JP2006178632A - Information processor, information processing method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain the high speed operation of a file access as regards an information processor, an information processing method, and a program. <P>SOLUTION: LBA (logical block addressing) management information for storing information showing the leading sector (LBA) and size of each of the segments of a file is prepared so that not only file management by a normal FAT file system but also file management by this LBA management information can be executed. As regards a file where the LBA management information is present in performing file access, the reading of file data is realized not by referring to an FAT region but by reading data by segment units according to the leading sector (LBA) and size shown by the LBA management information. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information processing apparatus corresponding to a storage medium that records and reproduces data in units such as files, and a method thereof. The present invention also relates to a program executed by such an information processing apparatus.

  In managing data stored in a medium (storage medium, storage device), a file system is widely used and managed in units of files. The FAT file system is one format of such a file system. Are known. As is well known, the FAT file system includes a directory entry and a FAT (File Allocation Table) area in order to manage the substance of stored data as a file.

  In order to access a file stored in a medium for the purpose of file reproduction under the FAT file system, first, a directory entry corresponding to the file to be accessed is accessed. In the directory entry, the recording start position on the medium in which the actual data as a file is stored is indicated by a cluster number (first cluster number). Incidentally, the cluster is a minimum data writing / reading unit for the medium in the processing hierarchy of the file system. In the processing hierarchy of the device driver below the file system, the sector is the minimum data write / read unit for the medium. A cluster is formed as an area in which a predetermined number of sectors are continued.

  The FAT area has a table structure with a set of FAT entries individually corresponding to all clusters in the medium. By storing the cluster number to be linked next to the FAT entry, a file can be stored. It is managed by cluster unit linkage (cluster chain). Therefore, referring to the FAT entry in the FAT area indicated by the first cluster number indicated in the directory entry, the cluster number to be the next chain destination stored here is obtained, and the FAT corresponding to this next cluster number is obtained. Browse the entry. Thereafter, the cluster chain forming the file to be accessed is recognized by following the FAT entry in the same manner according to the cluster number of the chain destination stored in the FAT entry. Then, according to the recognized cluster chain, the medium is actually accessed to read the data, and the data is transferred to, for example, an application on a higher layer than the file system. The application receives the transferred data, constructs file data, and executes data processing corresponding to a predetermined file.

  In this way, in the FAT file system, the file is managed as a cluster chain. Thus, for example, even if one file data is recorded discretely instead of being consecutive in cluster number, and fragments (fragmentation) are generated, these fragmented data portions are connected by a cluster chain. Therefore, it can be managed properly as one file.

  However, managing the file data by the cluster chain means that the FAT entry in the FAT area is sequentially traced and referred to in the order of the cluster chain as described in the file access procedure. Is required. For some time, it has been pointed out that there is a possibility that an overhead caused by this processing burden may occur, resulting in a disadvantage that the processing speed for file access decreases.

  Therefore, for example, on the assumption that a FAT file system is adopted, in addition to basic directory entries and FAT areas, management chain information (link information) for each file as management information for managing files. Patent Document 1 discloses a configuration in which a cluster link table having only a file name or a space information table indicating a space area on a medium is constructed and held with reference to information on directory entries and FAT areas. ing. In Patent Document 1, for example, when accessing a file or recording file data, by referring to these table information, compared to a basic access procedure in which only a directory entry and a FAT area are referred to, access to a medium is further improved. It is designed to be done efficiently.

JP 2004-86823 A

  It is an object of the present invention to make the access to the storage area to the media more efficient than in the past. Also, in order to achieve efficient media access, the system should be as simple as possible, and management information maintenance and other processes should be as light as possible.

In view of the above-described problems, the present invention is configured as an information processing apparatus as follows.
That is, information for managing a writing unit for writing data to the storage medium and a data unit portion formed by writing data to a storage area on the storage medium in which one or more predetermined data writing units are continuous. At least information items that can indicate the start position of the data unit part and information items that can indicate the end position of the data unit part as information items for specifying the position where the data unit part is written on the storage area The data unit part management information formed by storing is formed according to the writing result of the data unit part by the writing means, and comprises data unit part management means for holding it in a predetermined information storage area.

  Further, as an information processing method, a writing procedure for writing data to a storage medium and a data unit portion formed by writing data to a storage area on a storage medium in which one or more predetermined data writing units are continuous are provided. Information to be managed, at least as an information item for specifying the position where the data unit part is written on the storage area, an information item that can indicate the start position of the data unit part, and the end position of the data unit part A data unit part management procedure for forming data unit part management information formed by storing information items that can be indicated according to the result of writing the data unit part by the writing procedure and holding the data unit part management information in a predetermined information storage area; It was decided to be configured to execute.

  Further, the program is configured such that the information processing apparatus executes the procedure as the information processing method.

The information processing apparatus is also configured as follows.
That is, in order to manage the data stored in the storage medium as an independent data unit that is one independent data unit, and to manage that the independent data unit is formed by concatenating predetermined data writing units. Independent data unit management means having independent data unit management information and data stored in a storage medium are formed by writing data to a storage area on the storage medium in which one or more predetermined data write units are continuous Data unit part management information for managing as a data unit part, and for the independent data unit, based on using the data unit part management information corresponding to the data unit part forming the independent data unit, A data unit management means configured to be managed as a concatenation of one or more data unit parts, and a storage medium The independent data unit to be read, which is the independent data unit to be read, is managed by only the independent data unit management means or is managed by the independent data unit management means and the data unit part management means. And a data unit corresponding to the read-independent independent data unit provided in the data unit management unit when a determination result is obtained that both management is performed by the determination unit. By executing a read process for each data unit portion based on the management information, the read unit includes a read unit that executes the read process for the read-independent independent data unit.

  In addition, as an information processing method corresponding to the information processing apparatus, data stored in a storage medium is managed as an independent data unit which is one independent data unit. Independent data unit management procedure for processing independent data unit management information for managing as an independent data unit is formed, and writing one or more predetermined data to the data stored in the storage medium The data unit part management information for managing the data unit part as a data unit part formed by writing data in the storage area on the storage medium in which the unit is continuous is processed, and the independent data unit is an independent data unit. Based on the use of data unit management information corresponding to the data unit that forms the data unit. The data unit part management procedure that is managed as the data to be managed and the independent data unit to be read that is the independent data unit to be read from the storage medium are single-managed only by the independent data unit management procedure. If there is a determination result that determines whether or not both management is performed by the independent data unit management procedure and the data unit part management procedure, and that both management is performed by this determination procedure By executing the read processing for each data unit portion based on the data unit portion management information corresponding to the read target independent data unit processed by the data unit portion management procedure, the read processing for this read target independent data unit is performed. The reading procedure to be executed is configured to be executed.

  Further, the program is configured such that the information processing apparatus executes the procedure as the information processing method.

According to each of the above configurations, the data recorded in the storage medium is managed for each data unit portion formed by writing data to the storage area on the storage medium in which a predetermined data writing unit is continuous. Yes. In the data unit part management information for managing the data unit part, when indicating the storage position on the storage medium for the corresponding data unit part, the start position and the end position of the data unit part are shown. Information items to be obtained are stored.
When reading data from a storage medium in which such data management is performed, refer to the information item in the data unit part management information of the data unit part corresponding to the data to be read, and the start position and end position of the data unit part To be recognized. Then, data reading from the storage medium is started from the position recognized as the start position, and the data is read up to the position recognized as the end position, thereby forming the target data unit. Is read out appropriately.
That is, according to the present invention, as in an existing file system, access to data stored in a storage medium is not sequentially executed while following a chain of data write units called clusters, for example. Instead, once the start position and end position of the data unit part have been recognized, the data unit part can be read from the start position to the end position at once without referring to the management information. it can.

  In this way, according to the present invention, access to the storage medium can be made more efficient than in the case based on an existing file system, for example. In addition, since the data unit part management information used for access requires information items indicating the start position and end position of the corresponding data unit part, it is possible to avoid a complicated structure. Therefore, processing for creation, maintenance, etc. can be simplified without being complicated.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described. In this embodiment, a case where the configuration of the information processing apparatus according to the present invention is applied to a digital video camera is taken as an example.

FIG. 1 is a block diagram illustrating a configuration example of a digital video camera 1 according to the present embodiment.
In the digital video camera 1 shown in this figure, the optical system unit 2 includes an imaging lens, a diaphragm, and the like, and forms incident light on the photoelectric conversion unit 3 as imaging light. Further, the optical system unit 2 includes a focus adjustment mechanism for focus adjustment, a diaphragm variable mechanism that varies the diaphragm according to the diaphragm value, and the like. Is performed by a drive signal output from the camera function unit 6. The camera function unit 6 is configured to output a required drive signal so as to obtain an appropriate focus state, aperture state, and the like, under the control of the CPU 10.
For example, when an optical zoom function is to be provided, a zoom mechanism for moving the zoom lens is provided in the optical system unit 2 and driving for moving the zoom mechanism in accordance with the control of the CPU 10 in the same manner as described above. What is necessary is just to provide a part. Further, the camera function unit 6 may be configured to provide a strobe light emission function after providing a strobe.

  The photoelectric conversion unit 3 includes, for example, a CCD (Charge Coupled Device) that is a photoelectric conversion element, and performs imaging conversion by photoelectrically converting imaging light incident from the optical system unit 2 and imaged on the light receiving surface. Is output to the video signal processing unit 4. At the time of shooting, for example, an instruction of a shutter speed determined according to the exposure setting result is notified from the CPU 10 to the video signal processing unit 4. The video signal processing unit 4 outputs a scanning timing signal corresponding to the notified shutter speed to the photoelectric conversion unit 3. The photoelectric conversion unit 3 performs scanning according to the scanning timing signal, executes photoelectric conversion processing, and outputs a video signal.

The video signal processing unit 4 performs waveform shaping on the analog video signal (captured image signal) input from the photoelectric conversion unit 3 by performing gain adjustment and sample hold processing, for example, and then performs A / D conversion. By doing so, it is converted into digital video signal data. Then, for the digital video signal obtained by this conversion process, for example, a process for generating display luminance data is performed, and a video signal process for displaying on the display unit 7 is executed. Accordingly, the video signal processing unit 4 can also perform signal processing for a so-called on-screen display so that a character image or the like can be displayed superimposed on the captured image under the control of the CPU 10.
The actual display device employed as the display unit 7 is not particularly limited, but currently, liquid crystal display panels are widely employed.

In addition, the video signal processing unit 4 performs, for example, compression encoding processing by a predetermined method on the digital video signal obtained by converting the analog video signal input from the photoelectric conversion unit 3 to generate compressed video data. Is possible.
The digital video camera of this embodiment also has a still camera function. That is, it is possible to generate a still image data file in a predetermined format as a photograph for the captured image signal. Such image processing is also performed by the video signal processing unit 4.

Further, the video signal processing unit 4 uses an image (video) signal input from the photoelectric conversion unit 3, an AV (Audio Video) data file (AV file) read from a medium to be described later, and the like in a predetermined format. It can be converted into an analog video signal or a digital video signal and output to an external device or the like via the image input / output unit 5.
The image input / output unit 5 can input a video signal of a predetermined method from the outside, and the input video signal can be displayed on the display unit 7 through the processing of the video signal processing unit 4. Further, the video signal processing unit 4 converts the video signal input by the image input / output unit 5 into recording data and transfers it to the media controller 13 in the same manner as the analog video signal input from the photoelectric conversion unit 3. You can also.
Correspondingly, the image input / output unit 5 includes, for example, a video (image) signal output terminal / video signal input terminal according to a predetermined method.

