the specific data composed of AC signals is subjected to fade-in and fade-out processing before and after a predetermined period as shown in FIG. 13A in order to prevent noise generation before and after that. Is also one of the features. Further, as the predetermined period for inserting the specific data of the AC signal described above, in the case of music data, a silent section between songs is suitable.
[0117]
On the other hand, as shown in FIG. 13B, when the original CD 10 on which the specific data consisting of the AC signal is recorded is copied to the CD-R and this CD-R is reproduced, the code word over the predetermined period described above. Since a specific frequency component increases in the reproduction signal of the column, an unreadable section occurs, and noise of a low frequency component is generated by data interpolation in the reproduction device, for example, “Ghee” or “Gain”. Sounds such as “sounds” can be heard, so that the user can be informed that this CD-R is an abnormal optical disc, and copyright infringement on the digital information signal on the copied CD-R can be prevented. be able to.
[0118]
Next, FIG. 14A shows an example in which the AC signal data shown in FIG. 13A is replaced with specific data consisting of a DC signal that cannot be discerned as music source data AD. When the original CD 10 (FIG. 12), which is a recording medium according to the present invention, is reproduced, no particular frequency component is increased in the reproduction signal of the codeword string, and there is no problem and the audibility. Since it is reproduced as DC signal data that cannot be discriminated above, the user is completely unaware. Note that the specific data consisting of the DC signal is subjected to fade-in and fade-out processing before and after a predetermined period as shown in FIG. 14A in order to prevent generation of noise before and after the specific data. Is also one of the features. In addition, in the case of music data, the silent period between songs is suitable as the predetermined period for inserting the DC signal specific data described above.
[0119]
On the other hand, as shown in FIG. 14B, even when the original CD 10 on which the specific data consisting of the DC signal is recorded is copied to the CD-R, an unreadable section occurs in a predetermined period as described above. End up. Therefore, even in this case, the copied CD-R cannot be reproduced, so that copyright infringement on the digital information signal on the copied CD-R can be prevented.
[0120]
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 the q-bit code word C, as described above, it is converted into one code word Cx. When the code word string is generated by prefetching at least the next next code word Cy and the next next code word Cz, the specific data of the AC signal or DC signal that cannot be discerned from the above audibility is included in the music information. The case where it inserts in the silence area formed between music is demonstrated more concretely using FIGS.
[0121]
FIG. 15 is a schematic diagram for explaining a silent section between songs in a general CD,
FIG. 16 is a schematic diagram for explaining the case of specific data insertion form 1 in which specific data that cannot be discriminated in the sense of hearing 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 case of specific data insertion form 2 in which specific data that cannot be discriminated in the sense of hearing is inserted in a silent section between songs in the recording medium according to the present invention;
FIG. 18 is a schematic diagram for explaining a case of specific data insertion form 3 in which specific data that cannot be discriminated on the perception is inserted in a silent section between songs in the recording medium according to the present invention;
FIG. 19 is a schematic diagram for explaining the case of the specific data insertion form 4 in which specific data that cannot be discerned in the sense of hearing is inserted into a silent section between songs in the recording medium according to the present invention.
[0122]
Here, a case will be described in which specific data that cannot be discriminated in terms of audibility is recorded by being inserted into a silent section formed between songs on the original CD 10 (FIG. 12) that is a recording medium according to the present invention. Prior to this, a silent section in the case of a general CD (Compact Disc) in which music information is recorded as reference material for this will be described first.
[0123]
That is, as shown in FIG. 15, in the case of a general CD containing music information, in accordance with the CD standard “Red Book”, the TOC (not shown) formed in the lead-in area (not shown) formed on the inner circumference side. In Table of Contents, the start address of each song is recorded in advance as index information of music information. Further, a plurality of songs recorded in the data area on the CD track are recorded with a song number, an index number, an address, etc. for each song as shown in the figure.
[0124]
More specifically, when a plurality of songs recorded on a CD are generalized using n (where n is a natural number of 2 or more) and displayed, for example, the (n-1) th of the plurality of songs. A silent section is formed between the song No. and the nth song.
