JP2003242720A - Digital data recording and reproducing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To secure the maximum burst error correction length of an ECC block in the constitution of BIS+LDC while arranging identification signals (ID) at equal intervals. <P>SOLUTION: In 16 data blocks composed of 31 data strings including the data strings having the identification signals, in order to arrange the identification signals at fixed intervals, while changing the number of the data block to take out the data string to 1, 2, 3,..., 16, 1, 2,... every time one data string is taken out, the row number of the data string to be taken out from the data block is changed to 1, 2, 3,..., 31, 1, 2,... every time one data string is taken out and the data string is alternately taken out from two kinds of LDCs. The data strings are rearranged while preventing the data string from being taken out from the same BIS in the work of taking out the data strings for four times. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital data recording / reproducing method, and more particularly to a process of detecting an identification signal thereof.

[0002]

2. Description of the Related Art As an example of a method for reproducing a recording medium on which digital data is recorded, there is one described by Kenji Hayashi, "CD-Audio to PC-", Corona Publishing Co., Ltd., pp. 56-71 (1990). It describes a CD (Compact Disk) reproducing method, and the processing content and circuit configuration of a digital signal processing unit included in an apparatus for reproducing the signal.

A DVD (Digital Versatile D) having a data capacity (4.7 GB) about eight times as large as that of a CD is used as a medium for recording digital data which has been similarly modulated.
isc). An example of modulation / demodulation of data in recording / reproducing of this DVD is described in Masuda Harada, "All about digital video technology", Denpa Shimbun, pp.116-118 (1998).

Further, in recent years, each company has proposed a format of a next-generation optical disc having a data capacity (20's Gbit) of about 4 to 5 times that of a DVD. One proposal for this is T. Narahara, “Optical Disc System for Digit
al Video Recording, ”JJAP Vol.39 (2000) pp.912-919,
There is one described in 2000.

[0005]

However, although there is a description about the structure of the ECC block composed of BIS + LDC in the data format at the time of modulation / demodulation described therein, the details of the identification signal and each error correction code (BIS, LDC) are described. There is no description about the arrangement.

Further, in this ECC block structure, there is a problem that the maximum burst error correction length cannot be sufficiently secured only by performing PO interleaving for equalizing the identification signals (ID) as in the conventional DVD. is there.

When the IDs are not arranged at equal intervals, that is, when the IDs are densely distributed and sparsely distributed, in a data search process such as seeking on an optical disk, the specifications of the reproducing device or the like when the access time is sparse. Therefore, there is a problem that the time for cueing the data is simply delayed and that it is necessary to have many buffers for temporarily storing the data in the device.

The object of the present invention is to identify the identification signal (I
While arranging D) at equal intervals, the maximum burst error correction length of the ECC block having the BIS + LDC configuration is ensured.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an identification signal (ID) at equal intervals while ensuring the maximum burst error correction length of an ECC block having a BIS + LDC configuration. 31 including the data string that has
In each of the 16 data blocks consisting of the data string, the number of the data block from which the data string is taken out is 1 every time one data string is taken out so that the identification signal is at constant intervals
While changing to 2, 3, ..., 16, 1, 2, ..
Each time one data string is extracted, the row numbers of the data strings extracted from the data block are 1, 2, 3, ..., 31, 1, 2,
, And rearrangement of the data strings while preventing the data strings from being extracted from the same BIS in the work of extracting the data strings four times by alternately extracting the data strings from the two types of LDCs. I do.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the "Optical Disc" described in the prior art.
This is an ECC block using BIS + LDC described in "System for Digital Video Recording", and the present invention will be described by taking the configuration of this ECC block as an example.

FIG. 2 shows a BIS consisting of 64 Kbyte data.
It represents an ECC block of + LDC format.

In this figure, data is recorded or reproduced on the disc in a horizontal arrangement of ECC blocks, and one recording frame starts from a sync signal (SYNC).
It is composed of 6 bytes (1 row of 1 CC block), 1 physical 4K block is composed of 31 recording frames, and 1 ECC block is 16 physical 4K blocks (496
Recording frame).

Logical 2K blocks are arranged in the vertical direction in this figure, and SYNC represents a sync signal for specifying where in the ECC block a recording frame of one row is located at the time of reproduction as in the conventional DVD. Reed-Solomon code (RS [62,30,
33]), there are 24 BISs (Burst indicator subcodes) in 3 columns, and the Reed-Solomon code (RS [24
8,216,33]) which is LDC (Long-distance co
de) is 304 in 152 columns, excluding SYNC and BIS columns
If there is one, “Optical Disc System for Digital Video Re
cording ”.

