Abstract:
A recording/reproducing apparatus is capable of searching a file at high speed without an increase in number of times of rewriting the data on an external storage medium. The recording/reproducing apparatus includes: an input/output unit for receiving data from and sending data to an external storage medium and a storage unit for accumulating the data. The apparatus also includes a control unit for reading out a file system for controlling audio/video data. The audio/vide data has been recorded on the external storage medium from the external storage medium and then accumulating the file system in the storage unit through the input/output unit. The apparatus further includes a data base control unit for constructing a database on the basis of attribute information of the audio/video data contained in a file system accumulated in the storage unit and deleting data accumulated in the database at the time of removal of the external storage medium.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a recording/reproducing apparatus and an information processing method, specifically technology for facilitating search for data recorded on an external storage medium. 
         [0003]    2. Description of the Related Art 
         [0004]    Video cameras and recording/reproducing apparatuses with built-in cameras have been designed to record audio/video data (hereinafter referred to as A/V data) obtained by filming subjects in an external storage medium including a flash memory or the like. The external storage medium on which the A/V data has been recorded is connected to the recording/reproducing apparatus which may be called an editing machine or the like. Therefore, A/V data filmed by the recording/reproducing apparatus with a built-in camera can be edited in such an apparatus. 
         [0005]    In general, a file system is employed for the management of data recorded on an external storage medium. The term “file system” indicates a structuralized set of files and makes them easy to be accessed by unified operation, managing the relationship between the files and the external storage medium while allowing the user to obtain the namespace of these files. 
         [0006]    As a structure for managing the namespace efficiently, a tree structure using a root directory as an origin has been employed in many cases. In this case, nodes of the tree structure correspond to directories and leaf nodes thereof correspond to files. In such a tree structure, the position of each file is uniquely determined by the path from the root directory to the file. Furthermore, although files do not originally have addresses in the memory space of an external storage medium, the files may be mapped in the memory space in advance to allow the user to access them through the respective pointers. 
         [0007]      FIG. 1  shows the outline of a file system. In a file system Fs 11  shown in  FIG. 1 , if a request for access to a certain file is input into an interface part  101  of the file system Fs 11 , then the request is transmitted to a file management unit  102 . The request for access to the file is performed by specifying as a pointer an identifier, such as a file ID previously assigned to the file. 
         [0008]    The file management unit  102  converts a logical address on a memory space mapped by the file ID specified as a pointer into a physical address in the external storage medium (not shown). Subsequently, the file management unit  102  carries out a process of accessing an address in the external storage medium, which has been assigned by a physical address, and reading a specified file. In such a file system, typically, full text retrieval is performed by sequential-scanning search (sequential retrieval). 
         [0009]    The recording/reproducing apparatus attached with the external storage medium also performs a file search using the file system Fs 11 . In other words, the file system Fs 11  is accessed every time the search is performed. Therefore, the file system Fs 11  in the external storage medium is read to the main memory or the like on the recording/reproducing apparatus at the time of attaching the external storage medium to the recording/reproducing apparatus. When searching, a file system Fs 11 ′ on the main memory is accessed. 
         [0010]    Furthermore, at the time of removing (unmounting) the external recording medium, the file system Fs 11 ′ in the main memory of the recording/reproducing apparatus is written back to the external storage medium. By performing such a process, the contents of change added to the file system Fs 11 ′ in connection with an editing operation or the like will also reflect on the file system Fs 11  in the external storage medium. 
         [0011]    Referring now to  FIG. 2 , there is a flowchart that illustrates an exemplary process performed by a recording/reproducing apparatus when an external storage medium is attached thereto and removed therefrom. 
         [0012]    First, if the mounting of the external storage medium is detected on the recording/reproducing apparatus (Step S 21 ), then the file system Fs 11  in the external storage medium is read into the main memory of the recording/reproducing apparatus (Step S 22 ). Subsequently, it is determined whether the removal of the external storage medium is detected (Step S 23 ). Until it is detected, it is determined whether the recording or updating of audio/video (A/V) data is accepted (Step S 24 ). If the recording or updating of A/V data is not accepted, then the determination in Step S 24  is repeated. 
         [0013]    If the recording or updating of A/V data is accepted, then the process of recording or updating the A/V data on the external storage medium (Step S 25 ) is performed. The contents thereof being modified in connection with the recording or updating are then reflected on a file system Fs 11 ′ on the main memory of the recording/reproducing apparatus (Step S 26 ). At the time of detecting the removal of the external storage medium at Step S 23 , the file system Fs 11 ′ on the main memory is written back to the external storage medium (Step S 17 ). 
