JP2011145908A - Information recording and reproducing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording and reproducing device for reducing a possibility of data loss even when a recording medium with low reliability is used. <P>SOLUTION: The information recording and reproducing device reads and writes information by using a file system recording specified information in a prescribed position in a region where directory information on the recording medium is recorded. The device is equipped with a signal processing part for reading directory information from the recording medium to an internal memory, determining whether specified information is recorded in the prescribed position in directory information which is read, and updating directory information which is read and writing it back into the recording medium when specified information is determined to have been recorded. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an information recording / reproducing apparatus that accesses a file recorded on a recording medium via a file system.

  In recent years, the spread of digital cameras (or digital still cameras) using a semiconductor memory card as a recording medium has been remarkable. Digital cameras have a DCR (Design rules for camera file system) standardized by JEIDA (Japan Electronic Industry Association) in order to ensure data compatibility.

  FIG. 5 is a diagram for explaining an example of a directory / file configuration in a DCF standard-compliant recording medium (for example, a semiconductor memory card) used when recording a still image with a digital camera.

  In the figure, 501 is a root directory, 502 is a DCIM (Digital Camera Images) directory, 503 is a “100XXXXXX” directory (where XXXXXX represents five free characters), and 504 and 505 are still image files AAAA0001. JPG, AAAAxxxx. JPG (where AAAA is four free characters and xxx represents an integer from 0001 to 9999). Here, a free character is a character that can be used as a file name in a FAT (File Allocation Tables) file system.

  In the DCF standard, a plurality of DCF directories 503 for storing DCF objects such as still image files are placed directly under the DCIM directory 502 which is a DCF image root directory. The DCF directory name consists of a directory number from 100 to 999 and 5 free characters. For example, in the “100XXXX” directory 503, 100 corresponds to the directory number. When a free character is included, it is actually “100_PANA” or the like. Similarly, the free character in the DCF file name is “IMAGE0001.JPG”.

  Here, in the DCF standard, the file name is a short file name in the 8.3 format (file name is 8 characters, extension is 3 characters).

  The description is omitted here, but the same applies to moving images. In this case, the DCF object may be a moving image file (for example, extension MOV) instead of a still image file, or may be an SD (Secure Digital) video standard instead of the DCF standard. Hereinafter, a DCF standard still image will be described as an example unless otherwise described.

  Further, in a digital camera, a FAT file system is generally used as a file system. Since the FAT file system is used not only in a digital camera but also in various storage medium using devices, if the FAT file system records data, it is easy to use the storage medium from other devices.

  As an example of processing when data is recorded on a recording medium using the FAT file system, a procedure for recording new image data on the recording medium will be described. Given the image data to be recorded and the directory in which the image data is to be recorded, the directory directory to which the image data is to be recorded is searched from the root directory entry and subdirectory entry (hereinafter collectively referred to as the directory entry), A new entry for the image data is created in it. Next, an empty cluster that can record image data is searched from the FAT. After the image data is recorded in the empty cluster and the cluster use information is recorded in the FAT, information regarding the location of the stored data is recorded in the image data entry on the directory entry. A procedure for updating recorded data will be described. The directory entry in which the data to be updated is recorded is searched from the directory entry. Next, a cluster whose data is to be updated is searched from the FAT as necessary, and the data of the cluster is updated. Update the stored data entry on the directory entry.

  Here, when updating data on the recording medium such as image data and directory entries, it is performed in units of sectors which are the minimum unit of data management on the recording medium (only reading and writing can be performed in units of sectors). . Therefore, when updating only a part of the data in the sector, for example, when updating data less than the sector size, data cannot be directly updated to the recording medium. Thus, a so-called read-modify-write process is performed, in which data is updated on the buffer memory and then written back to the sector.

  As a technique related to a digital camera that records data on a recording medium such as a semiconductor memory card using the FAT file system as described above, there is one described in Patent Document 1.

JP 2007-128282 A

  However, the conventional information recording / reproducing apparatus such as the digital camera is designed on the assumption that data is correctly read out from the recording medium. Therefore, when a recording medium such as a semiconductor memory card with low reliability is used, There was a problem that data could be lost.

  Hereinafter, this problem will be specifically described. For example, when a low-reliability semiconductor memory card reads data from an internal flash memory in accordance with a read request from an information recording / reproducing device, it is different from data actually recorded for some reason (for example, all zeros). Data) may be output to the information recording / reproducing apparatus. When this occurs when recording a directory entry, the following occurs. That is, when read-modify-write processing is performed on a sector including a directory entry to be recorded, if all-zero data is read, other directory entries recorded in that sector are recorded as all-zero, The recorded directory entry is lost. As a result, the file corresponding to the directory entry cannot be seen, that is, the state is the same as if it was deleted.

