JPH08330977A - Data playback device - Google Patents

Abstract

[PROBLEMS] To reproduce data from a recording medium on which data is recorded at different transfer rates at the transfer rate at the time of recording. A data reproducing apparatus for reproducing data from a disk-shaped data recording medium in which data is recorded together with a signal indicating the transfer rate at different transfer rates, the process of reproducing and demodulating a digital signal from the disk. A circuit 41, an ECC decoder 42 that performs error correction processing on the reproduced digital signal for each sector, and a multiplexer 43 that separates the signal error-corrected by the ECC decoder into digital data and other signals are provided. Then, information on the transfer rate of the recording data is obtained from the digital data, and the data is reproduced at the transfer rate at the time of recording according to the information on the transfer rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique suitable for use in transmitting data via a transmission (recording / reproducing) medium having a slightly high error rate such as a magneto-optical disk.

[0002]

2. Description of the Related Art Conventionally, a so-called hard disk device has been known as a writable and large-capacity information storage disk device. This is generally used for computer data storage, and information is recorded as concentric circular (or spiral) tracks on a disk that rotates at a fixed and predetermined number of rotations.

As shown in FIG. 6, writing and reading of data to and from the hard disk device 1 are performed by the CPU 3 via the data bus 2. This is because the hard disk drive is driven at a constant rotation speed that is irrelevant (asynchronous) to the transfer rate of the input data to be recorded.
The PU3 makes a recording at a timing. This is because the data handled is intermittent data.

Data is exchanged between the hard disk drive 1 and the CPU 3 via a RAM 4 as a buffer memory.

[0005]

Since the recording / reproducing of the above-mentioned hard disk is generally performed under the controlled condition, the occurrence of burst error is small. For this reason, the error correction code does not have to be strong in the data format of this hard disk, and in many cases there is no parity for error correction. Even if there are data blocks, when the data blocks are arranged in a two-dimensional matrix, the parity is usually given only to one direction of the row and the column.

By the way, recently, it has been called the new media era, and various information has been provided to the world, so-called multimedia information. This information includes intermittent data such as computer data, semi-intermittent data such as still images and images, and completely continuous information such as digital audio.

It would be convenient if these various kinds of information could be stored in a disk and used by the user as appropriate. However, as described above, in the conventional disk device, the rotation speed is constant and the CPU generally controls the recording of data, and there has been no conventional method for dealing with multimedia information.

By the way, a magneto-optical disk is attracting attention as a rewritable mass storage device. Such mass storage devices may be able to store multimedia information.

Unlike the hard disk, this magneto-optical disk has a relatively large number of burst errors. Also, because of the large capacity, various additional information is added to the data and recorded, but it is necessary to prevent this additional information from becoming unreadable due to an error and to effectively use this additional information part. It is desirable to plan.

In consideration of the above points, the present invention does not provide a data and additional information that has a strong error correction capability and can effectively utilize the additional information part. It is what

[0011]

According to the present invention, K pieces of serialized data to be transmitted are sequentially divided into n pieces to form a two-dimensional array having m rows and n columns (m × n> K). When forming, (m × n−K) pieces of redundant data are subsequently added to the K pieces of serialized data to form the m-row × n-column two-dimensional array. R data of the (n−K) redundant data are arranged as an error detection code in an area including the last row and the last column of the two-dimensional array, and the first error correction is performed on the data of each row of the two-dimensional array. A code is generated, and a second code is generated for each column data of the two-dimensional array.
Error correction code is generated to form a product code, and the data of each row of the product code is sequentially transmitted.

Since it is a product code, the error correction capability for data is large, and the error correction code for this additional information is also large because the additional information is generated in exactly the same way as the data.

Further, additional information is added after the data to be transmitted, and the error detection code is added at the end of the data area. Therefore, the address control at the time of encoding and decoding the product code becomes easy, and the additional information can be easily extracted.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of the method of the present invention will be described with reference to the drawings by taking the case of transmitting data through a magneto-optical disk as an example.

[First Embodiment] Description of Format of Magneto-Optical Disk First, the format of a magneto-optical disk will be described. In this magneto-optical disk 11, as shown in FIG. 3, data is recorded as one track per one rotation, in which a track 12 is formed in a concentric circle shape or a spiral shape, and is recorded and reproduced.

