JP2000278645A - Device and method for recording data and device and method for reproducing data - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently suppress the occurrence of data errors while ensuring real time performance in the case of recording or reproducing data such as compressed image data where the real time performance is essential. SOLUTION: In this data recorder, a temporary storage register 34 temporarily stores information denoting the importance of a cluster being the recorded unit of data in the case of recording the data being the components of an AV data stream on a magnetic disk 5. On the occurrence of a write error, the importance of a cluster having the write error is recognized by referencing the temporary storage register 34 and the degree of retrial of writing the cluster having the write error on the magnetic disk again is selected depending on the importance of the cluster.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a data recording apparatus and a data recording method for recording digital data on a recording medium such as a magnetic disk, and a data reproducing apparatus and a data reproducing method for reproducing digital data from a recording medium. .

[0002]

2. Description of the Related Art Conventionally, a magnetic disk in which a magnetic film is formed on a metal substrate such as aluminum whose surface has been polished with high precision is used as a recording medium, and a magnetic head is mounted on a data recording area of the magnetic disk. 2. Description of the Related Art Hard disk drives are widely used in which a mounted flying slider flies so that a magnetic head writes data in a data recording area of a magnetic disk or reads data recorded in a data recording area of a magnetic disk.

The hard disk drive has a very high data recording density, is capable of storing a large amount of data, and has a high speed access to the recorded data. It is widely used as a storage device for storing data to be processed.

FIG. 8 shows a configuration example of a signal processing circuit in a hard disk drive.

The hard disk drive 1 shown in FIG.
When digital data (hereinafter, referred to as recording data) processed by a data processing device such as a host computer is recorded on a magnetic disk, a data processing device such as a host computer first sends a CPU (Central).
l Processing Unit) 101 is supplied with a recording command, and recording data is supplied to a host interface 103 in a hard disk controller 102.
The recording data supplied to the host interface 103 is temporarily stored in the buffer memory 105 under the control of the bus controller 104.

The CPU 101 instructs the sequencer 106 on which sector on the magnetic disk the recording data is to be recorded, based on a recording command supplied from a data processing device such as a host computer.

To position the magnetic head on the magnetic disk, the servo control circuit 107 calculates the current position of the magnetic head based on the position information detected by the magnetic head, and the VCM according to the current position of the magnetic head. (Vo
This is performed by controlling the driving current of an ice coil motor).

When the sequencer 106 confirms that the magnetic head is at the target position, the sequencer 106 reads the recording data from the buffer memory 105, and reads the recording data into the ECC (Er
rorCorrecting Code) circuit 108. The recording data supplied to the ECC circuit 108
08, the error correction code is added, and the channel IC 110
Is forwarded to The channel IC 110 performs processing such as channel encoding on the recording data transferred via the disk interface 109, and converts the recording data into a binary sequence signal. Then, the binary series signal is written on the magnetic disk as a magnetization reversal pattern by the magnetic head. The operation timing of the disk interface 109 is controlled by the sequencer 106.

When the servo control circuit 107 detects that it is difficult to continue normal operation due to an excessive position signal from the magnetic head while recording data is being recorded on the magnetic disk, the sequencer 106 Shifts to the retry (retry) mode, and performs the operation of recording the same sector again. Information that it is difficult to continue normal operation
In some cases, the signal is supplied directly from the servo control circuit 107 to the sequencer 106, and in another case, the signal is supplied to the sequencer 106 via the CPU 101.

On the other hand, the hard disk drive 100
When reproducing data recorded on a magnetic disk, a reproduction command is first supplied from a data processing device such as a host computer to the CPU 101, and a magnetization reversal pattern is read from the magnetic disk by a magnetic head.

For positioning of the magnetic head on the magnetic disk, the servo control circuit 107 calculates the current position of the magnetic head based on the position information detected by the magnetic head. This is performed by controlling the drive current of.

The magnetization reversal pattern read from the magnetic disk by the magnetic head is subjected to waveform equalization, signal detection, decoding of a channel code, and the like by the channel IC 110, and is restored to digital data (hereinafter referred to as reproduction data). Is done. This reproduced data may include an error in some cases, but is transferred to the disk interface 109 in the hard disk controller 102 as it is.

The operation timing of the disk interface 109 is controlled by the sequencer 106. When the sequencer 106 confirms that the magnetic head is at the target position, the sequencer 106 fetches the reproduction data from the channel IC 110 through the disk interface 109 and
The reproduced data is supplied to the ECC circuit 108.

The ECC circuit 108 performs error correction and error detection by decoding the error correction code added to the reproduced data. For example, when the error correction code of 8 symbols is added to the reproduction data, the ECC circuit 1
08 can correct an error in the reproduction data up to four symbols. However, if the number of symbols to be corrected is increased, the time required for error correction becomes longer and the processing speed becomes slower. Therefore, normally, the correction capability of the ECC circuit 108 is not used to the utmost, and for example, In the above example, error correction for up to two symbols is performed. And
When it is detected that the reproduced data after the correction further includes an error, the sequencer 106 shifts to the retry mode,
An operation of reproducing the same sector again is performed. In this case,
Error correction of reproduced data is performed by making full use of the correction capability of the ECC circuit 108.

As described above, the hard disk drive 100 normally performs high-speed decoding and improves retry and correction capabilities only when an error occurs, thereby ensuring data reliability while maintaining the overall reliability. Has been made to increase the processing speed.

The reproduced data on which error correction and error detection have been performed by the ECC circuit 108 are transmitted to the bus controller 104.
Is temporarily stored in the buffer memory 105. Then, the reproduction data stored in the buffer memory 105 is sequentially transferred to a data processing device such as a host computer via the host interface 103.

[0017]

By the way, with the development of digital technology in recent years, digitized moving image data is frequently processed on a computer. It is required to use a hard disk drive as a means for storing the moving image data processed on the computer.

Generally, such moving image data is MPE
It is handled in a form encoded by a G (Moving Picture Experts Group) encoding method. This method is an encoding method for compressing the moving image data using correlation (spatial correlation) in each frame constituting the moving image data, correlation (temporal correlation) between the frames, and the like. By performing processing after compression in such a manner, processing efficiency can be improved.

When recording and reproducing such moving image data, a so-called real-time property for recording and reproducing a data stream constituting the moving image without interruption is required. For this reason, when reproducing moving image data using a hard disk drive, a process may be performed in which data containing an error is directly output without performing a retry operation in which a temporal uncertainty element exists. . In this case, a process is generally performed in which the data including the error is complemented from the data before and after the data including the error so that the moving image data is less uncomfortable.

If a writing error occurs when recording moving image data using a hard disk drive, the buffer data for temporarily storing the recording data overflows because the recording data is sequentially transferred in real time. In general, a process is performed in which a retry operation in which a temporal uncertain element exists is not performed, and data in which a write error has occurred is discarded as it is.

As described above, when recording and reproducing data that requires real-time properties such as moving picture data using a hard disk drive, a retry operation is performed as compared with recording and reproducing data that does not require real-time properties. However, there is a problem that the probability that data contains an error is increased by the amount of not performing.

In particular, when moving image data is encoded by the above-described MPEG encoding method, this moving image data includes an I-picture (Intra-Picture: an intra-frame coded image) compressed using only the correlation within the frame. ) And a P-picture (Pred
ictive-Picture: Inter-frame forward prediction coded image)
And a B picture (Bidirectionally predictive-Picture: bidirectionally predictive coded image) compressed using the correlation with the preceding and following frames. And I
Since a picture is data that is the source of all pictures constituting a GOP (Group of Pictures), which is a block of data used for encoding, if an error occurs in this I picture, the GOP is All the constituent pictures are not correctly decoded, and the quality of the reproduced image data is significantly deteriorated.

The present invention has been made in view of the conventional problems described above, and high-quality data is reproduced at the time of reproducing data requiring real-time performance while ensuring the real-time performance. Recording apparatus and data recording method for recording data which requires real-time performance as well as high-quality data while ensuring real-time performance The purpose is to provide.

[0024]

A data recording apparatus according to the present invention is a data recording apparatus for recording compressed image data on a recording medium. Storage means for temporarily storing information indicating the degree of rewriting, retry means for performing an operation of rewriting a data block in which a write error has occurred on a recording medium when a write error occurs during a recording operation, and storage in the storage means. Switching means for switching the operation state of the retry means based on the information indicating the importance of the data block.

In this data recording apparatus, when recording compressed image data, the importance of the data block is recognized for each data block serving as a recording unit, and information indicating the importance of the data block is represented by: It is temporarily stored in the storage means.

When a write error occurs during the recording operation, the switching means rewrites the data block on the recording medium in accordance with the importance of the data block in which the write error has occurred. Switch the operation state of.

More specifically, for example, when the data recording apparatus records moving image data compressed by the MPEG encoding method, for each frame constituting the moving image, it is determined whether the frame is an I picture. , P picture or B picture
Whether the picture is a picture is recognized, and the information is temporarily stored in the storage means.

When the frame in which the writing error has occurred is an I picture or a P picture, for example, based on the information temporarily stored in the storage means, the switching means transmits the frame to the retry means again on the recording medium. In the case where the frame in which the writing error has occurred is a B picture, the operation state of the retry means is switched such that the retry means is not operated.
Alternatively, based on the information temporarily stored in the storage unit, the switching unit determines whether the frame in which the writing error has occurred is an I picture, a P picture, or a B picture. The number of times of writing the frame to the recording medium again is switched.

