RU2351025C1 - Method of recording/playing streams of coded groups to/from optical medium with protection of medium from defects - Google Patents

Abstract

FIELD: physics, computer engineering.

SUBSTANCE: invention relates to the field of digital recording/playing data streams to/from optical devices and can be used in measuring, computer and multimedia systems for recording and storing data. Method is based on partitioning of the input stream of coded groups in blocks and groups of blocks with numbers of coded groups in blocks and blocks in block groups, are installed taking into account the dimensioning specifications of the medium, adding each block to a working address coded group and each group block a pair of correcting blocks, recording the stream of group blocks onto the medium and test reading them immediately after recording, saving in a sliding regime of a fixed number of initial group blocks and comparing each group block read with the corresponding initial one, forming and allocating addresses to a faulty group block and its defective group block in working coded groups of the next recorded group block and putting it in two blocks on the spread positions of the initial blocks, corresponding to the defective block.

EFFECT: provides continuity of recording/playing of streams of coded groups with protection of the medium from damage, allows for an increase in the reliability of recording and storing of data.

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Description

The invention relates to the field of digital recording / playback of data streams to / from optical media with data protection from media defects and can be used in measuring, computer and multimedia data recording and storage systems.

A known method of recording code group streams on an optical medium with protection against media defects, including detecting defects in the process of recording code group streams on a given part of the medium and recording code groups corresponding to defects on other parts of the medium (US Pat. RF 2001110087, G11В 11/00 , 2003).

The disadvantages of this method are: violation of the continuity of recording data streams on a given section of the medium due to the need to record pieces of data that fall on the defective places of the medium on its other sections; the need to protect data from defects in the reservation of two different areas on the medium - one for normal recording, and the other for a replacement record in case of defects, as well as in recording and storing on the medium special address tables of substitute and replaced sections of the medium with the risk of table distortions ; the inability to protect data from defects arising from subsequent reproductions of recorded data.

There is also a known method of recording / reproducing code group streams to / from an optical medium with protection against media defects, including detecting defects in the process of recording code group streams on a given section of the medium and recording code groups corresponding to defects to other places on the medium, as well as replacing the process of reproducing streams of code groups from the carrier of code groups from defective places by code groups read from the corresponding other places of the carrier (US Pat. RF 2192673, CL G11B 20/18, 2002).

This method also has significant disadvantages. Firstly, when it is used, the continuity of recording codestream streams on a given section of the medium is violated, since the stream fragments corresponding to the defective sections are overwritten in specially allocated areas of the medium. Secondly, data is protected from defects in the method using a complex defect management system, which includes operations to create a list of primary defects (SPD) with their addresses - according to the results of media initialization and allocation of a backup media area for replacing defective block records in accordance with SPD , the formation of a list of secondary defects (SVD) with their addresses that occur during the recording of data on the medium, the allocation of a spare area for the rolling replacement of defective blocks during continuous recording of flows is given ny and selection on the media of a special area of defect management. Thirdly, the rigid orientation of the method to the recording format of the type of digital universal disk requires for any defect, regardless of its actual size, the replacement of the whole ECC block (16 sectors of 2 kilobytes each), which leads to large sizes of backup and spare areas of the media for replacement of all primary and secondary defects. Fourthly, the method does not provide protection against secondary defects in areas of the carrier with primary defects. Fifthly, the method does not provide data protection during the subsequent playback of recorded data from emerging tertiary defects.

Of the known methods for recording / reproducing code group streams onto / from an optical medium with protection against media defects, the closest to the proposed method is the method of recording / reproducing code group streams onto / from an optical medium with media defects protection, including detection of defects during recording stream of code groups to a given section of the medium and recording code groups corresponding to defects to other places on the medium, as well as replacing code groups from eating code groups from defective places with code groups read from the corresponding other places on the medium (US Pat. RF 2001117205, CL G11B 20/18, 2003).

However, this method also has a number of significant disadvantages. Firstly, when it is used, the continuity of recording codestream streams on a given section of the medium is also violated. Secondly, the protection of code group streams from primary and secondary defects in the method is also carried out using a complex defect management system, including the operations of allocating on the media a special area for defect control, designed to replace defective areas with replacement areas, and a special general purpose area for storage application drivers with which defects are monitored, and a primary and / or secondary defect table with addresses of defective and corresponding replacement areas, and a computer configured to implement defect inspection operations using defect tables. Thirdly, the method does not provide protection for the streams of code groups recorded on the medium, as well as for the data of the defect management system against tertiary defects that inevitably arise during subsequent reproductions of recorded information.

