JP2004078704A - Image and sound record/playback device and file read/write method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a continuous smooth moving image playback which reduces the number of seek occurrences when reading a large size file such as a moving image in an image and sound record/playback device which mounts a HDD (hard disc drive) and plays back image/sound data recorded in this HDD. <P>SOLUTION: Continuity of data in a file written in a disk is secured in units of a big cluster by managing the file such as the moving image data that is read/written to the hard disk drive in units of cluster by FAT file system and by reading/writing the file in units of the big cluster composed of two or more consecutive clusters. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a video / audio recording / reproducing system which includes a hard disk drive, records video and / or audio data transferred from an external device on the hard disk drive, and reads and reproduces the recorded data at an arbitrary timing. The present invention relates to a device and its file reading / writing method.
[0002]
[Prior art]
When reading and writing files to and from a hard disk drive, a file system is used to manage which files are stored where.
[0003]
Here, a FAT (File Allocation Table) file system will be described. In the FAT file system, one partition of a disk is managed in units called clusters, and information such as the state of each cluster and links between clusters is recorded and managed as FAT data in a FAT management area.
[0004]
The size of one cluster is determined within the constraints of the partition capacity and the size of the FAT entry. Consider a case where the size of one cluster is 64 sectors (= 32 kbytes).
[0005]
In this case, the continuity of data is guaranteed up to 32 kbytes, but if it exceeds 32 kbytes, a seek occurs, which is a movement of the head across a track on the disk to search for the next data. When this seek occurs, there is a possibility that data output from the hard disk drive is temporally interrupted due to the time required for the seek.
[0006]
[Problems to be solved by the invention]
If the data to be reproduced is of a nature that is not subject to time constraints, the interruption of data output from the hard disk drive does not matter much. However, when the data to be reproduced is a moving image, music, or the like, the interruption of the data output causes visual and auditory discomfort to the user.
[0007]
The file size of the moving image data is in the tens of megabytes or hundreds of megabytes class, which is much larger than the size of one cluster (32 kbytes). For this reason, a large amount of reading and writing of FAT data occurs when reading and writing a moving image of one file, and there has been a problem that efficiency is low.
[0008]
Further, in the FAT file system, the position of the FAT management area is fixed on the disc, and the reproduced video may be interrupted due to the effect of seek that occurs every time the read / write of the FAT data is switched between the read / write of the file. was there.
[0009]
In order to minimize the occurrence of seeking when reading and writing FAT data, a method of caching FAT data in a memory is usually adopted. However, when reading and writing large files such as moving image data, a large amount of data is read. Insufficient cache capacity for FAT data, resulting in access to the FAT management area on the disk.
[0010]
The present invention is intended to solve such a problem, and reduces the number of times of seeking when reading a file having a large file size such as a moving image, and realizes video / audio recording / reproducing that can realize smooth and smooth moving image reproduction. It is an object of the present invention to provide an apparatus and a method for reading and writing the file.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a video / audio recording / reproducing apparatus according to the present invention comprises a hard disk drive capable of reading and writing a file of video and / or audio data, and a read / write device for the hard disk drive. A control unit that manages files to be read and written in units of big clusters, which are two or more predetermined number of continuous clusters, by the FAT file system, and the hard disk drive. A playback unit that plays back video and / or audio data read from the drive.
[0012]
According to the present invention, continuity of data of a file written on a disk is guaranteed in units of N (N is a predetermined number of 2 or more) continuous clusters, which are big clusters. As a result, the frequency of seeking when reading a large file such as a moving image is reduced, and the moving image can be smoothly reproduced such that the moving image is less likely to be interrupted during reproduction.
[0013]
Further, in the video / audio recording / reproducing apparatus of the present invention, when writing the file to the hard disk drive, the control unit refers to the FAT provided by the FAT file system and sets one of the vacant areas. When the location information of the big cluster is cached, the file is written based on the cached location information, the contents of the FAT are updated, and when reading the file from the hard disk drive, the FAT is read. And caches the position information of each of the big clusters to which the file is written, and controls to read the file from the hard disk drive based on the cached position information. May be.
