JPH09213013A - Digital data recording method, digital data reproducing method, and tape-like recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enlarge the data recording possible capacity, to improve the access speed, to simplify data management and to enlarge extensibility, to magnetic tape. SOLUTION: Entities are formed with plural records and management information (Entity Headers) managing the records, the entities are applied to the data units of a fixed length and groups becoming the data units recorded in the magnetic tape are formed even if data in the inputted record units are not subjected to compression-processing. Index information constituted of GIT (group information table) and BAT(block access table) are stored in the respective groups and the access entry of BAT is made the information on the entity unit in such case.

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 method and a digital data reproducing method for recording and reproducing digital data, and a tape-shaped recording medium corresponding to the digital data recording method and the digital data reproducing method. It is about.

[0002]

2. Description of the Related Art A so-called tape streamer drive is known as a recording / reproducing apparatus capable of recording / reproducing digital data on a magnetic tape. Such a tape streamer drive can have an enormous recording capacity of, for example, several tens to several hundreds of megabytes depending on the tape length of a tape cassette as a medium. It is widely used for purposes such as backing up data recorded on media. Further, it is also suitable when used for storing image data having a large data size.

As the tape streamer drive as described above, for example, a tape cassette of 8 mm VTR is used as a recording medium, and a helical scan method by a rotary head is adopted to record / reproduce data. Proposed.

In the tape streamer drive using the 8 mm VTR tape cassette as described above, for example, an SCS is used as an input / output interface for recording / reproducing data.
I (Small Computer System Interface) is used. Then, at the time of recording, for example, data supplied from the host computer is input via the SCSI interface. This input data is assumed to be transmitted, for example, in units of a predetermined fixed-length data group, and the input data is subjected to compression processing by a predetermined method if necessary and is temporarily stored in the buffer memory. Then, the data stored in the buffer memory is supplied to the recording / reproducing system in units of fixed length called a predetermined group, and is recorded on the magnetic tape of the tape cassette by the rotary head. Further, during reproduction, the data on the magnetic tape is read by the rotary head and temporarily stored in the buffer memory. If the data from the buffer memory is compressed at the time of recording, it is expanded and transmitted to the host computer through the SCSI interface.

[0005]

Even in a tape streamer drive capable of handling a large amount of data as described above, it is possible to record as much data as possible in a recordable area of a magnetic tape, for example. It is preferable that the utilization efficiency of the capacity of the magnetic tape is improved. Further, it is preferable that the access speed at the time of reading the recorded data is as high as possible. Furthermore, the utilization efficiency of the data of the management information recorded together with the data for managing the recording / reproduction of the data can be improved, and the types of information that can be handled as the management information can be expanded. It is preferable that the improvement is achieved.

[0006]

In view of the above problems, the present invention has the following configuration as a recording method for recording input digital data on a recording medium. First, when compression processing is performed on digital data transmitted in a predetermined fixed-length transmission data unit, a plurality of transmission data units and management information including at least information regarding the compression processing of the plurality of transmission data units are stored. To form a processed data unit. Thereafter, the processing data unit is applied to the fixed-length recording data unit for recording on the recording medium, the management information on the processing data unit is stored, and the recording information is recorded on the recording medium for each recording data unit. Decided to do. When the digital data transmitted in a predetermined fixed length transmission data unit is not compressed, a plurality of transmission data units and a management indicating that at least these plural transmission data units are not compressed are managed. And a processed data unit formed by the information. Then, the processing data unit is applied to the fixed-length recording data unit for recording on the recording medium, and the management information on the processing data unit is stored.
Recording is performed on the recording medium for each recording data unit.

As a reproducing method for reproducing the data recorded on the recording medium, the recording medium is applied to the recording data unit based on the management information stored in the fixed-length recording data unit on the recording medium. The data is read out by accessing each processing data unit recorded as, and the compression processing is performed on the data group forming the processing data unit based on the management information about the data compression included in each processing data unit. If so, the data group forming the processing data unit is decompressed and output as reproduction data.
On the other hand, when the data group forming the processing data unit is not compressed, the data group forming the processing data unit is not expanded and output as reproduction data. .

Then, the bit assignment is adopted in the definition area for defining the management content of the management information included in the recording data unit.

As a recording medium for recording digital data, a processing data unit is formed by a transmission data unit externally transmitted with a predetermined fixed length and at least management information indicating the presence or absence of compression processing of these transmission data unit groups. , The processing data unit is applied to a fixed-length recording data unit to be recorded on the tape-shaped recording medium, and management information provided for each processing data unit is stored, and each recording data unit is stored. Data will be recorded.

According to the above configuration, for example, at the time of recording, a plurality of "transmission data units" are irrespective of whether or not compression processing is performed on the fixed length "transmission data units" transmitted from the host side. Form a "process data unit", and at this time, the "process data unit" stores at least management information relating to the compression process of the data forming the process data unit. Therefore, in the present invention, the "recording data unit" is based on the "processing data unit" regardless of the presence or absence of data compression.
Is formed. Therefore, the management information included in the “record data unit” includes information for managing in the “process data unit” regardless of the presence or absence of the compression process. Further, along with this, for example, at the time of reproduction, it becomes possible to access in "process data unit" and execute the reproduction operation. Further, in the present invention, in the management information included in the group, bit assignment is adopted to define the management content, which allows more types of information to be stored than the case where the value assignment is adopted. It becomes possible to define.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in the following order with reference to FIGS. 1. Configuration of tape cassette and recording / playback device 1. Data Format According to Embodiment of the Present Invention (a) Structure of Data Recorded on Magnetic Tape (b) Group Formation Process (Prior Art) (c) Group Formation Process (Embodiment) (d) Entity Structure of (e) Structure of GIT (f) Structure of BAT (g) Comparison between prior art and embodiment Processing operation of recording / reproducing apparatus based on data format of the present invention

1. Structure of tape cassette and recording / reproducing apparatus By the way, as a system of a tape streamer driver by the applicant of the present invention, a tape cassette in which a solid-state memory (nonvolatile memory) is attached to a recording medium and a tape cassette with this memory are recorded / reproduced. Although various inventions have been proposed, the present embodiment applies the system including the tape cassette with the memory and the tape streamer driver compatible with the tape cassette to the present invention. To be done.