         [0014]      FIG. 3  indicates the relationship between a recording/reproducing apparatus  100  and an external storage medium  200 . In the external storage medium  200  represented on the lower part of  FIG. 3 , A/V data Dt 11  and a file system Fs 11  including both a logic/physical address conversion table Tb 11  and attribute information Md 11  are recorded. Among them, the file system Fs 11  including the logic/physical address conversion table Tb 11  and the attribute information Md 11  is read (loaded) in a main memory on the recording/reproducing apparatus  100  at the time of attaching the external storage medium  200  to the recording/reproducing apparatus  100 . 
         [0015]    Furthermore, in the recording/reproducing apparatus  100 , if a request for access to a file is input into an interface unit  101  as a pointer access, the logic/physical address conversion table Tb 11 ′ and attribute information Md 11 ′ in the file system are updated according to the contents of the request. Thus, both the logic/physical address conversion table Tb 11 ′ and the attribute information Md 11 ′ which have been changed in this way are rewritten from the main memory to the external storage medium  200  at the time of removing the external storage medium  200  from the recording/reproducing apparatus  100 . 
         [0016]    While the amount of A/V data recorded on the external storage medium  200  by the recording/reproducing apparatus with built-in camera is a little, the search using the file system Fs 11  (Fs 11 ′) will be carried out properly. However, if the amount of A/V data recordable in the external storage medium  200  increases remarkably by an increase in capacity of the external storage medium  200 , or the like, it is assumed that the search using the file system Fs 11  will take too much time. 
         [0017]    If search for a large volume of data is required, a database is used in many cases.  FIG. 4  schematically illustrates the database. In database Db 11 , data is not structured but recorded in a byte stream format. Subsequently, a request for access to the data is input as an SQL sentence into a database control unit  110  (also referred to as a DB control unit) through an interface unit  101 , and the corresponding data is then extracted by the DB control unit  110 . In the database Db 11 , data is sorted at the time of recording data and the process for making an index is then performed. Therefore, time required for searching and data extraction can be shortened remarkably, as compared with the use of a file system without such a process. 
         [0018]    For this reason, efforts of employing database Db 11  in devices for handing A/V data have been also made. For example, Japanese Published Patent Application No. 2006-190075 describes that the attribute information of data being recorded in a magnetic table is recorded in a table formant on MIC (Memory In Cassette) to enable a search with SQL. 
       SUMMARY OF THE INVENTION 
       [0019]    In the apparatus having the file system Fs 11 ′ as described above, it is assumed that a recording/reproducing apparatus  100  and an external storage medium  200  may be configured as shown in  FIG. 5  when using a database Db 11  subordinately. In the external storage medium  200 , the information of database Db 11  is also accumulated in addition to A/V data Dt 11  and a file system Fs 11 . Subsequently, among them, when the external storage medium  200  is attached to the recording/reproducing apparatus  100 , the data of a logic/physical address conversion table Tb 11  and attribute information Md 11 , which are contained in the file system Fs 11 , and the data of database Db 11  are uploaded on the main memory of the recording/reproducing apparatus  100 . 
         [0020]    While the external storage medium  2000  is being attached to the apparatus, requests for adding, updating, and deleting files can be input by SQL through the interface unit  101  of the file system and then both the logic/physical address conversion table Tb 11 ′ and the attribute information Md 11 ′ are changed according to any of these processes. Furthermore, the updated attribute information Md 11 ′ is converted into byte-stream format data by a database control unit  110  and then accumulated in the database Db 11 . At this time, sorting of data and creation of an index are also carried out. In the recording/reproducing apparatus  100  as constructed as described above, when searching data, a request for file search by SQL through the interface unit  120  of the database Db 11  is input and the data corresponding to inquiry through SQL sentence is then extracted. 
         [0021]    When the external storage medium  200  is removed from the recording/reproducing apparatus  100 , the data of database Db 11 ′ is written back to the external storage medium  200  together with the file system Fs 11 ′ temporarily stored on the main memory of the recording/reproducing apparatus  100 . 
         [0022]    However, in such an operation form, the data of database Db 11  is also uploaded to the recording/reproducing apparatus  100  at the time of mounting the external storage medium  200  on the apparatus  100 . In general, since the volume of data in the database Db 11  is often higher than that of the file system Fs 11 , the time required for upload may be prolonged. In other words, there is an increase in processing time at the time of mounting the external storage medium  200  on the apparatus  100 . 