[0125]
Also, the song number n-1 corresponding to the n-1th song is assigned to the n-1th song from the performance end position (not shown) immediately after the performance of the n-2th song (not shown) is finished. The performance end position of music number n-1 corresponding to the (n-1) th song is recorded between the n-1th song and the nth song. It is set in a silent section formed between them. Further, the music number n corresponding to the nth music is recorded following the performance end position of the music number n-1 corresponding to the (n-1) th music.
[0126]
In addition, the n-1th song and the nth song can be assigned index numbers from 01 to 99 in order to indicate the order of movement in each song. The index number 01 (-99) is recorded from the position of the start address (not shown) of the (n-1) th song to the performance end position of the song number n-1 of this song, while n The index number 01 (-99) in the tune is recorded from the position of the start address of the nth song to the performance end position (not shown) of the song number n of this song. At this time, the start address (not shown) of the (n-1) th song and the start address of the nth song are within the silent section between the songs and are located before the leading end where the performance of each song starts. Is recorded.
[0127]
In addition, in the 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.
[0128]
As described above, the (n-1) th song ends at the performance end position of the song number n-1 of this song. On the other hand, the nth song is started from the position of the start address of this song.
[0129]
Here, when the song number, index number, and start address are recorded for each song corresponding to a plurality of songs recorded in the data area on the 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, an AC signal or specific data of a DC signal that cannot be discerned in the sense of hearing is illustrated in a silent section formed between the (n-1) th song and the nth song. 16 to 19 are inserted and recorded based on any one of the specific data insertion modes 1 to 4 shown in FIG.
[0130]
First, as shown in FIG. 16, in the case of the specific data insertion form 1 in the recording medium according to the present invention, on the original CD 10 (FIG. 12), for example, between the n-1th song and the nth song. The above-mentioned specific data is inserted and recorded in the section of the index number 00 which is in the silent section formed in FIG.
[0131]
As a result, when the original CD 10 in which the specific data is inserted and recorded in the section of the index number 00 is completely copied to the CD-R (copy recording medium), the copied CD-R also has the (n-1) th song. When the copied CD-R is played back, the data is recorded in the silent section formed between the tune and the nth song and the index number 00. In the same manner as above, since the unreadable section occurs due to the copied specific data and the CD-R cannot be reproduced, the copyright infringement on the digital information signal on the copied CD-R can be prevented in advance. .
[0132]
However, when copying the original CD 10 recorded with the specific data inserted into the section of the index number 00 to the CD-R, the user avoids the silent section between the songs with respect to the original CD 10 by random access. It is also possible to pack a plurality of songs from the start address position and copy them to the CD-R. In this case, since the silent section between each song is not copied onto the CD-R, each song on the original CD 10 The specific data recorded in the section of each index number 00 set in the above is also not copied, so that even if the copied CD-R is played back, the unreadable section does not occur, and the specific data on the original CD 10 is not generated. The data copy protection function will not function on the copied CD-R. In order to avoid this, in the present invention, even when the user packs a plurality of songs from the position of the start address of each song on the original CD 10 and copies them to the CD-R, each recorded in the silent section between each song. By adopting any one 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 prevention function in the original CD 10 can be further improved. Is.
[0133]
That is, as shown in FIG. 17, in the case of the specific data insertion form 2 in the recording medium according to the present invention, it is formed on the original CD 10 between, for example, the (n−1) th song and the nth song. The performance end position of music number n-1 of the (n-1) th song set in the silent section is the start address side of the nth music from the performance end position of music number n-1 in the case shown in FIG. The above-mentioned specific data is inserted and recorded between the end of the (n-1) th song and the performance end position of the song number n-1 extended here. Accordingly, the section in which the index number 00 is recorded is shortened.
[0134]
Although illustration is omitted here, the performance end position of the music number n-1 of the (n-1) th song is extended until it matches the position of the start address of the nth song, and the (n-1) th song is extended. Specific data may be inserted and recorded between the end of the song and the performance end position of song number n-1 extended to the start address here, and in this case, index number 00 is recorded. Although the section is deleted, the n-1st song ends at the performance end position of the song number n-1, and the nth song starts from the position of the start address of the nth song that is the same position as this position. Will not cause any trouble.