In addition, the digital video camera 1 according to the present embodiment includes an audio processing unit 8 and an audio input / output unit 9 so that audio signals can be input / output.
First, for voice input, a microphone or the like is provided as the voice input / output unit 9, and external voices are collected and converted into voice signals to be inputted. The audio signal input in this manner is output to the audio processing unit 8. The audio processing unit 8 performs audio signal processing such as conversion into compressed audio data encoded by an audio compression encoding method corresponding to compression encoding of a captured image.

The CPU 10 forms an AV file of a predetermined format from the compressed video data for the captured image obtained by the video signal processing unit 4 and the compressed audio data for the collected sound obtained by the audio processing unit 8. Control processing is executed. In this AV file, the playback time axis of the sound output by reproducing the compressed audio data is synchronized with the moving image output by reproducing the compressed video data. The configuration for actually forming the AV file may be a software configuration for digital signal processing obtained by the CPU 10 executing the program, or hardware for forming the AV file. In addition, the CPU 10 may be configured to control the operation of the hardware.
The data as the AV file is transferred to the media controller 13 as recording data, for example, under the control of the CPU 10. The CPU 10 can also transfer a still image data file of a predetermined format as a photographic image generated by the video signal processing unit 4 to the media controller 13 as recording data.

  The audio input / output unit 9 may be configured to include an audio signal input terminal and the like to input an audio signal from an external audio device or the like. The audio processor 8 converts the audio signal input from the audio signal input terminal into a digital audio data file in a predetermined format. The CPU 10 can also transfer data of such a digital audio data file to the media controller 13 as recording data.

  The media controller 13 is configured to be able to execute control processing related to data processing for these media in association with predetermined different types of external media (storage media) and external storage devices (storage devices) in cooperation with the CPU 10. Is done. Data processing for the media here refers to data to be stored in the media, such as media format processing and file write / read processing for file management information (file management information). Any related process.

In the present embodiment, a hard disk drive (HDD) is first connected to the media controller 13. The HDD is a storage device including a magnetic disk as a storage medium, which is called a hard disk as is well known, and currently, a large capacity of a gigabyte class can be obtained at a relatively low cost. As is well known, physical data is read / written from / to a magnetic disk as a storage medium by applying a magnetic field and detecting a magnetic field while tracing a track formed on the magnetic disk by a magnetic head. Realized.
In this case, the HDD may be fixedly incorporated in the digital video camera 1, for example, or may be removable from the digital video camera 1 (host) according to a predetermined standard. It may be said.

Also, in this figure, the media controller 13 is capable of data processing corresponding to a predetermined type of optical disk, magneto-optical disk, and a semiconductor storage device which is a storage device including a semiconductor memory element. .
In the case of dealing with optical discs and magneto-optical discs, it is actually provided with a device as a drive configured to be able to write / read data corresponding to these recording (storage) media, and these devices and media controllers 13 will be connected.
In the case of supporting a semiconductor memory device, the main body of the digital video camera 1 is provided with a slot in which the semiconductor memory device is attached and detached according to the actual standard of the semiconductor memory device. When the semiconductor memory device is properly loaded in the slot, the pin terminal of the semiconductor memory device is connected to the electrode at the connector portion of the slot, and the semiconductor memory device can communicate with the media controller 13. It will be connected as possible.

  As described above, the media controller 13 sends the recording data to the media (storage medium, storage device) connected to the media controller 13 in response to the transfer of the recording data. Is further transferred to the medium selected as the target. In the medium to which the data has been transferred, the data is written and stored in the storage area in accordance with an instruction from the media controller 13 side. In this way, data stored in the medium is stored and managed as a file. Note that management of files stored on the media is performed by a predetermined file system.

For example, when playing back an AV file as playback of a file stored in the medium, the CPU 10 and the media controller 13 access and read the designated AV file. The AV file read in this way is separated into compressed video data and compressed audio data by processing of the CPU 10, for example, and the compressed video data is transferred to the video signal processing unit 4, and the compressed audio signal is processed by the audio processing unit. 8 is handed over.
In this case, the video signal processing unit 4 and the audio processing unit 8 respectively perform necessary reproduction signal processing including demodulation processing on the compressed video data and the compressed audio data transferred as described above. As a result, an image obtained by reproducing the compressed video data is displayed on the display unit 7 and the audio input / output unit 9 has an audio signal obtained by reproducing the compressed audio data in synchronization with the reproduction time of the image. Then, it can be output as audio by the speaker, or can be output from the headphone terminal.

  In addition, for example, an audio data file reproduced from a medium is output as a predetermined format audio signal and audio data to the outside via the audio input / output unit 9 after being subjected to the audio signal processing of the audio processing unit 8. It is also possible. In this case, the audio input / output unit 9 includes an audio output terminal corresponding to a format of a predetermined audio signal and audio data output from the audio processing unit 8.

A CPU (Central Processing Unit) 10 executes various control processes for the digital video camera 1 by executing a program. The ROM 11 stores various setting information used for the CPU 10 to execute processing in addition to various programs executed by the CPU 10. The RAM 12 is used as a work area when the CPU 10 executes processing according to a program, and holds data such as various arithmetic processing results.
The non-volatile memory 12a is formed of a memory element such as a flash memory that does not erase the stored contents even when the power supply is stopped, and data writing / reading is executed under the control of the CPU 10. The The data (information) to be stored in the nonvolatile memory 12a is generally setting information whose contents are appropriately changed, but is not particularly limited, and the actual specifications of the digital video camera 1 are not limited. It is sufficient to store various necessary information according to the above.

In this case, the operation input unit 15 collectively indicates various operators provided in the digital video camera 1. For example, the operators in the operation input unit 15 include a shutter button operated at the time of taking a picture, an operator for selecting a shooting mode, an operator for increasing / decreasing parameters, and the like.
Furthermore, the operation input unit 15 in this case includes a configuration for realizing an input operation as a GUI using, for example, the display screen of the display unit 7.

  The communication unit 16 is a part configured by mounting hardware and software for communicating with an external device by a predetermined data communication method according to the control of the CPU 10. The data communication system supported by the communication unit 16 is not particularly limited regardless of whether it is wired or wireless, and the number of corresponding data communication systems should not be limited. At present, the data communication system can be a network such as Ethernet (trademark), data bus standards such as USB (Universal Serial Bus), IEEE (the Institute of Electrical and Electronic Engineers) 1394, etc. . In the case of wireless, short-range wireless communication between devices such as Bluetooth (trademark) and wireless LAN (Local Area Network) standards such as IEEE802.11a / b / g can be cited.

  The power supply unit 17 supplies operating power to various hardware devices in the digital video camera 1 and includes, for example, a power supply circuit that operates by receiving power supply from a battery or a power adapter.

As described above, in the digital video camera 1 according to the present embodiment, the AV file obtained by imaging / sound collection is mainly stored in the HDD, various optical disk-shaped recording media (including magneto-optical disks), and the semiconductor storage device. It can be stored in a medium (storage medium).
The file stored in the medium as described above is normally managed by a file system in a predetermined format. In this embodiment, the file is managed by a FAT (File Allocation Table) file system. It is supposed to be. As is well known, the FAT file system manages files by a tree-type directory structure, and data writing / reading is performed by a logical minimum data management unit called a cluster. It is said that. A cluster is a unit obtained by collecting a predetermined number of sectors, which are the minimum units of physical data writing / reading on a medium.

FIG. 2 shows a general system configuration of the FAT file system using a hierarchical model.
First, this hierarchical model is roughly divided into a software layer and a hardware layer as a lower layer.
In this case, the software layer corresponds to a program executed by the CPU and software processing realized by various firmware, middleware, and the like in a device serving as a host (in the embodiment, the digital video camera 1) for the medium. It is supposed to be. As shown in the figure, the software layer in this case includes the application 100, the file system 101, and the device driver 102 from the upper layer to the lower layer.
It can be considered that the physical storage area of the medium itself is located in the hardware layer.

  The application 100 has a file recording / playback function, for example, and is compatible with application software that uses media, and makes an access request at the file level to the file system 101.

The file system 101 corresponds to software that realizes a function as a file system. In this embodiment, since the FAT file system is adopted, the software that provides the functions of the file system 101 is also configured corresponding to the FAT file system.
In the file system 101, the access request at the file level from the application 100 is converted into a cluster level that is a data management unit in the FAT file system format, and an access request is made to the device driver 102.

  The device driver 102 corresponds to software for controlling a medium as a device to be controlled. An access request at a cluster level according to the FAT file system format from the file system 101 is recorded and reproduced on the medium 103. The access level to the medium 103 is requested after conversion to the sector level as a unit.

The medium 103 in this case is logically formatted (initialized) according to the FAT file system. In FIG. 1, a storage medium and storage device connected to the media controller 13 such as an HDD, an optical disk-shaped recording medium, and a semiconductor storage device correspond to the medium 103 here. Then, in response to the sector level access request from the device driver 102, the medium 103 reads data from the designated sector address and returns it to the device driver 102. That is, an access response at the sector level is executed.
The device driver 102 receives an access response from the medium 103 at the sector level, that is, receives data in units of sectors, and treats the received data as data in units of clusters and transfers it to the file system 101 (at the cluster level). Access response).
The file system 101 transfers data received from the device driver 102 to the application 100 as file level data. The application 100 executes a required process at the application level according to, for example, an operation input by the user on the data received as a file.

  Further, the FAT file system manages storage files with a tree-type directory structure, and manages files as a cluster unit set. Such file management and data management are realized by providing directory entries and table information called FAT as is well known. The directory entry is information indicating the location of a file or directory (subdirectory) on the medium at the cluster level, and the FAT is information indicating a chain (link or link) at the cluster level that forms the directory or file.

FIG. 3 shows the format structure of the media according to the FAT standard.
Although a plurality of FAT formats are defined, here, the format structure corresponding to each of the FAT16 and FAT32 formats is shown.
First, the format structure corresponding to the FAT 16 shown on the left side of FIG. 3 will be described.
The structure shown in this figure is logical according to LBA (Logical Block Addressing). In other words, the top sector is the top sector (LBA = 0), and the block (sector) number advances downward thereafter.
Further, in the FAT file system, one physical storage area can be divided into a plurality of partitions, but here, for the convenience of explanation, a format structure in the case of one partition is shown.

  First, the head sector represented as LBA = 0 is a boot area called MBR (Master Boot Recorder).

The structure of MBR is shown in FIG.
One sector has a size of 512 bytes. Therefore, the MBR is 512 bytes. In FIG. 4A, for the 512 bytes in the MBR area, the last byte position from the beginning is expressed by assigning a hexadecimal number from 0000h to 01FFh, and then arranged in units of 16 bytes. As shown. In the hexadecimal notation, h indicating the hexadecimal notation is added to the end of the numerical value, such as 0000h or 01FFh.
First, a 446-byte area from byte positions 0000h to 01BDh stores a code (boot code) for booting when used as an OS (Operating System) boot medium. It is an area.

  A 64-byte area from byte positions 01BEh to 01FDh in the MBR is used as a partition table, and stores predetermined information required for each partition at the time of startup. This partition table area is further divided into four areas in units of 16 bytes. These four divided areas are partitioned into partition 1, partition 2, partition 3, and partition 4 in order from the top. It is a corresponding area. Each area corresponding to each of these partitions is an entry area for each partition.

  Also, 55AAh is stored in the final 2-byte area in the MBR as an identifier that the current sector is the MBR.

The partition entry has a structure shown in FIG. First, the most significant byte position 00h is an area for storing a flag indicating whether or not the partition is designated as a startup drive.
In the subsequent 3-byte area at byte positions 01h to 03h, a value expressing the start sector of the partition in terms of CHS (Cylinder / Head / Sector) is stored. A 3-byte area consisting of byte positions 05h to 07h stores a value representing the end sector of the partition in CHS.
In addition, a value indicating the start sector of the partition by LBA is stored in a 4-byte area at byte positions 08h to 0Bh.

