JP4071460B2 - How to manage file information - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a file information management method. In particular, the present invention relates to a technique for verifying the reliability of file information acquired from a removable medium such as a CD-ROM (Compact Disc ROM) and a CD-R (CD Recordable).
[0002]
[Prior art]
Conventionally, the number of songs that can be recorded on a music CD (CD-DA) that has been widely spread has been limited to 99 songs. However, in recent years, as represented by MP3 (MPEG-1, Audio layer-III), AAC (Advanced Audio Coding), WMA (Windows Media Audio), and the like, music data compression techniques are rapidly progressing. By compressing the music data by these techniques, the number of songs as much as the recording capacity allows can be recorded on a CD-ROM, CD-R, or the like. And the music recorded on these discs is handled as a music data file and is managed by the concept of directory or folder.
[0003]
As described above, when a large amount of music data files are recorded on the disc, the method of directly searching the disc takes a long time to access the target file. Therefore, information such as the start / end address and data size of each file recorded on the disc is written in advance in the auxiliary memory in the disc reproducing apparatus. By using the information in the auxiliary memory, high speed access to the files recorded in the disk is realized. The file information is written into the auxiliary memory when the disc is set in the disc reproducing apparatus.
[0004]
By the way, when the disc playback device returns to the on state again after the off state (standby state), the music information is stored using the file information stored in the auxiliary memory without re-acquiring the file information. It is desirable to have access to data. For that purpose, the reliability of the file information stored in the auxiliary memory is important. This is because, for example, when the file information is destroyed during the standby state, the disk cannot be normally accessed. Various file information management methods in the auxiliary memory have been proposed.
[0005]
[Problems to be solved by the invention]
A conventional file information management method will be described with reference to FIGS. 7A and 7B are conceptual diagrams showing the configuration of the memory space of the auxiliary memory.
[0006]
First, in the management method shown in FIG. 7A, the file information 230 is written in the memory space 200 of the auxiliary memory, and at the same time, the same data (check data) 260, 260 is written to two points (or three points) in the memory space 200. Is written. Then, it is determined whether or not the file information 230 is normal depending on whether or not the contents of the check data 260 and 260 are the same.
[0007]
However, this method does not look at the file information itself, and has great anxiety about reliability.
[0008]
On the other hand, in the management method shown in FIG. 7B, the file information 230 is written into the memory space 200 and, at the same time, the check code 240 for the entire file information 230 is created. Then, by comparing the file information 230 with the check code 240, it is determined whether or not the file information 230 is normal.
[0009]
However, in this method, when it is determined that the file information is not normal, all of the file information is discarded. Therefore, information such as which position of the file information is damaged and what degree of damage is not obtained. Furthermore, a predetermined capacity area for storing file information is secured in the memory space 200 in advance. Here, when the number of files and folders actually recorded on the disk is smaller than the expected number of the areas reserved in the memory space 200, a free area in which invalid data remains is generated. However, in the method of FIG. 7B, the check code is created based on the data of the entire area including the data remaining in the empty area. Even if attention is paid to individual file information, if the area where the file information is stored has a fixed length, a check code must be created including the unused area. Therefore, there is a problem that the amount of processing necessary for creating the check code increases unnecessarily.
[0010]
The present invention, together with capable of managing file information individually, that provides management method of the file information that can reduce the amount of processing required to create the check code.
[0011]
[Means for Solving the Problems]
Managing file information according to one embodiment of this invention, the file information is added a step of reading a plurality of file information recorded in the information recording medium, the check code is created based on the file information In the auxiliary memory, the file information and the check code are collated to determine whether the file information is normal, and in the determination step, the file information is determined to be normal The file information in the auxiliary memory is used when it is determined, and the file information is reacquired from the information recording medium when it is determined that the file is not normal, and the check code is added. The step of recording the file information in the auxiliary memory is to create and attach the check code for each file information. And the check code plurality of the file information is added, the stored information for each block having a predetermined memory capacity are in the auxiliary memory, the result of storing the file information in the information block, said If there is an empty area in the information block, the check code ignores data existing in the empty area and is created only by the file information occupying the information block. The check code is generated by ignoring data after the file name length from the beginning of the file name in the information block .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the description, common parts are denoted by common reference symbols throughout the drawings.