  The present invention has been made to solve such problems, and an object thereof is to provide an information recording / reproducing apparatus that reduces the possibility of data loss even when a recording medium with low reliability is used.

  In order to solve the above problems, the information recording / reproducing apparatus of the present invention uses a file system in which specific information is recorded at a predetermined position in an area for recording directory information on a recording medium. An information recording / reproducing apparatus that performs writing, reads directory information from a recording medium into an internal memory, determines whether or not specific information is recorded at a predetermined position in the read directory information, and determines that it is recorded In this case, a signal processing unit is provided that updates the read directory information and writes it back to the recording medium.

  According to the information recording / reproducing apparatus of the present invention, the possibility of data loss can be reduced even when a recording medium with low reliability is used.

1 is a block diagram showing a configuration of a digital camera according to a first embodiment. The figure which shows the file system structure in the memory card 910 Illustration about directory entry 3 is a flowchart showing a flow of processing when updating a directory entry of the digital camera according to the first embodiment; FIG. 6 is a diagram for explaining an example of a directory / file configuration in a recording medium compliant with the DCF standard

  Embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
(Configuration of digital camera)
An embodiment of the present invention will be described using a digital camera as an example. FIG. 1 is a block diagram showing a configuration of a digital camera according to the present embodiment. According to the figure, the light collected by the lens 901 enters a CCD 902 driven by a CCD (Charge Coupled Device) drive circuit 903 and is converted into image data which is an electrical signal. Image data generated by the CCD 902 is converted into a digital signal by an A / D conversion circuit 904. The digital signal is stored in an SDRAM (Synchronous Dynamic Random Access Memory) 905 as image data captured by the lens 901. The image data stored in the SDRAM 905 is converted into a display image by a signal processing unit 906 and a CPU (Central Processing Unit) 907 and is output to an LCD (Liquid Crystal Display) 908. When shooting, when the user presses the shutter button 909, the CPU 907 determines that and instructs the CCD drive circuit 903 to perform a shooting operation. The image data captured by the CCD 902 by shooting drive is temporarily stored in the SDRAM 905, and subjected to predetermined processing by the signal processing unit 906, and then recorded on the memory card 910. The signal processing unit 906 accesses the memory card 910 using the FAT file system.

  The memory card 910 has a FAT file system directory and files created by an external device such as a digital camera or a PC. The signal processing unit 906 reads the directory entry and FAT of the memory card 910 as necessary, and accesses the directory / file.

(About file system and directory entry)
FIG. 2 is a diagram showing a file system structure in the memory card 910. The FAT includes FAT12, FAT16, FAT32, and VFAT that can use a long file name. Here, the FAT16 will be described as an example.

  In FIG. 2, 301 is a master boot record and partition table, 302 is a partition boot sector, 303 is FAT1, 304 is FAT2, 305 is a root directory entry, and 306 is a user data area. Further, as a directory entry structure as directory information which is information of files and directories included in the directory, 307 is a file name (8 bytes), 308 is a file extension (3 bytes), and 309 is a file attribute (1 byte). , 310 is reserved (1 byte), 311 is creation time for VFAT (10 ms) (1 byte), 312 is creation time for VFAT (2 bytes), 313 is creation date for VFAT (2 bytes), and 314 is access for VFAT Date (2 bytes), 315 is the upper 16 bits (2 bytes) of the cluster number for FAT32, 316 is the update time (2 bytes), 317 is the update date (2 bytes), 318 is the cluster start number (2 bytes), 319 Is the file size (4 bytes). A directory entry (32 bytes) is composed of 307 to 319. In this embodiment, the master boot record, partition table 301, partition boot sector 302, FAT1 (303), FAT2 (304), and root directory entry 305 are collectively referred to as a management area.

  The signal processing unit 906 reads the master boot record 301 according to an instruction from the CPU 907. In the master boot record 301, the identification information of the file system type (FAT12 / FAT16 etc.) of each partition and the start position of the partition boot sector 302 which is the first sector of the partition are recorded at the time of formatting.

  Thereafter, the signal processing unit 906 reads the partition boot sector 302. Here, information such as the number of bytes per sector, the number of sectors per cluster, the number of sectors per FAT, and the number of FATs is described. The partition boot sector is 512 bytes.

  FAT1 (303) starts from the sector next to the partition boot sector 302, and is duplexed with FAT1 (303) / FAT2 (304) to improve reliability (hereinafter, these are referred to as FAT without any particular distinction). . The FAT area is (number of sectors per FAT) × (number of FATs (2 in the example of FIG. 2)) bytes.