[0014]
According to this, the number of FAT data that must be cached when reading and writing a file can be greatly reduced, so that the number of clusters that can be continuously read and written increases, and high-speed reading and writing becomes possible.
[0015]
Further, in the video / audio recording / reproducing apparatus of the present invention, the control unit may include a first file of a type written in the hard disk drive in units of the big cluster and a first file of a type written in units of the cluster in the hard disk drive. It manages information for identifying a second file, and controls to switch between reading of the file in the unit of the big cluster and reading of the file in the unit of the cluster according to the type of each of the files. You may.
[0016]
According to the present invention, it is possible to coexist with a system that reads and writes files in cluster units, and to read and write relatively large files and small files such as moving images, videos, and music data in the same partition. When it is possible, the utilization efficiency of the disk storage area can be improved.
[0017]
To achieve the above object, a file reading / writing method for a video / audio recording / reproducing apparatus according to another aspect of the present invention includes a hard disk drive for storing video and / or audio data as a file. A file reading / writing method for a video / audio recording / reproducing apparatus for reading / reproducing the file from / to a hard disk drive, wherein the file read / written to / from the hard disk drive is managed in clusters by a FAT file system. In addition, the file is read and written in units of big clusters, which are two or more predetermined number of continuous clusters.
[0018]
According to the present invention, continuity of data of a file written on a disk is guaranteed in units of N (N is a predetermined number of 2 or more) continuous clusters, which are big clusters. As a result, the frequency of seeking when reading a large file such as a moving image is reduced, and the moving image can be smoothly reproduced such that the moving image is less likely to be interrupted during reproduction.
[0019]
Also, the file reading / writing method of the video / audio recording / reproducing apparatus according to the present invention is characterized in that, when the file is written to the hard disk drive, one or more free areas are referred to by referring to the FAT provided by the FAT file system. Caches the location information of the big cluster, writes the file based on the cached location information, updates the contents of the FAT, and reads the file from the hard disk drive. By referring to the cache, position information of each of the big clusters to which the file is written is cached, and the file is read from the hard disk drive based on the cached position information.
[0020]
According to the present invention, the number of FAT data that must be cached when reading and writing a file can be greatly reduced, so that the number of clusters that can be continuously read and written increases, and high-speed reading and writing becomes possible.
[0021]
Further, the file reading / writing method of the video / audio recording / reproducing apparatus according to the present invention may further comprise a first file of a type written to the hard disk drive in units of the big cluster and the hard disk drive in units of the cluster. Manages information for identifying a second file of the type written in the file, and switches between reading of the file in the unit of the big cluster and reading of the file in the unit of the cluster according to the type of each of the files It may be.
[0022]
According to the present invention, it is possible to coexist with a system that reads and writes files in cluster units, and to read and write relatively large files and small files such as moving images, videos, and music data in the same partition. When it is possible, the utilization efficiency of the disk storage area can be improved.
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0024]
FIG. 1 is a hardware block diagram showing a configuration of a video / audio recording / reproducing apparatus 100 according to an embodiment to which the present invention is applied.
[0025]
As shown in FIG. 1, the video / audio recording / reproducing apparatus 100 includes a hard disk drive 1 (hereinafter, referred to as an HDD), an HDD interface 2, a system bus 3, a CPU (Central Processing Unit) 4, and a ROM (Read). It includes an Only Memory 5, a RAM (Random Access Memory) 6, a user interface 7, a buffer memory 8, a decoder 9, an external interface 10, a video interface 11, an audio interface 12, a monitor 13, a speaker 14, and the like.
[0026]
The video / audio recording / reproducing apparatus 100 is a video / audio recording / reproducing apparatus for recording / reproducing data having a large file size such as moving image data, and employs the HDD 1 as a storage device for recording data having a large file size.
[0027]
Reading and writing of files to and from the HDD 1 is managed by the FAT file system. The HDD 1 is connected to a system bus 3 through a high-speed HDD interface 2 such as ATA / ATAPI, IEEE1394, USB, or the like.