First, a tape cassette corresponding to the tape streamer drive of the present embodiment will be described with reference to FIGS. 2 and 3.
This will be described with reference to FIG. FIG. 2 conceptually shows the internal structure of the tape cassette, and reels 2A and 2B are provided inside the tape cassette 1 shown in this figure, and a magnetic tape having a tape width of 8 mm is provided between the reels 2A and 2B. Three
Is wound, and digital data is recorded on the magnetic tape 3. The tape cassette 1 is provided with a non-volatile memory 4.
Power supply terminal 5A, data input terminal 5 from the module
B, a clock input terminal 5C, a ground terminal 5D, etc. are led out. The nonvolatile memory 4 stores the manufacturing date and manufacturing location of each tape cassette, the thickness and length of the tape, the material, management information of recorded data for each partition, user information and the like.

For example, in a normal tape streamer drive system, management information of recorded data for each partition is written to, for example, a head position of a partition on a magnetic tape of a tape cassette. The drive once accesses the management information at the head position of the partition and then shifts to the recording / reproducing operation. On the other hand, in the tape streamer drive system of the present embodiment, the management information of the recorded data is read from the non-volatile memory 4 in the state where the tape cassette 1 is simply loaded in the device side. For this reason, it is possible to improve the access speed, which was difficult with a normal tape streamer drive. In this specification, a detailed description of the information content to be stored in the nonvolatile memory 4 will be omitted.

FIG. 3 is a view showing an example of the appearance of the tape cassette 1, in which the entire housing includes an upper case 6, a lower case 7,
And a guard panel 8 and is basically the same in structure as a tape cassette used for a normal 8 mm VTR. The label surface 9 on the side surface of the tape cassette 1 is provided with terminal pins 10A, 10B, 10C, and 10D. The power supply terminal 5A, the data input terminal 5B, the clock input terminal 5C, and the ground described in FIG. Terminal 5D
And are connected to each.

Next, the structure of the tape streamer drive of this embodiment will be described with reference to FIG. This tape streamer drive uses a tape cassette having a tape width of 8 mm to record / reproduce on / from a magnetic tape by a helical scan method. In this figure, for example, two recording heads 12 are provided on the rotary drum 11.
A and 12B and two reproducing heads 13A and 13B are provided. The recording heads 12A and 12B have a structure in which two gaps having different azimuth angles are located close to each other. Similarly, the reproducing heads 13A and 13B also have a structure in which two gaps having different azimuth angles are arranged extremely close to each other.

The rotating drum 11 is rotated by the drum motor 11, and the magnetic tape 3 pulled out from the tape cassette 1 is wound around it. The magnetic tape 3
Are fed by a capstan motor and a pinch roller (not shown). The drum motor 14 is driven by the control of the mechanical controller 17. The mechanical controller 17 performs servo control and tracking control of the drum motor 14, and is bidirectionally connected to a system controller 15 that executes control processing of the entire system.

In this tape streamer drive, a SCSI interface is used for inputting / outputting data. For example, at the time of recording data, a fixed-length record (record) described later is sent from the host computer 25.
Data is sequentially input via the SCSI interface 20 in the unit of transmission data of d) and supplied to the compression / expansion circuit 21. In such a tape streamer drive system, there is also a mode in which data is transmitted from the host computer 25 in units of variable-length data sets, but in the present specification, data transmission is performed in fixed-length record units. I will explain on the assumption that you will be given.

In the compression / expansion circuit 21, if necessary, the input data is compressed by a predetermined method. In the case of the present embodiment, the compression / expansion circuit 21 employs a plurality of predetermined compression / expansion methods. For example, if the compression method by the LZ code is adopted, the data compression is performed as follows. To be done. In this LZ coding method, a dedicated code is assigned to a character string processed in the past and stored in the form of a dictionary. Then, the character string input subsequently is compared with the contents of the dictionary, and if the character string of the input data matches the code of the dictionary, this character string data is replaced with the code of the dictionary. Data of the input character string that does not match the dictionary is sequentially given a new code and registered in the dictionary. In this way, the data of the input character string is registered in the dictionary, and the character string data is replaced with the code of the dictionary, whereby the data compression is performed.

When the data is supplied from the host computer 25, for example, if the image data or the like has already been compressed, the compression / compression
Since it is not necessary to perform the compression processing by the decompression circuit 21, the compression / decompression circuit 21 outputs the data as it is without compressing the input data. In the case of the present embodiment, whether or not to perform this compression processing can be set in advance by the user, and the system controller 15 refers to the data input via the SCSI interface 20 to perform the compression processing. It is also made to judge the pros and cons of.

The output of the compression / expansion circuit 21 is supplied to the buffer controller 22, and the control operation of the buffer controller 22 causes the output of the compression / expansion circuit 21 to be temporarily stored in the buffer memory 23. The data stored in the buffer memory 23 is controlled by the buffer controller 22 so that the data of the magnetic tape 40 called a group is finally obtained as described later.
The data is handled as a unit of fixed length corresponding to the track, and this data is supplied to the modulation / demodulation circuit 18.

The modulation / demodulation circuit 18 modulates the input data so as to be suitable for magnetic recording, and the RF amplifier 1
9. The recording signal amplified by the RF amplifier 19 is supplied to the recording heads 12A and 12B so that data is recorded on the magnetic tape 3.