[0015]
A file information management method according to the first embodiment of the present invention will be described. FIG. 1 is a block diagram showing an outline of a disk reproducing apparatus.
[0016]
As shown in the figure, the disc playback apparatus 10 includes a playback unit 11, a digital signal processor (DSP) 12, a memory 13, a CPU 14, an operation panel 15, and speakers 16 and 17.
[0017]
A disc 18 is set in the reproducing unit 11 and data recorded on the disc 18 is reproduced. The disk 18 includes CD-DA, CD-ROM, CD-R and the like. When the disc 18 is a CD-DA, the digital stereo signal obtained from the disc 18 is converted into an analog stereo signal and reproduced by the speaker 16. When the disk 18 is a CD-ROM or CD-R, a digital signal obtained from the disk 18 is supplied to the digital signal processor 12.
[0018]
The digital signal processor 12 decodes the digital signal sent from the reproduction unit 11. A memory 13 is connected to the digital signal processor 12, and information in the disk obtained by decoding the digital signal is recorded in the memory 13. The memory 13 is a semiconductor memory such as SRAM (Static Random Access Memory). Further, the music data obtained by decoding the digital signal is converted into an analog stereo signal and reproduced by the speaker 17. The memory 13 may be built in the digital signal processor 12 or may be externally attached.
[0019]
An operation panel 15 is connected to the CPU 14. The operation panel 15 is provided with keys for reproduction, stop, skip, etc., and a numeric keypad. Then, the CPU 14 controls the playback unit 11 and the digital signal processor 12 in accordance with the operation of the operation panel 15 by the user of the disc playback apparatus 10.
[0020]
If the data held on the disk 18 is compressed in a format such as MP3, AAC, WMA, etc., the song information is handled as individual music data files. And it is managed by the concept of directory or folder in the disk. In the case of a normal CD-R or CD-ROM, the maximum number of folders that can be recorded is 256, and the total number of folders and files is 512. Hereinafter, unless otherwise specified, the term “file” is used without distinguishing between a file and a folder.
[0021]
Next, a method for managing file information in the disc reproducing apparatus will be described with reference to FIG. FIG. 2 is a flowchart of this management method.
[0022]
First, the disc 18 is set in the reproducing unit 11 as described above (step S1). The disc set here is a CD-ROM, CD-R or the like created using a compression technique (MP3, AAC, WMA, etc.) that handles music information as individual files.
[0023]
Next, the digital signal obtained from the disk 18 by the reproducing unit 11 is decoded by the digital signal processor 12. Then, the file information recorded in the disk 18 is read and recorded in the memory 13 (step S2). Subsequently, a check code is created based on the file information recorded in the memory and recorded in the memory 13 (step S3). Steps S2 and S3 will be described in detail with reference to FIG. FIG. 3 is a conceptual diagram of the memory space.
[0024]
As shown in the figure, in the memory space 20 of the memory 13, an area 21 in which, for example, 512 pieces of file information can be recorded is secured. By giving about 8 kbytes as the memory capacity of this area 21, a capacity of 16 bytes is assigned to one file information. The 16-byte area 22 allocated to one file information is hereinafter referred to as an information block. The file information 23 stored in the information block 22 is information consisting of, for example, 14 bytes including, for example, the start address, end address, and file size of the file in the disk. The address of the file is represented by “minute, second, frame”. Note that a frame is a unit of time obtained by dividing one second into 75.
[0025]
Then, the digital signal processor 12 creates a check code 24 for each file based on the file information 23 (step S3). This check code is created by a known method such as a check sum, CRC (cyclic redundancy check), ECC (error correcting code), or the like. The check sum is a value obtained by adding binary values indicating file information and using any numerical value of the lower bits as a check code. CRC is a method using a cyclic code. ECC is a method that can automatically correct errors in digital signals, and a code such as a Hamming code, a Reed-Solomon code, a BCH code, a Fire code, and an Iwadare code is selected and added. Such a check code is created for each piece of file information, and stored in the information block together with the file information. The number of check codes added to one file is not necessarily one. For example, two check codes may be added, one based on a check sum and the other based on a CRC. Rather, it is preferable to add a plurality of check codes from the viewpoint of improving the reliability of file information management. Since the capacity of one information block is 16 bytes and the file information is 14 bytes, 2 bytes are allocated to the check code.
