JP2002288927A - Data reproducing and processing method of disk playback device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the data reproducing and processing time in an optical disk playback device, etc., without performing a process such as seek even when data of a requested address are not included in a buffer. SOLUTION: When a next read command is received from a host computer in the midst of the look-ahead process, the look-ahead process is continued when the difference between the address on the disk wherein the data finally stored in the buffer are included and the address requested from the host computer is smaller than a prescribed threshold, and when the requested address is reached, the data are transferred to the host computer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk reproducing apparatus for reproducing data on a disk such as an optical disk such as a CD and a DVD, and more particularly to a data reproducing method for a disk reproducing apparatus employing a data pre-reading processing method. is there.

[0002]

2. Description of the Related Art In a disk reproducing apparatus such as an optical disk such as a CD or a DVD, at the time of reading data on the disk, the data on the disk is read and reproduced beyond a range specified by a read command from a host computer. In general, a prefetching process for temporarily storing data in a buffer in the device is performed.

[0003] By performing the pre-reading process, the disk reproducing apparatus can transfer data on the disk when data at an address designated by the next read command from the host computer is stored in a buffer in the reproducing apparatus. Since only the process of transferring the data stored in the buffer to the host computer without performing the reading process is required, the processing time for data reproduction can be reduced.

However, if the disk reproducing device receives the next read command from the host computer during the pre-reading process, and if the data at the specified address is not in the buffer, the reproducing device performs the pre-reading process. End, seeking to the specified address and reading the data on the disk are performed, so that it takes a long time for the data reproduction processing.

Conventionally, as a solution to this, for example, as described in JP-A-5-135483, when a next read command is received during the pre-reading process, this is a continuation of the next read command from the preceding read command. It is known that when the request is for reproducing address data, the pre-reading process is continued as it is, and the processing such as seeking for the target address is omitted, thereby improving the reproduction processing speed.

[0006]

The address requested by the host computer is not always the continuation of the previous read command. In some cases, a request is made to reproduce data several blocks after the address of the data reproduced by the previous read command. In the prior art, in such a case, since the addresses to be reproduced are not continuous, it is necessary to end the pre-reading process and perform a process such as seek to a target address before reproducing the data. Will take. A first object of the present invention is to
In the disk reproducing device, if the data at the address specified by the read command can be reproduced by continuing the pre-reading process, the process is continued without terminating the pre-reading process, and then the data is transferred to the address specified by the read command. An object of the present invention is to reduce the processing time of data reproduction by starting data transfer to the host computer from the point at which the data has been reached without performing processing such as seeking to a specified address.

Depending on the data playback speed, it may be faster to seek than to wait until the playback address specified by the playback request from the host computer is buffered. When the data reproduction speed is slow, the seek time becomes faster rather than seeking for buffering. Normal data reproduction and data transfer to the host are performed in parallel. In other words, when the data reproduction speed is low, a waiting time is required to transfer the next sector data to the host. In such a case, if the sum of the time until the requested address is stored in the buffer and the time for waiting for data transfer to the host is not taken into consideration, the performance is degraded. A second object of the present invention is to eliminate wasteful waiting in such a case in a disc reproducing apparatus and to perform a reproducing process more efficiently.

[0008] When a reproduction error occurs during the pre-reading process, the disk reproducing device performs a retry process for reading the data at the erroneous address again. Therefore, when the next read command is received from the host computer during the pre-reading process and the pre-reading process is continued without terminating, a reproduction error occurs before reaching the target address while reading data from the disk. In such a case, the playback device performs a retry process, so that it takes time for the data playback process. A third object of the present invention is to improve the efficiency of reproduction processing in a disk reproducing apparatus even if a reproduction error occurs before reaching a target address during pre-read processing.

When a reproduction error is a servo error such as an off-track, if the data is reproduced as it is, erroneous address data is buffered. Therefore, even if the error is ignored, there is no reliability of the data that can be normally reproduced next. A fourth object of the present invention is to improve the reliability of data without erroneous address data being buffered due to a servo error such as an off-track.