It is also explained that the 24 BISs include addresses and copy management information, and the LDC includes 2048 bytes of user data and 4 bytes of EDC.

In this form of ECC block, as a method of error correction, BIS error correction is first performed in order to deal with a long burst error, and the result and SYN are corrected.
It is expected that the erasure correction, which specifies the position of the error included in the LDC, will be performed by the LDC from the detection state of C. However, regarding the arrangement of BIS and the arrangement of LDC, Opti
There is no description in "cal Disc System for Digital Video Recording".

The erasure correction will be briefly described here.

Normal LDC (RS [248,216,3
3]), since 32 parities are added, 32 syndromes obtained at the time of error correction (each syndrome has a binary equation when there is one error, a 32 equation when there are 16 errors, and a 32 equation when there are 32 errors). It is possible to obtain a maximum of 32 unknowns (positions and values of 16 errors) from a 64-element equation. That is, it is possible to correct up to 16 errors.

However, by designating 32 error positions separately from the syndrome, all the syndromes can be used for the calculation of the error value, so that a maximum of 32 errors can be corrected. .

Therefore, when a burst error occurs in which errors continuously occur due to scratches or dust on an optical disk, a servo signal, a demodulation situation, and a product code such as a CD or a DVD are PI.
Erasure correction for identifying the error position is performed based on information such as the correction status of the code (or PO code), and the maximum burst error correction length is doubled to the normal error correction using only the syndrome.

Therefore, in this ECC block structure, the LDC can carry out erasure correction, that is, by giving the error position from other information (SYNC, BIS), error correction of a maximum of 32 bytes is possible.

Next, referring to FIGS. 3 to 15, the ECC of FIG.
An example of a data transformation process until a block is formed is shown. FIG. 3 shows a data field (2 Kbyte data) formed by adding 4 bytes of EDC to 2 Kbytes of data and forming 54 lines in units of 38 bytes per line.

FIG. 4 shows that 32 Kbytes of data are converted in units of 2 Kbytes into the format of 2 Kbytes of FIG. 3 and numbered from 1 to 16 in order.
And 9 to 12 are arranged as shown in the figure, and each row has a 76-byte unit and 216 rows have a 16-Kbyte data field (16
K byte data (A)) is formed and the remaining 5 to 8 and 1
Similarly, 16-Kbyte data (B) is formed from 3 to 16 2-Kbyte data.

FIG. 5 shows a Reed-Solomon code (RS [248,2) by adding each byte (216 bytes) of the 16 K-byte data of FIG.
16, 33]). The Reed-Solomon code here is LDC, and the added parity is PLDC.
Express as.

FIG. 6 shows a data field generated by interleaving the PLDC section added in FIG. 5 into 8 rows of 4 rows each and inserting it into the 16 Kbyte data section in units of 27 rows. Moreover, since the original 2 Kbyte data consisted of 54 lines as shown in FIG. 3, 2
Inserting 4 lines in units of 7 lines can be interpreted as extending 2K byte data of 54 lines to 62 lines.

FIG. 7 is a 32K byte data + PLD formed by superposing 16K byte data (A) on the two 16K byte data shown in FIG. 4 modified into the shapes shown in FIGS. 5 and 6.
It is C.

FIG. 8 shows the two 32 Kbyte data of FIG. 7+
64Kbyte data created by arranging two PLDCs horizontally +
PLDC.

In FIG. 9, the 64 Kbyte data shown in FIG. 8 is divided into four by 38 columns, and B consisting of 62 bytes including an ID is provided between them.
This is a data field of 155 bytes × 496 rows formed by inserting a 496-byte data string formed by vertically stacking IS (RS [62, 30, 33]) in eight stages. BIS is 3
The code length of BIS is L because it is an error correction code that is made by adding 32 bytes of parity to 0 bytes of data.
It is 62 bytes, which is ¼ of DC. Therefore, even when the error correction processing using only the normal syndrome is performed, it is possible to perform the error correction for the error of 16 bytes out of 62 bytes.

FIG. 10 shows the 64 Kbyte data + PL of FIG.
It is a data field of 156 bytes × 496 rows formed by adding 1 byte of SYNC that specifies where in the ECC block to each row of 155 bytes of DC.
Note that this data field is referred to as an ECC block, and each row of 156 bytes is referred to as a recording frame. The ECC block thus formed has the same format as the ECC block shown in FIG.