  A 4-byte area consisting of byte positions 0Ch to 0Fh stores a value indicating the data size (partition size) of the partition.

  A 1-byte area indicated by the byte position 04h stores a value indicating a type of a platform, a file system, or the like corresponding to the partition, which is also called a system identifier.

Returning to FIG.
An empty area corresponding to a predetermined number of sectors is provided after the head sector as the MBR. Then, an area in units of partitions is formed by a sector area after this empty area.

An area from the first sector to a predetermined number of bytes in one partition is a system area for storing system-related information.
In this system area, an area having a predetermined number of bytes starting from the first sector is a BPB (BIOS Parameter Block / Boot Parameter Block). As described above, necessary data to be used by the block device control program is stored. The information stored in the BPB includes information such as the number of FAT areas, the start sector of the main FAT area, and the number of sectors in the FAT area, which will be described below.

  Following BPB, FAT1 and FAT2 FAT areas are arranged in this order. Normally, one of the FAT1 and FAT2 areas is used as the main FAT area. The other FAT area is generally used as a spare area or backup area of the main FAT area, for example, as a mirror area obtained by copying the contents of the main FAT area.

These FAT areas are areas formed by arranging FAT entries in the order of cluster numbers in the data area. There is a one-to-one correspondence between a FAT entry and a cluster in the data area. In the FAT entry, as information on the cluster, for example, unused or in the corresponding file, according to the directory and file storage results. Information indicating any one of a cluster number, a defective cluster, an EOF (End Of File: last cluster in a file), etc. chained next to the current cluster is stored.
In the FAT16 format, the cluster number is expressed by 2 bytes (16 bits), and accordingly, the size of each FAT entry is also 2 bytes.

  Subsequent to the FAT1 and FAT2 areas, a root directory entry of a predetermined size is arranged. The root directory entry stores directory entries for directories and files in the root directory.

  A sector area lower than the root directory is a data area. Writing / reading data to / from this data area is managed by the FAT file system. Therefore, as shown in the figure, the file system format structure is such that the data area is managed in cluster units composed of a sequence of one or more predetermined number of sectors. As described above, the FAT area is formed with the FAT entries corresponding to all the clusters forming the data area in principle.

Next, a format structure corresponding to FAT32 shown on the right side of FIG. 3 will be described.
Even in the format structure corresponding to FAT32, MBR is arranged in the head sector represented by LBA = 0. Then, an area in units of partitions is arranged subsequent to the empty area of a predetermined number of sectors arranged after the MBR.

As a system area in the partition area of the FAT32 compatible format structure, an FSinfo area is provided after BPB.
The FSinfo is an area for storing predetermined information used to calculate the free space in the partition. The FAT areas of FAT1 and FAT2 are sequentially arranged following FSinfo.

  The FAT area in the case of the FAT32 format is also formed by arranging FAT entries corresponding to the clusters in a one-to-one order in the order of the cluster numbers. The FAT entries include predetermined entries for the corresponding clusters according to the directory and file storage results. Is stored. However, in the FAT32 format, since the cluster number is expressed by 4 bytes (32 bits), the size of each FAT entry is also divided by 4 bytes.

Further, in the FAT32 format structure, the root directory entry area provided in the system area in the FAT16 format structure is omitted.
In the FAT32 format structure, the root directory is placed in the data area. The starting cluster number of the root directory in the data area is indicated by a value stored in a predetermined area (RootClus) in the BPB. When accessing the root directory, the cluster number recognized with reference to the RootClus is accessed. To be. The starting cluster number of the root directory indicated by RootClus is usually 2.

  In this case as well, the data area is an area in which writing / reading of data is managed in cluster units by the FAT32 file system.

FIG. 5 shows the structure of a directory entry defined in the FAT file system. Here, the structure of the directory entry corresponding to FAT32 is shown.
In this case, the directory entry is 32 bytes. In this figure, each byte position from the upper byte to the lower byte is indicated by a value from 0h to 1Fh.
In 32 bytes forming the directory entry, an 8-byte area from the most significant byte position 0h to byte position 7h stores the name of the current file or current directory indicated by the current directory entry.
In the subsequent 3-byte area from the lower byte position 8h to the byte position Ah, an extension corresponding to the file format of the current file is stored.

In the subsequent lower byte position Bh, a value indicating the attribute for the current file / current directory is stored.
Here, the byte position Ch is a reserved area.
A 3-byte area from byte positions Dh to Fh stores a value indicating the creation time of the current file / current directory.
A 2-byte area at byte positions 10h to 11h stores a value indicating the creation date of the current file / current directory.
The 2-byte area at byte positions 12h to 13h stores a value indicating the date (last access date) when the current file / current directory was last accessed.

  In addition, depending on the total of 4 bytes of the 2-byte area by byte positions 14h-15h and 2-byte area by byte positions 1Ah-1Bh, the head position on the medium where the current file / current directory is stored is indicated by the cluster number. To be done. That is, the value of the leading cluster number for the current file / current directory is stored in this 4-byte area. For the 2-byte area at byte positions 14h-15h, the value of the upper 4 bytes for the leading cluster number is stored. For the 2-byte area at byte positions 1Ah-1Bh, the lower 4 bytes of the first cluster number are stored.

The 2-byte area at byte positions 16h to 17h stores a value indicating the time (recording time) when the recording (last update) for the current file / current directory is executed.
The 2-byte area at byte positions 18h to 19h stores a value indicating the date (recording date) when the recording (last update) for the current file / current directory was executed.
A 4-byte area from byte positions 1Ch to 1Fh stores a value indicating the size (capacity) of the current file / current directory.

FIG. 6 shows an example of file management by the FAT file system. In this figure, a case where the data is formatted according to FAT32 is shown.
Here, it is assumed that at least the file A, the file B, the file C, and the file D are stored in the data area, and the directory entries of the files A, B, C, and D are respectively shown in FIG. b) As shown in (c) and (d). As an explanation in this figure, the first cluster number in the directory entry (byte position 14h-15h / 1Ah-1Bh)
Since the information is the main information, there is a portion omitted for information on other areas.

FIG. 6E shows a part of the FAT area, and has the contents of the FAT entry corresponding to the storage results of the files A, B, C, and D. In FIG. 6 (e), only the FAT entry contents corresponding to only the files A, B, C, and D are extracted in consideration of simplicity of illustration and easy understanding. As described above, in FAT32, each FAT entry has a size of 32 bits.
In addition, the FAT entry in the FAT area shown in FIG. 6E is incremented for each digit of the cluster number corresponding to the FAT entry as shown as 00000000h, 00000010h, 00000020h, 00000030h. They are arranged in a matrix of rows and columns indicating + 00h to + 0Fh, which are values of the least significant digit added to the cluster number value indicated by each row. For example, a FAT entry at a position where a row of 00000000h and a column of + 07h intersect corresponds to the cluster number 00000007h.

In the FAT file system, the first cluster represented by the cluster numbers 00000000h and 00000001h and the second cluster following this are reserved areas (RSV). Accordingly, the FAT entries corresponding to the cluster numbers 00000000h and 00000001h are also defined as reserved areas.
As a value stored in the FAT entry, the cluster number to be chained next to the current cluster is represented by 00000002h to 0FFFFFF6h. Further, EOF (last cluster (file end cluster) in a file including the corresponding cluster) is represented by EOF = 0FFFFFFFh. Further, in FIG. 6E, “−” indicates that the cluster is unused, but actually, for example, it is represented by a value of 00000000h.

In order to access the file A, first, the directory entry of the file A shown in FIG. 6A is accessed. For example, the directory entry itself of the file A is accessed as follows.
Taking the case where the file access command is an absolute path as an example, in order to access the directory entry of file A, the root directory is first accessed, and the directory entry is followed from here according to the path. Is done. In the process of tracing a directory entry, a subdirectory of a certain current directory may be traced. As is well known, the parent-child relationship between a parent directory and a child directory is also expressed by the directory entry. The For this purpose, for example, the directory entry on the parent directory side is provided with a name indicating the child directory, and the directory entry of the child directory indicated by the directory entry on the parent directory side has the parent directory. A directory entry storing information indicating this in the name area is provided. As a result, the directory can be traced in both directions from the parent to the child and from the child to the parent.
As a result of tracing the directory entry according to the path as described above, the directory entry of the file A is finally reached as the access destination.

When the directory entry of the file A is accessed, the file A itself is subsequently accessed starting from the directory entry of the file A.
The access to the file A itself is conceptually as follows.
In order to access file A, the beginning (start) cluster number in the directory entry of file A is acquired. This leading cluster number indicates the starting cluster number in which data of file A is stored in the data area. In this case, it is 00000007h as shown in FIG. That is, at this stage, it is recognized that the start cluster number of file A is 00000007h.
Therefore, the file system accesses the FAT entry corresponding to the cluster number 00000007h in the FAT area shown in FIG. 6E, and refers to the value stored in the FAT entry. In this case, 00000008h is stored in the FAT entry corresponding to the cluster number 00000007h. As a result, the file system recognizes that the data of the file A is connected to the cluster data of the cluster number 00000008h following the cluster data of the cluster number 00000007h. Then, when accessing and referring to the FAT entry corresponding to the cluster number 00000008h, since 00000009h is stored here, the data of the file A is further followed by the cluster data of the cluster number 00000008h. It is recognized that the data of the cluster with the number 00000009h is concatenated. Therefore, when referring to the FAT entry with the cluster number 00000009h, since the value indicating EOF is stored here, the file A is recognized to end with the cluster with the cluster number 00000009h.
From this, it is recognized that the file A is formed by concatenating cluster data in the order of cluster numbers 00000007h-00000008h-00000009h as shown in the cluster chain of FIG. 6 (f). The file system is made to access the cluster having the cluster numbers 00000007h-00000008h-00000009h, and access to the file A is thereby performed.

As can be seen from the above description, the data position of the file stored in the data area is indicated by the top cluster number stored in the directory entry and the contents of the FAT entry in the FAT area that is referenced from this start cluster number. The file can be accessed by referring to the information.
It can also be seen that the management of files stored in the data area by the tree-type directory structure is expressed by directory entries.

The storage locations of the remaining files B, C, and D are managed as follows using the file management information including the directory entry and the FAT area.
First, regarding the file B, as shown in the directory entry of FIG. 6B, the cluster number of the first (starting) cluster of the file is 0000000Ah. Therefore, referring to the FAT entry corresponding to the cluster number 0000000Ah in the FAT area shown in FIG. 6E, the cluster number 0000001Fh is shown as chain information indicating the next cluster. Therefore, when the FAT entry is further traced to refer to the FAT entry corresponding to the cluster number 0000001Fh, the cluster number 00000025h is stored as chain information. The FAT entry corresponding to the cluster number 00000025h stores the cluster number 00000031h. The FAT entry corresponding to the cluster number 00000031h stores the cluster number 00000030h. The FAT entry corresponding to the cluster number 00000030h stores a value indicating EOF.
In this way, the file B is connected to the data stored in the cluster according to the order of the cluster numbers 0000000Ah-0000001Fh-00000025h-00000031h-00000030h as shown in FIG. 6 (g) by the directory entry and the FAT area. It is expressed that it is formed by.

  As for the file C, as shown in FIG. 6C, first, in the directory entry of the file C, the cluster number 0000001Bh is shown as the head (start) cluster of the file. Based on this, depending on the contents referred to from the FAT entry of the cluster number 0000001B in the FAT area shown in FIG. It is formed by concatenating data stored in a cluster in the order of 00000012h-00000013h-00000014h-00000003h.