According to this data recording apparatus, the operation of rewriting a data block in which a write error has occurred on a recording medium can be switched in accordance with the importance of the data block. When an error occurs, the operation of writing the data block to the recording medium is repeated until a write error does not occur. When a write error occurs in a data block of lower importance, the data block is recorded. By reducing the number of operations of writing to the medium again or by not performing such operations, the overall processing time can be reduced, and image data requiring real-time properties can be appropriately recorded on the recording medium, It is possible to efficiently suppress the occurrence of errors during playback and improve data reliability. Kill.

Another data recording apparatus according to the present invention is a data recording apparatus for recording digital data on a recording medium, wherein the digital data to be recorded is compressed image data or other data. Discriminating means for discriminating whether the digital data to be recorded is compressed image data, and for each data block serving as a recording unit, information indicating the importance of the data block. Storage means for temporarily storing data, retry means for rewriting the data block in which the write error has occurred on the recording medium when a write error occurs during the recording operation, and digital data to be recorded by the determination means being compressed. When the image data is determined to be Based on the information indicating the iodide, it is characterized by comprising a switching means for switching the operating state of the retry means.

In this data recording apparatus, when digital data is recorded, it is determined by the determining means whether the digital data is compressed image data requiring real-time processing or other data. Is done. When the discriminating means determines that the digital data to be recorded is compressed image data, the importance of the data block is recognized for each data block serving as a recording unit, and the importance of the data block is determined. The indicated information is temporarily stored in the storage unit. Then, when a write error occurs during the recording operation, the switching unit switches the operation state of the retry unit that performs the operation of rewriting the data block in which the write error has occurred on the recording medium.

On the other hand, when the discriminating means determines that the digital data to be recorded is data other than the compressed image data, for example, when a write error occurs during the recording operation, the retry means operates. An operation of writing a data block in which a write error has occurred on the recording medium again is performed in a certain operation state without switching the state.

According to this data recording device, when the digital data to be recorded is compressed image data requiring real-time processing, the operation of rewriting the data block in which the write error has occurred on the recording medium is performed. Since it can be switched according to the importance of the data block,
For example, when a write error occurs in a data block of high importance, the operation of writing the data block to the recording medium is repeated until a write error does not occur, and a write error occurs in a data block of low importance. In this case, by reducing the number of operations of writing the data block to the recording medium again, or by not performing such operations, the overall processing time can be reduced,
Image data requiring real-time properties can be appropriately recorded on a recording medium, and the occurrence of errors during reproduction can be efficiently suppressed, and data reliability can be improved.

Further, according to this data recording apparatus, when the digital data to be recorded is data other than the compressed image data, for example, the data block in which the write error has occurred is replaced with the data block until the write error no longer occurs. By repeatedly performing the operation of writing to the recording medium, the occurrence of errors during reproduction can be effectively suppressed, and the reliability of data can be greatly improved.

In the data recording method according to the present invention, when recording compressed image data on a recording medium, information indicating the importance of the data block is temporarily stored for each data block serving as a recording unit. Then, based on the temporarily stored information, when a write error occurs during the recording operation, the operation state of the operation of rewriting the data block in which the write error has occurred in the recording medium is switched.

More specifically, for example, when moving image data compressed by the MPEG encoding method by this data recording method is recorded, for each frame constituting the moving image, whether the frame is an I picture, Whether it is a P picture
Whether the picture is a B picture is recognized, and the information is temporarily stored.

Then, based on the temporarily stored information,
When a write error occurs during the recording operation, the operation state of the operation of rewriting the frame on the recording medium is switched according to the importance of the frame in which the write error has occurred. Specifically, for example, when the frame in which the writing error has occurred is an I picture or a P picture, the operation of writing the frame to the recording medium is performed again, and when the frame in which the writing error has occurred is a B picture, In this case, the operation state is switched such that the operation of writing the frame to the recording medium again is not performed.
Alternatively, the number of times of writing the frame again to the recording medium is switched according to whether the frame in which the write error has occurred is an I picture, a P picture, or a B picture.

According to this data recording method, the operation of rewriting a data block in which a write error has occurred on a recording medium can be switched according to the importance of the data block. When an error occurs, the operation of writing the data block to the recording medium is repeated until a write error does not occur. When a write error occurs in a data block of lower importance, the data block is recorded. By reducing the number of operations of writing to the medium again or by not performing such operations, the overall processing time can be reduced, and image data requiring real-time properties can be appropriately recorded on the recording medium, It is possible to efficiently suppress the occurrence of errors during playback and improve data reliability. Kill.

According to another data recording method of the present invention, when recording digital data on a recording medium, it is determined whether the digital data to be recorded is compressed image data or other data. When it is determined that the digital data to be recorded is compressed image data,
Information indicating the importance of the data block is temporarily stored, and based on the temporarily stored information, when a write error occurs during a recording operation, the data block in which the write error has occurred is again stored in the recording medium. The operation state of the writing operation is switched.

In this data recording method, when recording digital data, it is determined whether the digital data is compressed image data requiring real-time processing or other data. When it is determined that the digital data to be recorded is compressed image data, the importance of the data block is recognized for each data block as a recording unit, and information indicating the importance of the data block is temporarily stored. It is memorized.
Then, when a write error occurs during the recording operation,
The operation state of the operation of rewriting the data block to the recording medium is switched according to the importance of the data block in which the write error has occurred.

On the other hand, when it is determined that the digital data to be recorded is data other than the compressed image data, for example, when a write error occurs during the recording operation, the operation state is not switched without performing the operation. In a certain operation state, an operation of writing a data block in which a write error has occurred on the recording medium again is performed.

According to this data recording method, when the digital data to be recorded is compressed image data requiring real-time processing, the operation of rewriting the data block in which the write error has occurred on the recording medium is performed. Since it can be switched according to the importance of the data block,
For example, when a write error occurs in a data block of high importance, the operation of writing the data block to the recording medium is repeated until a write error does not occur, and a write error occurs in a data block of low importance. In this case, by reducing the number of operations of writing the data block to the recording medium again, or by not performing such operations, the overall processing time can be reduced,
Image data requiring real-time properties can be appropriately recorded on a recording medium, and the occurrence of errors during reproduction can be efficiently suppressed, and data reliability can be improved.

According to this data recording method, when the digital data to be recorded is data other than the compressed image data, for example, the data block in which the write error has occurred is replaced with the data block until the write error no longer occurs. By repeatedly performing the operation of writing to the recording medium, the occurrence of errors during reproduction can be effectively suppressed, and the reliability of data can be greatly improved.

According to the data reproducing apparatus of the present invention, in a data reproducing apparatus for reproducing image data compressed from a recording medium, information indicating the importance of the data block is temporarily stored for each data block as a reproduction unit. Storage means for storing, when an error occurs in a data block read from the recording medium, retry means for performing an operation of re-reading the data block in which the error has occurred from the recording medium; Switching means for switching the operation state of the retry means based on information indicating the importance of the data block.

In the data reproducing apparatus, when reproducing the compressed image data from the recording medium, the importance of the data block is recognized for each data block as a reproduction unit, and the importance of the data block is indicated. Information
It is temporarily stored in the storage means.

Then, when an error occurs in the data block read from the recording medium, the switching means operates according to the importance of the data block in which the error has occurred.
The operation state of the retry means for performing the operation of reading the data block again from the recording medium is switched.

More specifically, for example, in the case of reproducing moving image data compressed by the MPEG encoding method from a recording medium, the data reproducing apparatus uses an I picture for each frame constituting the moving image. , P picture or B picture, and the information is temporarily stored in the storage means.

Then, based on the information temporarily stored in the storage means, if the frame in which the error has occurred is an I picture or a P picture, the switching means transmits the frame again to the retry means from the recording medium. The read operation is performed, and when the frame in which the error has occurred is a B picture, the operation state of the retry means is switched such that the retry means is not operated. Alternatively, the switching unit, based on the information temporarily stored in the storage unit,
The retry unit switches the number of operations of reading the frame from the recording medium again depending on whether the frame in which the error has occurred is an I picture, a P picture, or a B picture.

According to this data reproducing apparatus, when an error occurs in a data block read from a recording medium, the operation of re-reading the data block in which the error has occurred from the recording medium depends on the importance of the data block. For example, if an error occurs in a data block having a high importance, the operation of reading the data block from the recording medium is repeated until the error does not occur, and the data block having a low importance is performed. If an error occurs, the number of operations of reading the data block again from the recording medium is reduced, or such an operation is not performed, thereby shortening the overall processing time and reproducing the data block while ensuring real-time performance. And the reliability of the reproduced data can be improved.

Another data reproducing apparatus according to the present invention is a data reproducing apparatus for reproducing digital data from a recording medium, which determines whether the digital data to be reproduced is compressed image data or other data. Discriminating means for discriminating, and when the discriminating means discriminates that the digital data to be reproduced is compressed image data, temporarily stores information indicating the importance of the data block for each data block serving as a reproduction unit. Storage means for performing, when an error occurs in a data block read from the recording medium, retry means for re-reading the data block in which the error has occurred from the recording medium, and digital data reproduced by the determination means. When it is determined that the data is compressed image data, the data stored in the storage means is stored. Based on the information indicating the importance of data blocks, it is characterized by comprising a switching means for switching the operating state of the retry means.