Therefore, the ECC block of FIG. 10 is set to 1 physical 4K block in 31-row units as in the case of FIG. 2, and the direction of physical data is set to the horizontal direction of this ECC block. In other words, the data recorded on the recording medium is one ECC block.
Each row is composed of 156-byte rows.

In the ECC block of FIG. 10, the data field (logical 2K block) obtained by adding PLDC to the 2K byte data of FIG. 3 is arranged as shown in FIG. That is, eight logical 2K blocks are arranged consecutively in the vertical direction of the ECC block in FIG.
It is arranged so that four blocks are arranged side by side.
A BIS is vertically inserted between each logical 2K block, and the vertical direction coincides with a break in a physical 4K block. Especially the vertical center, that is, the logical 2K block 4
And 5, 12 and 13, 20 and 21, 28 and 29 are LD
It is a break in C.

However, this is an example of an ECC block composed of BIS + LDC created by the procedure of FIGS. 3 to 10.
For example, suppose the 2 Kbyte data in FIG. 3 is 76 bytes x 2
There are 7 rows, and as shown in FIG. 12, 8 pieces of 2K byte data are overlapped to form 16K byte data (A) and 16 pieces corresponding to FIG.
By creating K-byte data (B) and then similarly converting the data, an ECC block of the same format as that of FIG. 2 is obtained, although the layout of logical 2 K-bytes is different as shown in FIG.

Further, 16 Kbyte data (A) in FIG.
4B is vertically stacked while arranging (B) 2K bytes of data 2 at the position of 2, 2 at the position of 3, 2 at the position of 5, and 9 at the position of 13 and 10 at the position of 13 By adopting such a configuration, it is possible to create an ECC block having a logical 2 Kbyte arrangement as shown in FIG. 14, and 2 Kbytes between two sets (total 4 types) of 16 Kbyte data combined in FIG. Figure 1 by changing the arrangement of data
It is also possible to take a logical 2K block arrangement such as 5.

Further, an example in which different logical 2K blocks are arranged in the same ECC block will be shown with reference to FIGS. 21 to 24.

FIG. 21A shows a data string in which 4-byte EDC is added to 2048-byte 2K-byte data. In FIG. 21B, the 2052 bytes of FIG.
It is a data field of 9.5 lines that can be folded back with 16 bytes. However, this FIG.
21A is combined and 19 E data fields of 9.5 rows × 2 in which two EDCs are arranged at the center and the end of the data field are treated as one set as shown in FIG. 21B.

FIG. 22 shows 216 bytes × 7 formed by arranging four data fields arranged in the format of FIG.
The 16-Kbyte data (B) is the same as the 16-Kbyte data (A) in six columns.

This 16 Kbyte data is the one shown in FIG.
The arrangement of 6 Kbyte data and 2 Kbyte data is different, but the format of the data field (the number of vertical and horizontal data) is the same.

The 16-Kbyte data is subjected to the data conversion of FIGS. 5 to 10 described above. Then, the arrangement of logical 2K blocks in the ECC block is as shown in FIG. Further, by changing the combination of the 16 Kbyte data (A) and (B) in FIG. 22, the logical 2 is shown in the upper stage as shown in FIG.
It is also possible to arrange K blocks 1 to 16 in the lower row and to arrange 17 to 32.

The ECC block used in the explanation again is shown in FIG.
It is assumed to be the same as that of FIG. 11 and FIG. 2 produced by the procedure of FIG.

FIG. 16 is for defining the terms used in the following description. As described with reference to FIG. 10, the BIS is sandwiched between four logical 2K blocks as shown in FIG. 17, and these three BISs are N-1, N-, respectively.
2, N-3 (N = 1, ..., 8). The relationship between the four logical 2K blocks and the physical 4K blocks is "4 × logical 2K block" = "2 × physical 4K" as shown in FIG.
It is a "block" and sandwiches this same BIS 2
BIS N (a) above one physical 4K block, B below
IS N (b). Also, 3 for each physical 4K block
It consists of one row (recording frame), and interleaving is performed in row unit (recording frame unit) at the time of data recording and reproduction.

Further, FIG. 17 shows the logic 2K shown in FIG.
It shows another configuration example of the block.