         [0023]    Likewise, data of database Db 11 ′ is read to the external storage medium  200  at the time of removing the external storage medium  200 . Thus, it also leads to an increase in processing time at the time of unmounting. 
         [0024]    In the database D 11 ′, furthermore, a so-called journaling process is often carried out for periodically backing up the intermediate results to increase the data maintainability. When this function is being enabled, log information is allowed to be suitably written in the external storage medium  200 . Thus, the number of times of rewriting the external storage medium  200  will increase inevitably. 
         [0025]    However, it is known that the external storage medium  200 , such as a flash memory, has low durability with respect to the number of times of rewriting the data thereon. Flash memories have been commonly said to withstand almost 100,000 times of rewriting in the case of single-level cell (SLC) type and almost 10,000 times in the case of multi-level cell (MLC) type. For this reason, when rewriting the data on the external storage medium  200  is performed frequently, the life of the external storage medium  200  will be shortened. Even if the use of the function of journaling is restricted, a large volume of database data can be also read and written on the external storage medium  200  when mounting or unmounting. When such an operation is performed, the external storage medium  2000  may be facilitated to be exhausted. 
         [0026]    The present invention has been made in consideration of the aforementioned circumstances and intends to provide a recording/reproducing apparatus which is capable of searching a file at high speed without increasing the number of times of rewriting the data on an external storage medium and also provide an information processing method using such an apparatus. 
         [0027]    According to any embodiments of the present invention, a recording/reproducing apparatus and an information processing method are configured to read a file system for managing video data currently recorded on the external storage medium and then construct a database based on the attribute information of the video data. Furthermore, data accumulated in the database can be deleted when removing the external storage. 
         [0028]    Accordingly, file search can be performed using a database engine. 
         [0029]    Furthermore, since data accumulated in the database is deleted at the time of removal of the external storage medium, the data may not be transmitted from the database to the external storage medium. 
         [0030]    According to the present invention, since search of a file is performed using database engine, a file search can be performed at high speed. 
         [0031]    Furthermore, since the data of the database is not stored in the external storage medium, the number of times of rewriting the data on the external storage medium can be suppressed to the minimum. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is an explanatory diagram illustrating an exemplary configuration of a related-art file system. 
           [0033]      FIG. 2  is a flowchart illustrating an exemplary process carried out by a related-art recording/reproducing apparatus. 
           [0034]      FIG. 3  is an explanatory diagram illustrating an exemplary relationship between a related-art recording/reproducing apparatus and an external storage medium. 
           [0035]      FIG. 4  is an explanatory diagram illustrating an exemplary construction of a related-art database. 
           [0036]      FIG. 5  is an explanatory diagram illustrating an exemplary relationship between a recording/reproducing apparatus and an external storage medium when introducing a related-art database. 
           [0037]      FIG. 6  is a block diagram illustrating an exemplary internal configuration of a system according to an embodiment of the present invention. 
           [0038]      FIG. 7  is an explanatory diagram illustrating an example of the relationship between a recording/reproducing apparatus and an external reproducing apparatus according to an embodiment of the present invention. 
           [0039]      FIG. 8  is a flowchart illustrating an exemplary process carried out by a recording/reproducing apparatus according to an embodiment of the present invention. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0040]    Hereinafter, a recording/reproducing apparatus according to an embodiment of the present invention will be described with reference to  FIG. 6  to  FIG. 8 . In the embodiment shown in the figures, the recording/reproducing apparatus is applied to an editing system. This editing system receives A/V data shot and recorded by the recording/reproducing apparatus through an external storage medium, such as a flash memory, and then edits and processes the received A/V data.  FIG. 6  is a block diagram illustrating exemplary configurations of a recording/reproducing apparatus  10  and an external storage medium  20  which constitute an editing system. 
         [0041]    The external storage medium  20  stores both A/V data Dt 1  filmed by a recording/reproducing apparatus or the like with a built-in camera and a file system Fs 1  for managing such A/V data Dt 1 . 
         [0042]    Next, the configuration of the recording/reproducing apparatus  10  will be described. The recording/reproducing apparatus  10  includes an I/O unit  11 , a compression/extension unit  12 , a system controller  13  as a control unit, and a memory  14 . The I/O unit  11  introduces A/V data Dt 1 , a control signal, or the like output from an external device such as the external storage medium  20  or an imaging apparatus (not shown) into the recording/reproducing apparatus  10 . In addition, the I/O unit  11  outputs A/V data sent from a compression/extension unit  12  described later to an external device such as a display device (not shown). 