The data reproducing operation will be briefly described. The recorded data on the magnetic tape 3 is reproduced by the reproducing head 13.
It is reproduced as an RF reproduction signal by A and 13B, and the reproduction output is supplied to the modulation / demodulation circuit 18 via the RF amplifier 19 and demodulated. The demodulated output of the modulation / demodulation circuit 18 is temporarily stored in the buffer memory under the control of the buffer controller 22, and is supplied from here to the compression / decompression circuit 21. In the compression / expansion circuit 21, if the data is compressed by the compression / expansion circuit 21 at the time of recording, the data expansion process is performed here based on the judgment of the system controller 15, and if it is uncompressed data, the data expansion process is performed. It is output as it is without performing. compression/
The output data of the decompression circuit 21 is reproduced as data via the SCSI interface 20 by the host computer 25.
Is output to

2. Data Format According to Embodiment of the Present Invention (a) Structure of Data Recorded on Magnetic Tape FIG. 4 shows a structure of data recorded on the magnetic tape 3. FIG. 4A shows the magnetic tape 3 wound around the reels 2A and 2B. In this embodiment, one magnetic tape 3 can be divided and used in units of partitions as shown in FIG. 4B, and in this case, the maximum number of partitions is 256. It is possible to set and manage. Therefore, in the present embodiment, recording / reproducing of data can be performed independently for each partition. For example, the recording unit of data in each partition is a group (see FIG. 4C). It can be divided into fixed-length units called "Groups", and recording is performed on the magnetic tape 3 in units of each group. In this case, one group corresponds to a data amount of 20 frames (Frame), and one frame has two tracks (Tra) as shown in FIG.
ck). Therefore, one group is 40
It will be formed by tracks.

The actual one partition shown in FIGS. 4A and 4B is formed by the data structure shown in FIG. In addition, in this figure, it is assumed that one partition is formed for the entire tape length. In the case of FIG. 5, the leader tape is physically located at the beginning with respect to the first part of the magnetic tape,
Next, a device area, which is an area for loading / unloading the tape cassette, is provided. The head of this device area is the head position PB of the physical tape
It is called OT (Phisycal Bigining of Tape). Following the device area, a system log area for storing tape usage history information and the like is provided, and a data area is provided thereafter. The beginning of the system log area is the logical tape start position LBOT (Logical Bigining o
f Tape). In this data area, first, a vendor group is provided in which information about vendors who create and supply data is provided, and then, actually, FIG.
A plurality of groups shown in (c) are formed continuously as shown as groups 1 to n here. Then, following the last group n, an EOD (End of Data) area indicating the end of the partition is provided. Then, the end of the EOD is set as a logical tape end position LEOT (Logical End of Tape). PEOT
(Phisycal Bigining of Tape) indicates the end position of the physical tape.

The structure of the data for one track is shown in FIG.
6A and 6B. FIG. 6A shows a data structure in block units. 1
The block consists of 1-byte SYNC data A1, followed by 6-byte ID data A2 used for searching, etc., and 2-byte I data.
It is composed of error correction parity A3 for D data and 64-byte data A4. Then, FIG.
The data for one track shown in (1) is formed by 471 blocks, and one track is provided with margins A11 and A17 for four blocks at both ends as shown in the figure. Tracking control is performed after the margin A11 and before the margin A17. ATF areas A12 and A16 for use are provided. Further, an ATF area A14 is provided in the middle of one track. As these ATF areas A12, A14 and A16, areas for 5 blocks are provided. And the above A
Between TF areas A12 and A14 and ATF area A1
Data areas A13 and A15 for 224 blocks are provided between the data areas A4 and A16, respectively.

FIG. 7 shows the data structure of one group. As described above, one group consists of 20 frames.
Then, as shown in FIG. 7, C3 for error correction is added to the last two frames of the 20 frames forming one group.
Parity is assigned. Although detailed description is omitted here, the C1 and C2 parities are added to the data shown in FIG. 6 so as to be completed on a track-by-track basis, for example. Then, at the time of recording the data, the data is sequentially written from the first frame of one group as shown by an arrow Ar1 in the figure. On the other hand, GIT (Group Info) showing the contents of the current group
The information of the rmation table) is 17 as shown by the arrow Ar2.
Writing is performed from the direction (indicated by arrow Ar2) opposite to the data writing direction from the second frame, and then,
A BA that serves as management information for each entity (or record in some cases) included in the current group, which will be described later.
The data of T (Block Access Table) is written. The GIT has a fixed length of 40 bytes, for example, and the BAT is created based on the contents of the group 4
It is made up of byte-by-byte access entries and is therefore of variable length depending on the content of the group. In this embodiment, GIT and BAT are collectively referred to as index information. The structures of these GIT and BAT will be described later.

(B) Group Forming Process (Prior Art) Here, as a signal processing process until forming the group shown in FIG. 7 at the time of recording, FIG. 8 and FIG. Since a method of recording by the process shown in FIG. 9 has been previously proposed as a prior art, this recording method will be described first.

By the way, as briefly described in FIG.
The data supplied from the host computer 25 to the tape streamer drive at the time of recording is supposed to be transmitted in fixed-length data units called records. In this case, one record has a size of 512 bytes, for example.

Then, if the input data is not compressed by the compression / expansion circuit 21 of the tape streamer drive, it is grouped by a plurality of record groups as shown in FIG. . FIG. 8A shows data in record units supplied from the host computer 25, and these records pass through the compression / expansion circuit 21 and are accumulated in the buffer memory 23 without being compressed. The record group accumulated here is stored in the buffer memory 23 as data r1, r2, r of the size of each record as shown in FIG.
3, r4, ... Are arranged according to the input order to form a group. This processing is realized, for example, by the buffer controller 22 executing processing on the data stored in the buffer memory 23 under the control of the system controller 15. Then, when forming the data in group units in this way, FIG.
The GIT described in 1. is created according to the data content. The access entry forming the BAT is created for each record included in the current group. As described above, when the compression processing is not performed on the data for each record input in the prior art, the input record is applied to the group as it is to form the group, and the magnetic field is generated as described above. Recording is performed on the tape 3 in units of groups.