BIS N (a) and (b) on FIG.
S0 on the SYNC in the first line of the above represents a SYNC code indicating a break (different from the other 30 lines) of one physical 4K block, and I0, I on BIS N-1, N-2, N-3.
1 and I2 are 3-byte identification signals (IDs) or IDs dedicated to IDs used to check that there are no errors in the IDs during playback
It represents E (ID Error Detecton Code). Here, four logical 2K blocks consecutive in the horizontal direction within the ECC block (logical 2K blocks 1, 9, 17, 2 in FIG.
5 relationship), the same ID is commonly used.

In FIG. 1, the IDs are generated at equal intervals (31-row units) while keeping the burst correction length of the data in which the IDs are arranged in the first row of the physical 4K block as shown in FIG. Represents the interleaving rule for each line.

In this figure, 1 to 16 assigned to the start position of the arrow are numerical values representing the reading order, and the reading order of 496 recording frames at the time of recording is determined by this numerical value. The recording frame selected in the physical 4K block is the number of rows of the recording frame in the physical 4K block selected immediately before plus one. However, since one physical 4K block consists of 31 rows of recording frames, 1 is set after 31. The order of interleaved recording sectors when this rule is specifically applied will be described below. 1: BIS1 (a) first line (ID), 2: BIS5 (a) second line, 3: BIS2 (a) third line, 4: BIS6 (a) fourth line, 5: BIS3 (a) 5 Line 6, 6: BIS7 (a) line 6, 7: BIS4 (a) line 7, 8: BIS8 (a) line 8, 9: BIS1 (b) line 9, 10: BIS5 (b) 10 Line 11, 11: BIS2 (b) line 11, 12: BIS6 (b) line 12, 13: BIS3 (b) line 13, 14: BIS7 (b) line 14, 15: BIS4 (b) 15 Line 16, 16: BIS8 (b) line 16, 17: BIS1 (a) line 17, 18: BIS5 (a) line 18, 19: BIS2 (a) line 19, 20: BIS6 (a) 20 Line 21, 21: BIS3 (a) line 21, ..., 30: BIS7 (b) line 30, 31: BIS4 b) 31st line, 32: BIS8 (b) 1st line (ID), 33: BIS1 (a) 2nd line, 34: BIS5 (a) 3rd line, ..., 61: BIS3 (b) 30th line , 62: BIS7 (b) 31st line, 63: BIS4 (b) 1st line (ID), 64: BIS8 (b) 2nd line, 65: BIS1 (a) 3rd line, ..., 94: BIS7 ( b) 1st line (ID), ..., 125: BIS3 (b) 1st line (ID), ..., 156: BIS6 (b) 1st line (ID), ..., 187: BIS2 (b) 1st line 218: BIS5 (b) first line (ID), 249: BIS1 (b) first line (ID), 280: BIS8 (a) first line (ID), ... , 311: BIS4 (a) first line (ID), ..., 342: BIS7 (a) first line (ID), ..., 37 : BIS3 (a) 1st line (ID), ..., 404: BIS6 (a) 1st line (ID), ..., 435: BIS2 (a) 1st line (ID), ..., 466: BIS5 (a) First line (ID), ..., 495: BIS4 (b), 30th line, 496: BIS8 (b), 31st line In addition, as another example, interleaving is applied as shown in FIG. In this case, the ID that appears in 31-line units
Is BIS1 (a), BIS5 (a), BIS2 (a),
BIS6 (a), BIS3 (a), ..., BIS16
Since it is (b), the ID that appears compared to the example shown in FIG.
There is an advantage that it is easy to find the regularity.

Next, it is shown that these interleave rules maximize the burst error correction length in this system. In computer applications, since the reliability of data is important, we show the case where data errors are considered to the maximum extent. As described with reference to FIG. 2, the LDC performs erasure correction to
It is possible to correct up to two (byte) errors. Therefore, considering that this ECC block is configured by stacking two stages of LDCs perpendicularly to the recording direction as shown in FIG. 7, it is possible to correct a burst error of up to 64 rows on the ECC block. It is possible.

However, in order to always be able to correct the burst error from the 32nd row to the 63rd row, the EC shown in FIG.
When the recording frames of the C block are continuously recorded from the top, burst errors of more than 33 lines may be fixed in one LDC, so that two LDCs may be recorded.
It is necessary to select recording frames alternately between ((A) and (B)).

