JP3839201B2 - Data recording / reproducing apparatus, data recording / reproducing method, and computer-readable recording medium - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a data recording and reproducing apparatus such as a DVD-RW drive and the data reproducing how.
[0002]
[Prior art]
A DVD-Recordable (DVD-R) disc that can record data only once, is completely compatible with a general playback DVD after recording, and can be read by a personal computer connected to a DVD player or DVD-ROM drive. Are known.
[0003]
Recently, the DVD can be rewritten by the number of times depending on the material of the disc, can be reproduced with only a small change that adds RF signal gain switching to the drive design, and can be rewritten at random using UDF (Universal Disk Format). Rewriteable (DVD-RW) discs have attracted attention.
[0004]
Conventionally, in a data recording / reproducing apparatus such as a DVD-RW drive for reading / writing data from / to a DVD-RW disc as described above, processing of data to be read and written is completely separated by a read operation and a write operation. It was.
[0005]
[Problems to be solved by the invention]
However, in the conventional data recording / reproducing apparatus, when a small change is repeated for the same data, a write access to the recording medium is generated every time the data change occurs. Since access is structurally slow, there is a bottleneck in the processing time of random access, and there is a problem that it takes time from data request to response.
[0006]
The present invention has been made to solve the above-described problems, and an object thereof is to improve the speed at the time of random access to a recording medium such as a DVD-RW disk.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a data recording / reproducing means for reading and writing data to and from a recording medium, and data for buffering read data read from the recording medium by the means and write data to be written to the recording medium. buffer means and its means when changes are made to the write data buffered rewritten on said data buffer means, writing back control means writes back to the recording medium and the rewritten write data every predetermined time And when the reading and writing of data to the recording medium are in a dormant state , all the write data on the data buffer means are written back to the recording medium in the order of the lowest change frequency per unit time. A data recording / reproducing apparatus provided with a control means is provided .
[0008]
In the data recording / reproducing apparatus as described above, after the write data of the data buffer means is written back to the recording medium, it is held on the means and there is a read request for the write data written back to the recording medium. In this case, write data holding / reading control means for reading from the data buffer means may be provided.
[0009]
Further, in the data recording / reproducing apparatus as described above, it is preferable to provide the same form buffer control means for buffering the read data and the write data in the same form on the data buffer means.
[0010]
Further , in the data recording / reproducing apparatus as described above, when there is no free space in the data buffer means, free space allocation control means for allocating the free data from the area storing the write data having the lowest change frequency per unit time. It is good to provide.
[0011]
Furthermore , in the data recording / reproducing apparatus as described above, it is preferable to provide a write-back frequency reduction control means for reducing the write-back frequency per unit time with respect to the write-back control means.
[0012]
In the data recording / reproducing apparatus as described above, means for allocating the data buffer means to a work area for decoding data read from the recording medium and encoding data to be written to the recording medium may be provided.
[0013]
Further, a row of oriented data recording and reproducing step of reading and writing of data to the recording medium, a data buffer process for buffering write data to be written to the read data and the recording medium read out from the recording medium, the buffered the write When the data is changed , the buffer is rewritten on the buffer, and the rewritten write data is written back to the recording medium every predetermined time, and the reading and writing of the data to the recording medium are in a dormant state. There is also provided a data recording / reproducing method comprising a resting write-back control step of writing all the write data on the data buffer back to the recording medium in the order of the lowest change frequency per unit time .
[0014]
In the data recording / reproducing method as described above, the buffered write data is retained even after being written back to the recording medium, and when there is a read request for the write data written back to the recording medium, It is preferable to have a step of reading from.
[0015]
Further , the data recording / reproducing method as described above may include a step of buffering the read data and the write data in the same form on the buffer.
[0016]
Further, in the data recording / reproducing method as described above, when there is no free space in the buffer , it is preferable to have a step of assigning the free data from the region storing the write data having the lowest change frequency per unit time. .
[0017]
Further, the data recording / reproducing method as described above may include a step of reducing the number of times the write data is written back per unit time.