[0135]
Therefore, when the original CD 10 is produced by adopting the technical idea of the specific data insertion form 2 as shown in FIG. 17, the specific data that cannot be discerned in the sense of hearing is in a silent section formed between songs, In addition, it is inserted and recorded in the section excluding the section of index number 00, and the user copies a plurality of songs from the position of the start address of each song to the original CD 10 and copies them to the CD-R. Even in this case, for example, since the (n-1) th song is always copied up 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- The specific data recorded between the performance end position of 1 is always copied onto the CD-R, so that 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 entire original CD 10 adopting the technical idea of the specific data insertion form 2 as shown in FIG. 17 is copied to the CD-R, the specific data is copied after the end of the (n-1) th song. It is obvious.
[0136]
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, it is formed on the original CD 10 between, for example, the (n-1) th song and the nth song. The position of the start address of the nth song set in the silent section is the performance of the song number n-1 of the n-1st song from the position of the start address of the nth song in the case shown in FIG. Moving to the end position side, the above-mentioned specific data is inserted and recorded between the position of the start address of the nth song and the leading end of this song. Accordingly, the section in which the index number 00 is recorded is shortened. Further, in this case, since the position of the start address of the nth song is moved to the (n-1) th song side, from the position of the start address of the nth song to the beginning of the nth song. In this case, the period from the start address position of the nth song to the beginning of the nth song is set within a time range in which the user can tolerate the silence state. This will not cause any trouble.
[0137]
Although not shown here, the start address of the music number n-1 is finished by matching the position of the start address of the nth music with the performance end position of the music number n-1 of the (n-1) th music. Specific data may be inserted and recorded between the position of the start address of the n-th song matched with the position and the leading end of the n-th song, and in this case, the section in which the 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 nth song is started from the position of the start address of the nth song which is the same position as this position. So it will not cause any trouble.
[0138]
Therefore, when the original CD 10 is produced by adopting the technical idea of the specific data insertion form 3 as shown in FIG. 18, the specific data that cannot be discerned in the sense of hearing is in a silent section formed between songs, In addition, it is inserted and recorded in the section excluding the section of index number 00, and the user copies a plurality of songs from the position of the start address of each song to the original CD 10 and copies them to the CD-R. Even in this case, for example, since it 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 this song on the original CD 10 is also CD. Since it is always copied onto -R, if the copied CD-R is played back, the CD-R cannot be played back by the specific data as described above. Of course, even if the original CD 10 adopting the technical idea of the specific data insertion form 3 as shown in FIG. 18 is copied to the CD-R, the specific data is copied following the start address of the nth song. Is obvious.
[0139]
Next, as shown in FIG. 19, in the case of the specific data insertion form 4 in the recording medium according to the present invention, the specific data insertion form 1 shown in FIG. 16, the specific data insertion form 2 shown in FIG. The original CD 10 is produced by combining the specific data insertion form 3 shown in FIG. 18, for example, between the end of the (n-1) th song and the performance end position of the song number n-1 of this song. The above specific data is inserted and recorded, and the specific data is also inserted and recorded in the section of index number 00. Further, between the position of the start address of the nth song and the leading end of this song The specific data is inserted into and recorded.
[0140]
In addition, although FIG. 19 illustrates the case where the three combinations of the specific data insertion forms 1 to 3 described above are combined, the present invention is not limited to this, and at least two combinations of the specific data insertion forms 1 to 3 are combined. Thus, the original CD 10 may be produced.
[0141]
Therefore, the original CD 10 produced by combining at least two or more of the specific data insertion forms 1 to 3 described above can be copied to the CD-R, or the user can select a plurality of songs from the start address position of each song. Even if the CD-R is copied to the CD-R, at least one or more specific data is always copied between 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 cannot be reproduced due to the above.
[0142]
In the above-described modulation apparatus, modulation method, and recording medium according to the present invention, the case of the EFM modulation (8-14 modulation) system used for the CD has been described. However, the present invention is not limited to the CD standard. , When converting the p-bit input data word D to the 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 prefetched, and predetermined The minimum run length (d + 1) T to the maximum run length (k + 2) without strictly adhering 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 ) Any p-q modulation that generates a codeword sequence by adding r-bit combined bits 1b that provide the best DSV value between adjacent codewords C and C so as to allow T is described above. Technology It can be applied to the idea.