         [0043]    For recording the A/V data Dt 1  transmitted from an imaging apparatus or the like in the external storage medium  20 , the compression/extension unit  12  compresses the A/V data Dt 1  input from the I/O unit  11  using a predetermined compression format under the control of a system controller  13 . In addition, if the A/V data Dt 1  recorded on the external storage medium is read and regenerated, the A/V data read based on the A/V data Dt 1  is expanded and then output to the I/O unit  11 . 
         [0044]    The system controller  13  includes a central processing unit (CPU) and the like and controls each part of the recording/reproducing apparatus  10 . Specifically, the system controller  13  performs, for example, a process of reading a file system Fs 1  from the external storage medium  20  and storing the file system Fs 1  in a storage unit  17 . The memory  14  stores data which is temporarily generated when the system controller  13  carries out any process. 
         [0045]    In addition, the recording/reproducing apparatus  10  includes a storage control unit  15 , a stream control unit  16 , and a storage unit  17  as a main memory, a file management unit  18 , and a DB control unit  19 . 
         [0046]    The storage control unit  15  controls the process for read and write of data on the external storage medium  20 . A stream control unit  16  controls processes in the compression/extension unit  12  and the storage control unit  15 . The storage unit  17  includes a semiconductor memory or the like, storing both the file system Fs 1  and the database Db 1  read from the external storage medium  20 . In this example, the file system Fs 1  accumulated in the storage unit  17  is referred to as a file system Fs 1 ′. 
         [0047]    The database Db 1  offers a mechanism for carrying out file search by SQL but not by sequential-scanning search. The items of a table are set to arbitrary items by the user at the time of initialization. The items to be selected are those of attribute information which the user want to use as keys when searching, such as “file name”, “maker”, “creation date”, and “recording format”. In this embodiment, furthermore, any journaling function is not used. 
         [0048]    A file management unit  18  controls the read and write of data on the file system Fs 1 ′. In other words, the file management unit  18  performs the addition of A/V data Dt 1  through the I/O unit  11  and also performs the addition, update, or deletion of information from the file system Fs 1 ′ when the instruction of updating or deleting a file through an operation input unit or the like (not shown). 
         [0049]    The DB control unit  19  generates a table using items. Here, the items are previously defined as those to be used for the database Db 1  among the attribute information of the file system Fs 1 ′ which has been read on the storage unit  17 . Then, the DB control unit  19  performs the process for converting the attribute information of the file system Fs 1 ′ into a byte stream format and writing the attribute information in the table. In addition, when the user inputs a key for search through the operation input unit or the like, the DB control unit  19  extracts data having a key corresponding to the input key from the database Db 1 . Specifically, the input key is converted into the SELECT statement of SQL and the data is then extracted using the SELECT sentence. 
         [0050]    Further, when the contents of the file system Fs 1 ′ are changed along with the recording, updating, or deleting of A/V data Dt 1 , the DB control unit  19  carries out the process for converts the contents related to the database Db 1 ′ among those being changed into the byte-stream formatted data. Then it carries out the process for writing such data in the database Db 1 ′. At this time, a process, such as one for sorting data or one for creating an index thereof, is also performed. 
         [0051]    Referring now to  FIG. 7 , an example of data exchanged between a recording/reproducing apparatus  10  and an external storage medium  20  will be described. In this case, the external storage medium  20  stores A/V data Dt 1 , a logic/physical address conversion table Tb 1  as a file system Fs 1 , and attribute information Md 1 . Among them, both the logic/physical address conversion table Tb 1  in the file system Fs 1  and the attribute information Md 1  are uploaded on the storage unit  17  of the recording/reproducing apparatus  10  when the external recording medium is mounted thereon. 
         [0052]    While the external storage medium  200  is being attached to the recording/reproducing apparatus  10 , the attribute information Md 11 ′ and the logic/physical address conversion table Tb 1  are changed depending on requests for adding, updating, and deleting files to be input through an interface unit  1 . In addition, the updated attribute information Md 11 ′ is converted into byte-stream formatted data and then accumulated in the database Db 1 . At this time, a date-sorting process and an index-creating process are also performed. 
         [0053]    When the external storage medium  20  is removed from the recording/reproducing apparatus  10 , only the file system Fs 1 ′ temporarily stored in the storage unit  17  of the recording/reproducing apparatus  10  is saved in the external storage medium  20 . 