[0026]
In this way, the file information 23 and the check code 24 are recorded in the information block 22 in the memory 13. If the number of files on the disk is less than 512, a part of the area 21 becomes a free area 25 (see FIG. 4), but no check code is created for this free area 24.
[0027]
After the subsequent performance of the disc, etc., it is assumed that the disc playback device is turned off (standby state) (step S4) and turned on again (step S5). Then, the DSP 12 collates the file information recorded in the memory 13 with the check code (step S6).
[0028]
As a result of the collation, when the file information matches the check code (step S7), it is determined that the file information recorded in the memory 13 is normal. On the other hand, if the file information does not match the check code (step S7), it means that the file information recorded in the memory 13 has been destroyed, and the file information is reacquired from the disk 18. (Step S8). Note that the re-acquisition of the file information may be performed only for the destroyed file information or may be performed for all file information.
[0029]
Thus, the file information recorded in the memory 13 is verified, and thereafter, the disk 18 is accessed using this file information.
[0030]
In the file information management method as described above, a check code is created and added for each file information. Therefore, (1) it can be determined whether or not each file information is normal, and it becomes easy to verify the damage rate of the file information, the distribution of the destroyed file information in the disk, and the like. Further, when any of the file information is destroyed, it is not necessary to reacquire the file information from the disk, and it is sufficient to reacquire only the destroyed file information. Therefore, the time required for reacquisition, power consumption, etc. can be reduced.
[0031]
Also, no check code is created / added to the empty area 25 of the area 21 reserved for storing file information in the memory 13. Therefore, (2) check code creation can be suppressed to the minimum necessary, and the processing time required for collating the file information with the check code can be reduced.
[0032]
Next, a file information management method according to the second embodiment of the present invention will be described. In the present embodiment, a file name is added to the file information in the first embodiment. FIG. 5 is a conceptual diagram of information blocks in the memory space.
[0033]
As shown in the figure, in the file information management method according to the present embodiment, the file name and its name length are managed as the file information in addition to the head, final address, and file size of the file. Then, a check code is created based on these addresses, file size, file name, and name length. In the information block 22 assigned to each file information in the memory 13, an area of 16 bytes is secured for a check code, an address, a file size, and a file name length, and a 128 byte area is secured for a file name. . Accordingly, an area having a capacity of 512 × 144 bytes≈74 kbytes is secured in the memory space for storing file information. A capacity of 128 bytes is secured for the file name, but the file name may be short, the entire capacity of 128 bytes is not required, and the surplus area becomes a free area (see FIG. 6). In this case, the check code is generated by ignoring the contents of the free area. That is, if the file name is 10 bytes, the remaining 118 bytes are an empty area. In this empty area, the previously recorded file name and the like remain. Therefore, since it is recorded that the file name is 10 bytes in the file name length, based on this information, only the data recorded up to 10 bytes from the beginning is stored for the area where the file name is stored. The check code is created by ignoring the subsequent 11 bytes to 128 bytes of data.
[0034]
According to the method as described above, the check code is created using only valid data in the memory space allocated for each individual file without considering the data in the unused area. That is, the check code is created using only the minimum necessary data. Therefore, in addition to the effects described in the first embodiment, the processing time for creating the check code can be reduced.
[0035]
The file name is usually the title of a song. In this case, by sending file information including the file name to, for example, a display unit provided on the operation panel 15, the name of the currently played song can be displayed on the display unit. Conventionally, since the check code is created using the data of the entire information block, it is necessary to send all the data in the information block to the display unit even when the file name is short. However, in this embodiment, the check code is created using only valid data. Therefore, only valid data in the information block may be sent to the display unit. That is, there is no need to send data in the empty area in the information block assigned to the file name. Therefore, the amount of data exchanged with the display unit can be reduced. This is not limited to the file name, but is the same even when other data is included as file information.