[0028]
The CPU 4 uses the programs and parameters stored in the ROM 5 to control the entire video / audio recording / reproducing apparatus 100, exchange data between devices, and execute various arithmetic processes.
[0029]
The ROM 5 stores a basic program and various parameters for operating the video / audio recording / reproducing apparatus 100. The basic program includes a program 15 necessary for construction and operation of the FAT file system.
[0030]
The RAM 6 is used not only as a work area for the CPU 4 but also as a cache area for FAT data. In the area of the RAM 6, a fixed capacity is allocated to the FAT data cache area.
[0031]
The user interface 7 receives commands from the user, such as recording, reproduction, and stop, and command inputs related to file operations such as file selection and deletion, and notifies the CPU 4 of the command inputs.
[0032]
The buffer memory 8 is a memory for temporarily storing video and music data such as moving image data that has been compression-encoded such as MPEG (Moving Picture Coding Experts Group) data read from the HDD 1.
[0033]
The decoder 9 decodes the MPEG data read from the buffer memory 8.
[0034]
The external interface 10 is a connection interface with an external information device such as an HDD recorder, for example, and can transfer video and music data to and from the external information device.
[0035]
The video interface 11 converts the moving image / video data decoded by the decoder 9 into a signal that can be displayed on the monitor 13 and supplies the signal to the monitor 13. As the monitor 13, for example, an LCD (Liquid Crystal Display) display or the like is used.
[0036]
The audio interface 12 converts the music / voice data decoded by the decoder 9 into a signal that can be output by the speaker 14 and supplies the signal to the speaker 14.
[0037]
Next, the FAT file system employed in the video / audio recording / reproducing apparatus 100 will be described.
[0038]
The FAT file system includes a directory entry and a FAT (File Allocation Table).
[0039]
As shown in FIG. 2, the directory entry 21 manages a correspondence between a file name 22, an attribute (date, size, etc.) 23, and a cluster number 24 at the head of the file.
[0040]
As shown in FIG. 3, the FAT 31 has a table structure for managing information indicating the connection of clusters constituting a file. Each entry 32 of the FAT 31 has a one-to-one correspondence with each cluster of the disk, and indicates the usage status of the corresponding cluster (whether it is free or not).
[0041]
In this embodiment, as shown in FIG. 4, it is possible to read / write a file from / to the HDD 1 in units of N (N is a predetermined number of 2 or more) continuous clusters. The N consecutive clusters are referred to herein as "big clusters". In the example of FIG. 4, one big cluster 33 is configured by 128 clusters.
[0042]
FIG. 5 shows a procedure for writing a file.
[0043]
When a file write request occurs, first, an empty area on the disk is searched in units of big clusters, and one or more big clusters for writing data of one file (in the example of FIG. 3) Search.
[0044]
That is, as shown in FIG. 5, first, the number of the cluster at the head of the disk is obtained (step 501). Although not shown in FIG. 4, several clusters at the head of the disk are reserved for a file system or used for a directory entry or the like. Done. Next, referring to the FAT 31, the free big cluster 33 is searched starting from the head cluster of the disc (step 502).
[0045]
However, when reading and writing in a normal cluster unit are supported, the written cluster may be included in the 128 clusters to be searched for the empty big cluster 33. In such a case, it is considered that the big cluster is not in an empty state, and the process shifts to checking the empty state of the next 128 clusters (steps 502a to 502c).
[0046]
The position information of the big cluster searched in this way is stored (cached) in a memory such as the RAM 6. That is, the found free big cluster is reserved for writing the file (step 502d). The position information of the big cluster stored at this time includes the number of the head cluster of the big cluster and the like. In the example of FIG. 4, cluster numbers 1, 257, and 359 are stored as big cluster information.
[0047]
If one or more big clusters at the write destination have been searched (secured) (YES in step 502e), the file is written in units of big clusters based on the cached position information of the big cluster (step 503).