If a reproduction error occurs before reaching the target address during the prefetching process and the prefetching process is continued ignoring the retrusion process, if the continuity of the data is impaired, the reliability of the data thereafter is reduced. There is no sex. A fifth object of the present invention is to improve the reliability of data in such a case in a disk reproducing apparatus.

[0011]

In order to achieve the first object, the present invention provides a method for receiving a next read command from a host computer during a pre-reading process. If the difference between the address on the disk to which the address belongs and the requested address from the host computer is smaller than a predetermined threshold, the read-ahead process is continued,
When the requested address is reached, the data is transferred to the host computer. In order to achieve the second object, the present invention is characterized in that the threshold value is switched according to a data reproducing speed from a disk or a data transfer speed with a host computer. In order to achieve the third object, the present invention provides a method for receiving a next read command from a host computer during a pre-read process, continuing the pre-read process without terminating the pre-read process, and requesting the data while reading data from a disk. If a reproduction error occurs before the address is reached, the prefetch processing is continued without performing the retry processing. In order to achieve the fourth object, the present invention is characterized in that when a reproduction error is other than a data error, the pre-reading process is terminated and the reproduction of the address specified by the read command is performed. In order to achieve the fifth object, the present invention checks the continuity of data, and if there is no continuity of data in a situation where no reproduction error has occurred, the pre-reading process is terminated to specify the data. And seeks data to reproduce the data.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to the drawings. In the following, CD-R
An OM drive device will be described as an example, but, needless to say, the present invention is not limited to this.

FIG. 1 shows a configuration example of a CD-ROM drive device as a disk reproducing device to which the present invention is applied. The optical disk 1 is driven to rotate by a motor 2, and the motor 2 is controlled by a rotation control unit 3 so that the linear velocity or the angular velocity becomes constant. This linear velocity or angular velocity can be changed stepwise by the main control unit 10.

The pickup 4 is controlled via the main control unit 10,
The optical disc 1 has a function of irradiating the optical disc 1 with laser light by the laser drive circuit 7 and reading data on the optical disc 1.
The pickup 4 is similarly subjected to seek control by the actuator control unit 5 via the main control unit 10 so that the laser spot is located at a target place. The reproduction data obtained by the pickup 4 is transmitted to the main control unit 10 via the signal control unit 6.
Sent to The buffer memory 8 is used by the main control unit 10 to temporarily store reproduction data. To the data in the buffer memory 8, the address of the data on the optical disk is added.

The main control unit 10 controls the entire drive device as the disk reproducing device, and is connected to a host computer 20 via an external interface 15. When the main control unit 10 receives a read command from the host computer 20, the actuator control unit 5,
It controls the signal control unit 6, the laser drive circuit 7, etc., receives the reproduction data via the reception control unit 6, stores it in the buffer memory 8, and transmits it to the host computer 20 via the external interface 15.

The main control unit 10 has a prefetch processing unit 9. The prefetch processing unit 9 includes a host computer 20.
After the read command is processed, the signal control unit 6 and the laser drive circuit 7 are instructed to continue reading data on the optical disc 1 after the address specified by the read command, and the reproduced data is sequentially read out. A process of storing the address in the buffer memory 8 together with the address is performed. Main control unit 10
Then, when the next read command is received from the host computer 20, it is checked whether there is data of the requested address in the buffer memory 8, and if so, the data in the buffer memory 8 is transmitted to the host computer 20.

The operation of the main controller 10 for reproducing a disc according to the present invention will be described below. FIG. 2 shows a flowchart of a data reproduction processing operation when a read command is received from the host computer 20. The main control unit 10 first determines whether the data at the address specified by the read command is present in the buffer memory 8 (step 101). It is determined whether the processing is in progress (step 102). If the prefetching process is being performed, the difference between the address on the disk 1 to which the prefetched data stored last in the buffer memory 8 belongs and the requested address from the host computer 20 is smaller than a predetermined threshold value. (Step 103), and if it is smaller than the threshold value, the read-ahead processing is continued as it is until the requested address from the host computer 20 is reached (steps 104 and 105). Read ahead data to host computer 2
0 (step 106), and the processing of the read command ends. As a result, even if the data at the address specified by the read command is not in the buffer memory 8, it is not necessary to perform processing such as seeking to the specified address.
Processing time for data reproduction can be reduced.