An object of the invention is the provision of continuous recording / playback of information flows of code groups on / from predetermined sections of optical media with information protection from media defects of all kinds, including primary, detected during media initialization, secondary, detected during recording of information on the medium, and tertiary, arising from subsequent reproductions of recorded information, in a simpler way that does not require the use of the so-called defect management system, warped on the allocation on the media and the organization of special areas of complex scheduling addresses and pieces replacement and the replacement data in the process of writing data, as well as during playback.

The technical result of the invention is the provision of continuous recording / reproduction of information flows of code groups to / from predetermined portions of a medium with protection from defects of all types and in a simpler way, increasing the reliability of recording and storage of information, extending the retention period of recorded information without losing the quality of its reproduction and service life carriers.

The technical result is achieved by the fact that in the method of recording / reproducing code group streams to / from an optical medium with protection against carrier defects, including detecting defects in the process of recording a code group stream to a given portion of the medium and recording code groups corresponding to defects to other places on the medium and also substitution during the reproduction of streams of code groups from the carrier of code groups from defective places with code groups read from corresponding other places of the carrier, according to the invention divide the code groups before recording them onto the medium in blocks and groups of blocks in accordance with the numbers of code groups in the block and blocks in the group set taking into account the dimensional characteristics of media defects, supplement each block with a service code group with a set value and form a pair in each block group corrective blocks of control code groups for odd and even blocks, respectively, write the extended groups of the supplemented blocks of code groups to the media and their control reading directly o after recording, keeping in a sliding mode the set number of initial supplemented groups of supplemented blocks and comparing each read group of blocks with the corresponding saved original group of blocks, if in the next read group of blocks of code groups defect-resistant defective blocks form values for each of them address code groups with addresses of the defective block group relative to the next recordable group of blocks and the corresponding defective block in the defective block group, p they place address code groups in the service code groups of the blocks of the next block group recorded on the media and replace its two blocks at established spaced positions with the original block corresponding to the defective block; during playback of the code group streams from the carrier, their delivery is delayed by buffering in the sliding mode the set number of read groups of blocks of code groups, they control defective blocks in each read group of blocks and, if a block is detected in the next read group code groups of one or two defective blocks restore each of them using the remaining blocks of the defective group, and if more than two defective blocks are found in the next read block group, they first recover some of the defective blocks by replacing each of them with the original block from established spaced positions of a delayed group of blocks with alternating values of service code groups different from the set values and corresponding to addresses of the defective group and the defective block in it, after which each of the two defective blocks of the defective group is restored using the blocks reconstructed by reverse substitutions and the rest of the blocks associated with it, as well as each of the two replaced blocks at the established positions of the corresponding delayed group of blocks using the rest associated with him her blocks.

Figure 1 presents a structural diagram of a variant of the device for implementing the method, figure 2 presents time diagrams explaining the essence of the method.

The device for implementing the method comprises (Fig. 1) a code group (KG) dispenser 1 for blocks (B) and blocks for code group blocks (GB) groups, a block 2 for generating corrective blocks (KB) of code groups and an addition of KG blocks to service KGs and groups of blocks with correction blocks, block 3 substitutions, block 4 records, block 5 for recording / reproducing flows of KG, block 6 for reading and decrypting, block 7 for defect control and substitution control, buffer memory 8, block 9 for reverse substitutions, block 10 correction of defective bl Cove (DB) 11 and generator CG of the output stream.

The distributor 1 is connected by an information input (1i) to the input of the device, the first (1us) and second (2us) installation inputs to the buses “m _KG ” and “m _B ”, respectively, and the output to the first information input (1i) of the unit 2, connected by the first (1us) and second (2us) installation inputs to the buses “m _KG ” and “m _B ”, respectively, and an output to the first information inputs (1i) of the BZU 8 and block 3 connected to the second (2i) and third (3i) information inputs to the second output (2) of unit 7 and to the first (1) output of the BZU 8, the second control input (2 unit) to the first output (1) of unit 7, and an output to the information input (1i) of the recording unit 4 connected to the “On media” bus.