[0048]
When the reserved free big cluster is gone (YES in step 504), the FAT 31 is updated (step 505).
[0049]
Updating of the FAT 31 is performed as follows.
[0050]
As shown in FIG. 4, since the data of the file is continuously recorded from the first cluster (number 1) to the last cluster (number 128) of the big cluster 1, the entry corresponding to each cluster of the FAT 31 has , Except for the entry corresponding to the last cluster (number 128) of the big cluster 1, the number of the cluster next to the own cluster is entered. Then, as the entry corresponding to the last cluster of the big cluster, the number (257) of the first cluster of the next big cluster 2 is entered. After writing to the end of the file, end-of-file information (EOF) is written as the value of the entry corresponding to the cluster including the end position of the file.
[0051]
If normal cluster unit writing is supported, after writing the file as described above, it is explicitly stated that this file is a file written in big cluster units (step 506). . For example, there is a method of storing a list of files written in units of big clusters as a file, or having a directory entry as a file attribute.
[0052]
Next, an operation of reading a file written in a unit of a big cluster as described above will be described. FIG. 6 shows a procedure for reading a file.
[0053]
First, it is checked whether the file to be read is a file written in a big cluster unit by checking the above file list or referring to the attribute of the file recorded in a directory entry ( Steps 601 and 602).
[0054]
If it is confirmed that the file is written in units of big clusters, the number of the first cluster (1 in the example of FIG. 4) constituting the file is acquired from the directory entry 21 and cached in the memory (step 603). ).
[0055]
Subsequently, referring to the FAT 31, the number of the first cluster of the next big cluster (257 in the example of FIG. 4), which is entered at the first cluster number +127 (the last cluster number of the big cluster 1), is cached in the memory. Similarly, the number of the first cluster of the next big cluster (359 in the example of FIG. 4) is cached in the memory. This procedure is repeated until all of the leading cluster numbers are cached for all the big clusters 1, 2, and 3 constituting the file, or until the cache area prepared in the memory is filled (steps 604 and 605).
[0056]
Thereafter, the data of the file is read from the disk according to the leading cluster number of each big cluster cached in the memory (steps 606, 607, 608).
[0057]
If the last cluster number entry of the big cluster does not contain a valid value when obtaining the first cluster number of the big cluster, this means that this big cluster is the last big cluster of the file. I do. Also, in order to know which cluster of this big cluster is a valid cluster, FAT data of the big cluster is searched in order to detect a cluster number including EOF, and this is set as a file read end position. Remember. Based on this information, the end of reading the file can be controlled.
[0058]
As described above, according to this embodiment, the continuity of the data of the file written to the disk is guaranteed in units of a big cluster, which is N (N is a predetermined number of 2 or more) continuous clusters. As a result, the frequency of seeking when reading a large file such as a moving image is reduced, and the moving image can be smoothly reproduced such that the moving image is less likely to be interrupted during reproduction.
[0059]
Further, since the number of FAT data to be cached when reading / writing a file is reduced to approximately 1 / N, data of approximately N times the size can be continuously (even without interruption due to reference to the FAT) even if the cache capacity is the same. ) Reading and writing can be performed, and high-speed reading and writing can be realized.
[0060]
According to an experiment, it took about 200 seconds to write one hour of moving image data having a reproduction bit rate of 1.5 Mbps to a disk, but according to the present invention, one big cluster was composed of 128 clusters. In this case, the result was that about 45 seconds were enough.
[0061]
Furthermore, in this embodiment, it is possible to coexist with a system that reads and writes files in cluster units, and by switching and operating the optimal reading and writing unit flexibly according to the file size and attributes, moving images, In a case where a large file and a small file such as video and music data can be read and written in the same partition, it is possible to prevent a decrease in the use efficiency of the disk storage area.
[0062]
Note that the present invention is not limited to any of the above-described embodiments, and can be appropriately modified and implemented within the scope of the technical idea of the present invention.