  The root directory entry 305 starts from the next sector of the FAT. In the case of FAT16, the root directory entry can store 512 directory entries 307 to 319, and 32 bytes × 512 = 16384 bytes.

  User data 306 is an area for storing actual file data and subdirectory entries. In the case of FAT16, the user data 306 starts from the sector next to the root directory entry.

  The file name 307 and the file extension 308 in the directory entry store the file name and extension in the 8.3 format, and the file attribute 309 identifies the directory (1) / file (0) based on whether bit 4 is 1 or not. it can.

  Further, the first character or two characters of the file name 307 has the following special meaning. 0x00: empty entry, 0x2e (.): Current directory, 0x2e2e (...): parent directory, 0xe5, 0x05: deleted entry (available), etc. However, 0x2e and 0x2e2e can be used only when the file attribute 309 is a directory. The positions of the directory entry of the current directory (.) And the directory entry of the parent directory (..) are fixed at the top and second of each subdirectory entry, respectively. That is, the file name of the first entry in each subdirectory entry area is always “.”, And the file name of the second entry is “..”. In other words, the first byte of each subdirectory entry is 0x2e, which is information indicating the current directory, and 2 bytes from the 33rd byte are 0x2e2e, which is information indicating the parent directory.

  FIG. 3 is an explanatory diagram relating to a directory entry for realizing the directory / file structure of FIG. In this figure, only information necessary for explanation is shown in the directory entries 307 to 319 in FIG. In the following, the directory 503 is a 100_PANA directory, and the still image files 504 and 505 are IMAGE0001. JPG file, IMAGE0002. It will be described as a JPG file.

  3, 401 is a root directory entry (corresponding to 305 in FIG. 2), 402 is a user data area (corresponding to 306 in FIG. 2), 403, 418, 423, 428, 453, and 463 are file names (in FIG. 2). 307, 404, 419, 424, 429, 454, 464 are file extensions (corresponding to 308 in FIG. 2), and 405, 420, 425, 430, 455, 465 are bit 4 (in FIG. 2). 309, corresponding to bit 4 of 309), 406, 421, 426, 431, 456, 466 are cluster start numbers (corresponding to 318 in FIG. 2), 407, 422, 427, 432, 457, 467 are file sizes (in FIG. 2). 319). Note that the deleted directory entry and empty directory entry described above in FIG. 2 are omitted. That is, it is assumed that the directory entry next to the directory entries 403 to 407, 418 to 422, and 428 to 432 is an empty directory entry.

  Directories and files under the root directory 501 are registered in the root directory entry. That is, it indicates that a directory entry related to the DCIM directory 502 is registered.

  Directory entries 418 to 422 of the 100_PANA directory 503 under the DCIM directory 502 exist at addresses in the user data calculated from the cluster start number 406, and IMAGE0001. JPG file 504, IMAGE0002. Directory entries 423 to 427 and 428 to 432 of the JPG file 505 exist at addresses in the user data calculated from the cluster start number 421.

  The directory entries 453 to 457 of the current directory (.) Under the DCIM directory 502 exist at addresses in the user data calculated from the cluster start number 456, and the directory entries 463 to 467 of the parent directory (..) Exists in the address of the root directory entry calculated from the cluster start number 466. The same applies to the current directory (.) And the parent directory (..) under the 100_PANA directory 503. In addition, the directory entry of the current directory (.) And the directory entry of the parent directory (..) do not exist in the root directory entry.

  In the present embodiment, information about each directory such as directory entries 403 to 407 is simply referred to as an entry, and a set of entries of files and directories stored in the same directory logically (for example, directory entry 453). -457, a set of directory entries 463-467 and directory entries 418-422) may be referred to as directory entry areas.

(Operation when updating directory entry)
When the digital camera records image data in the memory card 910, the signal processing unit 906 records the image data itself in the user data area 306 and updates the management area. Also, when the digital camera reads out image data from the memory card 910 and reproduces it, the signal processing unit 906 updates the management area. Specifically, at the time of reproduction, the access date for VFAT in the directory entry of the read file is updated. Hereinafter, the operation at the time of directory entry update occurring in these update processes will be described.

  FIG. 4 is a flowchart showing the flow of processing when updating the directory entry of the digital camera. When recording or reproducing image data, the signal processing unit 906 updates the directory entry as necessary. Each directory entry has a size of 32 bytes and is smaller than the sector size, which is the minimum unit of access to the memory card 910. Therefore, read modify write is performed to record (update) the directory entry.