In this data reproducing apparatus, when reproducing digital data from a recording medium, it is determined whether the digital data is compressed image data requiring real-time performance or other data. It is determined by means. When the discriminating means determines that the digital data to be reproduced is compressed image data, the importance of the data block is recognized for each data block as a reproduction unit, and the importance of the data block is determined. The indicated information is temporarily stored in the storage unit. When an error occurs in the data block read from the recording medium, the switching unit switches the operation state of the retry unit that performs an operation of reading the data block in which the error has occurred again from the recording medium.

On the other hand, when the discriminating means determines that the digital data to be reproduced is data other than the compressed image data, for example, when an error occurs in the data block read from the recording medium, The retry unit performs an operation of reading the data block in which an error has occurred from the recording medium again in a constant operation state without switching the operation state.

According to this data reproducing apparatus, when the digital data to be reproduced is compressed image data that requires real-time processing, the operation of reading out the data block in which the error has occurred from the recording medium again is performed by the data reproducing operation. Since the switching is performed in accordance with the importance of the block, for example, when an error occurs in a data block having a high importance, the operation of reading the data block from the recording medium repeatedly until the error does not occur is performed. When an error occurs in a data block having a low data block, the number of operations for reading the data block again from the recording medium is reduced, or by not performing such an operation, the processing time as a whole is reduced, and the real-time property is improved. Playback can be performed while securing, and the reliability of the played back data is improved. Door can be.

Further, according to the data reproducing apparatus, when the digital data to be reproduced is data other than the compressed image data, for example, the data block in which the error has occurred may be repeatedly used until the error does not occur. By performing the operation of reading from the recording medium, the reliability of the reproduced data can be significantly improved.

Further, in the data reproducing method according to the present invention, when reproducing the compressed image data from the recording medium, information indicating the importance of the data block is temporarily stored for each data block as a reproduction unit, Based on the temporarily stored information, when an error occurs in a data block read from the recording medium, an operation state of an operation of rereading the errored data block from the recording medium is switched. I have.

Specifically, for example, in the case of reproducing moving image data compressed by the MPEG encoding method from a recording medium by this data reproducing method, for each frame constituting a moving image, the frame is an I-picture. , P picture, or B picture is recognized, and the information is temporarily stored.

Then, based on the temporarily stored information,
When an error occurs in a frame read from the recording medium, the operation state of the operation of reading the frame again from the recording medium is switched according to the importance of the frame in which the error has occurred. Specifically, for example, if the frame in which the error occurred is an I picture or a P picture, the operation of reading the frame from the recording medium is performed again. If the frame in which the error occurs is a B picture, The operation state is switched such that the operation of reading the frame from the recording medium is not performed again. Alternatively, whether the frame in which the error occurred is an I picture,
The number of operations of reading this frame from the recording medium again is switched according to whether the frame is a picture or a B picture.

According to this data reproducing method, when an error occurs in a data block read from a recording medium, the operation of re-reading the data block in which the error has occurred from the recording medium depends on the importance of the data block. For example, if an error occurs in a data block having a high importance, the operation of reading the data block from the recording medium is repeated until the error does not occur, and the data block having a low importance is performed. If an error occurs, the number of operations of reading the data block again from the recording medium is reduced, or such an operation is not performed, thereby shortening the overall processing time and reproducing the data block while ensuring real-time performance. And the reliability of the reproduced data can be improved.

Another data reproducing method according to the present invention provides a method for reproducing digital data from a recording medium.
It is determined whether the digital data to be reproduced is compressed image data or other data. If the digital data to be reproduced is determined to be compressed image data, a data block serving as a reproduction unit is determined. For each time, information indicating the importance of the data block is temporarily stored, and based on the temporarily stored information, when an error occurs in the data block read from the recording medium, this error occurs. The operation state of the operation of reading the data block from the recording medium again is switched.

In this data reproducing method, when reproducing digital data from a recording medium, it is determined whether the digital data is compressed image data requiring real-time performance or other data. You. When it is determined that the digital data to be reproduced is compressed image data, the importance of the data block is recognized for each data block serving as a unit of reproduction, and information indicating the importance of the data block is temporarily stored. It is memorized. Then, when an error occurs in the data block read from the recording medium, the operation state of the operation of reading the data block again from the recording medium is switched according to the importance of the data block in which the error has occurred.

On the other hand, when it is determined that the digital data to be reproduced is data other than the compressed image data, for example, when an error occurs in a data block read from the recording medium, the operation state is switched. Without performing the above operation, the data block in which the error has occurred is read again from the recording medium in a constant operation state.

According to this data reproducing method, when the digital data to be reproduced is compressed image data that requires real-time processing, the operation of re-reading the data block in which the error has occurred from the recording medium is performed by the data read operation. Since the switching is performed in accordance with the importance of the block, for example, when an error occurs in a data block having a high importance, the operation of reading the data block from the recording medium repeatedly until the error does not occur is performed. When an error occurs in a data block having a low data block, the number of operations for reading the data block again from the recording medium is reduced, or by not performing such an operation, the processing time as a whole is reduced, and the real-time property is improved. Playback can be performed while securing, and the reliability of the played back data is improved. Door can be.

Further, according to this data reproducing method, when the digital data to be reproduced is data other than the compressed image data, for example, the data block in which the error has occurred can be repeated many times until the error does not occur. By performing the operation of reading from the recording medium, the reliability of the reproduced data can be significantly improved.

[0064]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a data recording / reproducing apparatus to which the present invention is applied will be described below with reference to the drawings. In the following description, an example will be described in which a data recording / reproducing apparatus is configured using a fixed hard disk drive in which a magnetic disk is provided in advance in the apparatus main body, but the present invention is not limited to this example. Instead, for example, it may be configured using another external storage device such as a removable hard disk drive configured to be capable of inserting and removing a magnetic disk into and from the apparatus main body, and an optical disk drive using an optical disk as a recording medium. It is possible.

FIG. 1 shows an example of the configuration of a data recording / reproducing apparatus to which the present invention is applied. The data recording / reproducing device 1 shown in FIG. 1 has a configuration in which a host-side data processing device 2 and a hard disk drive 3 serving as an external storage device are connected via a host interface bus 4. 2. The digital video data and digital audio data processed in step 2 are recorded on the magnetic disk 5 in the hard disk drive 3, and the digital video data and digital audio data recorded on the magnetic disk 5 in the hard disk drive 3 are reproduced. It has been made possible. As the host interface, for example, the extended IDE standard (ATA standard)
Is used.

The overall operation of the data recording / reproducing device 1 is managed by the CPU-A 6 in the data processing device 2. A ROM 8 and a RAM 9 are connected to the CPU-A 6 via a CPU-A bus 7, respectively. Firmware for the CPU-A 6 to manage the entire operation of the data recording / reproducing apparatus 1 is stored in the ROM 8. The RAM 9 is used as a work area of the CPU-A6.

The data recording / reproducing apparatus 1 is provided with a switch, a remote controller, a keyboard, a liquid crystal display, and the like (not shown) as a user interface mechanism. The input from the user interface mechanism or the output to the user interface mechanism is managed by the CPU-A6.

The CPU-A 6 is connected to the CPU-A bus 7
Is connected to the AV interface 10. In the data recording / reproducing apparatus 1, an instruction to write data to the magnetic disk 5 by the hard disk drive 3 or an instruction to read data from the magnetic disk 5 by the hard disk drive 3 is issued by the CPU-A.
6 is performed by issuing a recording command or a reproduction command defined in the extended IDE standard from the AV interface 10 to the hard disk drive 3.

The CPU-A 6 is connected to the CPU-A bus 7
Is connected to the memory control circuit 11 via the. The memory control circuit 11 compresses and multiplexes the input image signals and audio signals and outputs the resulting signals as an AV data stream. The memory control circuit 11 converts the AV data stream read from the magnetic disk 5 by the hard disk drive 3 into an image. It is separated into data and audio data, and is connected to an AV decoder 13 which interpolates and expands these and outputs them as normal image signals and audio signals. The memory control circuit 11 has a host memory 1 for temporarily storing data supplied to the hard disk drive 3 or data supplied from the hard disk drive 3.
4 are connected.

FIG. 2 shows a hierarchical structure of firmware stored in the ROM 8 and executed by the CPU-A 6. As shown in FIG. 2, a first layer below the firmware includes a user interface unit for performing input / output with respect to the user interface mechanism, and an encoder for controlling the operations of the AV encoder 12 and the AV decoder 13. A decoder management unit, a host memory management unit for controlling the operation of writing and reading data to and from the host memory 14 by the memory control circuit 11, and a hard disk drive for operating each device provided in the hard disk drive 3 It is built with device drivers.

The upper second layer of the firmware is constructed by system management software which manages each section constituting the lower first layer and controls the operation of the data recording / reproducing apparatus 1 as a whole. The functions of the system management software include a data recording / reproducing device, such as instructing and managing recording and reproducing operations of each channel, and grasping and managing the operating status of each hardware resource such as the hard disk drive 3 and the host memory 14. 1 includes all functions that are not included in the lower first layer.

The flow of processing for recording data on the magnetic disk 5 of the hard disk drive 3 by the data recording / reproducing apparatus 1 configured as described above will be described. When data is recorded on the magnetic disk 5 of the hard disk drive 3 by the data recording / reproducing apparatus 1, first, an analog image signal such as an NTSC signal and an analog sound signal are converted into digital data by an A / D converter (not shown). , And then input to the AV encoder 12.