The reading and decoding unit 6 with the information input (1i) is connected to the “From the carrier” bus, and the output is connected to the first information input (1i) of the unit 7 and to the second information input (2i) of the BZU 8 connected to the third (3Up), fourth (4Un) ) and fifth (5Up) control inputs to the first (1), second (2) and third (3) outputs of block 7, respectively, sixth control input (6Up) to the first output of block 9, second output (2) to the second information input ( 2i) of block 7, the third (3) output to the first (1i) information input of block 10, and the fourth output to the second information input 9, connected by the first information input (1i) to the fourth output (4) of block 7, the second control input (2Up) to the third (3) output of block 7, and the second output to the third information input (1i) of the BZU 8. Block 10 connected by an output to the information input (1i) of the shaper 11, the output associated with the output bus "Output" of the device.

The recording / playback control unit 5 is connected by the first (1 unit) and second (2 unit) control inputs to the “Record” and “Play” buses, respectively, the first (1 unit) and second (2 unit) installation inputs to the installation buses “m _KG ” and “m _B ”, respectively, the first output (1) to the first control inputs (1 unit) of the distributor 1, blocks 2, 3, 4, 7 and BZU 8, and the second output (2) to the first control inputs (1 unit) of blocks 6, 9, 10 and shaper 11 and to the second control inputs (2Up) of block 7 and BZU 8.

Figure 2 shows: a) an example of a fragment of the input stream of the CG distributed over blocks and groups of blocks, where each CG (usually of eight bits - bytes) is conventionally represented by a vertical bar, each source block from the set number m of _CG code groups is marked with a curly a bracket below and each group of blocks from a fixed number m _B blocks is indicated by arrows; b) - an example of a fragment of a sequence of groups of blocks GB ₁ , GB ₂ , ... GB ₇ recorded on a medium, in which each GB is supplemented by a pair of correction blocks KB ₁ (for odd positions B) and KB ₂ (for even positions B) and each B is supplemented service KG, conventionally represented by a vertical rectangle, while the unshaded rectangle indicates the initial value of the service KG, and the darkened one indicates the address of the defective GB or defective B in it; in GB _{3, a} hatch conditionally marked a defect with a conditionally accepted established maximum length equal to the duration of 4 blocks (in example B _3.1- B _3.4 ); in GB _{5, the} dimming of the rectangles marks an entry in its service code groups A (GB ₃ ) - address KG of defective GB ₃ and A (B _3,3 ) - address KG of defect-free defective block B _3,3 , for example, A ( GB ₃ ) is written for reliability in all blocks at odd positions, and A (B _3,3 ) - also for reliability in all blocks at even positions, with the arrow arrows with the inscription "Replacing the original block B _3,3 " the replacement of two blocks at established and for reliability spaced positions, namely B _5.1 at the first (odd) and B _5.4 at solid (even) positions, the original block corresponding to the defective B _3.3 ; in GB ₆ also the dimming of the rectangles - images of the service KG shows the record of the address KG - A (GB ₃ ) and A (B _3,4 ) in them and also with their alternation, and with directional arrows with the inscription "Replacing the original block B _3,4 " from the bottom, conventionally shown is the replacement of two blocks at established spaced positions — B _6.1 and B _{6.4 by the} original of the defective block B _3.4 ; c) - a fragment of GB _3- GB ₆ reproduced previously recorded sequence, where in GB ₃ oblique hatching conventionally shows the same media defect as in figure 2, b; in GB ₅ curly brackets above the blocks at the first and fourth installed positions and the line connecting them with the inscription “Reverse replacement B _3.3 ” and the arrow at the end conditionally indicate the operation of reverse replacement of the defective block B _{3.3 with} its original value, and in GB ₆ in a similar manner, the reverse substitution operation of the defective block B _{3,4 is} shown; g) - a fragment of the generated stream of reproduced KG, identical to the original stream of KG of the form of figure 2, a.

A method for recording / reproducing code group streams onto / from an optical medium with protection against media defects includes operations that implement special modes for recording code group streams on a medium and reproducing them from a medium, and is carried out as follows.