[0018]
Further, the data recording / reproducing method as described above may include a step of assigning the buffer to a work area for decoding data read from the recording medium and encoding data to be written to the recording medium.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below with reference to the drawings.
In this embodiment, a DVD drive intended for a DVD-RW disc, which has attracted attention as a substitute for a hard disk as a portable rewritable medium due to a recent drop in the disc price, is a structural problem in the DVD media. The random access speed is improved by applying a read / write cache function.
[0020]
FIG. 1 is a block diagram showing the configuration of the main part of a DVD drive according to an embodiment of the present invention.
The DVD drive of this embodiment includes an optical pickup (PU) 2 that reads / writes data from / to the DVD-RW disc 1 and a DVD decoder (DVD-DEC) 3 that demodulates read data read from the DVD-RW disc 1. And a DVD encoder (DVD-ENC) 4 for modulating write data to be written to the DVD-RW disc 1.
[0021]
Also, a cache buffer (Cache Buffer) 5 that is a read / write cache for storing read data and write data, and a host interface that is connected to the host computer and exchanges data between the host computer and the cache buffer 5. (HOST I / F) 6 and a CPU 7 which is a microcomputer which performs overall control of the DVD drive and performs control processing according to the present invention.
[0022]
That is, the PU 2 and the CPU 7 serve as data recording / reproducing means for reading and writing data to and from the recording medium, and the cache buffer 5 reads the read data read from the recording medium by the data recording / reproducing means and the recording medium. corresponds to the function of the data buffer means for buffering write data to be written, the CPU7 rewriting in the data buffer means when changes in buffered the write data is added to the data buffer means, the rewritten write data It functions as a write-back control means for writing back to the recording medium every predetermined time.
[0023]
Further, the cache buffer 5 and the CPU 7 hold the write data of the data buffer means on the recording medium after the write data is written back to the recording medium, and when there is a read request for the write data written back to the recording medium. It functions as a write data holding / reading control means for reading from the data buffer means.
[0024]
Further, the cache buffer 5 and the CPU 7 serve as the same form buffer control means for buffering the read data and the write data in the same form on the data buffer means.
[0025]
Further, the CPU 7 writes back all the write data on the data buffer means to the recording medium in the order of the lowest frequency of change per unit time when the reading and writing of data to the recording medium are in a dormant state. Acts as a resting write-back control means.
[0026]
Further, the CPU 7 functions as a free area allocation control means for allocating a free area from the area storing the write data having the lowest change frequency per unit time when there is no free space in the data buffer means.
[0027]
Further, the CPU 7 functions as a write-back number reduction control means for reducing the number of write-backs per unit time with respect to the write-back control means.
[0028]
Further, the DVD-DEC 3, DVD-ENC 4 and CPU 7 function as means for allocating the data buffer means to a work area for decoding data read from the recording medium and encoding data to be written to the recording medium.
[0029]
First, a conventional DVD drive will be briefly described.
In a conventional DVD drive, a read operation and a write operation for a DVD-RW disc are completely independent of each other in the data flow, and the data remaining in the buffer may be used in the read operation, but this is combined with the write operation. I never used it.
For this reason, when small changes are repeated for the same data, access to the DVD-RW disc occurs each time a data request is made.
[0030]
Therefore, in the DVD drive according to the embodiment of the present invention shown in FIG. 1, a read / write cache is added to the conventional DVD drive, and data once written to the DVD-RW disc is also stored on the read / write cache. Can be used as read data, as long as the write operation is explicitly reduced by write back timing adjustment by an algorithm, and the number of write operations is reduced, thereby reducing the number of write operations. -The life of the RW disk can be extended.
[0031]
As shown in FIG. 1, this DVD drive is provided with a cache buffer 5 which is a read / write cache buffer between a host interface 6, a DVD-DEC 3 and a DVD-ENC 4. The target data during the write operation is assumed to be data on the cache buffer 5.
[0032]
FIG. 2 is an explanatory diagram of the read / write operation for the cache buffer and the DVD-RW disc in the DVD drive shown in FIG.