  For the file D, the directory number of the file D shown in FIG. 6D indicates the cluster number 0000002Ch as the head (start) cluster of the file. Based on this, as the contents referred to from the FAT entry of the cluster number 0000002C in the FAT area shown in FIG. It is formed by concatenating data stored in a cluster in the order of 0000002Eh-0000002Fh-00000038h-00000039h-0000003Ah-0000003Bh.

Based on the format contents of the FAT file system described so far, first, the circumstances leading to the present invention will be described with reference to FIG.
Here, assuming that three files (independent data units) of files A, B, and C have been recorded on the medium, an example of recording states of these files A, B, and C on the medium is shown in FIG. ).

In FIG. 7A, a part of a data area in a medium formatted under the FAT file system (here, FAT32) is schematically shown in cluster units (data write units). The 15 clusters from cluster a to cluster o shown in this figure are actually cluster groups that are arranged in ascending order of cluster numbers.
First, the cluster a which is the head in the cluster area shown in this figure is used as a directory entry storage cluster for storing directory entries. According to the normal rule of FAT32, a cluster used as a directory entry storage cluster may store as many directory entries as can be stored according to the cluster size.
A cluster is normally formed by continuously sizing the size of sectors (lower data write units) to a power of 2 (1, 2, 4,... 64, 128...). As an example, if the cluster size is 32 KB based on a sector size of 512 bytes, the directory entry is 32 bytes, so that a maximum of 1024 directory entries can be stored in one directory entry.
In the directory entry storage cluster in this case, as shown in FIG. 7B, a total of three directory entries corresponding to each of the files A, B, and C are packed by 32 bytes from the head. It is assumed that it is stored in this way.

As shown in FIG. 7A, the file A is recorded in a state of being fragmented into three segments (data unit parts) of segments 1, 2, and 3. Here, the segment refers to a group of data portions recorded continuously using one or more clusters (data writing units) on the medium (in the partition).
Segment 1 is an area recorded using three consecutive clusters of clusters b, c, and d. The segment 2 is recorded by using an area of two consecutive clusters of clusters g and h. Segment 3 is recorded using an area of three consecutive clusters of clusters m, n, and o. In this case, the file data of file A is formed by concatenating the data in the segments in the order of the segment numbers.
File B is recorded so as to be completed as one segment using two consecutive clusters of clusters e and f.
File C is recorded so as to be completed as one segment using four consecutive clusters of clusters i, j, k, and l.

  The procedure for accessing the file data in order to reproduce the file recorded on the medium in this way is as follows. Here, the file A will be described as an example, but the procedure described below is the same for the files B and C consisting of one segment, and a general file access procedure under the FAT file system is as follows. Is.

In order to access the file A, first, the directory entry of the file A recorded in the cluster a is accessed to obtain the head cluster number. In this case, the leading cluster number indicates cluster b. Therefore, by accessing the cluster b indicated by the leading cluster number, the actual data for the leading cluster of the file A can be read.
Thereafter, in order to read the actual data of the file A, it is necessary to recognize a cluster chained after the cluster a. For this purpose, the FAT area shown in FIG. 6E is referred to. As an access to the first FAT area for this purpose, the FAT entry corresponding to the first cluster number stored in the directory entry is searched and read into the work RAM area for the FAT area secured in the RAM 12, for example. At this time, not only the FAT entry corresponding to the target first cluster number but also the FAT entry work RAM area for the FAT area are grouped according to the size set as the FAT area work RAM. Can be read and held. For example, from the FAT entries held in the work RAM area for the FAT area, the cluster number of the chain destination of the FAT entry corresponding to the head cluster number is first recognized. That is, the cluster number which becomes the second cluster as the file A is recognized. Then, the actual data of the second cluster is read by accessing the cluster of the recognized number and executing the data reading.

Subsequently, for the FAT entry held in the FAT area work RAM area, the media cluster is accessed while tracing the cluster chain by referring to the information of the next chain destination cluster number as described above. The actual data of file A is read. In this process, it is assumed that the cluster chain cannot be traced any more for the FAT entry held in the work RAM area for the FAT area. That is, when the cluster number of the chain destination next to a certain FAT entry is recognized, the FAT entry corresponding to the chain destination cluster number is not held in the FAT area work RAM area. . In this case, the FAT entry previously held in the FAT area work RAM area is discarded, the FAT area on the medium is accessed, the FAT entry of the last recognized cluster number is searched, and this FAT entry is searched. Are read out and stored in the FAT area work RAM area. Then, referring to the next chain destination cluster number stored in the FAT entry as described above, the actual data of the file is read in units of clusters in the order of the cluster chain.
Then, this procedure is repeated, and finally, at the stage where reading of the actual data of the cluster corresponding to the FAT entry in which EOF is indicated as the next chain destination cluster number is completed, for file playback, etc. The access to the file A will end. For example, the file data of the file A read out at the file system level in this way is passed to, for example, an application for file reproduction that is an upper processing layer for the file system, and the file reproduction is performed by this application. Therefore, a decoding process for reproduction, a reproduction output process according to a predetermined mode, and the like are performed.

In this way, access to the file data under the FAT file system is executed. However, according to the above procedure, the FAT area on the medium is accessed until the access to one file is completed. It can be seen that the procedure of accessing, searching for the target FAT entry, and reading it into the work RAM may be executed a plurality of times.
Such access to the FAT area is a processing that is correspondingly heavy for the CPU. Therefore, as the number of executions per unit time for the access operation to the FAT area increases, overhead increases. There is a possibility that problems such as the remarkable decrease in data processing speed for file reproduction and the like cannot be ignored.
In addition, the number of executions of the access operation to the FAT area per unit time increases as the file size increases and the number of used clusters increases, and the assignable size of the work RAM area for the FAT area increases. It can be said that the smaller the value, the higher the tendency.

  As a large-sized file, a moving image file can be cited at present, but the moving image file has time series characteristics, and real-time characteristics and a high data rate are required for reproduction. For example, when such a moving image file is played back, if a processing time delay of a certain level or more occurs as an overhead caused by access to the FAT area, for example, reading from the media is not in time, and the playback buffer is underexecuted. There is a high possibility that a proper reproduction operation cannot be obtained in a flow state.

From the viewpoint of the allocatable size of the work RAM area for the FAT area, the following can be said. For example, in a personal computer or the like, it is possible to allocate an appropriate size for the work RAM area for the FAT area by mounting a RAM of an appropriate size from the beginning. It is possible to increase the work RAM area for the area.
On the other hand, in a device in which a RAM is fixedly built in the device in advance, the RAM capacity is determined in balance with cost and general performance required for the digital video camera 1. Become. However, the actually set RAM capacity is correspondingly small, and therefore the size that can be allocated to the work RAM area for the FAT area is also reduced.
For this reason, the problem of a decrease in data processing speed due to access to the FAT area is required to have a high data rate real time property with a large size such as a moving image file in a device in which a RAM or the like is fixedly incorporated. This is especially true for devices that process files. Incidentally, the digital video camera 1 of the present embodiment is also one of such devices.

  Therefore, the present embodiment is configured to obtain a file access operation that can obtain a higher data processing speed as compared with the case where access to the FAT area is essential. This point will be described below.

FIG. 8 shows an example of recorded contents of a medium under the present embodiment. 8 also shows a state in which three files A, B, and C having the same contents as those in FIG. 7 are recorded on the medium in order to make the comparison with FIG. 7 easy to understand. .
Also in this case, FIG. 8A schematically shows a part of the data area in the medium formatted under the FAT 32 in cluster units. In other words, this embodiment is also based on the fact that the FAT file system is adopted as the processing hierarchy of the file system.
In FIG. 8A, 17 clusters including clusters a-1, a-2, a-3, and b to o are shown. In actuality, these clusters a-1, a-2, a-3, and b to o are continuous areas so that the cluster numbers are in ascending order. Even when this is viewed as an LBA (sector), the LBA value (sector number) is incremented on the premise of the column order of the clusters a-1, a-2, a-3, and b to o.

The recording states of the files A, B, and C shown in FIG. 8A on the medium are the same as those in FIG. That is, the file A is fragmented into three segments 1, 2, and 3, and the file data of the file A is formed by concatenating the data in the segments in the order of the segment numbers. Segment 1 is recorded using three consecutive clusters of clusters b, c, d, segment 2 is recorded using two consecutive clusters of clusters g, h, and segment 3 is recorded as clusters m, n. , O are recorded using three consecutive clusters. The file data of file A is formed by concatenating data in segments in the order of segment numbers.
File B is recorded so as to be completed in one segment using two consecutive clusters of clusters e and f.
File C is recorded so as to be completed in one segment using four consecutive clusters of clusters i, j, k, and l.

  In addition, as shown in FIG. 8A, as clusters a-1, a-2, and a-3, three clusters are provided as directory entry storage clusters (information storage areas). Yes. Cluster a-1 is a directory entry storage cluster corresponding to file A, and clusters a-2 and a-3 are directory entry storage clusters corresponding to files B and C, respectively. That is, in this embodiment, a directory entry storage cluster for one cluster is formed for each file.

The structure of the directory entry storage cluster (a-1) corresponding to the file A is shown in FIG.
As shown in this figure, in the directory entry storage cluster corresponding to the file A, first, the directory entry (entry information) corresponding to the file A is stored in the first 32-byte area. That is, a directory entry corresponding to the file is placed at the head of the directory entry storage cluster corresponding to one file.
In addition, in the case of this file A, the LBA access information (data unit management information) 1, 2, and 3 is arranged so as to sequentially fill the empty area following the directory entry.

Although the structure of the LBA access information will be described later, one LBA access information corresponds to one segment and has the same 32-byte size as the directory entry. In the case of file A, it consists of three segments, segments 1, 2, and 3. Therefore, LBA access information 1, 2, and 3 are provided corresponding to these segments 1, 2, and 3, respectively. Become.
In addition, when the file A is formed by concatenating data in the order of segments 1, 2, and 3, the directory entry storage cluster ( a-1). That is, the LBA access information is placed in an arrangement order corresponding to the order of the segments forming the file.

  Further, as shown in FIG. 8C, the directory entry storage cluster a-2 corresponding to the file B first stores the directory entry corresponding to the file B in the first 32 bytes. Since the file B in this case is completed by one segment consisting of two clusters of clusters e and f, only one LBA access information is required. Therefore, the LBA access information 1 of the file B is placed as one LBA access information corresponding to one segment consisting of the two clusters e and f with respect to the 32 bytes following the directory entry.

  The directory entry storage cluster a-3 corresponding to the file C is shown in FIG. Also in this case, first, the directory entry corresponding to the file C is stored in the first 32 bytes in the directory entry storage cluster a-3. The file C in this case is also completed with one segment consisting of four clusters i, j, k, and l. Therefore, the LBA access information 1 of file C corresponding to one segment consisting of the four clusters i, j, k, and l is placed in the 32 bytes following the directory entry.

As described above with reference to FIG. 5, one byte (8 bits) as the byte position Ch in the directory entry is a reserved area. In the present embodiment, in this reserved area, FIG. As shown, an area for storing the LBA flag (holding state information) is defined.
In FIG. 9, the area of the byte position Ch of the directory entry is shown by a bit string structure of 8 bits from bit position 0 to bit position 7. Here, 1 bit at bit position 7 is assigned as a bit area for the LBA flag.

The LBA flag is a flag indicating whether or not LBA access information is stored in the current directory entry storage area for storing the current directory entry. When a bit value of 0 is stored as the LBA flag, it indicates that no LBA access information is stored in the current directory entry storage area. On the other hand, when a bit value of 1 is stored as the LBA flag, this indicates that LBA access information is stored in the current directory entry storage area.
In the reserved area of the directory entry, the bit position other than the bit position 7 may be set as an area for storing the defragmentation reserved area reservation flag.
Also, for convenience of explanation, the remaining 7-bit area from bit position 0 to bit position 6 in the reserved area at byte position Ch of the directory entry is undefined, and stores a bit value of 0 for each. It shall be.