In the recording mode of the code group streams onto the medium, according to the “Record” signal supplied to the first control input of block 5, and according to the corresponding control pulses from its first output in the distributor 1, the KG stream is sequentially divided into blocks of m _KG code groups and groups of m _B KG blocks. The values of m _KG and m _B are set taking into account the dimensional characteristics of the flows of defects of all three types: primary D ₁ detected during initialization and formatting of the medium and being the longest, secondary D ₂ arising during the working recording of data, and tertiary D ₃ arising in the process of working playback of recorded data and being the shortest of all defects. Dimensional characteristics, such as the extent of defects of each type and their intervals, are determined during the testing of carriers and corresponding devices of specific types. In particular, the value of m _{KG is} set so that the length of the print recorded on the media block KG was not less than the set maximum value D _{3, MAX the} length of tertiary defects. In this case, each tertiary defect with less than D _{3, MAX} duration can distort no more than two adjacent blocks in GB, restored using its two corrective and other defect-free blocks. The minimum allowable value of m _B in GB with a set value of m _KG is determined by the formula: m _{B, MIN} ≤n (D _{1, MAX} ) / (m _KG +1) +2, where n (D _{1, MAX} ) is the number of prints recorded KG (whole and rounded up) that fit on the primary defect with the maximum length D ₁ taken _{, MAX} , (m _KG +1) - the number of KG in the block, increased by 1 taking into account the introduction of official KG, +2 - increase in the number blocks in GB due to the introduction of two correction blocks. When choosing a working value of m _B, it is also necessary to take into account the maximum allowable amount of information redundancy introduced in GB.

From the output of the distributor 1, the distributed KG flow of the form of FIG. 2, is fed to block 2, with the help of which each GB is formed and supplemented with two correction blocks KB ₁ and KB _{2 of the} control KG obtained, for example, by group addition modulo a given number, for example, the modulus of the highest value of KG, the values of all the first, all second, etc. code groups of GB blocks, and also supplement each GB block with a service KG with a set initial value, for example, zero (in Fig. 2, b are shown as unshaded rectangles at the beginning of each block). From the output of block 2, the distributed and augmented KG stream of the form of FIG. 2, b is fed to the block 3 of substitutions, from the output of which the KG of the blocks of each GB are transferred to block 4, with the help of which they are recorded on the medium, as well as in the 8 memory for temporary storage the sliding mode of the set number of source, until they are recorded on the media, supplemented groups of supplemented blocks. Moreover, the number of such source GBs is set not less than the sum of one actually defective GB, the maximum number of GBs with substitutions, and an integer number of GBs corresponding to the time interval Δt _З. GB read read delays relative to their write. In the example, the minimum number of such GBs in the ROM 8 when the conditionally accepted value Δt _З. is equal to the duration of one GB (namely GB ₄ in figure 2), and with two GBs with substitutions, is four. The working value of the number of temporarily stored source GBs is set somewhat larger (for example, five GB), taking into account the unlikely, but possible occurrence during the recording of the KG stream, a defect with a greater length than that accepted for the maximum, which ensures the protection of information from such a defect.

Read from the media with a delay of Δt _З. relative to the record, and the decrypted GBs in the form shown in FIG. 2, b, from the output of block 6 are fed to the first information input of block 7, the second information input of which from the second output of the BZU 8 is supplied with the same delay by the corresponding source GBs, each block is compared read GB with the corresponding source GB, by comparison, install defective blocks, determine the number of non-correctable DBs and their numbers in the defective GB and form address KG - A (GB) and A (DB). So, in the example, during the control reading of GB ₃ , the defective blocks B _3,1- B _3,4 (indicated by hatching in Fig. 2, b) are identified in this way and the address code group A (GB ₃ ) of the defective GB _{3 is formed} with the address relative to the next recorded GB ₃ , for example, in the form of code 00000010, and the address of the defective blocks KG - A (B _3.3 ), for example, in the form of code 00000011, and A (B _3.4 ), for example, in the form of code 00000100. If the number DB in GB is more than two (in the example, 2 blocks), then from the first output of block 7, a substitution signal is supplied to the second control input of block 3 and the fourth control input of the BZU 8, s about the second output of block 7 to the second information input of block 3 and the third control input of the BZU 8 serves address KG, the values of which from the BZU 8 from the first output to the third information input of the block 3 serves the original GB ₆ corresponding to the defective, and in block 3 place address CGs in the service CGs (in FIGS. 2, b and 2, marked with blackout) of all blocks of the next recordable GB ₅ and replace its two blocks at the established spaced positions B _5.1 and B _{5.4 with the} original block corresponding to the first of the replaced defective blocks B _3.3 , and then carry out illogical operations in block 3 to replace in the next recordable GB ₆ its two blocks B _6.1 and B _6.4 at established spaced positions by the original block B _3.4 corresponding to the second defective block, etc. Substitution operations in GB ₅ and GB ₆ are marked on the second line of FIG. 2, b with arrows and corresponding inscriptions under the replaced blocks.