Then, at the time of reproduction, the data is read from the magnetic tape 3 while referring to the index information in the group, so that the data is handled on a record-by-record basis and finally through the SCSI interface 20. Data is supplied to the host computer 25.

On the other hand, when compressing the data input from the host computer 25 record by record, when viewed in record units, the data size of each record after compression differs depending on its data content.
For example, as described above, the process of grouping records by applying them to groups as they are is based on the premise that the records are not compressed and have a fixed length. At times, it is possible to manage in record units and read from the magnetic tape 3. Therefore, if the data size of the record is variable as a result of performing the compression process on the record, even if the records are grouped as they are according to the method shown in FIG. Is not done.

Therefore, when compression processing is performed on records, grouping is finally performed as shown in FIG. For example, when the records shown in FIG. 9A are sequentially input to the tape streamer drive and subjected to compression processing, the data size thereof changes depending on the data content of each record. In this case, in the previous stage of grouping, a predetermined plurality of compressed records form a data unit called an entity shown in FIG. 9B. For example, in the case of the tape streamer drive of FIG. 1, the entityization by the record group is performed in the buffer memory 23 under the control of the system controller 15. In addition,
In this figure, one entity is formed by four records, but it is only shown schematically here,
The number of records actually included in one entity is arbitrarily set. In this entity, as shown in FIG. 9B, an entity header (Entity Header) indicating the data content of the entity is first formed, and subsequently, a plurality of compressed records are located. The contents of the entity header will be described later.

After the records are made into entities as described above, the data are grouped by a plurality of entities E1, E2, E3, E4, and E5 as shown in FIG. 9C, for example. In this case, the BAT access entry described with reference to FIG. 7 is created for each entity. Recording is performed for each group on the magnetic tape 3 by the group obtained as described above.

The entities actually applied to the group are the entities E11 and E1 shown in FIG.
2, E13, E14, E15, the entity fits within one group according to its data length and start position (entities E11, E12, E14)
There is a case (entity E13, E15, E16) that spans two or more consecutive groups. An entity that fits within one group is defined as "Entire Entity" by the BAT of the current group. When an entity spans two groups like the entity E15, the front part of the entity across the two groups is “Start Part of Entity” and the rear part is “Last Part of Entity”. Is defined.
As for the entity E13 that extends over three groups, as shown in the figure, for each part of the entity divided by each successive group, "Start
Part of Entity ”,“ Middle Part of Entity ”,“ La
It is defined and managed as "st Part of Entity". Although not shown here, when an entity is spread over two groups, this entity is a “Start Part of Entity” or a “Last Part of” for each group.
It is defined and managed as "Entity". In addition, “File M provided between entity 14 and entity 15
"ark" corresponds to a position where a file mark indicating a delimiter for each data file is attached, and therefore the following entity 15 becomes data of another file. Although not shown here, a save set mark is attached to a data delimiter recorded by one save (record) operation.

Further, the entities E11 and E1 shown in FIG.
4, the mark * marked at the beginning of E15 is an access point, and in the present embodiment,
For example, LBOT, separator mark (file mark,
It is added to the start position of the record at the beginning of the entity when the attribute of the entity is changed such as save set mark) or algorithm change. As a result, it is possible to execute appropriate reproduction signal processing in response to the attribute change of the entity by referring to the access point during reproduction.

At the time of reproduction in this case, G
By referring to IT and BAT, it is possible to access by entity and read data from the magnetic tape 3, and finally the reproduced data is supplied to the host computer 25 via the SCSI interface 20. It

That is, in the prior art, as a signal process for recording the input data, when the record is not compressed, the data is grouped by record (FIG. 8) and compressed. If there are multiple records and the corresponding Entity H
A data unit called an entity with content information "eader" is formed, and grouping is performed using this entity (FIG. 9).

(C) Group Formation Process (Embodiment) On the other hand, in the tape streamer drive of this embodiment, when input data is recorded,
When compression processing is applied to the input data, the signal processing similar to that described with reference to FIG. 9 is used to finally perform grouping. However, when compression processing is not applied,
Next, as described with reference to FIG. 10, the input data is grouped and recording on the magnetic tape is executed.

For example, in the tape streamer drive of the present embodiment, assuming that data is input from the host computer 25 in record units as shown in FIG. 10A, in this case, compression by the compression / expansion circuit 21 is performed. It is assumed that processing is set not to be performed.
In this case, in the tape streamer drive of the present embodiment, the entity is formed by the uncompressed record group as shown in FIG. Then, a group is formed by applying the entities thus formed. The number of records included in one entity can be arbitrarily defined as in the case of FIG. In this case, the entity has a fixed length because it is made into an entity by a predetermined number of fixed-length record groups that are not compressed. Further, the relationship of the entity to the group in this case is based on the above description with reference to FIG. As can be understood from the above description, in the present embodiment, with respect to data input in record units, an entity is formed by a plurality of records regardless of the presence or absence of compression processing, and grouping is performed based on this entity. To be done.

(D) Entity Structure Here, the structure of an entity based on the recording method according to the present embodiment will be described with reference to FIGS. 12 and 13. Figure 12 shows the entity structure (Entity Map S
tructure) is shown. As shown in the figure, the entity is considered to be formed such that a data string for each byte with bit numbers 0 (LSB) to 7 (MSB) is continuous. A byte number starting from "0" is added to the data string of each 1 byte. Here, in the entity header shown in FIGS. 9B and 10B, an area of 8 bytes from the first byte number 0 to the byte number 7 is given, and the byte number 0 of the entity header. "Head" that indicates the data length
er Length ”is placed. For example, if an access point exists in the current entity, recording of a record is supposed to start from byte number n, and this byte number n is defined by "Header Length". Therefore, in this case, data indicating n = 8 is stored.