FIG. 10 shows an example of the structure of LBA access information.
As described above, the LBA access information has the same 32-byte size as the directory entry. Then, as shown in the figure, the value of E5h is stored for the first byte position 0h. In the FAT file system, when E5h is stored in the first byte of a 32-byte information unit, it is defined as indicating that the directory entry has been deleted. Therefore, the existing FAT file system handles the LBA access information as a deleted directory entry. Thereby, when performing file access to a medium by an information processing apparatus other than that corresponding to the present embodiment, a failure due to storing LBA access information is prevented. In the existing FAT file system, a conventional file access is executed using the directory entry and the FAT area. That is, consideration is given so as to obtain compatibility with an existing FAT file system.

The subsequent 2-byte area at the lower byte positions 1h-2h indicates the value of the number assigned to the current LBA access information within the range corresponding to the file.
The 2-byte area at byte positions 3h-4h indicates the total number of LBA access information within the range corresponding to the corresponding file.

A 4-byte area from byte positions 5h to 8h stores the value of the start LBA indicating the recording start position (start position) on the medium of the segment to which the current LBA access information corresponds. That is, the start position of the data recorded on the medium is not expressed by the cluster originally supported by the FAT file system, but by the sector level corresponding to the device driver which is a lower processing layer.
A 4-byte area from byte positions 9h to Ch stores a value indicating the size of the segment to which the current LBA access information corresponds. Here, the size is expressed by the number of sectors as the size expression, corresponding to the fact that the start position of the segment is expressed at the sector level by the head LBA.
The remaining 19-byte area from the lower byte positions Dh to 1F is set as a reserved area.

Based on the description of the LBA flag and the LBA access information shown in FIGS. 9 and 10, the file management in this embodiment will be described again with reference to FIG.
First, the file A will be described.
In the directory entry of file A, LBA flag = 1 is set to indicate that LBA access information exists.

It should be noted that the directory entry of the present embodiment adopts the basic structure described with reference to FIG. 5 except that the LBA flag area is defined.
Accordingly, in each area other than the reserved area (byte position Ch) of the directory entry of file A, an appropriate value is stored according to the actual contents of file A and the like by processing at the file system level. For example, the actual cluster number as the cluster b is stored in the first cluster number (byte positions 14h-15h, 1Ah-1Bh), and the file data of the entire file A is stored in the size (byte positions 1Ch to 1Fh). The effective data size is indicated.
In addition, although not shown in FIG. 8A, the medium is also provided with a FAT area, and maintenance is performed according to the file processing result by processing as a file system.

This means that in the present embodiment, the file can be recorded / reproduced even by a normal FAT file system. That is, regarding file access, it can be executed by the same procedure as described with reference to FIG. In addition, as described above, E5h is stored at the head of LBA access information, so that LBA access information is handled as a deleted directory entry during file access by a normal FAT file system. It is never mistaken for a legitimate directory entry and used.
In the case of this embodiment, as shown in FIGS. 8B, 8C, and 8D, when viewed as a directory entry, the files are discretely recorded in different clusters for each file. . However, according to a well-known algorithm for accessing a directory entry, it is not an obstacle to access that the directory entry is discretely recorded in different clusters for each file. In the conventional FAT file system (FAT32), a plurality of directory entries are permitted to be stored in different clusters.

  As described above, in response to the LBA flag = 1 being set in the directory entry of the file A, as shown in FIG. 8B, the directory entry storage cluster includes the LBA following the directory entry. Access information is provided. In the case of file A, three pieces of LBA access information 1, 2, and 3 are sequentially arranged according to being recorded on the medium in a state of being fragmented into three segments, ie, segments 1, 2, and 3. become.

The content of LBA access information 1 of file A is as follows.
First, E5h is stored in the first byte (byte position 0h). As described above, E5h is stored in the first byte for all LBA access information.
In the LBA access information number area (byte positions 1h-2h), a value indicating the number 1 is stored as the LBA access information corresponding to the file A.
A value indicating the total number of LBA access information corresponding to the file A is stored in the area of the total number of LBA access information (byte positions 3h-4h). Since the number of LBA access information corresponding to file A is 3, a value indicating 3 is stored.
In the head LBA area (byte positions 5h to 8h), the LBA value (sector number) of the sector that is the head (start position) of segment 1 of file A is stored. That is, the LBA value of the sector at the head of cluster b is stored.
The size area (byte positions 9h to Ch) stores a value indicating the number of used clusters by the number of sectors as the size of the segment 1 of the file A. Since the segment 1 in this case uses three clusters b, c, and d, a value expressing the three clusters by the number of sectors is stored.

The contents of the LBA access information 2 of the file A are as follows.
First, E5h is stored in the first byte (byte position 0h), and the LBA access information number area (byte position 1h-2h) stores a value indicating that the LBA access information corresponding to file A is No. 2. To do. In the area of the total number of LBA access information (byte positions 3h-4h), a value indicating 3 is stored as in LBA access information 1. As for the value of the total number of LBA access information, the same value is stored in all LBA access information corresponding to the same file.
In the head LBA area (byte positions 5h to 8h), the LBA value (sector number) of the start sector of cluster g, which is the head of segment 2 of file A, is stored.
The size area (byte positions 9h to Ch) stores a value indicating the size of segment 2 of file A (number of used clusters = 2) by the number of sectors.

The contents of LBA access information 3 of file A are as follows.
E5h is stored in the first byte (byte position 0h), and the LBA access information number area (byte position 1h-2h) stores a value indicating that the LBA access information corresponding to file A is number 3 To do. In the area of the total number of LBA access information (byte positions 3h-4h), a value indicating 3 is stored as in the LBA access information 1 and 2.
In the head LBA area (byte positions 5h to 8h), the LBA value (sector number) of the start sector of cluster m, which is the head of segment 3 of file A, is stored.
The size area (byte positions 9h to Ch) stores a value indicating the size of the segment 3 of the file A (number of used clusters = 3) by the number of sectors.

Since the files B and C are composed of one segment, only the LBA access information 1 is arranged as LBA access information corresponding to the files B and C, respectively.
As LBA access information 1 of files B and C, E5h is stored in the first byte (byte position 0h), and the LBA access information number area (byte position 1h-2h) indicates the number 1 Is stored. A value indicating 1 is stored as the area of the total number of LBA access information (byte positions 3h-4h).
For the first LBA area (byte positions 5h to 8h), file B stores the LBA value (sector number) of the start sector of cluster e, and file C stores the LBA value (sector number) of the start sector of cluster i. Store.
For the size area (byte positions 9h to Ch), file B stores a value indicating the size of 2 clusters (clusters e, f) by the number of sectors, and file C stores 4 clusters (clusters i, j, k, A value indicating the size of l) by the number of sectors is stored.

  By constructing the directory entry storage cluster in this way, in this embodiment, in addition to file access by processing as a normal FAT file system, file access with reference to LBA access information is possible. Become. The concept of file access using LBA access information will be described using file A in FIG. 8 as an example.

First, in the LBA access information 1, the start position for the segment 1 of the file A is indicated by the head LBA, and the size of the segment 1 is indicated. Therefore, by using these information items, it is possible to access the area from the start position to the end of segment 1 and read data. That is, it is possible to complete the data reading of the segment 1 portion in the file A. Based on the above, it can be said that the size information in the LBA access information is information indicating the end position of the segment.
Similarly, since the LBA access information 2 indicates the start LBA and size for the segment 2 of the file A, access from the start position to the end of the segment 2 is executed, and the segment 2 Data can be read.
Further, according to the head LBA stored in the LBA access information 3 and the size, access from the start position to the end of the segment 3 of the file A can be executed and the data of the segment 3 can be read.
Then, if the data of the segments 1, 2, and 3 of the file A read as described above are logically connected in the order of the segment numbers, the file data of the file A can be obtained.
Incidentally, for the files B and C, the file data is obtained at the stage where the reading of the data according to the first LBA access information 1 is completed.

  The flowchart of FIG. 11 shows processing that is executed by the CPU 10 in order to realize file access processing for reproducing a file recorded on a medium. The processing shown in this figure is realized, for example, when the CPU 10 executes a program such as an OS (Operating System) or a predetermined application 100 stored so as to be installed in the ROM 11 (or a medium such as an HDD). Therefore, media control such as data processing for media is processing under the FAT file system hierarchical structure shown in FIG. The same applies to the flowcharts described below.

  As for a file recorded on a medium corresponding to the present embodiment, the file management by the normal FAT file system is indispensable, as will be understood from the processing at the time of file recording to be described later. It is possible to manage only by using the FAT file system and LBA access information.

  Corresponding to this, when starting file access, first, as in the case of the normal FAT file system file access procedure, as shown in step S101, the directory entry of the file to be accessed recorded on the medium. To access and perform a read. For example, the directory entry that has been read is held in the work RAM.

In the next step S102, it is determined whether or not a bit value of 1 is set for the LBA flag by referring to the LBA flag in the byte position Ch area of the directory entry that has been read.
Here, if a negative determination result is obtained assuming that a bit value of 0 is set for the LBA flag, it means that the LBA access information corresponding to the access target file is not stored. Therefore, file access using LBA access information cannot be executed. Therefore, in this case, the process proceeds to step S111, and data read processing for file access according to the normal FAT file system is executed. The process for reading data (file access) in step S111 is realized by executing the procedure described in FIG. In addition, when executing the processing in step S111, the LBA access information is treated as a deleted directory entry because E5h is stored at the head, thereby hindering normal file access. The fact that it does not come is as explained above.

  On the other hand, if a positive determination result is obtained in step S102 that the bit value of 1 is set for the LBA flag, processing for file access using LBA access information in step S103 and subsequent steps. Migrate to

  As file access processing using LBA access information, first, in step S103, N = 1 is set for a variable N indicating the number of LBA access information, and then LBA access information N is referred to in step S104. Therefore, in this case, the LBA access information 1 is referred to. For this purpose, a 32-byte area following the directory entry accessed in step S101 is referred to.

In step S105, it is determined whether or not there is only one LBA access information corresponding to the file to be reproduced. For this purpose, it is only necessary to determine whether or not the value stored in the LBA access information total area (byte positions 3h-4h) in the LBA access information referred to in step S104 is 1.
If an affirmative determination result is obtained in step S105 that there is only one LBA access information corresponding to the file to be reproduced, the processing in step S110 is performed by skipping the processing in steps S106 to S109. Migrate to The case where there is only one LBA access information corresponds to the corresponding file having a structure composed of one segment.

On the other hand, if a negative determination result is obtained in step S105 that the LBA access information corresponding to the file to be reproduced is 2 or more, the processes in steps S106 to S109 are executed. Note that a negative determination result obtained in step S105 indicates that the reproduction target file has a structure composed of a plurality of segments.
In step S106, the medium is accessed and the data of the data is accessed based on the value of the head LBA (byte positions 5h to 8h) and the size (byte positions 9h to Ch) stored in the LBA access information N currently being referenced. Perform a read.
The LBA access information N to be referred to in step S106 is LBA access information 1 (N = 1) when the process in step S106 is the first executed after the process in step S104. become.
For reading data based on the head LBA (byte positions 5h to 8h) and size (byte positions 9h to Ch) stored in the LBA access information N, first, as the head LBA (byte positions 5h to 8h), Access the indicated LBA (sector number). Then, using this accessed LBA as the data read start position, the data corresponding to the size (byte positions 9h to Ch) is read in the LBA order. In the reading process in step S106, file management information such as a FAT entry is not accessed again during the reading process. To the last, based on the start LBA (byte positions 5h to 8h) and size (byte positions 9h to Ch) stored in the LBA access information N currently being referenced, the end position corresponding to the size from the read start position The data recorded in the continuous storage area up to is read at a time.
The data read in this way is once stored in the work RAM and then transferred to the upper processing layer such as a file playback application.
With the completion of the processing in step S106, reading of the data of the segment corresponding to the LBA access information N that is the reference target at this stage among the plurality of segments forming the file is completed.