However, it is difficult to specify the position of an error which is a condition for performing erasure correction only by selecting an alternate recording frame from two LDCs, and therefore it is not sufficient as a condition for maximizing the burst error correction length. is there. This is an E consisting of BIS + LDC as described above.
This is because the error position used for LDC erasure correction in the CC block is obtained from the BIS result. Therefore, since 16 errors can be detected from one BIS, LDC interleaving is performed between two BISs, for example,
When BIS1 (a) and BIS5 (a) are continuously performed, burst errors exceeding 33 lines are distributed only to two BISs and two LDCs, and one BIS and one LDC have one burst error.
Since the error of 7 lines is included, the BIS becomes uncorrectable, and as a result, the LDC is also unable to correct the error.

Therefore, one LDC has two or more BIs.
It is necessary to add a condition that frames are sequentially selected for recording between Ss. From the above, the condition for maximizing the burst error correction length is to select recording frames alternately between four or more BISs and two LDCs. Therefore, it is understood that the interleaving rule of the recording frame described with reference to FIGS. 1 and 19 is an example satisfying this condition, and it is possible to create other similar rules.

FIG. 20 shows the number of bytes of the ID of FIG. 16 changed. Although ID and IDE are set to 3 bytes in FIG. 16, FIG. 20 is an example in which this is expanded to 6 bytes. In this case, considering the interleaving rules of FIGS. 1 and 19, I
The lower information of the ID that changes into a 4 Kbyte block is placed in 0, I1, and I2, and the upper information of the ID that does not change in the same ECC block is placed in I3, I4, and I5.

For example, the 6-byte ID part is composed of 6 bytes, the ID is 4 bytes and the IDE is 2 bytes. The 4-byte ID is 0x00030,000 in units of physical 4K blocks.
When incrementing from 1 by 1, the same ID
The IDs from 0x0003000 to 0x0003000F are included in this.

At this time, the 2-byte EDC is set to I0 and I1 as I2, and the lowermost 1 byte of ID is set to I3, I4 and I5, and the upper 3 bytes of ID are set to 0x00, 0x03 and 0x00, respectively, and I3, I4 and I5 are set to I3, I4 and I5, respectively. Since the same value is set in the ECC block, the next value is always read after the first row including the ID (I0, I1, I2) of the physical 4K block, which is a recording frame, is read as described in FIG. Since the second row of the physical 4K block is read, the 6-byte ID is input at a fixed interval of 39 bytes after detecting SYNC indicating the beginning of the physical 4K block, and the same condition as when the ID part is 3 bytes ( A 6-byte ID is input according to the positional relationship between the ID associated with the 4K block and the data.

[0052]

As described above, by recording data on a medium using the ID arrangement and interleaving as described above, the identification signal (ID) is arranged at equal intervals like the CD, DVD, etc., and the BIS + LDC configuration is provided. It is possible to secure the maximum burst error correction length of the ECC block taking

[Brief description of drawings]

FIG. 1 is a diagram showing an interleave order performed when recording an ECC block formed from BIS + LDC.

FIG. 2 is an ECC block formed from BIS + LDC.

FIG. 3 is a data field composed of 2 Kbytes of data.

FIG. 4 Two data fields consisting of 16 Kbyte data

FIG. 5: Data field consisting of 16 Kbyte data + PLDC

[FIG. 6] Interleaved “16 Kbyte data +
PLDC ”data field

FIG. 7: Data field consisting of 32 Kbyte data + PLDC

FIG. 8: Data field consisting of 64 Kbyte data + PLDC

FIG. 9: 64-Kbyte data + P with 3 columns of BIS added
Data field consisting of LDC

FIG. 10: 4K bytes data + PLD with SYNC added
Data field consisting of C + BIS (ECC block)

FIG. 11 is a diagram showing a relationship between a logical 2K block and an ECC block.

FIG. 12: Two data fields (2) consisting of 16 Kbyte data

FIG. 13 is a diagram (2) showing a relationship between a logical 2K block and an ECC block.

FIG. 14 is a diagram (3) showing the relationship between a logical 2K block and an ECC block.

FIG. 15 is a diagram showing a relationship between a logical 2K block and an ECC block (4).

FIG. 16 is a diagram showing an arrangement of two physical 4K blocks including the same BIS and an ID.

FIG. 17 is a diagram showing a relationship between two physical 4K blocks including the same BIS as a logical 2K block.

FIG. 18 is a diagram showing another configuration of a logical 2K block.

FIG. 19 is a diagram (2) showing an interleaving order performed at the time of recording an ECC block formed from BIS + LDC.