[0033]
In the DVD drive of this embodiment, the CPU 7 reads and writes data to and from the DVD-RW disk 1 by the PU 2, and reads the read data read from the DVD-RW disk 1 and the write data to be written to the DVD-RW disk 1. When the change is made to the buffered write data, it is rewritten on the cache buffer 5, and the rewritten write data is written back to the DVD-RW disc 1 every predetermined time.
[0034]
That is, the CPU 7 writes the data back to the DVD-RW disc 1 (write back) as a factor having a predetermined interval generated by an algorithm controlled by the CPU 7 instead of at the time of changing the data. Absorbs substantial light access.
[0035]
Thus, when data is changed, overwriting is changed on the cache buffer 5 as much as possible, and the write access time: WA can be shortened by reducing the number of times of write back to the DVD-RW disk 1 (see FIG. 2).
[0036]
Next, if the data once written to the DVD-RW disk 1 is not explicitly held in the cache buffer 5, the data must be read again from the DVD-RW disk 1 in the subsequent reading of the same data. Therefore, the corrected and written data can be read at high speed.
[0037]
In the DVD drive of this embodiment, the CPU 7 retains the write data buffered in the cache buffer 5 after it has been written back to the DVD-RW disc 1, and receives a read request for the write data written back to the DVD-RW disc 1. If there is, the corresponding data is read from the cache buffer 5.
That is, in response to a read request, if there is target data on the cache buffer 5, returning this data absorbs substantial read access.
[0038]
Thus, by reducing the direct data read operation from the DVD-RW disc 1 as much as possible, the read access time RA can be shortened (see FIG. 2).
[0039]
Next, if the holding mode on the cache buffer 5 is distinguished between read data and write data, it becomes difficult to mix both of the data.
[0040]
Therefore, in the DVD drive of this embodiment, the CPU 7 stores the read data and write data holding format on the cache buffer 5 which is a problem when the read / write cache is realized, in the data on the DVD-RW disc 1. The data is matched by formal conversion with the attribute of whether or not it corresponds to the corresponding data in, and the read data and the write data are buffered in the same form on the cache buffer 5.
[0041]
In other words, it is treated as intermediate data of the same format having the same or a mismatch with the corresponding data on the DVD-RW disc 1 as a parameter, and write access is regarded as an operation for matching the intermediate data with the corresponding data on the DVD-RW disc 1. When the state between the intermediate data and the corresponding data on the DVD-RW disc 1 does not match, adjustment is performed so that the data is matched by write back by an algorithm.
[0042]
Further, in order to reduce the number of parts, the format of the input / output buffer of DVD-DEC3 and DVD-ENC4 is also converted to match this format.
By the above conversion, the write operation can be regarded as an operation for changing the mismatch state between the data on the cache buffer 5 and the data on the DVD-RW disc 1 to a matching state.
[0043]
Thus, the read data and the write data are held in the same manner in the cache buffer 5 so that the read data and the write data can be mixed.
[0044]
Next, random access to the DVD-RW disc of the DVD drive has a period of frequent access and a period of no access at all, and is intermittent in this respect. Since the upper limit of the number of accesses per unit time is restricted by the DVD drive, this is a processing bottleneck.
[0045]
Therefore, in the DVD drive of this embodiment, when the CPU 7 is in a dormant state of reading and writing data to the DVD-RW disc 1, all the write data on the cache buffer 5 is changed most frequently per unit time. Write back to the DVD-RW disc 1 in ascending order.
[0046]
Further, when the cache buffer 5 runs out of free space, the CPU 7 assigns the free data from the region storing the write data with the lowest change frequency per unit time.
[0047]
That is, when the CPU 7 detects the hibernation state of the DVD drive, it forcibly starts an algorithm for executing write back, and sets the eviction condition from the buffer when the cache buffer 5 becomes full. Write the discrepant data to the DVD-RW disc 1 at a low level.
[0048]
In addition, when the cache buffer 5 used for writing new data becomes full, the CPU 7 assigns an area with the lowest change frequency per unit time to write back an area for storing the data.