  In step S107, the variable N indicating the number of the LBA access information is incremented by 1, and the LBA access information N is referred to in step S108. Thereby, in step S108, the LBA access information corresponding to the segment following the segment processed in the last step S106 is referred to.

  In step S109, it is determined whether or not the LBA access information that is currently referred to is the final one by the processing in step S108. For this determination, in the LBA access information currently being referenced, the value stored in the number area (byte positions 1h to 2h) and the value stored in the total number (byte positions 3h-4h) To determine whether or not the values are the same.

If a negative determination result is obtained in step S109 that it is not the final LBA access information, it means that there is still a segment that has not yet been read. Therefore, in this case, by returning to the process of step S106, based on the head LBA (byte positions 5h to 8h) and the size (byte positions 9h to Ch) indicated by the LBA access information that is currently the reference target. Data is read from the media and transferred to the upper processing layer. That is, the process for the segment following the segment processed in the previous step S106 is executed.
In this way, when the file is recorded in a state composed of a plurality of segments, the process of step S106 is repeated according to the number of segments. Then, after executing the process of step S106 for the last previous segment, a positive determination result is obtained in step S109 through the processes of steps S107 and S108, and the process proceeds to step S110. become.

As described above, when the file to be accessed has a structure composed of a plurality of segments, an affirmative result is obtained in step S109 and the last segment is to be processed, or the file to be accessed If a positive determination result is obtained in step S105 because the data is continuously recorded in a state where no fragment is generated, the process proceeds to step S110.
Also in step S110, the last segment or the storage area in which one file data is continuously recorded is targeted, and in the same manner as in step S106, the LBA access information corresponding to the last segment or the access target file is supported. From the read start position to the end position corresponding to the size based on the start LBA (byte position 5h to 8h) and size (byte position 9h to Ch) stored in the LBA access information stored only one The process of reading the data recorded in the continuous storage areas at once is executed.

However, in the processing stage of step S110, the end of the file is included for the read data.
As is well known, in the cluster including the end position of the file data (final cluster of the file), the file data end to the end of the cluster except when the file data size is an integer multiple of the cluster size. It will contain invalid data that occupies up to. For example, FIG. 8A also shows a state in which the end of the file data is filled with invalid data in each final cluster of the files A, B, and C.

However, since the size information stored in the LBA access information is obtained by converting the number of clusters used by a segment (or file data formed by one segment) into the number of sectors, the number of clusters is substantially reduced. It is meant to point to.
For this reason, the data read by the processing of step S110 and held in the work RAM may include invalid data following the end of the file data. Incidentally, since the segment that is read by the process of step S106 is not the final segment, the file data is written so as to completely fill the used cluster, and does not include invalid data.

Therefore, in step S110, when the read data is transferred to the upper processing layer, the invalid data is discarded and only valid file data is transferred. For this purpose, the file size indicated in the directory entry accessed in step S101 is used. The size information indicated in the directory entry indicates the size as file data (actual data). Therefore, in the present embodiment, for example, the value indicated by this size is obtained as a remainder value when divided by the cluster size. As a result, the size of the invalid data at the end of the read data held in the work RAM can be recognized. Therefore, data of the size obtained by subtracting the size of the invalid data from the size of the read data held in the work RAM is read from the head and transferred to the upper processing layer. As a result, only valid data is transferred.
Although not shown in this figure, the upper processing layer, which is an application for file reproduction, for example, constructs file data by sequentially concatenating the data transferred in FIG. Perform the required processing on the data.

Thus, in this embodiment, it is possible to access a file using LBA access information.
In file access using this LBA access information, one segment of data, that is, all data written using a continuous cluster area is accessed at a time by referring to one LBA access information. It is possible to execute reading. In other words, regarding the access to one segment, there is no need to search the FAT entry by repeatedly executing the access to the FAT area, unlike the file access according to the normal FAT file system.

In an easy-to-understand example, if the data that forms one file is continuously recorded on the medium without fragmentation, no matter how large the data size is for the file access using LBA access information, the FAT area The access from the start position to the end of the file data can be accessed at once and read without intervening access to the file. That is, in the file access using the LBA access information, when reading the file data of the same size, the access to the FAT area is not executed, so that the file access according to the normal FAT file system is performed. High-speed file data can be read out. As a result, the transfer rate of read data can be easily maintained at a certain level or more, which is advantageous particularly when a moving image file or the like is reproduced.
The same applies to a file recorded in a state of being divided into a plurality of segments as in file A in FIG. That is, the area for one segment can be accessed at a time and data can be read without being accessed in the middle of the FAT area. Therefore, for a file in which fragmentation has occurred, it is sufficient to access the LBA access information as many times as the number of fragments until the completion of reading of the file data. Compared with the case where access to the FAT area is executed, The number of accesses to the management information area is very small.

The LBA access information of this embodiment is a fixed length of 32 bytes, and is defined to be arranged in the order corresponding to the segment order of the file so as to continue to the first directory entry in the directory entry storage cluster. Yes.
Assuming this, in order to be able to access LBA access information in the order of segments forming the file, it is realized by a simple and simple algorithm that reads every 32 bytes following the directory entry. The processing burden for access can be greatly reduced as compared to the case of accessing the FAT area.
In other words, the LBA access information manages the order corresponding to the connection order of the segments in the file also by storing the information of the LBA access information number, but depending on the arrangement order in the storage area in the directory entry storage cluster In addition, the order corresponding to the connection order of the segments in the file is managed.

  In this embodiment, the LBA access information is stored together with the directory entry in the directory entry storage cluster. That is, a directory entry and LBA access information corresponding to the same file are stored in an area for one cluster. By adopting the FAT file system, the data processing in the file system is at the cluster level. On this assumption, for example, the work RAM area may be set to a size by an integer multiple of the cluster. . From this point of view, in this embodiment, by accessing the directory entry storage cluster on the medium and executing reading, LBA access information can be acquired simultaneously with the directory entry. In this case, the reference processing of the LBA access information after acquiring the directory entry does not require access to the medium, and is access to the work RAM, and can be performed at a higher speed.

As described above, the file access based on the LBA access information in the present embodiment is configured to obtain a higher file processing speed than before by eliminating access to the FAT area.
In addition, since the management information (LBA access information) mechanism for this purpose is simple, as described above, the processing associated with file access is light, and the above-mentioned file processing speed is high. It will be possible to promote the transformation. Further, since the LBA access information itself is formed with simple information items as illustrated in FIG. 10, for example, it is possible to perform light processing as maintenance accompanying file update or the like.

In order to enable file access using the LBA access information as described above, first, various kinds of information for file management according to the newly recorded file on the medium. It is necessary to perform maintenance so as to obtain the contents described with reference to FIGS.
Therefore, the flowchart of FIG. 12 shows processing operations performed by the CPU 10 for recording a new file on the medium and maintaining file management information in accordance with the recording of the new file. Here, the file management information refers to directory entries and FAT areas that are file management information corresponding to a normal FAT file system, and LBA access information that is file management information corresponding to LBA access.

First, when it comes to the timing at which processing for writing and storing (recording) a new file on a medium is reached, in step S201, the CPU 10 determines whether or not the current new recording target file is an LBA access compatible file. Determine whether or not. Here, the LBA access compatible file refers to a file managed so as to be accessible using the LBA access information.
In this embodiment, all files to be recorded on the medium may be uniformly managed as files that can be accessed using the LBA access information. Depending on the type of the file, a file managed only by the normal FAT file system is distinguished from a file managed so as to be accessible using the LBA access information.

More specifically, for example, a file of a still image, text format or the like that has a relatively small file size and does not require real-time property is managed only by a normal FAT fill system.
Even if these files are normally accessed by the FAT file system, the number of accesses to the FAT area is small, so that the overhead caused by this is hardly a problem.
Further, when file management is performed only by a normal FAT file system, the directory entry corresponding to the file is one cluster unit as shown in FIGS. 8B, 8C, and 8D. There is no need to use it, and it can be packed into one cluster as shown in FIG. 7 (b). Therefore, the consumption of the cluster can be suppressed and the storable capacity can be saved accordingly.
On the other hand, a file with a relatively large file size, such as a file in a video format, and a file type that requires a relatively high data rate is handled as an LBA access compatible file. In this way, priority is given to increasing the data processing speed corresponding to file access.

  There are several possible methods for determining whether or not the new recording target file is an LBA access compatible file in step S201. For example, it is conceivable that a file format to be used as an LBA access compatible file is determined in advance and the file format of the new recording target file is determined. In this case, for example, if an extension is provided as a file identifier, it is possible to determine by referring to this extension. Further, for example, it may be configured to make a determination based on information such as a file size and a data rate.

  If it is determined in step S201 that the new recording target file is not an LBA access compatible file and a negative determination result is obtained, the process proceeds to step S217. In step S217, normal file data recording processing according to only the FAT file system is executed. Note that the file data recording process only in accordance with the normal FAT file system is a well-known technique, and a description thereof will be omitted here.

  On the other hand, when a positive determination result is obtained in step S201 that the new recording target file is an LBA access-compatible file, the process proceeds to steps S202 to S216. As will be described later, this processing sequence is used to store a new recording target file on the medium in such a manner that file management is performed by both file management by the FAT file system and file management by LBA access information. It becomes processing.

First, in step S202, one cluster is reserved as a directory entry storage cluster from clusters that are unused at the present stage by referring to the FAT area or the like.
In the next step S203, a directory entry corresponding to the new recording target file is created for the cluster secured as described above. As a process for this, first, the first 32 bytes of the cluster secured as the directory entry storage cluster is further secured as a directory entry area, and each information item in the directory entry is converted into an actual new recording target file. The corresponding value is stored. It should be noted that the contents of each information item in the directory entry are already determined at this stage, including the cluster from which the new recording target file is to be recorded (first cluster number).
In the same step S203, after securing the directory entry as described above, E5h is set in advance for the byte position that is the first byte (byte position 0h) of the LBA access information in the directory entry storage cluster. The processing to be performed is also executed. That is, assuming that the directory entry storage cluster starts from the 0th byte, E5h is sequentially set for every 32 × n (n is a natural number) bytes of the directory entry storage cluster. The As a result, when this directory entry storage cluster is processed by a normal FAT file system, only the first 32 bytes of the area is recognized as a valid directory entry, and the remaining area is filled with erased directory entries. Will be recognized as.

  In step S204, m = 1 is set for the variable m indicating the number of continuous clusters, and N = 1 is set for the variable N indicating the number of the LBA access information.

In step S205, one actual data storage cluster, which is a cluster for storing actual data (file data) of a new recording target file, is secured.
In this case, at the time of the process of the first step S205, the leading cluster for storing the file data of the new recording target file is secured as the actual data storage cluster. As described above, the leading cluster has already been determined and confirmed at the stage of executing the process of step S203. When determining the leading cluster, for example, referring to the FAT area, one cluster is selected from the unused clusters in the stage at that time according to a predetermined rule.
In the second and subsequent processing of step S205, a cluster to be chained to the cluster secured as the actual data storage cluster in the previous step S205 is searched as the actual data storage cluster by referring to the FAT area. The unused clusters are selected according to a predetermined rule.