In the byte number 1, an algorithm number ("Algorithm Number") is indicated by a binary system. This algorithm number is defined, for example, as shown in FIG. 13, and when the algorithm number is “0”, it indicates that no access point is attached to the current entity, If the value is “1”, the access point exists in the current entity, and the record in the current entity is uncompressed data, that is, the entity having the structure described in FIG. 10B. Is shown. When the algorithm number is "3" or "32", it is assumed that the access point exists in the current entity and the data in the current entity is compressed by a predetermined method. The algorithm numbers are "2", "4" to "31", and "33" to "25".
In the case of "5", it is considered as undefined (Reserved).

Further, in FIG. 12, byte numbers 2 to 4 are used.
In the area of 3 bytes, "Original record Length", which is information of the original data length of the record, is indicated.
In this case, 512 bytes are indicated as described above. In the subsequent 3-byte area of byte numbers 5 to 7, "Record count in this Entity", which is information on the number of records to be included in the entity, is stored, and information on the number of records defined in advance is stored. As the number of records, for example, if there is a file mark indicating a file delimiter and a save set mark indicating a save position delimiter at the time of data saving, these file mark and save set mark are also included in the number of records. To be included. Then, the data of the record group is stored in the succeeding byte number 8 and subsequent byte strings, and thus one entity is formed.

(E) Structure of GIT As described above, GIT (Group Information Table) and BAT (Block A) are used as index information in one group.
Although a ccess table) is provided, the GIT will be described first.

FIG. 14 shows the structure of GIT.
The GIT has a fixed length of 40 bytes, for example, and stores management information relating to the current group as described below. In this case, fields F1 to F16 are shown in the figure.
Are arranged. In these fields F1 to F16, first, the field F2 is a field of "Group Number" and has an area of 3 bytes, and information of a unique group number assigned to the current group is stored therein. Field F3 consists of 4 bytes "Record C
The information of the total number of records included in the current group from the logical tape start position LBOT described with reference to FIG.

The field F4 is "File Mark Coun
"t", which is composed of 4 bytes, stores information on the total number of file marks included in the current group from the LBOT, and similarly "Save-S" of field F5, which is also 4 bytes.
The “et Mark Count” area stores information on the total number of save set marks included in the current group from the LBOT. Field F7 (3 bytes) contains "Group Number o
This is an area of "f the Previous Record", and stores the file number or save set mark in the group before the current group, or the group number information of the last group in which the beginning of the record exists. In addition, field F9 (3 bytes) “Group Number of the Prev
The area of "ious FileMark" stores the group number information of the group in which the last recorded file mark exists, and is stored in the "Group Numb" field F11 (3 bytes).
The area of “Er of the Previous Save-set Mark” stores group number information of the last recorded group in which the save set mark exists.

Field 12 (2 bytes) is "Block Ac
Area of "cess Table Count", BA of the current group
Information on the number of T access entries is stored. BAT
Is a unit of 4-byte access entry, which will be described later.

Field 13 (2 bytes) contains "Count
Information of the number of records in the current group is stored as the area of "Records in current Basic Group".
In this case, the number of records includes the number of file marks and save set marks in the current group. Also, field 14 (2 bytes) is "Count of File Marks in c
"urrent Basic Group" is stored information of the number of file marks in the current group, and field 15 (2 bytes) is "Count of Save-set Marks in current Basic".
Information regarding the number of save set marks in the current group is stored.

The fields F1, F6, F8 and F10 are also included.
(1 byte each) and field F16 (4 bytes) are undefined.

(F) BAT Structure BAT is formed by one or more access entries. The individual access entries that form the BAT indicate information about the records, filemarks and save set marks that will be included in the group. Therefore, since the number of BAT access entries changes according to the content of the entity applied for each group, the data size of BAT has a variable length.

One access entry has 4 bytes as shown in FIG. And the first 1st byte (1
st Byte) is a flag byte to which a BAT flag is assigned, defines an access entry as described later, and the remaining 2nd to 4th bytes (2nd to 4th B)
3 bytes in total is used as a count field indicating the contents related thereto. If there are a plurality of access entries forming the BAT, the access entry to be written first in the group is GI.
The remaining access entries arranged immediately before T are written in order from the direction opposite to the data recording direction as indicated by the arrow Ar2 in FIG. 7 described above.

The BAT flag assigned to the first byte of the access entry is defined as shown in FIG. According to this figure, the BAT flag number is bit-assigned, and the BAT flag number is assigned by the binary system. When the BAT flag number is 1 (00000001), it is defined as "Entire Entry". If defined as an "Entire Entry", the entity represented by this access entry will be
ntity]. That is, like the entities E11, E12, and E14 shown in FIG. 11, the entity is started / finished in the current group. Then, the count field represents the number of bytes of the entity. When the BAT flag number is 2 (00000010), "St
"Art Part of Entry", and the entity indicated by this access entry is [Star
t Part of Entity] (Star of entity 13 in FIG. 11)
t Part of Entity: SPE)),
This Start Part of Entit by count field
The number of bytes in y] is shown. BAT flag number 3 (000
In the case of (00011), "Middle Part of Entry" is defined, and the entity in the current group is set to "Middle Part of Entry".
Entity] (Middle Part of Entity 13 in FIG. 11)
of Entity: MPE), and the count field indicates the number of bytes. When the BAT flag is 4 (00000100), "Last Part of Entr
y ”is defined to indicate that the corresponding entity is a [Last Part of Entity] (see Last Part of Entity: LPE of entity 13 in FIG. 11) in the current group, and the count field indicates the number of bytes. Shown. The BAT flag number 5 (00000101) is
It is called "Total Count of Entry". `` Total Count of
The "Entry" is arranged immediately after the above "Last Part of Entry", and in principle, both are made to be in the same group. In this case, the count field represents the number of bytes of the entire entity indicated by the immediately preceding “Last Part of Entry”. For example, in FIG. 11, “Total Count of Entry” is the entity 13
In the group including the Last Part of Entity (LPE), the number of bytes of the entire entity 13 is indicated by the count field that is arranged next to the “Last Part of Entry”.