The digital image data input to the AV encoder 12 is compressed by the image data compressor 15 in the AV encoder 12 to a data rate of, for example, about 1/5. The digital audio data input to the AV encoder 12 is compressed by an audio data compressor 16 in the AV encoder 12. As a data compression method, a DV coding method, an MPEG coding method, and the like have been put to practical use. According to these data compression methods, the original digital data is subjected to discrete cosine transform, inter-frame motion detection, requantization, two-dimensional Huffman coding, and the like, thereby compressing the data rate.

The digital image data compressed by the image data compressor 15 and the digital audio data compressed by the audio data compressor 16 are multiplexed in the MUX 17 to form an AV data stream.
Here, an example will be described in which the MPEG2 encoding method is used as the data compression method, and the data rate of the AV data stream is 8 Mbit / sec.

This AV data stream is temporarily written to the host memory 14 via the memory control circuit 11 once. Then, the CPU-A 6 issues an instruction to the memory control circuit 11 in accordance with the host memory management unit of the firmware, so that clusters, which are groups of data to be recorded on the magnetic disk 5 of the hard disk drive 3, are sequentially read from the host memory 14. Is read.

The clusters sequentially read from the host memory 14 are sent out of the data processing device 2 via the AV interface 10 and supplied to the hard disk drive 3 via the host interface bus 4. Then, the clusters supplied to the hard disk drive 3 are sequentially recorded on the magnetic disk 5 by the hard disk drive 3.

FIG. 3 shows a relationship between a cluster which is a data recording unit in the data recording / reproducing apparatus of the present embodiment and a GOP (Group of Pictures) defined by the MPEG2 encoding method. In the data recording / reproducing apparatus of this example, as shown in FIG. 3, a cluster is a group of data obtained by dividing an AV data stream for each picture constituting a GOP. The GOP is composed of 15 pictures, that is, 15 frames of images. here,
Since one frame is equivalent to 1/30 second, one GOP
Is equivalent to 0.5 seconds. In the data recording / reproducing apparatus of the present example, since the data rate of the AV data stream is 8 Mbit / sec, one GO
The data amount of P is 4 Mbit. Therefore, this G
The data amount of one cluster obtained by dividing the OP into 15 is several tens kbits to several Mbits.

On the other hand, the size of a sector which is the minimum recording unit of the hard disk drive 3 is 512 bytes (409
6 bits). Therefore, each cluster is allocated a number of sectors corresponding to the size of the corresponding picture. That is, when a recording command is issued from the data processing device 2, the hard disk drive 3 continuously records sectors for one cluster based on the recording command.

Here, the data to be recorded is recorded on the magnetic disk 5 after an error correction code is added in the hard disk drive 3. For example, the data to be recorded is divided into three interleaves for each sector having a data amount of 512 bytes as shown in FIG. It is recorded on the magnetic disk 5. The hard disk drive 3 included in the data recording / reproducing apparatus 1 to which the present invention is applied is difficult to continue normal operation due to an excessive head position signal when recording data is recorded on the magnetic disk 5 (writing). When an error is detected, switching of a so-called retry (retry) operation for recording the cluster again on the magnetic disk 5 is performed in accordance with the importance of the cluster in which the write error has occurred. If the cluster is data important for decoding such as an I picture or a P picture, a retry operation is performed and the cluster is recorded again on the magnetic disk 5, and the cluster in which a write error has occurred is a B picture. If the data is not very important for decoding, the retry operation is not performed and the write error It is adapted to supply information to the effect that occurs in the data processing apparatus 2.

This hard disk drive 3
When a write error is detected during the recording operation, a different number of retry operations may be performed according to the importance of the cluster in which the write error has occurred.

That is, when the hard disk drive 3 included in the data recording / reproducing apparatus 1 to which the present invention is applied detects that a write error has occurred, the hard disk drive 3 performs a retry operation according to the importance of the cluster in which the write error has occurred. It only needs to be configured so that the state can be switched,
This will be described later in detail.

Next, the flow of a process of reproducing data recorded on the magnetic disk 5 of the hard disk drive 3 by the data recording / reproducing apparatus 1 will be described. When reproducing the data recorded on the magnetic disk 5 of the hard disk drive 3 by the data recording / reproducing apparatus 1, first, the CPU-A6 of the data processing apparatus 2 uses the user interface unit by the firmware system management software. The AV data stream name to be reproduced is specified in accordance with the input information from, and the logical block address in the hard disk drive 3 where each cluster constituting the AV data stream is recorded is obtained. And C
The PU-A 6 issues a playback command defined on the host interface bus 4 to the hard disk drive 3 by a hard disk device driver of firmware. The hard disk drive 3 reads each sector constituting the cluster from the magnetic disk 5 based on the reproduction command.

Further, the CPU-A 6 reconstructs a cluster from the sectors read from the magnetic disk 5 by the hard disk drive 3 in the host memory 14 through the memory control circuit 11 by the firmware host memory management unit. Storage area.

Each sector constituting a cluster read from the magnetic disk 5 is supplied to the data processing device 2 via the host interface bus 4 after being subjected to error correction processing in the hard disk drive 3.

When the hard disk drive 3 detects that an error has occurred in the cluster after error correction, the hard disk drive 3 reads the cluster again from the magnetic disk 5 according to the importance of the cluster in which the error has occurred. Switch the so-called retry (retry) operation, for example,
If the cluster in which the error has occurred is important data for decoding, such as an I picture or a P picture, a retry operation is performed, and the cluster is read out again from the magnetic disk 5. When the data is not so important for decoding as described above, information indicating that a write error has occurred is supplied to the data processing device 2 without performing a retry operation.

[0086] This hard disk drive 3
When it is detected that an error has occurred in the cluster after error correction, a different number of retry operations may be performed according to the importance of the cluster in which the error has occurred.

That is, when the hard disk drive 3 included in the data recording / reproducing apparatus 1 to which the present invention is applied detects that an error has occurred in an error-corrected cluster, it responds to the importance of the cluster in which the error has occurred. It is sufficient that the operation state of the retry operation is switched over, and this will be described later in detail.

Each sector read from the magnetic disk 5 by the hard disk drive 3 is sequentially transferred to the host memory 14 via the host interface bus 4, the AV interface 10 and the memory control circuit 11, where the host memory 14 Reconfigured as a cluster.

When reading of one cluster is completed,
As in the above-described processing, a reproduction command is issued to the hard disk drive 3 by the CPU-A 6, and the hard disk drive 3 reads each sector forming a subsequent cluster from the magnetic disk 5. Then, each sector read from the magnetic disk 5 is transferred to the host memory 14, and the subsequent cluster is reconfigured in the host memory 14.

The clusters reconstructed in the host memory 14 are sequentially sent from the host memory 14,
The data is input to the AV decoder 13 via the memory control circuit 11 as an AV data stream. AV decoder 1
The AV data stream input to 3 is demultiplexed by the MUX 18 in the AV decoder 13 and separated into compressed digital image data and compressed digital audio data.

If the compressed digital image data separated by the MUX 18 has an error in the data, the error is interpolated in the image data interpolation circuit 19 from the data before and after the error. Then, the compressed digital image data is expanded by the image data expander 20 and output from the AV decoder 13 as normal digital image data.

On the other hand, if the compressed digital audio data separated by the MUX 18 has an error, the error is interpolated in the audio data interpolation circuit 21 from the data before and after the error. The compressed digital audio data is sent to the audio data expander 22.
And expanded as normal digital sound data by A
It is output from the V decoder 13.

These digital image data and digital sound data are converted into analog image signals and analog sound signals such as NTSC signals by a D / A converter (not shown) and supplied to an external device such as a monitor.

FIG. 5 shows a recording command issued by the CPU-A 6 of the data processing device 2 to the hard disk drive 3 via the host interface bus 4 in the data recording / reproducing device 1 according to the present invention.

In the recording command, as in the case of the ATA standard recording command, the number of write sectors is specified in the Sector Count register, and the Sector Number register and Cylin
derLow register, Cylinder High register and Device / H
The lower 4 bits of the ead register specify the write start logical block address. In this recording command, the command type is specified in the Command register.
For example, in this Command register, the command identification code 8
7h indicates that this command is a command for recording data of the AV data stream. In this recording command, the attribute of the cluster to be recorded is specified in the Features register. For example, when the AV data stream is data compressed by the MPEG encoding method, this Features register is used. , It is determined whether the cluster to be recorded is an I picture, a P picture, or a B picture.

FIG. 6 shows a reproduction command issued by the CPU-A 6 of the data processing device 2 to the hard disk drive 3 via the host interface bus 4 in the data recording / reproducing device 1 according to the present invention.

In the case of this playback command, the number of sectors to be read is specified in the Sector Count register, as in the case of the ATA standard playback command.
derLow register, Cylinder High register and Device / H
The read start logical block address is specified by the lower 4 bits of the ead register. In this playback command, the command type is specified in the Command register.
For example, in this Command register, the command identification code 8
6h indicates that this command is a command for reproducing the data of the AV data stream. In this recording command, the attribute of the cluster to be reproduced is specified in the Features register. For example, when the AV data stream is data compressed by the MPEG encoding method, this Features register is used. , It is determined whether the cluster to be reproduced is an I picture, a P picture, or a B picture.

FIG. 7 is a detailed block diagram of the inside of the hard disk drive 3 of the data recording / reproducing apparatus 1 according to the present invention. The flow of the process of writing data supplied from the data processing device 2 to the magnetic disk 5 by the hard disk drive 3 will be described below.