[0143]
Furthermore, when the input data word D to be p-q modulated is music information and the p-bit input data word D is converted to a q-bit code word C, the next code following one code word Cx A minimum run length (d + 1) T to a maximum run length (k + 1) that is at least prefetched from the word Cy and the next next code word Cz and is set based on a predetermined run length restriction rule RLL (d, k) R bit combined bit 1b that provides the best DSV value between adjacent codewords C and C so as to allow minimum run length (d + 1) T to maximum run length (k + 2) T without strictly adhering to T To generate a code word string and record the p-q modulated music information on the original CD 10 (FIG. 12), the AC signal or the specific data of the DC signal that cannot be discerned audibly and the music in the music information Shape between songs In order to further improve the performance of the copy protection function, the above-mentioned specific data is in the silent section formed between songs and is indexed. What is necessary is just to insert and record in the area except the area of number 00.
[0144]
【The invention's effect】
According to the modulation device, the modulation method, and the recording medium according to the present invention described in detail above, a p-bit input data word is converted into a q-bit code word, and r-bit combined bits are provided between adjacent code words. When generating a code word string by adding without strictly adhering to a predetermined run length restriction rule, in particular, at least the next code word following one code word and the next next code word are prefetched, and A plurality of sets of codeword strings are generated by temporarily adding a plurality of sets of coupled bits of r bits between one codeword and the next codeword without strictly observing a predetermined run length restriction rule, A plurality of sets of combined bits of r bits are temporarily added between a next codeword in a set of codeword strings and at least the next next codeword without using a predetermined run length restriction rule. Many codeword strings from one codeword to the next After that, one set of codeword strings whose absolute value of the DSV value is closest to zero is selected from the DSV values of a large number of codeword strings, and this one set of codeword strings is selected. One decision code that is finally determined by combining one codeword to the next codeword through the combination bit using the combination bit added between one codeword and the next codeword Since the word string is output, the recording medium in which a large number of the determined code word strings are recorded can be normally reproduced without causing any trouble, and when the copy recording medium copied from the recording medium is reproduced, Since the reproduction signal of the decision codeword sequence copied in series increases the specific frequency component and the DSV value also fails and cannot be reproduced, the copyright to the digital information signal on the copied copy recording medium Preventing infringement Can.
[0145]
Also, AC signal data or DC signal data that cannot be discerned as an input data is input over a predetermined period by the modulation device of the present invention or the modulation method of the present invention, and this input data word is subjected to pq modulation. When the encoded recording is performed on a recording medium and a copied recording medium is reproduced, an audible sound such as “Ghee” or “Gear” is generated during the unreadable period due to DSV control failure. Therefore, 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 copied recording medium.
[0146]
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 the AC signal or the specific data of the DC signal that cannot be discerned by hearing is input over a predetermined period. In addition, the specific data described above is inserted into a silent section formed between songs, or the specific data is in a silent section formed between songs and the index. When the copy recording medium copied from this recording medium is reproduced by inserting it in the section excluding the section of number 00 and recording it on the recording medium, an unreadable section occurs due to the copied specific data. 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, where FIG. 1A shows music source data and FIG. 1B shows an EFM signal;
FIG. 2 is a diagram showing a coding table at the time of 8-14 modulation.
FIGS. 3A and 3B are diagrams for explaining DSV control during 8-14 modulation. FIGS.
FIG. 4 is a block diagram schematically illustrating a conventional modulation device.
FIGS. 5 (a) to 5 (c) add a coupling bit between one code word and the next code word following a predetermined run-length restriction rule using a conventional modulator. FIG. FIG. 6 is a diagram for explaining a state in which DSV values of a plurality of sets of codeword strings are calculated when (000), (001), and (010) are temporarily added as combined bits when generating a codeword string. is there.
FIG. 6 is a longitudinal sectional view showing an optical disc with copy prevention measures taken as an example of a conventional example.
FIG. 7 is a block diagram schematically illustrating a modulation apparatus and a modulation method according to the embodiment of the present invention.