         [0054]    Next, an example of the process in the recording/reproducing apparatus  10  of the present embodiment will be described with reference to the flowchart of  FIG. 8 . First, if the recording/reproducing apparatus  10  detects that the external storage medium  20  is mounted (Step S 1 ), then the file system Fs 1  is read from the eternal storage medium  20  to the storage unit  17  of the recording/reproducing apparatus  10  (Step S 2 ). Subsequently, among the attribute information managed in the file system Fs 1 , items previously specified by the user are registered as those of a table of the database Db 1  (Step S 3 ). 
         [0055]    Next, it is determined whether the removal of the external storage medium  20  is detected (Step S 4 ). Until it is detected, it is determined whether the recording (addition) or update (change or delete) of A/V data Dt 1  is accepted (Step S 5 ). If the recording or update of the A/V data Dt 1  is not accepted, then the process returns to Step S 4  and then proceeds therefrom. 
         [0056]    If the recording or update of the A/V data Dt 1  is accepted, the process for recording the A/V data Dt 1  in the external storage medium  20  or the process for updating the A/V data Dt 1  is performed (Step S 6 ). The contents of the data being changed by the recording or updating process is reflected on the file system Fs 11 ′ on the storage unit  17  of the recording/reproducing apparatus  10  (Step S 7 ). Subsequently, the contents registered or updated with respect to the attribute information Md 1 ′ of the file system Fs 1 ′ are also registered or updated in the database Db 1  (Step S 8 ). In other words, the file system Fs 1 ′ and the database Db 1 , which are stored in the storage unit  17 , can be updated synchronously. 
         [0057]    Next, it is determined whether a request for search of A/V data is input through the interface unit  1  (see  FIG. 7 ) (Step S 9 ). If the request for search of A/V data is input, then the corresponding A/V data is extracted from the database Db 1  (see  FIG. 6  and  FIG. 7 ). If the search request is not accepted, then the process returns to Step S 4  and proceeds therefrom. 
         [0058]    Furthermore, at the time of detecting removal of the external storage medium  20  at Step S 4 , the data of the database Db 1 ′ on the storage unit  17  is deleted (Step S 11 ) and the file system Fs 1 ′ is then stored in the external storage medium  20 . 
         [0059]    According to the above embodiment, the database Db 1  having the items specified by the user as a table is constructed on the storage unit  17  of the recording/reproducing apparatus  10 . Therefore, using the attribute information specified as items of the database Db 1  as a key, a file can be easily searched. 
         [0060]    In this case, the search is performed using the engine of the database Db 1 , so that time required for the search can be considerably shortened as compared with the search with a file system. 
         [0061]    In this case, furthermore, even if the amount of A/V data Dt 1  accumulated in the external storage medium  20  is extremely large, the search can be performed using the database engine at high speed. 
         [0062]    In this case, furthermore, the database Db 1  constructed in the storage unit  17  of the recording/reproducing apparatus  10  includes only items specified by the user, so that the database Db 1  will not use resources of the recording/reproducing apparatus  10 . Therefore, the resources of the recording/reproducing apparatus  10  can be effectively used. 
         [0063]    Furthermore, according to the above embodiment, time required for the mount can be prevented from increasing because only the table of database Db 1  is constructed when the external storage medium  20  is attached to the recording/reproducing apparatus  10 . 
         [0064]    Furthermore, when the external storage medium  20  is removed from the recording/reproducing apparatus  10 , the deletion of data from the database Db 1  and the storage of the file system Fs 1 ′ therein are only performed. Thus, time required for unmounting may not be affected. 
         [0065]    Furthermore, according to the above embodiment, a journaling function is not used during the construction of database Db 1 . Thus, the number of times of rewriting the data on the external storage medium  20  can be kept to the minimum necessary. 
         [0066]    Furthermore, according to the above embodiment, the database Db 1  is constructed when the external storage medium  20  is attached. The data accumulated in the database Db 1  is then deleted at the time of removal of the external storage medium  20 . In other words, there is no need of storing the database Db 1  in the external storage medium  20 . Thus, the external storage medium  20  can be prevented from redundant rewriting. 
         [0067]    In this case, the database Db 1  is automatically constructed at the time of attaching the external storage medium  20 , so that the recording/reproducing apparatus  10  can be provided with compatibility with a device free of database engine. Therefore, a system with high expandability can be constructed. 
         [0068]    Furthermore, the above embodiment has been described with reference to the exemplary recording/reproducing apparatus as one for reading out A/V data Dt 1  accumulated in the external storage medium  20 . Alternatively, it may be applied to any of other apparatuses, such as a simple viewer. 
         [0069]    The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2008-128642 filed in the Japan Patent Office on May 15, 2008, the entire content of which is hereby incorporated by reference. 
         [0070]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.