In the playback mode from the carrier of the KG stream recorded in the above manner by the “Playback” signal supplied to the second control input of the control unit 5, and by the corresponding control signals from its second output, the GB stream read and decoded in block 6 is of the form of FIG. 2, c the output goes to the second information input of the BZU 8 for temporary storage in the sliding mode of the set number (in the example of five) of read GB and with a corresponding delay comes from the third output of the BZU 8 to the first information input of block 1 0 correction of defective blocks. At the same time, the read GB stream is fed from the output of block 6 to the first information input of block 7, with which the DB is monitored in each read GB, and if one or two DBs that occur at the defect are found in the next read GB, a DB address code is generated and place it in the service CGs of all defect-free GB blocks - if the GB has one DB, or the address code of one DB is placed in the service CGs, for example, all odd Bs and KBs, and the address code of the second DB in the service CGs of all even Bs and KBs if GB two db. They provide a GB, supplemented with DB addresses, from the fourth output of block 7 to the first information input of block 9, from the first output of which they feed to the sixth control input of the BZU 8 the current address of the same GB, but with the original values of the service KG, and from the second output to the third information input BZU 8 - supplemented by GB addresses and write it instead of GB with the original values of service KG.

In case of detection in block 7 in a read next GB (in the example of GB ₃ in FIG. 2, c) more than two DBs (in FIG. 2, in blocks B _3,1- B _3,4 marked with hatching) the first two of all DB (in example B _3.1 and B _3.2 ) under the terms of the record are not subject to replacement, and the remaining DBs (in example B _3.3 and B _3.4 ) are to be restored by subsequent reverse substitutions with their original values, located in read from the GB media (in example B _3.3 in GB ₅ and B _3.4 in GB ₆ ). In block 7 is formed address codes nonreplaced DB - A (D _3.1, and A (B _3.2) are placed in ₃ GB code A (D _3.1) to service all odd CG defectless B and CB _1, and the code A (B _3.2 ) in the service KG of all even B and KB ₂ and serves supplemented with address codes GB ₃ from the fourth output of block 7 to the first information input of block 9, in which the current address of the source GB _{3 is formed} in the BZU 8 and serves it from the first entering the sixth control input BLT 8, which is supplied simultaneously with the second unit 9 outputs the third data input BLT 8 supplemented with ₃ GB addressable codes which of the respective control pulses from unit 5 is recorded in the BSC instead of the original 8 GB _3. Upon detection unit 7 in a subsequent read GB (GB in Example ₅ in FIG.2) of the two alternating values of service CG different from the set values, that is a sign of the presence in the GB of two substituted blocks at established spaced positions (in Example B _5.1 and B _5.2 ), a reverse substitution enable signal is generated and fed from the third output of block 7 to the second control input 9 and the fifth control input of the BZU 8 and simultaneously transmit from the fourth output of unit 7 to the first information read out unit 9 GB input _5. In block 9: by the reverse substitution enable signal, address codes A (GB ₃ ) and A (B _3,3 ) are selected from the service GB ₅ ; they are fed from the first output to the sixth input of the BZU 8 and the source GB ₃ is read from the fourth output of the BZU 8 to the second information input of block 9; from the read GB ₅ received from block 7, one of two blocks with the same values at the set diversity positions is selected, i.e. B _5.1 or B _5.4 and carry out the reverse replacement of the defective block B _3.3 in the original GB ₃ and place the address code of the first unsubstituted defective block in it in the service KG of all its odd blocks, i.e. code A (B _3.1 ), after which the augmented GB _{3 is} fed from the second output of block 9 to the third input of the BZU 8 and recorded instead of the original GB ₃ ; for reliable marking of blocks B _5.1 and B _5.2 distorted by substitution in GB _5, they generate codes of their addresses A (B _5.1 and A (B _5.4 ) and place the first in the service KG of all odd B, and the second in the service KG of all even B GB ₅ , after which the changed GB _{5 is} fed from the second output of block 9 to the third input of the BZU 8, the sixth control input of which from the first output serves the current address of GB ₅ , and the address ₅ , supplemented by the address codes of distorted blocks of GB ₅ , is recorded in the BZU 8 instead of the original read GB ₅ .