The data supplied from the data processor 2 is transferred to the magnetic disk 5 by the hard disk drive 3.
First, the CPU-A of the data processing device 2
6, a recording command issued via the host interface bus 4 is transmitted to the hard disk controller 30.
Is supplied to the CPU-B31 via the. In particular,
This recording command is input to the host interface 32 in the hard disk controller 30 connected to the data processing device 2 via the host interface bus 4 for each cluster to be recorded, and the recording command input to this host interface 32 is Are transferred to the CPU-B 31 connected to the host interface 32 via the CPU-B bus 33.

The host interface 32 in the hard disk controller 30 has a data processing device 2
, Data to be recorded is supplied for each cluster via the host interface bus 4.

When the recording command is supplied, the CPU-B 31 cooperates with the hard disk controller 30 to
The logical block address of the cluster supplied from the data processing device 2 to the host interface 32 is converted into a physical address inside the hard disk drive 3 (for example, disk surface number, track number, sector number, etc.).

Further, the CPU-B 31 reads the attribute of the cluster to be recorded (for example, whether the cluster to be recorded is an I picture,
(A picture or a B picture), and the information to that effect is stored in the temporary storage register 34 in the hard disk controller 30.

The cluster supplied to the host interface 32 has a data amount of several sectors, for example, 256 sectors, and these several sectors of data are temporarily stored in the buffer memory 36 under the control of the bus controller 35. .

The CPU-B 31 instructs the sequencer 37 on which sector on the magnetic disk 5 the cluster supplied from the data processor 2 is to be recorded.

Magnetic head 38 on magnetic disk 5
The servo control circuit 39 that has received the target track number from the CPU-B 31 and the host interface 32 determines the current position of the magnetic head 38 based on the track number on the magnetic disk 5 detected by the magnetic head 38. VCM (Voice) for calculating and moving the magnetic head 38 in accordance with the current position of the magnetic head 38
This is performed by controlling the drive current of a Coil Motor 40.

When the sequencer 37 confirms that the magnetic head 38 is at the target position, the sequencer 37 stores the cluster temporarily stored in the buffer memory 36 into the hard disk drive 3.
Length of the logical data sector set in (512 Bytes)
e), and sequentially read out from the buffer memory 36.

The cluster read from the buffer memory 36 is supplied to an ECC (Error Correcting Code) circuit 41, and the ECC circuit 41 adds an error correction code to each sector.

Each sector to which the error correction code is added in the ECC circuit 41 is synchronized with the rotation of the magnetic disk 5 rotated by the spindle motor 42,
Channel IC via disk interface 43
The data is transferred to a recording channel circuit 45 in 44. In addition,
The rotation speed of the magnetic disk 5 by the spindle motor 42 is controlled by a spindle motor control circuit 46.

The recording channel circuit 45 in the channel IC 44 performs a process such as channel coding on each sector transferred through the disk interface 43, and transfers these sectors from the magnetic head 38 and the magnetic disk 5. Is converted into a binary sequence signal suitable for the characteristics of the recording channel. Then, the signal of this binary sequence is
The recording amplifier 47 associates the recording current waveform with a rectangular recording current waveform, and writes the magnetization reversal pattern on the magnetic disk 5 by the magnetic head 38. The operation timing of the disk interface 43 is determined by the sequencer 37
Is controlled by

In the data recording / reproducing apparatus 1, the buffer memory 36 of the hard disk drive 3
When recording data with a data amount exceeding the capacity of
The transfer of data from the data processing device 2 to the hard disk drive 3 is temporarily stopped when data enough to be stored in the buffer memory 36 is transferred. Then, the data temporarily stored in the buffer memory 36 is read out from the buffer memory 36 and sequentially recorded on the magnetic disk 5.

When the data temporarily stored in the buffer memory 36 is recorded on the magnetic disk 5 and the buffer memory 36 has a certain amount of free space (for example, the data amount for one track), the data transfer is resumed. Is done. Then, the subsequent data is transferred from the data processing device 2 to the hard disk controller 3 by an amount corresponding to the free space of the buffer memory 36. The data recording / reproducing apparatus 1 repeats the above operations to sequentially record data of a data amount exceeding the capacity of the buffer memory 36 on the magnetic disk 5.

Here, while data is being recorded on the magnetic disk 5, the servo control circuit 39 detects that it is difficult to continue normal operation due to an excessive head position signal (write error). There are cases. In this case, the hard disk drive 3 performs the following processing.

When a write error is detected by the servo control circuit 39, first, the temporary storage register 34 storing information indicating the attribute of the cluster to be recorded is referred to identify the attribute of the cluster in which the write error has occurred. . Then, according to the attribute (importance) of the cluster in which the write error has occurred, a retry operation for recording the cluster again on the magnetic disk 5 is performed, or information indicating that a write error has occurred without performing the retry operation is provided. The operation state of the retry operation, such as whether to supply the data to the data processing device 2 or how many times the retry operation is permitted, is switched.

More specifically, for example, if a write error is detected while clusters constituting an AV data stream compressed by the MPEG encoding method are sequentially recorded on the magnetic disk 5, first, a temporary storage is performed. The register 34 is referenced, and the cluster in which the write error has occurred is the IOP of the GOP.
Whether the picture is a picture, a P picture, or a B picture is identified.

When the cluster in which the write error has occurred is identified as an I-picture or P-picture important for decoding, the switch 50 is closed and an instruction for a retry operation is given to the sequencer 37.

When an instruction for a retry operation is given, the sequencer 37 shifts to a retry mode, and performs an operation of writing a cluster in which a write error has occurred on the magnetic disk 5 again. The sequencer 37 repeats the above retry operation until no write error is detected, so that I pictures and P pictures important for decoding can be appropriately recorded on the magnetic disk 5. Note that while the retry operation is being performed, recording of subsequent data is not performed. On the other hand, the data to be recorded is data constituting an AV data stream that requires real-time properties, and is thus continuously transferred from the data processing device 2 to the hard disk drive 3. Therefore, if the retry operation is performed indefinitely, the buffer memory 36 may overflow. Therefore, even when the retry operation is performed, the retry operation may be limited to the extent that the buffer memory 36 does not overflow, instead of being performed unlimitedly. Also, I
Since there is a difference in the degree of importance between the picture and the P picture, a difference may be made in the number of times that retry is allowed between them.

On the other hand, when the cluster in which the write error has occurred is identified as data that is not so important for decoding, such as a B picture, the switch 50 is opened and no instruction for the retry operation is given to the sequencer 37. . Therefore, in this case, no retry operation is performed. In this case, the information that a writing error has occurred
The data is supplied from the hard disk drive 3 to the data processing device 2 via the host interface bus 4.

While the retry operation is being performed, as described above, subsequent data is not recorded. Therefore, if a retry operation is performed for all data in which a write error has occurred, the buffer memory 36 overflows, and as a result, data of high importance is discarded without being recorded on the magnetic disk 5. In some cases.

In the data recording / reproducing apparatus 1 to which the present invention is applied, as described above, the hard disk drive 3
However, the operation state of the retry operation is switched according to the importance of the cluster in which the write error has occurred.For example, when a write error occurs in a higher importance cluster, a retry is performed, and a write error occurs in a lower importance cluster. Since the retry is not performed when it occurs, the storage area of the buffer memory 36 is effectively used to minimize the deterioration of data quality required for real-time data reproduction. Can be recorded appropriately.

The above is the description of the hard disk drive 3
However, although an example in which the retry operation is switched or not performed according to the importance of the cluster in which the write error has occurred has been described, the hard disk drive 3
The number of retry operations, that is, how many retry operations are allowed may be switched according to the importance of the cluster in which the write error has occurred.

In this case, for example, if a write error occurs in a cluster constituting the AV data stream compressed by the MPEG encoding method, the temporary storage register 34 is referred to as in the above-described example. It is identified whether the cluster in which the write error has occurred is an I picture, a P picture, or a B picture of the GOP. Then, when the cluster in which the write error has occurred is identified as an I picture, the number of retry operations allowed is set to a relatively large number, and the cluster in which the write error has occurred is identified as a P picture. At this time, the number of times that the retry operation is allowed is set to be equal to or less than the case of the I picture, and when the cluster in which the writing error has occurred is identified as the B picture,
The number of times that the retry operation is permitted is set to be equal to or less than that in the case of the P picture.

That is, when the cluster in which a write error has occurred is an I picture, the number of times a retry operation is permitted is m1, and the cluster in which a write error has occurred is P1.
When the number of times that the retry operation is allowed is a picture and the number of times the retry operation is allowed is m2, and when the cluster in which a writing error occurs is a B picture, the number of times that the retry operation is allowed is m3, m1 ≧ m2 ≧ m3 is satisfied. In this manner, the number of times that the retry operation is permitted is set according to the importance of each cluster.

Data recording / reproducing apparatus 1 to which the present invention is applied
Similarly, when the hard disk drive 3 switches the number of times that the retry operation is allowed according to the importance of the cluster in which the write error has occurred, the storage area of the buffer memory 36 is similarly enabled. By utilizing the data, it is possible to appropriately record data requiring real-time property so that deterioration of data quality at the time of reproduction is minimized.

Next, the flow of processing for reading data from the magnetic disk 5 and supplying it to the data processing device 2 by the hard disk drive 3 shown in FIG. 7 will be described below. When data is read from the magnetic disk 5 by the hard disk drive 3 and supplied to the data processing device 2, first, a playback command issued via the host interface bus 4 by the CPU-A 6 of the data processing device 2 It is supplied to the CPU-B31 via the controller 30. Specifically, the reproduction command is input to the host interface 32 in the hard disk controller 30 connected to the data processing device 2 via the host interface bus 4 for each cluster to be reproduced, and is input to the host interface 32. The reproduced command is transferred to the CPU-B 31 connected to the host interface 32 via the CPU-B bus 33.