[0063]
Although the big cluster is composed of 128 clusters, any two or more continuous clusters may be used. However, if the number of clusters constituting the big cluster is too small, the speed of reading / writing files from / to the disk cannot be improved much. Conversely, if the number is too large, many unused clusters may be generated in the big cluster, and the utilization efficiency of the disk storage area decreases.
[0064]
Further, the present invention can be applied to a case where a storage device other than the HDD is used as long as the FAT file system can be applied.
[0065]
【The invention's effect】
As described above, according to the present invention, the continuity of data of a file written on a disk is guaranteed in units of N (N is a predetermined number of 2 or more) continuous clusters, which are big clusters. In addition, the frequency of seeking when reading a large-sized file such as a moving image is reduced, so that the moving image is less likely to be interrupted during reproduction.
[Brief description of the drawings]
FIG. 1 is a hardware block diagram illustrating a configuration of a video / audio recording / reproducing apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of a directory entry of the FAT file system.
FIG. 3 is a diagram showing a configuration of a FAT of a FAT file system.
FIG. 4 is a diagram for explaining an extended part of the FAT file system according to the present invention.
FIG. 5 is a flowchart showing a procedure for writing a file.
FIG. 6 is a flowchart showing a procedure for reading a file.
[Explanation of symbols]
1 hard disk drive 2 HDD interface 3 system bus 4 CPU
5 ROM
6 RAM
7 User Interface 8 Buffer Memory 9 Decoder 10 External Interface 11 Video Interface 12 Audio Interface 13 Monitor 14 Speaker 15 FAT File System Program 21 Directory Entry 22 File Name 23 Attribute 24 First Cluster Number 31 FAT
33 Big Cluster 100 Video / Audio Recording / Reproducing Device

Claims (6)

A hard disk drive capable of reading and writing video and / or audio data files;
A file read / written from / to this hard disk drive is managed in units of clusters by the FAT file system, and the file is read / written in units of big clusters, which are two or more predetermined number of continuous clusters. A control unit for controlling;
A video / audio recording / reproducing apparatus, comprising: a reproducing section for reproducing video and / or audio data read from the hard disk drive. When writing the file to the hard disk drive, the control unit refers to the FAT provided by the FAT file system, caches location information of one or more big clusters that are free areas, Based on the cached position information, the file is written and the contents of the FAT are updated. When the file is read from the hard disk drive, the file is written with reference to the FAT. 2. The video / audio recording / reproducing apparatus according to claim 1, wherein position information of each of the big clusters is cached, and the file is read from the hard disk drive based on the cached position information. apparatus. The control unit stores information for identifying a first file of a type written in units of the big cluster and a second file of a type written in units of the cluster on the hard disk drive. 2. The video / audio recording / reproducing apparatus according to claim 1, wherein the control is performed so as to switch between reading of the file in the unit of the big cluster and reading of the file in the unit of the cluster according to the type of each of the files. apparatus. A file reading / writing method for a video / audio recording / reproducing apparatus, comprising: a hard disk drive that stores video and / or audio data as a file; and reading and reproducing the file from the hard disk drive.
Managing the file read / written to / from the hard disk drive in units of clusters using a FAT file system and reading / writing the file in units of big clusters, which are two or more predetermined number of continuous clusters A file reading / writing method for a video / audio recording / reproducing device, characterized by comprising: When writing the file to the hard disk drive, cache the location information of one or more of the big clusters, which are free areas, with reference to the FAT provided by the FAT file system. When writing the file based on the FAT and updating the contents of the FAT, and reading the file from the hard disk drive, referring to the FAT, each of the big clusters in which the file is written 5. The method according to claim 4, wherein the position information is cached, and the file is read from the hard disk drive based on the cached position information. A first file of a type written to the hard disk drive in units of the big cluster and a second file of a type written to the hard disk drive in units of the cluster; 5. The video / audio recording / reproducing apparatus according to claim 4, wherein information is managed, and reading of the file by the big cluster unit and reading of the file by the cluster unit are switched according to the type of each of the files. 6. How to read and write files.

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