On the other hand, in step 103, it is determined that the difference between the address on the disk 1 to which the data lastly stored in the buffer memory 8 belongs and the requested address from the host computer 20 is larger than a predetermined threshold value. If so, the main control unit 10 ends the prefetching process (step 107), controls the actuator control unit 5 to seek to the requested address (step 108), and reads the data on the disk 1 via the signal control unit 6. Is read and stored in the buffer memory 8 (step 109), and the data is transferred to the host computer 20 (step 1).
06), the read command processing ends.

If it is determined in step 101 that the data at the address specified by the read command is not in the buffer memory 8 and if it is determined in step 102 that the pre-reading process is not being performed, the main The control unit 10 controls the actuator control unit 5 to seek to the requested address (Step 108), reads the data on the disk 1 (Step 109), transfers the data to the host computer 20 (Step 106), and reads the read command. Is completed. If the data at the address specified by the read command is found in the buffer memory 8 in step 101, the main control unit 10 immediately transfers the data in the buffer memory 8 to the host computer 20 (step 106). Terminates command processing.

Although omitted in FIG. 2, step 10
In parallel with the data transfer of No. 6, under the control of the pre-reading processing unit 9, pre-reading of data of a predetermined block on the disk 1 after the requested address is performed.

Here, depending on the data reproduction speed, it may be faster to seek than to wait until the address specified by the read command from the host computer 20 is buffered. If the data playback speed is slow,
Processing time is faster if seeking is performed rather than waiting for buffering. Further, normal data reproduction and data transfer to the host computer 20 are performed in parallel. That is, when the data reproduction speed is low, a waiting time is required to transfer the next sector data to the host computer 20. In such a case, the time until the requested address is stored in the buffer memory 8 and the time required for the host computer 20
If the sum of the data transfer wait time and the sum of the data transfer wait time is not considered, the performance is reduced.

In step 103 of FIG. 2, the main control unit 10 compares the difference between the address on the disk 1 to which the data lastly stored in the buffer memory 8 belongs and the requested address from the host computer 20. The threshold value for comparison, the data reproduction speed and the host I
/ F so that it can be set to an optimum value by switching according to the data transfer speed. This makes it possible to further reduce the processing time.

Next, the retry processing will be described. FIG. 3 shows a flowchart of a general retry process at the time of data reproduction.

The disk reproducing apparatus is a host computer 2
When receiving a read command from 0, seek is performed to the requested address (step 201). Thereafter, errors are monitored until the requested address is reached (steps 202 and 20).
3) If an error occurs, retry processing is performed (step 2)
06), seek to the requested address again (step 20)
1). In step 203, when the requested address is reached without error, a process of reading data from the disk 1 is performed (step 204). An error (data error) is also determined in the process of reading from the disk 1 (step 2).
05) If an error occurs, a retry process is performed in the same manner (step 206), and seek to the requested address is again performed (step 201).

In the retry processing in step 206, the request address is updated to the address on the disk 1 to which the data lastly stored in the buffer memory 8 belongs, or the disk rotation speed is set to make the data on the disk 1 easier to read. Processing to decelerate.

Such a retry process is also performed during the pre-read process. Therefore, in the case where the next read command is received from the host computer 20 during the pre-reading process and the pre-reading process is continued without ending, the read error occurs before the data is read from the disk 1 before reaching the target address. , If the disk playback device performs a retry process, it takes time for the data playback process.