When the reproduction command is supplied, the CPU-B 31 cooperates with the hard disk controller 30 to
The logical block address of the cluster read from the magnetic disk 5 is converted into a physical address inside the hard disk drive 3 (for example, disk surface number, track number, sector number, etc.). Then, the CPU-B 31 operates the servo control circuit 39 to move the magnetic head 38 to a target physical address. The magnetic head 38 reads the magnetization reversal pattern recorded here from the position corresponding to the target physical address on the magnetic disk 5.

Further, the CPU-B 31 determines the attribute of the cluster to be read (for example, whether the cluster to be read is an I picture,
(A picture or a B picture), and the information to that effect is stored in the temporary storage register 34 in the hard disk controller 30.

The magnetization reversal pattern read from the magnetic disk 5 by the magnetic head 38 is amplified by the reproduction amplifier 48 and then supplied to the reproduction channel circuit 49 in the channel IC 44.

The signal supplied to the reproduction channel circuit 49 in the channel IC 44 is
According to 9, the bit data is detected as a binary data sequence after synchronization, a decoding process that is the inverse of the channel coding performed at the time of recording is performed, and the data is reproduced as a data sector. This data sector may contain an error, but the hard disk controller 3
0 is transferred to the disk interface 43.

The operation timing of the disk interface 43 is controlled by the sequencer 37. When the sequencer 37 confirms that the magnetic head 38 is at the target position, the sequencer 37
The reproduction data is fetched from the reproduction channel circuit 49 of the channel IC 44 and supplied to the ECC circuit 41.

The ECC circuit 41 performs an error correction process on the reproduction data supplied from the disk interface 43. Then, the reproduced data on which the error correction has been performed by the ECC circuit 41 is temporarily stored in the buffer memory 36 as 512-byte logical data for each sector under the control of the bus controller 35. Then, the data stored in the buffer memory 36 is sequentially transferred to the data processing device 2 via the host interface 32 and the host interface bus 4.

In the data recording / reproducing apparatus 1, the buffer memory 36 of the hard disk drive 3
If you want to play back data that exceeds the capacity of
Reading of data from the magnetic disk 5 is temporarily stopped when data enough to be stored in the buffer memory 36 is read. Then, the data temporarily stored in the buffer memory 36 is read from the buffer memory 36 and transferred to the data processing device 2.

When the data temporarily stored in the buffer memory 36 is transferred to the data processing device 2 and a certain amount of space (for example, the data amount for one track) is created in the buffer memory 36, the magnetic disk 5 The reading of the data is restarted. Then, the subsequent data corresponds to the data amount corresponding to the free space of the buffer memory 36,
It is read from the magnetic disk 5. The data recording / reproducing apparatus 1 can reproduce data having a data amount exceeding the capacity of the buffer memory 36 by repeating the above operation.

At the time of reproduction, the ECC circuit 4
In some cases, it is detected that an error has occurred in the error-corrected data. In this case, the hard disk drive 3 performs the following processing.

When the ECC circuit 41 detects that an error has occurred in the data after error correction, first, the temporary storage register 34 in which information indicating the attribute of the cluster is stored.
Is referred to identify the attribute of the cluster in which the error has occurred. Then, the attribute (importance) of the cluster in which the error occurred
Depending on the retry operation of reading the cluster from the magnetic disk 5 again, or without performing the retry operation,
The switching of the operation state of the retry operation, such as supplying information to the effect that an error has occurred to the data processing device 2 or the number of times the retry operation is permitted.

More specifically, for example, when it is detected that an error has occurred in data after error correction during reproduction of a cluster constituting an AV data stream compressed by the MPEG encoding method, first, temporary storage is performed. The register 34 is referred to identify whether the cluster in which the error has occurred is an I picture, a P picture, or a B picture of the GOP.

When the cluster in which the error has occurred is identified as an I-picture or P-picture important for decoding, the switch 50 is closed and an instruction for a retry operation is given to the sequencer 37.

When an instruction for a retry operation is given, the sequencer 37 shifts to a retry mode, and performs an operation of reading a cluster in which an error has occurred from the magnetic disk 5 again. The sequencer 37 repeats the above retry operation until no error is detected, so that I pictures and P pictures important for decoding can be reproduced without errors. During the retry operation, subsequent data is not read from the magnetic disk 5. On the other hand, since the data to be reproduced is data constituting an AV data stream that requires real-time processing, the data stored in the buffer memory 36 is continuously transferred to the data processing device 2. Therefore, if the retry operation is performed indefinitely, the buffer memory 36 may become empty. Therefore, even when the retry operation is performed, the retry operation may be limited to the extent that the buffer memory 36 does not become empty, instead of performing the retry operation indefinitely. Also, since there is a difference in the degree of importance between the I picture and the P picture, the number of times that retry is allowed may be different between them.

On the other hand, when the cluster in which the error has occurred is identified as data that is not so important for decoding, such as a B picture, the switch 50 is opened and no instruction for the retry operation is given to the sequencer 37. Therefore, in this case, no retry operation is performed. In this case, information indicating that an error has occurred is supplied from the hard disk drive 3 to the data processing device 2 via the host interface bus 4.

While the retry operation is being performed, the subsequent data is not read from the magnetic disk 5 as described above. Therefore, if a retry operation is performed for all data in which an error has occurred, the buffer memory 36 becomes empty, and it may not be possible to ensure the real-time property of reproduced data.

In the data recording / reproducing apparatus 1 to which the present invention is applied, as described above, the hard disk drive 3
However, the operation state of the retry operation is switched according to the importance of the cluster in which the error occurred, for example, when an error occurs in a high importance cluster, a retry is performed, and when an error occurs in a low importance cluster, Is not retried, so that the storage area of the buffer memory 36 is effectively used so that data requiring real-time performance is minimized while real-time performance is ensured. Can be properly reproduced.

The above is the description of the hard disk drive 3
Has described an example in which the retry operation is switched between whether or not to perform the retry operation according to the importance of the cluster in which the error has occurred. However, the hard disk drive 3 performs the retry operation in accordance with the importance of the cluster in which the error has occurred. Number of operations,
That is, how many times the retry operation is permitted may be switched.

In this case, for example, when an error occurs in a cluster constituting the AV data stream compressed by the MPEG encoding method, the error is caused by referring to the temporary storage register 34 as in the above-described example. Is identified as a GOP I picture, P picture, or B picture. When the cluster in which the error has occurred is identified as an I-picture, the number of times the retry operation is permitted is set to a relatively large number, and when the cluster in which the error occurs is identified as a P-picture, , The number of times the retry operation is permitted is set to be equal to or less than that of the I picture, and when the cluster in which the error has occurred is identified as the B picture, the number of times the retry operation is permitted is the P picture. It is set equal to or less than the case.

That is, when the cluster in which the error has occurred is an I picture, the number of retry operations allowed is n.
When the number of times that the retry operation is permitted is n2 when the cluster in which the error occurs is a P picture, and the number of times that the retry operation is permitted is n3 when the cluster in which the error occurs is a B picture Where n1 ≧ n2 ≧
The number of retry operations allowed is set according to the importance of each cluster so as to satisfy n3.

Data recording / reproducing apparatus 1 to which the present invention is applied
As described above, even when the hard disk drive 3 switches the number of times the retry operation is permitted according to the importance of the cluster in which the error has occurred, the storage area of the buffer memory 36 is similarly effectively used. Then, data requiring real-time property can be appropriately recorded so that deterioration of data quality is minimized while real-time property is secured.

In the above description, the data constituting the AV data stream required to have real-time properties is recorded on the magnetic disk 5 in the hard disk drive 3 and the data constituting the AV data stream recorded on the magnetic disk 5 Although the data recording / reproducing apparatus 1 configured to reproduce the data has been described as an example, the data recording / reproducing apparatus to which the present invention is applied is not limited to the above example.
In addition to the data stream, it may be configured to be able to record and reproduce other digital data such as a document file. Digital data such as document files do not require real-time performance,
That is, since it is required that data errors are extremely small, the data recording / reproducing apparatus is configured to be capable of recording / reproducing other digital data such as a document file in addition to the AV data stream. The AV
It is desirable that the contents of the processing be different between when handling the data constituting the data stream and when handling other digital data.

Hereinafter, the flow of the recording process and the flow of the reproducing process of the data recording / reproducing apparatus configured to be able to record / reproduce other digital data in addition to the AV data stream will be described. The data recording / reproducing apparatus has the same basic configuration as that of the data recording / reproducing apparatus 1 described above, and performs the same processing as that of the data recording / reproducing apparatus 1 except for the retry operation. The description of the same processing as that of the device 1 will be omitted, and only the characteristic portions of the data recording / reproducing device 1 will be described using the same reference numerals as those of the data recording / reproducing device 1.

When digital data is recorded on the magnetic disk 5 by the data recording / reproducing apparatus, a recording command issued from the data processing apparatus 2 via the host interface bus 4 is transmitted to the CP of the hard disk drive 3.
By being supplied to the U-B 31, it is recognized whether or not the data to be recorded is data constituting the AV data stream. Specifically, the recording command Comm shown in FIG.
From the and register, it is recognized whether the data to be recorded is data constituting the AV data stream.