[0036]
As described above, according to the file information management method according to the first and second embodiments, file information can be individually managed and the amount of processing required for creating a check code can be reduced. Management methods can be provided.
[0037]
In the above embodiment, CD-R and CD-ROM have been described as examples of music data recording media. However, the present invention is not limited as long as music data is recorded in the form of a file or a folder. In particular, in the case of a large capacity DVD (Digital Versatile Disc) or the like, it can be said that the effects of the present invention are further remarkably exhibited. This is because a conventional CD-R or CD-ROM has a maximum number of files of 512, but the number of files handled by a DVD is several to several tens of times. Therefore, it is very inefficient to re-acquire all files when one file is destroyed. However, according to the present invention, management can be performed in units of individual files, and file information can be managed efficiently.
[0038]
In the above embodiment, first, file information for all files is written in the memory, and then a check code is created for each file information. However, each time the individual file information is written into the memory, a check code corresponding to the file information may be created and added.
[0039]
The maximum number of files that can be stored in the memory has been described as 512, but of course this is merely an example, and the value can be freely selected according to the specification.
[0040]
Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. Furthermore, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be extracted as an invention.
[0041]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a file information management method capable of individually managing file information and reducing the amount of processing necessary for creating a check code.
[Brief description of the drawings]
FIG. 1 is a block diagram of a disc playback apparatus that implements a file information management method according to a first embodiment of the invention.
FIG. 2 is a flowchart of a file information management method according to the first embodiment of the invention.
FIG. 3 is a conceptual diagram of a memory space in which file information is stored by the file information management method according to the first embodiment of the invention.
FIG. 4 is a conceptual diagram of a memory space in which file information is stored by the file information management method according to the first embodiment of the invention.
FIG. 5 is a conceptual diagram of file information managed by the file information management method according to the second embodiment of the invention.
FIG. 6 is a conceptual diagram of file information managed by the file information management method according to the second embodiment of the invention.
7A and 7B are conceptual diagrams of a memory space in which file information is stored by a conventional file information management method, where FIG. 7A is a method of writing check data, and FIG. 7B is a method of using a conventional check code. By memory space.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Disc reproducing apparatus 11 ... Reproducing part 12 ... DSP
13 ... Memory 14 ... CPU
DESCRIPTION OF SYMBOLS 15 ... Operation panel 16, 17 ... Speaker 18 ... Disk 20, 200 ... Memory space 21, 210 ... File information storage area 22 ... Area 23, 230 ... File information 24, 240 ... reserved for storing file information Code 25 ... free space 260 ... check data

Claims (3)

Reading a plurality of file information recorded on the information recording medium;
Adding a check code created based on the file information and recording the file information in an auxiliary memory;
Collating the file information with the check code and determining whether the file information is normal;
If it is determined in the determining step that the file information is normal, the file information in the auxiliary memory is used, and if it is determined that the file information is not normal, the file information is read from the information recording medium. Re-acquiring, and adding the check code and recording the file information in an auxiliary memory includes creating and adding the check code for each file information ,
The plurality of file information to which the check code is added are stored for each information block having a predetermined memory capacity in the auxiliary memory,
As a result of storing the file information in the information block, if there is an empty area in the information block, the check code ignores the data existing in the empty area and occupies the information block. Created by file information only,
The file information includes a file name and a file name length of the file,
The method of managing file information, wherein the check code is created by ignoring data after the file name length from the beginning of the file name in the information block . The step of reacquiring the file information includes:
The only reacquire the file information is determined not as normal in determining, creating a check code based on the file information again, how to manage file information claim 1 Symbol mounting, characterized in that the addition. The file information is created using any one of a group consisting of a method using a lower bit of the sum of each bit constituting the file information, a method using an error correction code, and a method using a cyclic code. managing file information according to claim 1 or 2, wherein the plurality of the check codes are added.

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