In step S206, the last (current) actual data storage cluster secured in step S205 is the first cluster of the new recording target file, or the cluster number of the actual data storage cluster secured in the last step S205 is Then, it is determined whether or not the cluster number of the actual data storage cluster secured in the previous step S205 is discontinuous.
If the current step S206 is the next step after the first execution of the process of step S205, the actual data storage cluster secured this time is the first cluster, and a positive determination result is obtained as step S206. It will be.
Also, if the cluster number of the actual data storage cluster secured this time is not a value incremented by 1 with respect to the cluster number of the actual data storage cluster secured last time but is discontinuous, an affirmative result is obtained in step S206. The discrimination result is obtained. Note that the cluster number of the actual data storage cluster secured this time is discontinuous with the cluster number of the actual data storage cluster secured last time. This means that the actual data storage cluster secured this time is the second and subsequent segments. Corresponds to being the first cluster. In the present embodiment, since it is assumed that a file in which no fragment has occurred on the medium is formed by one segment, the case where a positive result is obtained in step S206 is the actual data storage secured this time This is when the cluster is the first cluster of the segment.
On the other hand, if the actual data storage cluster secured this time is not the first cluster of the file and the first cluster of the segment, a negative determination result is obtained in step S206.

If a positive determination result is obtained in step S206, the process proceeds to step S211.
In step S211, it is determined whether or not m = 1 for a variable m indicating the number of continuous clusters held at the current stage. If a positive determination result is obtained assuming that m = 1, the actual data storage cluster secured this time is the first cluster of the first segment. In this case, step S212, The process of S213 is skipped and the process of step S214 is executed. The process of step S214 will be described later.

  On the other hand, if a negative determination result is obtained in step S211 because m = 1 is not satisfied, the actual data storage cluster secured this time is the head of the second and subsequent segments among the plurality of segments forming the file. That is a cluster. In this case, after executing the processes of steps S212 and S213, the process proceeds to step S214.

In step S212, LBA access information N corresponding to the variable N currently held is created. The LBA access information created in this step S212 corresponds to the segment that is the previous one in the concatenation order with respect to the segment including the actual data storage cluster secured this time.
The process for creating the LBA access information N here is as follows.
First, when the cluster is divided in units of bytes, the first byte is treated as the 0th byte. In step S212, a 32-byte area starting from the (32 × N) -th byte is secured as an LBA access information N area in the directory entry storage cluster secured in step S202. For example, in the case of LBA access information 1 (N = 1), the 32 byte area up to the 63rd byte is secured as the LBA access information 1 area starting at the 32nd byte in the directory entry storage cluster. In the case of LBA access information 2 (N = 2), a 32-byte area up to the 95th byte is secured as the LBA access information 2 area starting from the 64th byte in the directory entry storage cluster. For confirmation, the state of E5h has been stored at the 32nd byte, 64th byte, 96th byte, etc. at the beginning of each LBA access information by the processing of step S203. It has become.
By such processing, the LBA access information is stored so as to be embedded 32 bytes at a time in the order of the number following the directory entry in the directory entry storage cluster.

In step S212, appropriate values are stored in the byte area corresponding to each information item in the LBA access information secured as described above. First, for the number (byte position 1h-2h), the same value as the variable N currently held is stored. Since the total number of LBA access information (byte positions 3h-4h) is not determined at this stage, no particular value is stored. Alternatively, a predetermined provisional value may be stored.
In the first LBA (byte positions 5h to 8h), the value of the first LBA held so far by the process of the last step S214 is stored.
The size (byte position 9h to Ch) area stores the segment size to which the current LBA access information corresponds. In this embodiment, as described above, this size is obtained by converting the number of used clusters of the segment into the number of sectors. Therefore, it can be obtained by multiplying the number m of continuous clusters currently held by the number of sectors per cluster.

  In step S213, the variable m indicating the number of continuous clusters is reset to m = 1, and the variable N indicating the LBA access information number is incremented by one. As a result, the LBA access information number N corresponds to the segment including the actual data storage cluster secured this time.

In step S214, the LBA value (sector number) of the leading sector in the actual data storage cluster secured this time is acquired as information on the leading LBA and is retained. The head LBA held here has the meaning as the head LBA of the segment including the actual data storage cluster secured this time. In order to obtain the sector number as the first LBA here, for example, to obtain the first LBA using the number of sectors occupied by the system area in the partition and the cluster number of the actual data storage cluster secured this time An arithmetic result may be obtained by performing arithmetic processing using a predetermined arithmetic expression.
After finishing the process of step S214, it progresses to the process of step S208.

  In response to the fact that the actual data storage cluster secured this time is the second and subsequent clusters in the segment, if a negative result is obtained in the previous step S206, the process proceeds to step S207, and the variable m indicating the number of continuous clusters Is incremented by 1, and the process proceeds to step S208.

In step S208, a process for writing and recording the actual data of the file is executed on the actual data storage cluster secured in the last step S205. Also, the size (for example, byte unit) of the actual data recorded at this time is held.
In step S209, processing for updating the contents of the FAT area is executed as necessary so that the data write result to the cluster in step S208 is reflected. Specifically, for example, a required value is set for an appropriate FAT entry so that the cluster chain for the cluster to which data is written in step S208 is indicated. Alternatively, when writing up to the end of the file data is performed, a process of storing a value indicating EOF in the FAT entry corresponding to the actual data storage cluster secured this time is executed.
In step S210, necessary information items are updated according to the data write result to the cluster in step S208. A size can be mentioned as an information item updated in this step S210. That is, the size stored so far is updated to an incremented value by adding the actual data write size held in step S208.

  By the way, it is assumed that a new recording target file consists of one segment and is recorded using only one cluster. In this case, the processing sequence from steps S201 to S204 to steps S205 → S206 → S214 → S208 to S210 is followed to step S215 to be described next, where an affirmative determination result is immediately obtained.

  In step S215, it is determined whether or not it is the stage where the recording of the file data is finished. In this determination, it may be determined whether or not the end of the actual data recorded in the last step S208 coincides with the end of the file data. If a negative determination result is obtained in step S215 that the recording is not finished, the process returns to step S205. As a result, until the data writing up to the end of the file data is completed, the actual data storage cluster is selected (secured) one by one, and the actual data of the file is written to the media in cluster units, and the writing result is Accordingly, the process of updating the FAT area and the directory entry is repeatedly executed. In addition, in the process of securing the actual data storage cluster, if data is newly recorded in the next segment, the segment that has been written to date is corresponding to this LBA access information corresponding to is created.

If the recording to the medium up to the end of the file data is completed and a positive determination result is obtained in step S215, the process proceeds to step S216.
In step S216, LBA access information N corresponding to the variable N currently held is created. The LBA access information creation itself may be the same as the LBA access information creation process in step S212.
However, here, the total number of LBA access information (byte positions 3h-4h) in all the LBA access information created so far and stored in the directory entry storage cluster is managed. That is, step S216 is a process executed in response to the end of recording of file data, and the total number of LBA access information is determined only after the end of recording of file data. Therefore, in step S216, the total number of LBA access information stored in the directory entry storage cluster (byte positions 3h-4h) including the LBA access information created in the same step S216 is determined. Stores a value indicating the total number of LBA access information.

  For reference, in the file system hierarchical model shown in FIG. 2, a configuration example showing the internal functions of the file system 101 in more detail is shown in FIG. In this figure, as in FIG. 2, the entire system hierarchy model including the application 100, the file system 101, the device driver 102, and the medium 103 is shown. Further, the configuration shown in this figure corresponds to only a normal FAT file system.

  As shown in this figure, when the processing executed by software as the file system 101 is viewed as a functional block, it can be considered that the file system 101 includes the recording control unit 200 and the media control unit 210.

  The recording control unit 200 executes various control processes related to recording (writing) and reading of data with respect to a medium, and includes a directory entry control unit 201, a FAT control unit 202, and a cluster control unit 203. Further, the media control unit 210 includes a position calculation unit 211 as a functional part capable of exchanging data with the device driver 102 in order for the file system to control the media.

The directory entry control unit 201 in the recording control unit 200 performs various necessary control processes for the directory entry, such as creating, deleting, and updating the directory entry in accordance with the data processing results such as writing and erasing files on the medium. Execute. The FAT control unit 202 executes various necessary control processes for the FAT area, such as rewriting a predetermined FAT entry in the FAT area in accordance with the file data processing result for the medium. The cluster control unit 203 executes various control processes for causing processes in the file system to be executed at the cluster level.
For example, assuming that data to be written to the medium 103 is transferred from the application 100 as a file unit process, the cluster control unit 203 converts the file level data into data at the cluster level. Then, it instructs the position calculation unit 211 of the media control unit 210 to write data to the media 103 at the cluster level.
The position calculation unit 211 calculates the position (cluster number) of the cluster to which the file data is to be written from the unused area of the media recognized by referring to the contents of the FAT area managed by the FAT control unit 202. To do. Then, the cluster unit data to be written is transferred to the device driver 102 and the cluster number to which this data is to be written is instructed. The device driver 102 finally converts the instructed cluster number into a physical sector address (LBA) of a storage area on the medium, and executes data writing to the medium at the sector level. .

At the same time, the file system rewrites (updates) the directory entry and the FAT area so that the file written and stored in the medium as described above is properly managed on the FAT file system. .
For example, first, the directory entry control unit 201 creates a directory entry for the file to be recorded this time. At this time, in cooperation with the FAT control unit 202, a cluster in which a file is to be recorded is determined from the free area in the FAT area. Along with this, the value stored in the starting cluster in the directory entry is also determined. Further, in response to the determination of the cluster on which the file is to be recorded, the FAT control unit 202 sets the FAT entry of the required cluster number so that the contents such as the cluster chain for the file are indicated in the FAT area. Rewrite the value.
Then, the directory entry created in this way and the rewritten contents of the FAT area are processed by the cluster control unit 203 and the media control unit 210 (position calculation unit 211) in the same manner as described above, so that the predetermined area of the media Write to and store.

  14 also shows a more detailed configuration of the internal functions of the file system 101 in the file system hierarchical model shown in FIG. However, the configuration shown in this figure corresponds to the configuration of the present embodiment. In other words, the configuration corresponds to the file management by the normal FAT file system and the file management by the LBA access information. In this figure, the same parts as those in FIG.

14 differs from the configuration of FIG. 13 in that the directory entry control unit 201 in the recording control unit 200 is also configured to execute processing in cooperation with the position calculation unit 211 in the media control unit 210. ing.
That is, in the present embodiment, the processing function of the directory entry control unit 201 includes a maintenance function such as creation and management of LBA access information. In the LBA access information, the start LBA indicating the start position of the segment is stored, and a value expressing the size information by the number of sectors is stored. In order to acquire the information of the start LBA and the size, The directory entry control unit 201 uses the cluster-sector conversion function in the position calculation unit 211. Taking the process of acquiring the start LBA as an example, first, the directory entry control unit 201 notifies the position calculation unit 211 of the start cluster number of the segment. Then, the position calculation unit 211 executes a calculation process for converting the notified start position of the segment into a sector number, and returns the sector number as the calculation result to the directory entry control unit 201. The directory entry control unit 201 treats the received sector number as the value of the first LBA.

Also, when performing file access using LBA access information, the directory entry control unit 201 reads the required LBA access information from the directory entry storage cluster, and calculates the position information of the head LBA and the size based on the number of sectors. An instruction to access the medium 103 is given by direct delivery to the unit 211. In response to the data read instruction, the position calculation unit 211 reads the specified number of sectors (size) from the medium 103 continuously with the specified start LBA (sector number) as the read start position. The device driver 102 is controlled.
Note that the data read from the medium 103 using the LBA access information as described above is passed to the application side by the same processing as in a normal FAT file system. That is, in this case as well, the device driver 102 accesses the medium 103 at the sector level, reads data, and passes it to the position calculation unit 211. In the position calculation unit 211, the received data is converted so as to be managed as cluster unit data, and is transferred to, for example, the cluster control unit 203. The cluster control unit 203 extracts, for example, actual data as a file from the cluster unit data transferred from the position calculation unit 211 and transfers it as file data to the appropriate application 100.