When the data to be recorded is recognized as data constituting the AV data stream, the CPU-B 31 reads the cluster to be recorded from the Features register of the recording command in the same manner as in the data recording / reproducing apparatus 1 described above. (For example, whether the cluster to be recorded is an I picture, a P picture, or a B picture) is identified, and information to that effect is stored in the temporary storage register 34 in the hard disk controller 30.

When a write error occurs in the recorded data, the temporary storage register 34 is referred to to determine the attribute (importance) of the cluster in which the write error has occurred, as in the data recording / reproducing apparatus 1 described above. The operation state of the retry operation of the sequencer 37 is switched according to the identified cluster attribute. That is, for example, MP
When a write error occurs in the data compressed by the EG encoding method, the cluster in which the write error has occurred is referred to as GO.
Depending on whether the picture is a P I picture, a P picture, or a B picture, switching is performed such as whether to perform a retry operation or how many times the retry operation is permitted.

On the other hand, when it is recognized that the data to be recorded is data other than the data constituting the AV data stream, if a write error occurs in the record data, the sequencer 37 operates until the write error does not occur. Processing such as repeating the retry operation many times is performed.

According to this data recording / reproducing apparatus, as described above, if the data to be recorded is data constituting an AV data stream that requires real-time processing, when a write error occurs, this write The operation state of the retry operation for rewriting the cluster in which the error has occurred is switched according to the importance of the cluster in which the writing error has occurred, so that data requiring real-time performance is minimized in the degradation of data quality during reproduction. It can be properly recorded so as to be limited.

According to this data recording / reproducing apparatus,
As described above, when the data to be recorded is data other than the data constituting the AV data stream, when a write error occurs, for example, a process of repeating the retry operation many times until the write error does not occur. Is performed, the occurrence of an error at the time of reproduction can be effectively suppressed, and the reliability of data can be greatly improved.

Next, when reproducing the digital data recorded on the magnetic disk 5 by the data recording / reproducing apparatus, a reproduction command issued from the data processing apparatus 2 via the host interface bus 4 is transmitted to the hard disk drive 3. By being supplied to CPU-B31,
It is recognized whether the data to be reproduced is data constituting the AV data stream. Specifically, it is recognized from the Command register of the playback command shown in FIG. 6 whether the data to be played back is the data constituting the AV data stream.

When it is recognized that the data to be reproduced is data constituting the AV data stream, the CPU-B31 reads the cluster to be reproduced from the Features register of the reproduction command in the same manner as in the data recording / reproducing apparatus 1 described above. (For example, whether the cluster to be reproduced is an I picture, a P picture, or a B picture) is identified, and the information to that effect is stored in the temporary storage register 34 in the hard disk controller 30.

Then, the data is read from the magnetic disk 5 and
When the ECC circuit 41 detects that the error-corrected data has an error, the temporary storage register 3 is provided in the same manner as the data recording / reproducing apparatus 1 described above.
4, the attribute (importance) of the cluster in which the error has occurred is identified, and the operation state of the retry operation of the sequencer 37 is switched according to the attribute of this cluster. That is, for example, when an error occurs in data compressed by the MPEG encoding method, whether the cluster in which the error occurred is an I picture, a P picture,
Depending on whether the picture is a picture, switching is performed such as whether or not to perform the retry operation or how many times the retry operation is permitted.

On the other hand, when it is recognized that the data to be reproduced is data other than the data constituting the AV data stream, the data read from the magnetic disk 5 and subjected to error correction processing by the ECC circuit 41 is added to the data. When it is further detected that there is an error, the sequencer 37 performs, for example, a process of repeating the retry operation many times until no error occurs in this data.

According to this data recording / reproducing apparatus, as described above, if the data to be reproduced is data constituting an AV data stream that requires real-time processing, the error-corrected data has further errors. When this is detected, the operating state of the retry operation for reading out the cluster in which the error has occurred from the magnetic disk 5 is switched according to the importance of the cluster in which the error has occurred. Can be appropriately reproduced so that deterioration of data quality is minimized while real-time property is ensured.

According to the data recording / reproducing apparatus,
As described above, when the data to be reproduced is data other than the data constituting the AV data stream, when it is detected that the error-corrected data further has an error, for example, the error correction is performed until the error does not occur. Since a process of repeating the retry operation is performed many times, the occurrence of errors can be effectively suppressed, and the reliability of data can be greatly improved.

[0159]

According to the data recording apparatus of the present invention, when a write error occurs during a recording operation, the operation of rewriting the data block in which the write error has occurred on the recording medium depends on the importance of the data block. Can be switched accordingly, reducing overall processing time,
Image data requiring real-time properties can be appropriately recorded on a recording medium, and the occurrence of errors during reproduction can be efficiently suppressed, and data reliability can be improved.

In another data recording apparatus according to the present invention, when digital data is recorded on a recording medium, the digital data is compressed image data requiring real-time processing, or other digital data. If the digital data is determined to be compressed image data, and if a write error occurs during the recording operation, the importance of the data block in which the write error occurred is determined. Accordingly, the operation state of the operation of rewriting the data block in which the writing error has occurred on the recording medium is switched. On the other hand, when it is determined that the digital data is data other than the compressed image data, the recording operation is performed. If a write error occurs during writing, the data block in which the write error occurred In, the process of writing back the recording medium is performed, when recording the image data compressed real time is required, while ensuring the real-time data to reduce the processing time as a whole,
When efficiently suppressing the occurrence of errors during reproduction, improving the reliability of data, and recording data other than compressed image data, for example, a data block in which a write error has occurred may be replaced with a write error. By performing the operation of writing to the recording medium many times until the data disappears, it is possible to effectively suppress the occurrence of an error at the time of reproduction and greatly improve the reliability of data.

Further, in the data recording method according to the present invention, when a write error occurs during a recording operation, an operation of rewriting a data block in which a write error has occurred on a recording medium is performed according to the importance of the data block. Switching, the overall processing time can be shortened, image data requiring real-time processing can be appropriately recorded on a recording medium, and the generation of errors during reproduction can be suppressed efficiently. As a result, data reliability can be improved.

In another data recording method according to the present invention, when digital data is recorded on a recording medium, the digital data is compressed image data which requires real-time processing or other data. Is determined, and if it is determined that the digital data is compressed image data, if a write error occurs during the recording operation, the data block in which the write error has occurred is rewritten on the recording medium. The operation state of the operation is switched according to the importance of the data block in which the write error has occurred. On the other hand, if the digital data is determined to be data other than the compressed image data, the write error occurs during the recording operation. When a write error occurs, the data block in which the write error has occurred is re-written to the recording medium in a certain operating state. When recording compressed image data that requires real-time processing, the overall processing time is shortened to ensure data real-time processing, and errors during playback are recorded. When data other than compressed image data is recorded by efficiently suppressing the occurrence of data and recording data other than compressed image data, for example, a data block in which a write error has occurred Also, by performing the operation of writing to the recording medium, it is possible to effectively suppress the occurrence of an error at the time of reproduction, and to greatly improve the reliability of data.

In the data reproducing apparatus according to the present invention, when an error occurs in the data block read from the recording medium, the operation state of the operation of reading the errored data block from the recording medium again is as follows: Since switching can be performed according to the importance of the data block, the processing time as a whole can be shortened, and data requiring real-time performance can be reproduced while securing the real-time performance. Reliability can be improved.

In another data reproducing apparatus according to the present invention, when digital data is reproduced from a recording medium, the digital data is compressed image data which requires real-time processing, or other digital data. If the digital data is determined to be compressed image data, and if an error occurs in a data block read from the recording medium, the data in which the error has occurred is determined. When the operation state of the operation of re-reading the data block in which the error has occurred from the recording medium is switched according to the importance of the block, and when it is determined that the digital data is data other than the compressed image data, When an error occurs in a data block read from the recording medium, the errored data Since the process of reading the lock again from the recording medium is performed in a fixed operation state, when reproducing the compressed image data that requires real-time performance, the overall processing time is reduced to improve the real-time performance of the data. In addition to securing the data, improving the reliability of the data by efficiently suppressing the occurrence of errors and reproducing data other than the compressed image data, for example, the data block in which the error has occurred may be used until the error no longer occurs. By performing the operation of reading data from the recording medium many times, it is possible to effectively suppress the generation of an error and greatly improve the reliability of data.

Further, in the data reproducing method according to the present invention, when an error occurs in a data block read from a recording medium, the operation state of the operation of reading the errored data block from the recording medium again is changed. Since switching is performed according to the importance of the data block, the processing time as a whole can be shortened, and data requiring real-time characteristics can be reproduced while securing the real-time characteristics, and the reproduced data can be reproduced. Data reliability can be improved.

Further, in another data reproducing method according to the present invention, when reproducing digital data from a recording medium, the digital data is compressed image data requiring real-time processing or other data. And if the digital data is determined to be compressed image data, when an error occurs in the data block read from the recording medium, the data block in which the error has occurred is identified. The operation state of the operation of re-reading from the recording medium is switched according to the importance of the data block in which the error has occurred. On the other hand, if it is determined that the digital data is data other than the compressed image data, the recording is performed. When an error occurs in a data block read from the medium, the data block in which the error has occurred is replaced with a certain operation. In this state, the process of reading the data from the recording medium again is performed. Therefore, when reproducing the compressed image data that requires real-time performance, the overall processing time is reduced to ensure the real-time performance of the data. At the same time, when the occurrence of errors is efficiently suppressed to improve the reliability of data and data other than the compressed image data is reproduced, for example, a data block in which an error has occurred is repeated until the error no longer occurs. Also, by performing the operation of reading from the recording medium, the occurrence of errors can be effectively suppressed, and the reliability of data can be greatly improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the configuration of a data recording / reproducing device to which the present invention is applied, and is a block diagram showing the inside of a data processing device in detail.