FIGS. 8A to 8C show a case where a modulation apparatus according to the present embodiment is used between one code word and the next code word that follows the run length restriction rule in the CD standard without strict adherence. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next next codeword are pre-read, and between one codeword and the next codeword A pair of combined bits (000) is provisionally added to the two and three sets of combined bits (000), (001), and (010) are provisionally added between the next codeword and the next codeword. It is a figure for demonstrating the state which calculated each DSV value of many sets of codeword strings sometimes.
FIGS. 9 (a) to 9 (c) show that between the one code word and the next code word following the code length without strictly complying with the run length restriction rule in the CD standard using the modulation apparatus of the present embodiment. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next next codeword are pre-read, and between one codeword and the next codeword A pair of combined bits (001) is provisionally added to and three sets of combined bits (000), (001), and (010) are provisionally added between the next codeword and the next codeword. It is a figure for demonstrating the state which calculated each DSV value of many sets of codeword strings sometimes.
FIGS. 10 (a) to 10 (c) show that between the one code word and the next code word following the code length without strictly adhering to the run length restriction rule in the CD standard using the modulation apparatus of the present embodiment. When a codeword string is generated by adding a combination bit, the next codeword following one codeword and the next next codeword are pre-read, and between one codeword and the next codeword A pair of combined bits (010) is provisionally added to and three sets of combined bits (000), (001), and (010) are provisionally added between the next codeword and the next codeword. It is a figure for demonstrating the state which calculated each DSV value of many sets of codeword strings sometimes.
FIG. 11 is a diagram showing a frequency spectrum difference according to a DSV value variation of a codeword string between the case of the original CD of the present embodiment according to the present invention and the case of a CD-R in which the original CD is copied. .
FIGS. 12A and 12B are a perspective view and a longitudinal sectional view for explaining an optical disc serving as a recording medium of the present embodiment according to the present invention.
FIG. 13A shows a case where the original CD of the present invention produced by encoding specific data of an AC signal that cannot be discerned as audible music source data AD is reproduced, and FIG. 13B shows the original CD of the present invention. It is the figure which showed the case where the copied CD-R was reproduced | regenerated.
FIG. 14A shows a case where an original CD of the present invention produced by encoding specific data of a DC signal that cannot be discerned as auditory data AD is reproduced, and FIG. 14B shows the original CD of the present invention. It is the figure which showed the case where the copied CD-R was reproduced | regenerated.
FIG. 15 is a schematic diagram for explaining a silent section between songs in a general CD.
FIG. 16 is a schematic diagram for explaining a case of specific data insertion form 1 in which specific data that cannot be discerned in perception 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 case of specific data insertion mode 2 in which specific data that cannot be discerned in perception is inserted in a silent section between songs in the recording medium according to the present invention.
FIG. 18 is a schematic diagram for explaining a case of specific data insertion form 3 in which specific data that cannot be discerned in perception 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 case of specific data insertion form 4 in which specific data that cannot be discerned in perception is inserted in a silent section between songs in the recording medium according to the present invention.
[Explanation of symbols]
1 ... EFM signal,
1a ... sync signal, 1b ... combined bit, 1c ... subcode,
1d: first code word string, 1e: C2 error correction code,
1f ... second codeword string, 1g ... C1 error correction code,
10: an optical disc as a recording medium of the present embodiment according to the present invention,
11 ... Transparent disk substrate, 12 ... Recording track,
20 ... Conventional modulator,
21 ... 8-14 modulation circuit, 22 ... combined bit addition circuit,
23... DSV value arithmetic circuit, 24... DSV value comparison circuit / combined bit selection circuit,
30: Modulator of this embodiment,
31 ... 8-14 modulation circuit,
32A ... first combined bit addition circuit, 32B ... second combined bit addition circuit,
33A: first DSV value calculation circuit, 33B: second DSV value calculation circuit,
34 ... DSV value comparison circuit / combined bit selection circuit,
35: Decision code word string output circuit.