Therefore, the main control unit 10 receives the next read command from the host computer 20 during the pre-reading process and continues the pre-reading process without terminating (step 104 in FIG. 1). If a reproduction error occurs before arriving at the requested address while data is being read from the disk 1, the error is ignored and retry processing is not performed, and prefetching is continued until the requested address is reached. If the playback error is temporary,
When the requested address is reached, correct data is obtained. Thereby, the reproduction process can be performed efficiently.

On the other hand, if the reproduction error is a servo error such as an off-track or the like, and if the reproduction is performed as it is, erroneous address data will be buffered. Therefore, even if the error is ignored, there is no reliability in the data that can be normally reproduced next. Therefore, the main control unit 10 limits the case of ignoring the error to the case of a data error (step 205 of FIG. 3), and the case of other than the data error (step 202 of FIG. 3), Is ended, and the address specified by the read command is reproduced. This eliminates buffering of erroneous address data due to a servo error such as an off-track or the like, thereby improving data reliability.

Similarly, if the continuity of data is impaired, there is no reliability of the data thereafter. Therefore, the main control unit 10 checks the continuity of the data. If there is no continuity of data in a state where no reproduction error has occurred, the pre-reading process is terminated and the address specified by the read address is read. To perform data reproduction. As a result, erroneous address data is not buffered, and data reliability is improved.

[0030]

As described above, according to the disk reproducing apparatus to which the present invention is applied, the following effects can be achieved. (1) When the next read command is received from the host computer while the data on the disk is being pre-read,
Even if the data at the specified address is not in the buffer, it is not necessary to perform a process such as seeking to the specified address, so that the processing time for data reproduction can be reduced. (2) By switching the threshold determined based on the data reproduction speed and the data transfer speed on the host I / F, the reproduction processing time can be further reduced. (3) When the next read command is received from the host computer during the pre-reading process, and when the pre-reading process is continued without terminating, the data is reproduced before reaching the target address while the data is being read from the disk. Even when an error occurs, unnecessary retry processing is not performed, so that the efficiency of the reproduction processing can be improved. (4) Since erroneous address data due to a servo error such as an off-track is not buffered, data reliability is improved. (5) If there is no continuity of data, erroneous address data will not be buffered.
Data reliability is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of a disk reproducing apparatus to which the present invention is applied.

FIG. 2 is a flowchart of one embodiment of a disk reproducing process according to the present invention.

FIG. 3 is a flowchart of a retry process at the time of data reproduction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Motor 3 Rotation control part 4 Pickup 5 Actuator control part 6 Signal control part 7 Laser drive circuit 8 Buffer memory 9 Look-ahead processing part 10 Main control part 20 Host computer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G11B 20/18 G11B 20/18 572F

Claims (5)

[Claims] 1. A data reproducing method in a disk reproducing apparatus using a pre-read processing method, wherein data in a specified range or more on a disk is read by a read command from a host computer and temporarily stored in a buffer. When the next read command is received from the host computer during the pre-reading process, the difference between the address on the disk to which the data lastly stored in the buffer belongs and the requested address from the host computer exceeds a predetermined threshold value. A data reproduction processing method characterized by continuing the pre-reading processing when the value is smaller than the above, and transferring the data to the host computer when the requested address is reached. 2. The data reproduction processing method according to claim 1, wherein the threshold is switched according to a data reproduction speed from a disk or a data transfer speed with a host computer. 3. The data reproduction processing method according to claim 1, wherein the next read command is received from the host computer during the pre-reading process, and the pre-reading process is continued without terminating and the data is read from the disk. A data reproduction processing method characterized in that if a reproduction error occurs before reaching a requested address during the process, a prefetch process is continued without performing a retry process. 4. The data reproduction processing method according to claim 3, wherein when the reproduction error is other than the data error, the pre-reading process is terminated and the reproduction of the address specified by the read command is performed. Data playback processing method. 5. The data reproduction processing method according to claim 3, wherein the continuity of the data is checked, and if the continuity of the data is not found in a situation where no reproduction error has occurred,
Ends the prefetching process and seeks to the specified address,
A data reproduction processing method characterized by performing data reproduction.