FIG. 20 is a diagram showing an arrangement of two physical 4K blocks including the same BIS and an ID (2).

FIG. 21 is a data field (2) composed of 2 Kbyte data.

FIG. 22: Two data fields (3) consisting of 16 Kbyte data

FIG. 23 is a diagram (5) showing the relationship between a logical 2K block and an ECC block.

FIG. 24 is a diagram (6) showing the relationship between a logical 2K block and an ECC block.

[Explanation of symbols]

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) H04N 5/85 H04N 5/85 Z 5/91 5/91 P 5/92 5/92 H (72) Invention Osamu Kawamae 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa F-Term (Reference), Hitachi, Ltd. Digital Media Development Division 5C052 AA01 AB02 DD04 5C053 FA15 FA23 GB06 GB14 GB15 JA21 5D044 BC02 CC04 DE02 DE37 DE53 DE68 EF05

Claims (12)

[Claims] 1. A digital data recording method for recording digital data, each of which can have a different length, wherein the digital data has an identification code, and the identification code is arranged at regular intervals. A digital data recording method characterized by rearranging digital data. 2. A digital data recording method, wherein in a plurality of data strings including a data string having an identification signal, the data strings are rearranged so that the identification signals have a constant interval. 3. A plurality of data blocks composed of a plurality of data strings including a data string having an identification signal, the data strings being taken out while changing the data blocks for taking out the data strings so that the identification signals are at regular intervals. A digital data recording method characterized by rearranging. 4. In a plurality of data blocks formed by superposing a plurality of data strings including a data string having an identification signal, the data blocks for extracting the data strings are changed so that the identification signals have a constant interval, and A method for recording digital data, characterized in that the retrieved data sequence is rearranged while changing the row number of the data sequence retrieved from the data block. 5. A plurality of data blocks including a plurality of data strings including a data string having an identification signal, wherein the data blocks are taken out so that the identification signals are at regular intervals. A method for recording digital data, characterized in that the retrieved data sequence is rearranged while being changed to. 6. A plurality of data blocks consisting of a plurality of data strings including a data string having an identification signal, wherein the data block is taken out every time one data string is taken out so that the identification signal has a constant interval. The digital data recording method is characterized in that the extracted data strings are rearranged while changing the row number of the data strings extracted from the data block each time one data string is extracted. 7. In 16 data blocks consisting of 31 data strings including a data string having an identification signal, said data block extracting a data string each time one data string is taken out so that said identification signal has a constant interval. , 16, 16, 2, and so on, and each time one data string is taken out, the row numbers of the data strings taken out from the data block are 1, 2, 3 ,. Three
A method for recording digital data, characterized in that the retrieved data sequence is rearranged while changing the sequence of 1, 1, 2, .... 8. The digital data recording method according to claim 7, wherein the identification signal is 2 columns out of 31 data columns, and all the identification signal parts having a difference in 16 data blocks are in the Nth row (N = 1, 2, ..., 30), and the identification signal having no difference in 16 data blocks is arranged in the (N + 1) th row. 9. A plurality of data blocks formed by stacking a plurality of data strings including a data string having an identification signal, wherein the plurality of data blocks are error correction coded in a direction in which the data strings are stacked. The digital data recording method is characterized in that the data strings are rearranged while changing the data blocks for extracting the data strings so that the identification signals have a constant interval. 10. A plurality of second data blocks formed by overlapping a plurality of first data blocks formed by overlapping a plurality of data strings including a data string having an identification signal, wherein the plurality of first data blocks are formed. Error-correction-encoding is performed in the direction in which the data strings are overlapped in some of the data strings overlapped in the unit of the data block, and the plurality of first data blocks are included in the unit of the plurality of second data blocks. The second data block is error-correction coded in a sequence other than the error-correction-coded sequence in the unit of data block, and the second data block is taken out so that the identification signal has a constant interval. A method for recording digital data, characterized in that the data sequence is rearranged while changing each time it is taken out. 11. The digital data recording method according to claim 10, wherein the first data block from which the data string is extracted is 4 bytes.
A method for recording digital data, characterized in that the data strings are rearranged while changing them all differently in the work of extracting the data strings one time. 12. The digital data recording method according to claim 11, wherein each time one data string is taken out, data taken out while changing a row number in the first data block of the data string taken out from the first data block. A method for recording digital data, characterized in that columns are rearranged.