Claims (13)

In a modulation device that converts a p-bit input data word into a q-bit code word, adds r-bit coupling bits between adjacent code words, generates a code word string, and outputs the code word string ,
modulation means for prefetching at least the next code word following one code word and the next next code word when converting the p-bit input data word into the q-bit code word;
A plurality of sets of coupled bits of the r bits are temporarily added between the one codeword and the next codeword without strictly observing a predetermined run-length restriction rule to generate a plurality of sets of codeword strings; Further, a predetermined set of run-length restriction rules are not strictly observed between the next code word in the plurality of code word strings and at least the next next code word for the plurality of sets of combined bits. A combined bit adding means for generating a plurality of sets of code word strings from at least the one code word to the next next code word,
DSV value calculation means for calculating each DSV value of a large number of codeword strings generated by the combined bit adding means;
Comparison / selection means for selecting one set of code word strings whose absolute value of DSV value is closest to zero among the DSV values of a large number of code word strings obtained by the DSV value calculation means. When,
Using the combined bits added between the one codeword and the next codeword in the one set of codeword strings selected by the comparison / selection means, from the one codeword to the combined bits And a decision codeword string output means for outputting one decision codeword string finally determined by combining up to the next codeword. The modulation device according to claim 1.
The adjacent codes that allow the maximum run length (k + 2) T without strictly adhering to the maximum run length (k + 1) T set based on the run length restriction rule RLL (d, k) for the codeword string. A modulation apparatus, characterized by adding r r combined bits between words. The modulation device according to claim 1 or 2,
The code word string output in strict compliance with the run length restriction rule RLL (d, k) is input with specific data that includes a component of a specific frequency over a predetermined period as the input data word, In addition, the modulation apparatus outputs the codeword string without strictly adhering to the run length restriction rule RLL (d, k) during that period. The modulation device according to claim 3, wherein
The modulation device according to claim 1, wherein the specific data is AC signal data or DC signal data that cannot be discriminated from the sense of hearing. The modulation device according to claim 3, wherein
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is inserted into a silent section formed between songs. A modulation device. The modulation device according to claim 3, wherein
In the case where the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is in a silent section formed between songs. And a modulation apparatus inserted in a section excluding the section of index number 00. In a modulation method for converting a p-bit input data word into a q-bit code word and adding a r-bit combined bit between adjacent code words to generate a code word string and outputting the code word string ,
when converting the p-bit input data word into the q-bit code word, a first step of prefetching at least the next code word following one code word and the next next code word;
A plurality of sets of code by temporarily adding a plurality of sets of combined bits of r bits between the one codeword and the next codeword without strictly observing a predetermined run length restriction rule RLL (d, k). A word sequence is generated, and further, a plurality of sets of combined bits of the r bits are set to a predetermined run length between the next codeword in the plurality of codeword sequences and at least the next next codeword. A second step of generating a large number of code word strings from at least the one code word to the next code word by temporarily adding the restriction rule RLL (d, k) without strictly adhering;
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 code word strings in which the absolute value of the DSV value is closest to zero among the DSV values of the plurality of code word strings obtained in the third step;
Using the combined bits added between the one codeword and the next codeword in the one set of codeword sequences selected in the fourth step, the combined bits are converted from the one codeword. And a fifth step of outputting one determined codeword string finally determined by combining up to the next codeword. The modulation method according to claim 7, wherein
The adjacent code that allows the maximum run length (k + 2) T without strictly adhering to the maximum run length (k + 1) T set based on the run length restriction rule RLL (d, k) for the codeword string. A modulation method, characterized by adding the r combined bits between words. The modulation method according to claim 7 or 8,
The code word string output in strict adherence to the run length restriction rule RLL (d, k) is input with specific data that includes a component of a specific frequency over a predetermined period as the input data word, In addition, the modulation method is characterized in that during the period, the codeword string is output without strictly observing the run length restriction rule RLL (d, k). The modulation method according to claim 9, wherein
The modulation method according to claim 1, wherein the specific data is AC signal data or DC signal data that cannot be discriminated in terms of hearing. The modulation method according to claim 9, wherein
When the input data word is music information and the specific data that cannot be discerned in terms of audibility is input over a predetermined period, the specific data is inserted into a silent section formed between songs. A modulation method characterized by the above. The modulation method according to claim 9, wherein
In the case where the input data word is music information and the specific data that cannot be discerned in terms of audibility is input for a predetermined period, the specific data is in a silent section formed between songs. And a modulation method that is inserted in a section excluding the section of index number 00. A recording medium on which the code word string encoded by any one of the modulation device according to claim 1 or 6 or the modulation method according to claims 7 to 12 is recorded.

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