[0049]
In this way, when the DVD drive enters the hibernation state, an intermittent random operation with respect to the DVD-RW disc is performed by an algorithm that writes back all the inconsistent data to the DVD-RW disc in the order of the lowest change frequency per unit time. Uniform access in time and improve the usage efficiency of DVD drives.
Therefore, the number of write accesses to the DVD-RW disc per unit time can be reduced, and the life of the DVD-RW disc can be extended.
[0050]
Next, the sector life of a DVD-RW disc is defined by the maximum number of writes for that sector, and sectors that exceed the maximum number of writes become unusable.
In a normal DVD drive, an unusable sector is replaced with another sector by alternation processing, but the capacity of the DVD-RW disc is reduced accordingly.
[0051]
Therefore, in the DVD drive of this embodiment, the CPU 7 reduces the number of write backs (write back) per unit time to a predetermined number.
[0052]
Next, when the read data is demodulated and the write data is modulated by the respective buffers as in a normal DVD drive, three types of buffers having different structural purposes are provided, including the cache buffer as described above. This increases the cost of manufacturing the device.
[0053]
Therefore, the DVD drive of this embodiment allocates the cache buffer 5 to a work area for decoding data read from the DVD-RW disk 1 and encoding data to be written to the DVD-RW disk 1.
Then, the cache buffer 5 is shared with the DVD-DEC3 and DVD-ENC4 work buffers.
[0054]
FIG. 3 is a flowchart showing the read / write processing in the DVD drive of this embodiment.
The CPU 7 determines whether or not the DVD drive is in a hibernation state in step (indicated by “S” in FIG. 1). If the DVD drive is in a hibernation state, the process proceeds to step 2 to determine whether or not there is mismatched data. If there is no unmatched data, the process returns to the first process. If there is unmatched data, the process proceeds to step 3 to select data (area) having the lowest change frequency per unit time, and proceeds to step 4 to perform the write access process. To return to the first process.
[0055]
If it is determined in step 1 that the drive is not in the hibernation state, the process proceeds to step 5 to determine whether or not there is a data request from the host computer. If there is not, the process returns to the first process. It is determined whether or not there is target data on the buffer. If there is, the process proceeds to step 7 to select the same data (area), and the process proceeds to step 8 to determine whether or not it is a read request.
[0056]
If the request is a read request in step 8, the process proceeds to step 9 to execute a read access process, and the process proceeds to step 10 to execute a process of transferring read data to the host computer, and the process returns to the first process.
If it is not a read request in step 8, it is determined as a write request, the process proceeds to step 13 to execute a process of transferring write data to the DVD-RW disc, and the process returns to the first process.
[0057]
If it is determined in step 6 that there is no target data on the cache buffer, the process proceeds to step 11 to determine whether or not there is an empty area on the cache buffer, and if there is, the process proceeds to step 12 to select an empty area. Then, the process of steps 8 to 10 or step 13 described above is executed, and the process returns to the first process.
[0058]
If it is determined in step 11 that there is no free space, the flow proceeds to step 14 to select data (area) having the lowest change frequency per unit time, and the flow proceeds to step 15 to execute the write access (write back) process. Proceeding to step 8, the process of steps 8 to 10 or step 13 described above is executed, and the process returns to the first process.
[0059]
It should be noted that a program for realizing the above means by the CPU 7 may be recorded in a ROM (not shown) in advance, or may be recorded on various recording media such as FD, MO, CD-ROM, DVD-RW and the like. The CPU 7 may be installed in a DVD drive so that it can be referred to.
[0060]
The DVD drive of this embodiment eliminates the need for write access to the DVD-RW disk for the same data during the interval, and can improve the processing time from an average data request to a response.
[0061]
When data once written is read again, if it is held in the cache buffer (cache hit), data to be read at high speed can be returned to the host computer without accessing the DVD-RW disc.
[0062]
Furthermore, by making the holding form on the cache buffer the same, it is easy to mix read data and write data.
[0063]
In addition, intermittent access to random access to the DVD-RW disc can be made uniform over time, and the use efficiency of the DVD drive can be improved.
[0064]
Furthermore, by reducing the number of write accesses to the DVD-RW disc, the capacity and life of the DVD-RW disc can be extended in a tendency that is inversely proportional to the reduction rate.