FIG. 2 is a diagram showing a firmware configuration of the data processing device.

FIG. 3 is a diagram showing a relationship between a GOP and a cluster which is a unit of recording and reproduction in the data recording / reproducing apparatus.

FIG. 4 is a diagram showing a sector format including an error correction code of data processed by a hard disk drive provided in the data recording / reproducing apparatus.

FIG. 5 is a diagram showing an example of a recording command used in the data recording / reproducing device.

FIG. 6 is a diagram showing an example of a reproduction command used in the data recording / reproducing device.

FIG. 7 is a diagram showing an example of the configuration of a data recording / reproducing apparatus to which the present invention is applied, and is a block diagram showing the inside of a hard disk drive in detail.

FIG. 8 is a block diagram showing a configuration example of a conventional hard disk drive.

[Explanation of symbols]

1 data recording / reproducing device, 2 data processing device, 3 hard disk drive, 5 magnetic disk, 6 CPU
-A, 30 hard disk controller, 31 CP
UB, 32 host interface, 34 temporary storage register, 36 buffer memory, 37 sequencer, 38 magnetic head, 41 ECC circuit, 50 switch

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C053 FA23 GA11 GB06 GB07 GB08 GB11 GB15 GB21 GB30 GB37 GB40 HA40 JA30 KA01 KA05 KA08 KA24

Claims (28)

[Claims] 1. A data recording apparatus for recording compressed image data on a recording medium, wherein for each data block serving as a recording unit, storage means for temporarily storing information indicating the importance of the data block; When a write error occurs during the operation, retry means for performing an operation of writing the data block in which the write error has occurred again to the recording medium, based on information indicating the importance of the data block stored in the storage means And a switching means for switching the operation state of the retry means. 2. The method according to claim 1, wherein the switching means switches whether the retry means is operated or not based on information indicating the importance of the data block stored in the storage means. The data recording device according to the above. 3. The retry unit according to claim 3, wherein the switching unit rewrites the data block in which the write error has occurred to the recording medium based on the information indicating the importance of the data block stored in the storage unit. The data recording device according to claim 1, wherein the data recording device is switched. 4. A data recording apparatus according to claim 1, further comprising: a write error information output means for outputting information indicating that a write error has occurred when a write error occurs during a recording operation. . 5. The image data is moving image data compressed by an MPEG encoding method, and the storage means stores, for each frame constituting the moving image,
Information indicating whether the frame is an I picture, a P picture, or a B picture is temporarily stored, and the switching means generates a write error based on the information stored in the storage means. 2. The data recording apparatus according to claim 1, wherein the operation state of the retry unit is switched according to whether the frame is an I picture, a P picture, or a B picture. 6. The data recording apparatus according to claim 1, wherein a magnetic disk is used as said recording medium, and a data writing means for writing said image data to said magnetic disk by a magnetic head is provided. 7. A data recording apparatus for recording digital data on a recording medium, comprising: discriminating means for discriminating whether the digital data is compressed image data or other data; Storage means for temporarily storing, for each data block serving as a recording unit, information indicating the importance of the data block when it is determined that the digital data is compressed image data; and a write error during the recording operation. When rewriting is performed, retry means for performing an operation of rewriting the data block in which the writing error has occurred on the recording medium, and when the discriminating means determines that the digital data is compressed image data, The operation of the retry unit is performed based on the information indicating the importance of the data block stored in the storage unit. Data recording apparatus characterized by comprising a switching means for switching the state. 8. When recording compressed image data on a recording medium, information indicating the importance of the data block is temporarily stored for each data block serving as a recording unit, and the temporarily stored information is stored in the storage unit. A data recording method characterized in that when a write error occurs during a recording operation, an operation state of an operation of rewriting the data block in which the write error has occurred in the recording medium is switched. 9. The data according to claim 8, wherein whether or not an operation of rewriting a data block in which a write error has occurred on the recording medium is performed or not is performed based on the temporarily stored information. Recording method. 10. The data recording method according to claim 8, wherein the number of operations of rewriting a data block in which a write error has occurred on the recording medium is switched based on the temporarily stored information. 11. The data recording method according to claim 8, wherein when a write error occurs during the recording operation, information indicating that the write error has occurred is output to the outside. 12. The image data is moving image data compressed by the MPEG encoding method, and for each frame constituting the moving image, the frame is
Information indicating whether the picture is a picture, a P picture, or a B picture is temporarily stored. Based on the temporarily stored information, a frame in which a writing error has occurred is an I picture or a P picture. 9. The data recording method according to claim 8, wherein an operation state of an operation of rewriting a data block in which a write error has occurred on the recording medium is switched according to whether the data block is a B picture. 13. The data recording method according to claim 8, wherein a magnetic disk is used as said recording medium, and said image data is written on said magnetic disk by a magnetic head. 14. When digital data is recorded on a recording medium, it is determined whether the digital data is compressed image data or other data. If it is determined that there is, for each data block serving as a recording unit, information indicating the importance of the data block is temporarily stored, and based on the temporarily stored information, a write error occurs during a recording operation. A data recording method characterized by switching an operation state of an operation of rewriting a data block in which the write error has occurred to the recording medium when the error occurs. 15. A data reproducing apparatus for reproducing compressed image data from a recording medium, wherein for each data block serving as a reproduction unit, storage means for temporarily storing information indicating the importance of the data block; Retry means for performing an operation of re-reading the data block in which the error has occurred from the recording medium when an error occurs in the data block read from the storage medium; and information indicating the importance of the data block stored in the storage means. A data reproducing device comprising: a switching unit that switches an operation state of the retry unit based on the data. 16. The apparatus according to claim 15, wherein the switching means switches whether the retry means is operated or not based on information indicating the importance of the data block stored in the storage means. A data reproducing apparatus according to claim 1. 17. The retry unit according to claim 17, wherein the retry unit reads the data block in which the error occurred from the recording medium again based on the information indicating the importance of the data block stored in the storage unit. 16. The data reproducing device according to claim 15, wherein the data is switched. 18. An apparatus according to claim 15, further comprising: error information output means for outputting information indicating that an error has occurred when an error occurs in a data block read from said recording medium. Data playback device. 19. The image data is moving image data compressed by the MPEG encoding method, and the storage means stores, for each frame constituting the moving image,
Information indicating whether the frame is an I picture, a P picture, or a B picture is temporarily stored, and the switching means determines a frame in which an error has occurred based on the information stored in the storage means. 16. The data reproducing apparatus according to claim 15, wherein the operation state of the retry means is switched according to whether the image is an I picture, a P picture, or a B picture. 20. The data reproducing apparatus according to claim 15, wherein a magnetic disk is used as said recording medium, and said data reproducing device includes data reading means for reading said image data from said magnetic disk by a magnetic head. 21. A data reproducing apparatus for reproducing digital data from a recording medium, comprising: discriminating means for discriminating whether the digital data is compressed image data or other data; When it is determined that the data is compressed image data, for each data block serving as a reproduction unit, storage means for temporarily storing information indicating the importance of the data block; and read out from the recording medium. When an error occurs in the data block, retry means for re-reading the data block in which the error occurred from the recording medium, and when the discrimination means determines that the digital data is compressed image data. Based on the information indicating the importance of the data block stored in the storage means, Data reproducing apparatus, characterized in that it comprises a switching means for switching the operating state of the tri means. 22. When reproducing compressed image data from a recording medium, information indicating the importance of the data block is temporarily stored for each data block as a reproduction unit, and based on the temporarily stored information. And a data reproducing method characterized in that when an error occurs in a data block read from the recording medium, an operation state of an operation of re-reading the data block in which the error has occurred from the recording medium is switched. 23. The data reproducing apparatus according to claim 22, wherein the operation of reading or re-reading the data block in which the error has occurred from the recording medium is performed or not based on the temporarily stored information. Method. 24. The method according to claim 2, wherein the number of operations of re-reading a data block in which an error has occurred from the recording medium is switched based on the temporarily stored information.
2. The data reproducing method according to 2. 25. The data reproducing method according to claim 22, wherein when an error occurs in the data block read from the recording medium, information indicating that the error has occurred is output to the outside. 26. The image data is moving image data compressed by the MPEG coding method, and for each frame constituting the moving image, the frame is
Information indicating whether the picture is a picture, a P picture, or a B picture is temporarily stored, and based on the temporarily stored information, the frame in which the error has occurred is an I picture or a P picture. 23. The data reproducing method according to claim 22, wherein an operation state of an operation of re-reading a data block in which an error has occurred from the recording medium is switched according to whether the data block is a B picture. 27. A data reproducing method according to claim 22, wherein a magnetic disk is used as said recording medium, and said image data is read from said magnetic disk by a magnetic head. 28. When reproducing digital data from a recording medium, it is determined whether the digital data is compressed image data or other data. If the digital data is compressed image data, it is determined that the digital data is compressed image data. If it is determined, information indicating the importance of the data block is temporarily stored for each data block serving as a reproduction unit, and based on the temporarily stored information, data read from the recording medium is read. A data reproducing method characterized in that when an error occurs in a block, an operation state of an operation of re-reading the data block in which the error has occurred from the recording medium is switched.