Next, BAT flag number 6 (00000111)-
In case of 10 (00001010), "Entire Unproce"
ssed Entry "," Start Part of Unprocessed Entry "
, "Middle Part of Unprocessed Entry", "Last
Part of Unprocessed Entry ”,“ Total Count of Unpr
“Ocessed Entry”, and is set according to the contents of the entities in the group, especially when a group including the entity is created based on the uncompressed record formed. Note that the definition content and the content indicated by the field count are as described above in "Enti
reEntry ”,“ Start Part of Entry ”,“ Middle Part ”
of Entry ”,“ Last Part of Entry ”,“ Total Count
As a general rule, it conforms to “of Entry”.

In the case of the BAT flag number 11 (00001011), "Separator Mark Entry" is defined, and this access table indicates the area of the file mark or save set mark. In this case, the separator mark corresponding to the access table is
If it is a mark, the field count is "0", and if it is a save set mark, the field count is "1".

In the case of BAT flag number 12 (00001011), "Skip Entry" is defined, and this "Skip Entry" indicates the last byte of the user data in the current group. Then, the count field indicates the number of bytes remaining in the group. Therefore, the minimum value of the count field corresponds to the total number of bytes of the index information area including GIT and BAT in the current group. B
AT flag number 0 and BAT flag number 013 to 2
55 is undefined.

Further, in the tape streamer drive system of the present embodiment, EWP (Early Warning Po
There is a concept of int), which is a point shown to warn that the end of the recordable area of the magnetic tape is near. For example, if data is recorded over this EWP, the AEW will be
Information that it is P (After Early Warning Point) is added. This AEWP is defined by treating the MSB in 1 byte of the BAT flag number as AEWP. If the AEWP bit is set to "0", the access entry with the BAT flag numbers 0 to 127 is used as described above. If the AEWP bit is set to "1" for these BAT flags, the BAT flag number is set to each. The BAT flag numbers are 128 to -1, and the above-mentioned BAT flag numbers 0 to 127 are BAT.
To each definition content of the flag, the content that is recorded beyond the EWP is added ((w
It is shown as it AEWP).

(G) Comparison between Prior Art and Present Embodiment Here, when the difference in the format at the time of recording between the tape streamer drive of the prior art and this embodiment is confirmed, in the prior art, the host computer side Regarding the data transmitted in fixed length record units,
When the data compression processing is not performed, the grouping is performed as it is without forming the entity by the record group as described with reference to FIG. 8. When the data compression processing is performed, the description is described with reference to FIG. As described above, after the records are made into entities, grouping is performed. On the other hand, in the tape streamer drive of the present embodiment, when the data compression processing is performed, the processing is performed in the same manner as in FIG. 9. However, even when the data compression processing is not performed, the processing is performed in FIG. As described above, the records are made into an entity, and then grouped.

Comparing the prior art and the present embodiment based on this point, first, in the case of recording uncompressed data in the tape streamer drive of the prior art, there is no entity, and therefore the access of the BAT. BAT per group because the entry is written as information about the record, not the entity
The data size of is compared to the group of compressed data,
It was usually very large. On the other hand, in the present embodiment, the record group is made into an entity even for non-compressed data, so that the BAT access entry is written as information related to the entity. By this, even if it is uncompressed data, BAT
It is possible to reduce the data size by reducing the number of access entries. As a result, the width of the area occupied by BAT in one group is reduced, the storage area for user data is greatly expanded as compared with the prior art, and the apparent data recordable capacity is increased.

In the prior art, in order to reproduce uncompressed data, BA for each record recorded in the group
Since the recording data is read by referring to the access entry of T, the tape streamer drive executes the reading from the magnetic tape while accessing in record units. For this reason, the access speed cannot be increased. On the other hand, in the present embodiment, even when reproducing uncompressed data, it is possible to refer to the access entry stored as the information for each entity and access the data in entity units to read the data. That is, since the reading is performed for each data size of a plurality of record groups, the access speed is further increased.

The number of records to be included in the entity is "Record count in th" in the entity header.
It can be arbitrarily set within a manageable number by the 3-byte area of "is Entity", but the merit of the present embodiment described above becomes more remarkable as the number of records to be included in the entity is set. .

Further, in the prior art, the BAT flag number given to the flag byte of the BAT is a value assignment although a specific example is omitted here, so that the information of the access entry cannot be efficiently used. I was there. On the other hand, in the present embodiment, since the bit assignment is performed as shown in FIG. 16, the utilization efficiency of information is improved, and the types of information defined by the BAT access table are increased as compared with the prior art. It is possible to make the data management expandable.

Further, in the prior art, when data is compressed, the BAT flag entries 1 to 5, 11 shown in FIG.
12, -128 to -123, -117, -116 are used, and BAT flag numbers 1 to 5 and -128 to -12 are used as BAT access entries for uncompressed data.
3, instead of 3, BAT flag numbers 6-10 and BAT
The entry of flag numbers 122 to 118 for unprocessed data (uncompressed data) was used. In the case of non-compressed data, the access entry is stored as information about the record.

On the other hand, in the present embodiment, both compressed data and non-compressed data are entities. Therefore, in managing the entity by BAT, the BAT flag numbers 6 to 10 and BA in FIG. 16 are used.
The BAT flag numbers 1 to 5 and -128 to-originally used for processed data (compressed data) are used without using the access entries of the T flag numbers -122 to -118 for unprocessed data (uncompressed data). 12
The access entries 3 and 3 can be commonly used and used for data management. Whether the recorded data is compressed data or uncompressed data can be identified by the value of the algorithm number stored in the byte number 1 of the entity header (see FIGS. 12 and 13). .