[0065]
Furthermore, by using the cache buffer also as a work buffer for data modulation and demodulation, the cost required for the buffer can be suppressed.
[0066]
【The invention's effect】
As described above, according to the data recording / reproducing apparatus, data recording / reproducing method, and computer-readable recording medium of the present invention, data can be reduced by reducing the number of random accesses to a recording medium such as a DVD-RW disc. Can be read and written at high speed.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a main part of a DVD drive according to an embodiment of the present invention.
2 is an explanatory diagram of a read / write operation with respect to a cache buffer and a DVD-RW disc in the DVD drive shown in FIG. 1;
FIG. 3 is a flowchart showing read / write processing in the DVD drive shown in FIG. 1;
[Explanation of symbols]
1: DVD-RW disc 2: PU
3: DVD-DEC 4: DVD-ENC
5: Cache buffer 6: Host I / F
7: CPU

Claims (12)

A data recording and reproduction means for reading and writing of data to the recording medium, and a data buffer means for buffering write data to be written to the read data and the recording medium read out from said recording medium by said means, buffered in said means wherein When the write data is changed , the data buffer means rewrites the data, and the write-back control means for writing the rewritten write data back to the recording medium every predetermined time; and reading and writing data to the recording medium Data comprising: a resting write back control means for writing back all the write data on the data buffer means to the recording medium in the order of the lowest change frequency per unit time when the rest state is entered. Recording / playback device. The data recording / reproducing apparatus according to claim 1, wherein
Write data held in the data buffer means is held on the recording medium after being written back to the recording medium, and is read from the data buffer means when there is a read request for the write data written back to the recording medium. A data recording / reproducing apparatus comprising a control means. The data recording / reproducing apparatus according to claim 1 or 2,
A data recording / reproducing apparatus, comprising: a same form buffer control means for buffering the read data and the write data in the same form on the data buffer means. The data recording / reproducing apparatus according to any one of claims 1 to 3 ,
A data recording / reproducing apparatus comprising: a free area allocation control means for allocating a free area from an area storing write data having the lowest change frequency per unit time when there is no free space in the data buffer means. The data recording / reproducing apparatus according to any one of claims 1 to 4 ,
A data recording / reproducing apparatus, comprising: a write-back number reduction control means for reducing the number of write-backs per unit time for the write-back control means. The data recording / reproducing apparatus according to any one of claims 1 to 5 ,
A data recording / reproducing apparatus comprising: means for assigning the data buffer means to a work area for decoding data read from the recording medium and encoding data to be written to the recording medium. A data reproducing step for reading and writing of data to the recording medium, a data buffer process for buffering write data to be written to the read data and the recording medium read out from the recording medium, is changed to the write data the buffer A rewrite on the buffer when added, and a write-back control step of writing the rewritten write data back to the recording medium every predetermined time, and when reading and writing of data to the recording medium are suspended. A data recording / reproducing method comprising: a resting write-back control step of writing all write data on the data buffer back to the recording medium in order of lowest change frequency per unit time . The data recording / reproducing method according to claim 7 , wherein
Also retained after the write data the buffer written back to the recording medium, data recording said when there is a read request for the write data written back to the recording medium is characterized in that it comprises a step of reading from the said buffer Playback method. The data recording / reproducing method according to claim 7 or 8 ,
A data recording / reproducing method comprising the step of buffering the read data and the write data in the same form on the buffer. The data recording / reproducing method according to any one of claims 7 to 9 ,
A data recording / reproducing method comprising a step of allocating, from an area storing write data having the lowest change frequency per unit time, to an empty area when an empty area of the buffer runs out. The data recording / reproducing method according to any one of claims 7 to 10 ,
A data recording / reproducing method comprising a step of reducing the number of times of writing back of the write data per unit time. The data recording / reproducing method according to any one of claims 7 to 11 ,
A method for recording and reproducing data, comprising the steps of: allocating the buffer to a work area for decoding data read from the recording medium and encoding data to be written to the recording medium.

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