In the description so far, regarding the file management in units of segments, the first LBA is stored in the number of LBA access information, and the size is represented by the number of sectors, so that it is at the sector (LBA) level. Based on that. However, as a concept of the present invention, file management in units of segments may be performed not at the sector level but at a cluster level similar to the FAT file system, for example. That is, in the access information structure illustrated in FIG. 5, the head LBA is the head cluster, and the size is represented by the number of used clusters in the segment. Even in the case of access information having such a structure, it is not necessary to access the FAT area when executing reading of data in segment units, so that the improvement in data processing speed is achieved as in the case of the embodiment. Is done. In this case, for example, FIG. 13 is sufficient as the model configuration of the processing hierarchy.
However, as can be seen from FIG. 14, when segment-unit file management is executed at the sector level, the directory entry control unit 201 and the position calculation unit 211 are configured to perform a directly linked process. Therefore, the processing in the file system for data access can be made more efficient accordingly.

  Also, the media format for performing file management in segment units using LBA access information (data unit management information) should not be limited to the contents described with reference to FIGS. Conceivable. For example, in the description of FIG. 8, the LBA access information is data having a 32-byte structure completed for each segment. For example, information on a plurality of segments forming one file is stored together in a predetermined structure. It is also possible to form as unit data.

  The file management in the embodiment is based on the premise that the FAT file system is adopted. For example, a recording format that guarantees that a file is recorded on a medium in a state where it is always completed in one segment. In such a case, a file management system that adopts only a file management method in units of segments based on the present invention may be considered.

Further, the file system used together with the file management in segment units is not limited to the FAT file system described in the embodiment, and other file systems such as HSF (Hierarchical File System) are used. And may not be limited in particular.
In addition, the file management in segment units based on the present invention is effective when applied to a moving image format file, as described above, for example. As the file format and type targeted by the present invention, It should not be limited in particular.
The present invention can also be applied to unit data in a format that cannot be handled as a file.

  Further, the effect of the data processing speed improvement according to the present invention includes, for example, an HDD, an optical disk, a magneto-optical disk, etc. when accessing the head and the data recording surface as long as it is connected to the media controller 13 in FIG. It can be said that the relative position can be remarkably obtained with a type of media that physically moves. This is because the seek operation for physically moving the head is accompanied in accessing the FAT area, and the time required for the seek operation (seek time) becomes one of the largest causes of overhead. However, for example, when accessing data at addresses that are logically and physically separated in a semiconductor memory device, for example, overhead such as heavy address conversion processing may occur, and the data processing speed may decrease. It can be said that there is. Considering this, the present invention can be applied to a case where a file is updated for a medium other than the type accessed by the head.

As for the relationship between the media and the host side device, for example, in addition to media connected using physical connection means such as cables and connectors, it is connected to the host wirelessly via Bluetooth, wireless LAN (Local Area Network), etc. It is also possible to target media.
Further, the information processing apparatus of the present invention should not be limited to the digital video camera described in the embodiment. For example, the information processing apparatus may be used in various storage media such as a digital still camera and a reservation recording device for a television broadcast program. Correspondingly, the present invention can be applied to any device capable of data processing such as data writing / reading. In particular, the present invention has been described as being very effective for a device that cannot secure a sufficient size for the work RAM for the FAT area due to the fact that the RAM is fixedly incorporated. The concept of the invention is not limited to such a device, but should be applied to, for example, a personal computer and various information processing devices having expandability according to the personal computer.

It is a block diagram which shows the structural example of the digital video camera of embodiment of this invention. It is a figure which shows the system configuration | structure of a FAT file system by a hierarchical model. It is a figure which shows the format structure of the medium in a FAT file system. It is a figure which shows the structure of MBR in a FAT file system. It is a figure which shows the structure of the directory entry in a FAT file system. It is a figure which shows the example of management of the file recording position by a FAT file system. It is a figure which shows the example of the recording content of the medium corresponding to the file management by a normal FAT file system. It is a figure which shows the example of the recording content of the medium corresponding to the file management by the segment unit using LBA access information with the file management by a normal FAT file system. It is a figure which shows the example of a definition of the LBA flag in this Embodiment. It is a figure which shows the structural example of the LBA access information in this Embodiment. It is a flowchart which shows the process for file reproduction | regeneration (file access) corresponding to this Embodiment. It is a flowchart which shows the process for file recording corresponding to this Embodiment. It is a figure which shows the structure corresponding to the case where file management is performed only by a FAT file system as a processing function in the hierarchy of a file system. It is a figure which shows the structure corresponding to the case where the file management by a segment unit using a FAT file system and LBA access information is performed as a processing function in the hierarchy of a file system.

Explanation of symbols

  1 digital video camera, 2 optical system unit, 3 photoelectric conversion unit, 4 video signal processing unit, 5 image input / output unit, 6 camera function unit, 7 display unit, 8 audio processing unit, 9 audio input / output unit, 10 CPU, 11 ROM, 12 RAM, 12a nonvolatile memory, 13 media controller, 15 operation input unit, 16 communication unit, 100 application, 101 file system, 102 device driver, 200 recording control unit, 201 directory entry, 202 FAT control unit, 203 Cluster control unit, 210 media control unit, 211 position calculation unit

Claims (14)

Writing means for writing data to the storage medium;
Information for managing a data unit part formed by writing data to a storage area on the storage medium in which one or more predetermined data writing units are continuous, and at least the data unit part on the storage area is written Data unit part management information formed by storing information items that can indicate the start position of the data unit part and information items that can indicate the end position of the data unit part as information items for specifying the position, A data unit management means that is formed according to the writing result of the data unit by the writing means and is held in a predetermined information storage area;
An information processing apparatus comprising: The data unit management means manages data units corresponding to a plurality of data unit units forming one independent data unit in order to manage independent data units formed by linking one or more data unit units. For the department management information, it is configured to perform connection order correspondence management according to a predetermined mode for indicating the connection order within the independent data unit.
The information processing apparatus according to claim 1. The data unit part management means arranges the plurality of data unit part management information in the information storage area according to the arrangement order corresponding to the connection order of the data unit parts in the independent data unit as the connection order correspondence management. Hold
The information processing apparatus according to claim 2. Independent data having entry information storing predetermined information as a starting point for accessing one independent data unit, which manages independent data units formed by concatenating one or more data unit parts. Further comprising unit management means,
The information processing apparatus according to claim 1. The data unit management means is
At least the data unit management by the lower data write unit corresponding to the lower processing hierarchy corresponding to the processing hierarchy for executing direct data writing to the storage medium than the independent data unit management means corresponds to Information items that can indicate the start position stored in the information are managed,
The information processing apparatus according to claim 4. The independent data unit management means stores holding state information indicating whether or not data unit management information corresponding to the same independent data unit is held at a predetermined position in the entry information. Have been
The information processing apparatus according to claim 4. The independent data unit management means arranges the entry information at the head in a predetermined information storage area corresponding to one independent data unit,
The data unit part management means stores one or more data unit part management information corresponding to one or more data unit parts forming one independent data unit in an information storage area corresponding to the same independent data unit. Is arranged to follow the
The information processing apparatus according to claim 4. The independent data unit management means and the data unit part management means are:
The predetermined data storage area corresponding to the one independent data unit is the data writing unit corresponding to the independent data unit management means.
The information processing apparatus according to claim 7. The data unit management means is
The data unit part management information is formed to have the same size as the entry information and the entry information is shown to be erased.
The information processing apparatus according to claim 1. A writing procedure for writing data to a storage medium;
Information for managing a data unit part formed by writing data to a storage area on the storage medium in which one or more predetermined data writing units are continuous, and at least the data unit part on the storage area is written Data unit part management information formed by storing information items that can indicate the start position of the data unit part and information items that can indicate the end position of the data unit part as information items for specifying the position, A data unit part management procedure that is formed according to the writing result of the data unit part by the writing procedure and is held in a predetermined information storage area,
The information processing method characterized by performing. A writing procedure for writing data to a storage medium;
Information for managing a data unit part formed by writing data to a storage area on the storage medium in which one or more predetermined data writing units are continuous, and at least the data unit part on the storage area is written Data unit part management information formed by storing information items that can indicate the start position of the data unit part and information items that can indicate the end position of the data unit part as information items for specifying the position, A data unit part management procedure that is formed according to the writing result of the data unit part by the writing procedure and is held in a predetermined information storage area,
For causing an information processing apparatus to execute the program. Manages data stored in a storage medium as an independent data unit, which is an independent data unit, and is independent for managing an independent data unit formed by concatenating predetermined data writing units. Independent data unit management means comprising data unit management information;
Data unit management information for managing data stored in a storage medium as a data unit formed by writing data to a storage area on the storage medium in which one or more predetermined data write units are continuous The independent data unit is formed as a concatenation of one or more data unit parts based on using the data unit part management information corresponding to the data unit part forming the independent data unit. Data unit management means adapted to manage as:
Whether the independent data unit to be read, which is the independent data unit to be read from the storage medium, is single-managed by the independent data unit manager only, or the independent data unit manager and the data unit part manager Determining means for determining whether or not both management by
If the determination means obtains the determination result that the both management is performed, the data unit section management means includes data based on data unit section management information corresponding to the read-independent independent data unit. Read means for executing the read process for the read-independent independent data unit by executing the read process for each unit part;
An information processing apparatus comprising: Manages data stored in a storage medium as an independent data unit, which is an independent data unit, and is independent for managing an independent data unit formed by concatenating predetermined data writing units. An independent data unit management procedure adapted to process data unit management information;
Data unit management information for managing data stored in a storage medium as a data unit formed by writing data to a storage area on the storage medium in which one or more predetermined data write units are continuous The independent data unit is processed based on the use of the data unit part management information corresponding to the data unit part forming the independent data unit. A data unit management procedure adapted to be managed as formed as a concatenation;
Whether the read-target independent data unit that is the independent data unit to be read from the storage medium is single-managed by only the independent data unit management procedure, or the independent data unit management procedure and the data unit part management procedure A determination procedure for determining whether or not both-side management is performed by
When the determination result that the both management is performed is obtained by the determination procedure, based on the data unit part management information corresponding to the read target independent data unit processed by the data unit part management procedure. A read procedure for executing the read process for the read-independent independent data unit by executing the read process for each data unit part;
The information processing method characterized by performing. Manages data stored in a storage medium as an independent data unit, which is an independent data unit, and is independent for managing an independent data unit formed by concatenating predetermined data writing units. An independent data unit management procedure adapted to process data unit management information;
Data unit management information for managing data stored in a storage medium as a data unit formed by writing data to a storage area on the storage medium in which one or more predetermined data write units are continuous The independent data unit is processed based on the use of the data unit part management information corresponding to the data unit part forming the independent data unit. A data unit management procedure adapted to be managed as formed as a concatenation;
Whether the read-target independent data unit that is the independent data unit to be read from the storage medium is single-managed by only the independent data unit management procedure, or the independent data unit management procedure and the data unit part management procedure A determination procedure for determining whether or not both-side management is performed by
When the determination result that the both management is performed is obtained by the determination procedure, based on the data unit part management information corresponding to the read target independent data unit processed by the data unit part management procedure. A read procedure for executing the read process for the read-independent independent data unit by executing the read process for each data unit part;
A program that causes an execution information processing apparatus to execute.

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