3. Processing operation of recording / reproducing apparatus based on data format of the present invention Next, an operation at the time of recording / reproducing of the tape streamer drive corresponding to the data format of the present embodiment described above will be described. The operation will be described.

FIG. 17 is a flow chart showing the signal processing operation at the time of recording of the tape streamer drive of the present embodiment shown in FIG. For example, when the routine shown in this figure is being executed, as described above with reference to FIG.
It is assumed that data is transmitted in record units via the I interface 20. In this state, the system controller 15 first performs step F1.
In 01, it is determined whether the data compression setting for the recorded data of the tape streamer drive main body is turned on or off by the user. Here, when the data compression setting by the user is set to OFF, the processing proceeds to step F108, and the processing operation for recording the data that is not subjected to the compression processing is executed. If the data compression setting by the user is set to ON in step F101, the process proceeds to step F102.

In step F102, the system controller 15 identifies the contents of the data currently input and determines whether or not to actually execute the data compression on the current input data. . For example, even if the data compression is turned on by the user, the data size does not become small even if the compression process is performed depending on the format of the input data, such as image data already compressed in the MPEG format. ,
Or, on the contrary, the data size may increase. It is preferable that such input data is not subjected to the compression process in consideration of the efficiency of the recording capacity even if the data compression is set to ON by the user. Therefore, the system controller 15 refers to the data input via the SCSI interface 20, and determines whether or not to perform data compression based on the data format or the like. Then, when it is determined that the data compression is not performed, the process proceeds to step F108, but when it is determined that the data compression is performed, the step F103 is performed.
By proceeding to, the processing for compressing and recording the data is executed.

In step F103, an algorithm number (see FIG. 13) corresponding to the compression method set by the user or the compression method selected by the system controller 15 itself in step F102 is set. Then, in the next step F104, the data compression algorithm corresponding to the above-mentioned algorithm number is set in the compression / expansion circuit 21, and the control is executed so that the data compression by the selected method is performed.

In the subsequent processing of steps F105 → F106, the processing of the data signal described above with reference to FIG. 9 is executed. That is, in step F105, the system controller 15 forms an entity by a predetermined number of record groups each having a variable length after data compression (FIG. 9).
The control for (a) → (b) is executed. At the time of this processing, the system controller 15 creates an entity header to be included in the entity. At this time, the information of the algorithm number set in step F103 is the entity header described in FIGS. 12 and 13. It is stored in the area of byte number 1 (1 byte). Specifically, based on FIG. 13 described above, the algorithm number is set to “3” or “32” according to the compression method. If no access point is provided for the entity, the algorithm number is set to "0". After forming the entities in this way, the system controller 15 proceeds to step F106.
To form a group (see FIG. 9 (b) → (c)). Then, at the time of this processing, FIG.
4, GIT and BAT shown in FIGS. 15 and 16 are created for each group. Step F10 above
5, the series of processing operations shown in F106 are realized by the system controller 15 controlling the writing and reading processing of the buffer controller 22 for the data accumulated in the buffer memory 23, for example.

After that, the system controller 15 executes the control of the required functional circuit portion by the processing of step F107 so that the recording on the magnetic tape is performed in the group unit formed by the processing operations up to step F106. To be done.

On the other hand, based on the determination result of step F101 or F102, when the compression / expansion circuit 21 records the data without performing the data compression, first, the system controller 15 proceeds to step F108. , Set the algorithm number corresponding to uncompressed data. For example, based on the formats shown in FIGS. 12 and 13 described above, the algorithm number in this case is set to “1”. Also in this case, if no access point is provided for the entity, the algorithm number is set to "0".

Next, the system controller 15 executes the signal processing described in FIG. 10 by the processing of steps F109 → F110. In step F109, an entity is formed by the data of each record stored in the buffer memory 23 without being compressed (FIG. 10 (a) → (b)). At this time, the value of the algorithm number set in step F108 is written in the 1-byte area of the byte number 1 of the created entity header. Then, in the following step F110, data grouping is performed as described with reference to FIGS. 10B to 10C, and then the process proceeds to step F107 to perform the process for recording data on the magnetic tape. It

Next, the flow chart of FIG. 18 shows the processing operation during reproduction of the tape streamer drive of this embodiment. In this routine, the system controller 15 first executes the reproduction head 13A, the data recorded on the magnetic tape 3 as the processing of step F201.
It is assumed that the processing operation of each functional circuit unit is executed so that the reading is performed by 13B. Also, at the time of reading this data, the group index information (GI
T and BAT),
As described above, since the record data stores the BAT access entry information in entity units regardless of the presence or absence of compression processing, the record data can always be accessed and read in entity units. it can.

In step F202, the information of the entity header is extracted from the record data sequentially read in units of entities, the information of the algorithm number of byte number 1 is referred to, and in the next step F203, the algorithm number discrimination processing is performed. I do. That is, the presence / absence of the compression process and the compression method if the compression process is performed are determined. If the algorithm number indicates uncompressed data, the decompression processing by the compression / decompression circuit 21 is passed for the data forming the entity (step F204), and finally S
Host computer 2 through CSI interface 20
The control of the required functional circuit unit is executed so that the data is output as reproduction data for F5 (F206). Specifically, FIG.
If the algorithm number is defined as described above, the above process is performed when it is determined in step F203 that the algorithm number is "1".

On the other hand, in step F203, the algorithm number indicates that the data is compressed data (in FIG. 13, algorithm numbers "3" and "3").
2)), the compression / expansion circuit 21 is controlled so that the data forming the entity is expanded by the method corresponding to the algorithm number (step F205), and the expanded data is extracted. Is output as reproduction data (step F206).