  When recording new image data, the signal processing unit 906 secures an area for a new directory entry, and when updating existing data, specifies a directory entry corresponding to the target file. The signal processing unit 906 reads the entire directory entry area including the entry to be updated identified in this way into the SDRAM 905 (S701).

  Next, the file names of the two entries from the top of the read directory entry area are confirmed, and it is determined whether or not they are information (.) Indicating the current directory and information (..) indicating the parent directory in order. (S703). If the first two entries match these ("Y" in S703), it is determined that this directory entry has been read correctly, and the desired entry is updated on the SDRAM 905 (S704). When the update is completed, the read directory entry area is written again into the memory card 910 (S705), and the update process is terminated.

  On the other hand, if the first two entries do not match these ("N" in S703), it is determined that this directory entry has not been read correctly, and the read entry and the updated entry are written to the memory card 910. An error process such as displaying an error message on the LCD 908 is performed without performing the returning process (S706).

  As described above, in the directory entry update process that occurs at the time of data recording and reproduction with respect to the memory card 910, the first two entries in the directory entry area are information (.) Indicating the current directory, and information indicating the parent directory ( .)), It can be confirmed whether or not the directory entry is correctly read from the memory card 910. Therefore, the possibility that it can be detected when correct data cannot be read, which may occur when using a memory card with low reliability, can be increased, and the possibility of data loss can be reduced.

(Other embodiments)
The first embodiment of the present invention has been described above. However, the present invention is not limited to these. Therefore, other embodiments of the present invention will be described collectively in this section.

  In the digital camera according to the first embodiment, when updating a directory entry, the entire directory entry area including the update target entry is read and updated to the SDRAM 905. However, only one sector including the update target entry is read. You may make it update. In this case, if the file names of the first two entries are confirmed only when the sector is the first sector of the directory entry area in step S703, data could not be read correctly from the memory card 910. Sometimes, the possibility of erasing other entries included in this sector can be reduced.

  In the digital camera according to the first embodiment, when updating a directory entry, the entire directory entry area including the entry to be updated is read and updated in the SDRAM 905 and written to the memory card 910 each time. May be used as a cache of directory entries. That is, when the entry data that has been read once is continuously held in the SDRAM 905 and the next entry to be updated is already in the SDRAM 905, the entry is not read from the memory card 910 again. Update processing is performed, and this is written into the memory card 910. By doing so, the number of times of reading from the memory card 910 can be reduced, and the chance of occurrence of an event that data cannot be read correctly from the memory card 910 can be reduced. Can be reduced.

  When updating the directory entry, the digital camera according to the first embodiment checks the file names of the two entries from the top of the read directory entry area, and sequentially indicates information (.) Indicating the current directory, and the parent directory. Whether or not the information is the information (...) to be shown is determined, but it may be determined whether or not the directory entry has been read correctly by checking only one of them.

  According to the information recording / reproducing apparatus of the present invention, it is possible to reduce the possibility of data loss even when a low-reliability recording medium is used. Therefore, the file recorded on the recording medium is accessed via the file system. It can also be applied to digital cameras, mobile phones, personal computers and the like.

901 Lens 902 CCD
903 CCD drive circuit 904 A / D conversion circuit 905 SDRAM
906 Signal processor 907 CPU
908 LCD
909 Shutter button 910 Memory card

Claims (4)

An information recording / reproducing apparatus that performs reading and writing using a file system in which specific information is recorded at a predetermined position in an area for recording directory information on a recording medium,
Read the directory information from the recording medium into the internal memory, determine whether or not the specific information is recorded at the predetermined position in the read directory information, and read if it is recorded An information recording / reproducing apparatus comprising a signal processing unit that updates the directory information and writes it back to the recording medium. An information recording / reproducing apparatus that performs reading and writing using a file system in which specific information is recorded at a predetermined position in an area for recording directory information on a recording medium,
Read the directory information from the recording medium into the internal memory, determine whether or not the specific information is recorded at the predetermined position in the read directory information, and read if it is not recorded An information recording / reproducing apparatus comprising a signal processing unit that does not write information based on the directory information back to the recording medium. The information recording / reproducing apparatus according to claim 1, wherein the specific information is at least one of information relating to a current directory and information relating to a parent directory. An information recording / reproducing method for performing reading and writing using a file system in which specific information is recorded at a predetermined position in an area for recording directory information on a recording medium,
Reading the directory information from the recording medium into an internal memory;
A determination step of determining whether or not the specific information is recorded at the predetermined position in the read directory information;
If it is determined that the information is recorded in the determining step, the read directory information is updated and written back to the recording medium;
An information recording / reproducing method comprising:

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