Similarly, all the above steps are repeated regarding the next read block group GB _6, in the first and fourth B _6.1 B _6.4 which installed unit is placed original block B _3.4, which is substituted in the ₃ GB second displaceable defective block B _{3, 4} , after which GB ₃ , including two defective blocks B _3.1 and B _3.4 , two restored by reverse substitutions blocks B _3.3 and B _3.4 and the remaining defect-free B and KB, are overwritten in BZU 8.

Each GB read from the media in the original or supplemented form in blocks 7 and 9 is delayed by the time it takes to read and temporarily store in GB 8 the set number (in the example of five) GB from the third output of GB 8 to the information input of block 10, in which non-zero values service CGs in GB are a sign of the presence in it of either one defective or distorted replacement block - for identical values of service CGs in all other Bs, or two such blocks - for different values of service CGs of all other odd and all other even B's, the overhead value KG in the first case a single location in GB defective block, and the second - the value of the service B is odd CG location or first defective block and the replacement of the distorted value CG of office D is even such a location B in the second GB. In block 10, the value of each CG of a defective or replacement-distorted block is restored, for example, by modulo summing the highest CG value of the values of the corresponding CG of all other GB-related GB blocks. Figure 2, in conventionally shown by arrow lines, the restoration of defective B _3.1 according to the values restored by reverse substitution B _3.3 , control KB _3.1 and the remaining blocks of GB ₃ at odd positions and the restoration of defective B _3.2 according to the values restored reverse substitution B _3.4 , control KB _3.2 and the remaining blocks of GB ₃ in even positions.

From the output of block 10, the GB stream with the restored defective and distorted reverse substitutions blocks is fed to the shaper 11, with the help of which each GB is freed from service KG and correction blocks, the KG repetition rate is brought to the nominal value in the form of Fig. 2, g is fed to the output of the device.

Thus, the method for recording / reproducing code group streams to / from optical media provides continuous recording / reproduction of code group streams to / from a given media section and protects the code group stream from primary, secondary and tertiary media defects with lengths not exceeding the set maximum values , in a simpler way, without the use of defect management systems that require special areas on the media to be used in the known analogue methods and the prototype method and organizing complex dispatching of addresses and fragments of substitute and replaceable data streams during recording and playback. The application of the method improves the reliability of recording and storage of data streams on optical media, increasing the number of readings of recorded information without losing its quality, extending the life of media.

Claims (1)

A method for recording / reproducing code group streams to / from an optical medium with protection against media defects, including detecting defects in the process of recording a code group stream on a given section of the medium and recording code groups corresponding to defects to other places on the medium, as well as substitution during playback code group streams from a code group medium from defective places by code groups read from corresponding other places on the medium, characterized in that the code groups are distributed before they are written to the medium for blocks and groups of blocks in accordance with the numbers of code groups in a block and blocks in a group set taking into account the dimensional characteristics of media defects, each block is supplemented with a service code group with a set value and a pair of correction blocks of control code groups for odd and even blocks, respectively, write the supplemented groups of supplemented blocks of code groups to the medium and their control reading immediately after recording, keeping in sliding mode at the established number of initial augmented groups of augmented blocks and comparing each read group of blocks with the corresponding saved original group of blocks, if the next read group of blocks of code groups of defective blocks cannot be corrected, the values of the address code groups with the addresses of the defective block group are generated for each of them relative to the next recordable group of blocks and the corresponding defective block in the defective group of blocks, the address code groups are placed in the service to one group of blocks of the next group of blocks recorded on the medium and replace its two blocks at established spaced positions with the original block corresponding to the defective block, while reproducing the code group streams from the medium, they are delayed by buffering in the sliding mode a set number of read groups of code group blocks, control of defective blocks in each read group of blocks and in case of detection in the next read group of blocks of code groups of one or two defective blocks kov carry out the restoration of each of them with the help of the remaining blocks of the defective group associated with it, and if more than two defective blocks are found in the next read group of blocks, first they recover part of the defective blocks by replacing each of them with the original block from the established spaced apart positions of the delayed groups of blocks with alternating values of service code groups different from the set values and corresponding to the addresses of the defective group and the defective block in it, after e which is reduced each of the two defective defective block group by using the recovered inverse substitutions and other related block it, as well as each of two units substituted at positions corresponding to the delayed set of blocks remaining group using its associated blocks.

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