It should be noted that the data format described as the embodiment so far can be variously modified as long as it includes the data signal processing with the record group as the entity regardless of the presence or absence of the data compression processing. The processing operation at the time of recording / reproducing of the tape streamer drive may be changed. Further, in the tape streamer drive of the present embodiment, it is possible to reproduce the data recorded on the magnetic tape through the processing shown in FIG. 8 as the prior art. In this case, the BAT access entry (see FIG. 16) of the record data is created in record units as described above, and the BAT flag number is "6" to "10" corresponding to the uncompressed (unprocessed) data. , And “-122” to “-118” are used,
Data can be reproduced without problems by accessing in record units. Further, the tape streamer drive of the present embodiment is provided with a nonvolatile memory.
Although it has been described as being compatible with the mm tape cassette, it is actually possible to record / reproduce data of the same format recorded in the 8 mm tape cassette having no nonvolatile memory. Further, the tape streamer drive according to the present invention can be naturally applied to a tape streamer drive corresponding to only a tape cassette having no non-volatile memory.
It can also be applied to recording media other than mm tape cassettes and tape streamer drives corresponding to these.

[0076]

As described above, according to the present invention, when data is recorded on a magnetic tape, for example, an entity is formed by a plurality of records regardless of the presence or absence of data compression processing. The entities are assigned to the groups and finally recorded in group units. As a result, first, the access entry of the BAT provided as management information in the groups becomes information on the entities. As a result, the number of BAT access entries is small even for non-compressed data, so that the data size can be reduced, and the amount of recordable data on the tape is increased accordingly. In addition, since the BAT access entry is managed on an entity-by-entity basis when reading data, it is possible to access and read on an entity-by-entity basis rather than on a record-by-record basis even for uncompressed data. The access speed during playback will be improved.

Further, the BA of the access entry of BAT
The T-flag is value-assigned in the prior art, but is bit-assigned in the present invention, so that the utilization efficiency of information is improved and the types of information defined by BAT can be increased. Therefore, the scalability of data management is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of a tape streamer drive which is a recording / reproducing apparatus of an embodiment of the present invention.

FIG. 2 is a plan view schematically showing the internal structure of the tape cassette according to the present embodiment.

FIG. 3 is a perspective view showing the external appearance of the tape cassette according to the present embodiment.

FIG. 4 is a schematic diagram showing a data structure recorded on a magnetic tape.

FIG. 5 is a schematic diagram showing a data structure in one partition recorded on a magnetic tape.

FIG. 6 is a schematic diagram showing a data structure of tracks on a magnetic tape.

FIG. 7 is a schematic diagram showing a data structure of a group.

FIG. 8 is an explanatory diagram conceptually showing a signal processing process until grouping of uncompressed data.

FIG. 9 is an explanatory diagram conceptually showing a signal processing process until grouping of compressed data.

FIG. 10 is an explanatory diagram conceptually showing a signal processing process until grouping of uncompressed data.

FIG. 11 is a conceptual diagram showing a relationship between entities and groups.

FIG. 12 is a schematic diagram showing a data structure of an entity.

FIG. 13 is a diagram illustrating the definition of an algorithm number.

FIG. 14 is a schematic diagram showing a data structure of GIT.

FIG. 15 is a schematic diagram showing a data structure of BAT.

FIG. 16 is a diagram illustrating the definition of a BAT flag.

FIG. 17 is a flowchart showing a processing operation at the time of recording of the tape streamer drive of this embodiment.

FIG. 18 is a flowchart showing a processing operation during reproduction of the tape streamer drive according to the present embodiment.

[Explanation of symbols]

1 tape cassette, 3 magnetic tape, 4 non-volatile memory, 11 rotating drum, 12A, 12B recording head, 13A, 13B reproducing head, 15 system controller, 17 mechanical controller, 18 modulation / demodulation circuit, 19 RF amplifier, 20 SCSI interface , 21 compression / expansion circuit, 22 buffer controller, 23 buffer memory, 25 host computer

Claims (5)

[Claims] 1. A digital data recording method for recording input digital data on a recording medium, wherein a plurality of the above-mentioned transmissions are carried out when compression processing is performed on digital data transmitted by a transmission data unit of a predetermined fixed length. For a fixed-length recording data unit for recording on a recording medium after forming a processing data unit formed of a data unit and management information including information on compression processing of at least these plural transmission data units While applying the above-mentioned processing data units, storing management information about these processing data units, recording is performed on a recording medium for each recording data unit, and transmission is performed by a predetermined fixed length transmission data unit. If compression processing is not applied to digital data that is Also, after forming a processing data unit formed by management information indicating that the plurality of transmission data units have not been compressed, the fixed length recording data unit for recording on the recording medium is A digital data recording method, characterized in that processing data units are applied, management information regarding these processing data units is stored, and recording is performed on a recording medium for each recording data unit. 2. The digital data recording method according to claim 1, wherein the definition area defining the management content of the management information included in the recording data unit adopts bit assignment. 3. A digital data reproducing method for reproducing digital data recorded on a recording medium, the method comprising: recording data from the recording medium to the recording data unit based on management information stored in a fixed-length recording data unit on the recording medium. A data group forming a processing data unit is accessed based on the management information on data compression included in each processing data unit by accessing and reading the data for each processing data unit recorded so as to be applied to When compression processing has been performed, decompression processing is performed on the data group forming the processing data unit and output as reproduction data, and the compression processing is not performed on the data group forming the processing data unit. Output as reproduction data without decompressing the data group forming the processing data unit. A digital data reproducing method characterized by the above. 4. The digital data reproducing method according to claim 3, wherein the definition area for defining the management content of the management information included in the recording data unit adopts bit assignment. 5. A processing data unit as a recording medium for recording digital data, comprising a transmission data unit externally transmitted in a predetermined fixed length and at least management information indicating presence / absence of compression processing of these transmission data unit groups. Is formed,
The above-mentioned processing data unit is applied to a fixed-length recording data unit to be recorded on the tape-shaped recording medium, and management information provided for each processing data unit is stored, and data is recorded for each recording data unit. A tape-shaped recording medium on which is recorded.