One track 12 of this magneto-optical disk 11
Is composed of a plurality of sectors equally divided in the circumferential direction, and each sector stores a predetermined number of data in which an error correction code, an error detection code, etc. are generated and added.

In the case of FIG. 3, one track consists of (n + 1) sectors as shown in FIG. A, and in this example, one track is 32 sectors. The format of the data recorded in one sector is as shown in FIG. That is, one sector includes a header part, a data part, and a gap part GAP provided after the header part and after the data part, respectively.

A preamble signal is recorded at the head of the header portion, and an address synchronization signal ASYNC is added to an address signal ADD composed of a track address TA and a sector address SA to which an error correction code ECC is added. What has been done is recorded twice.

In the data section, a preamble signal is recorded at the head of the data section, and thereafter, data and the data to which an error correction code ECC and the like are added are recorded.

[Embodiment 2] Description of data structure when data size is 512 bytes In this case, 512 bytes is standard as the unit data amount to be recorded in the data portion of one sector, considering that it is used as a storage device of a computer. It is said that In this case, the structure of the data part is as shown in FIG. That is, in the case of FIG. 1, the number of data is 512 bytes from D _{0 to} D ₅₁₁ , and as the actual data, 16 bytes of additional information is added after the 512 bytes of data D _{0 to} D _511. 48 bytes in the row direction and 11 bytes in the column direction 48
A matrix array of × 11 = 528 bytes is used.

That is, 512 bytes of data D _{0 to} D
12 bytes after ₅₁₁ are used as a reserve area, and a track number, a sector number, data identification information, etc. are inserted in this area. Then, 4 bytes of CRC code for error detection is generated for 524 bytes of data including this reserved area, and is inserted into the last 4 bytes area of the additional information. And a total of 528 bytes is shown in FIG.
As shown in (4), they are arranged in a matrix of 48 × 11.

Then, the first error correction code C ₁ (this is, for example, 52,48 Reed-Solomon code) is set as 4 bytes for one row in the row direction with respect to 528 bytes including 4 bytes of this CRC code. Similarly, a second error correction code C of 2 bytes is added for each column in the column direction.
₂ (this is, for example, 13,11 Reed-Solomon code) is added.

Then, as shown in the figure, data is sequentially written and read one row at a time in the row direction of this matrix arrangement. Then, when the data is read from the buffer memory and recorded on the disk 11, for example, a synchronization signal is inserted for each row, and further for each predetermined byte, which facilitates data synchronization at the time of data processing on the reproducing side. .

From the above, in this case, 16 bytes of additional information (including CRC code) related to this data is added to 512 bytes of data to form a block of 528 bytes, and this is 11 lines. , 48 columns are arranged to generate and add a parity C _{1 in} the row direction and a parity C ₂ in the column direction to form a product code, which is recorded and reproduced as one sector of the disk 11.

In this case, what is recorded on the track is that the matrix data of FIG. 1 is sequentially read out in the row direction as serialized data, and if a burst error occurs, the data in the row direction is affected. become.

However, even if all the data in the row direction is invalid for one row, it can be corrected by the parity C _{2 in the} column direction. Therefore, even if all of the additional information portion is destroyed by a burst error, it can be correctly restored by error correction.

In the case of this example, the track number T
The rNo and the sector number Se are also recorded in the header section before the data section, and the track number TrN
Additional information that can be effectively used when reproducing data such as o and sector number Se is double protected (three in this example because it has already been double written in the header portion).

It should be noted that instead of data in byte units, data of 16 bits or 12 bits per word can be divided into 512 bytes to form a product code and transmitted. At this time, for example, information for identifying the number of bits of one word is recorded in the identification information ID of the additional information section.

Further, although it becomes possible to record data having different transfer rates by changing the number of rotations of the disk, information indicating the transfer rate may be recorded in this identification information ID.

[Embodiment 3] Description of Data Structure when Data Size is 1024 Bytes FIG. 2 shows an example of the data structure when transmitting (recording) data of 1024 bytes which is double 512 bytes. In the example, for 1024 bytes of data, 1 for each of the first half and the latter half of 512 bytes of data
By adding 6 bytes of additional information, a total of 1056 bytes of data is arranged in a matrix of 48 columns × 22 rows.

Then, 16 bytes of additional information consisting of data such as a track number and a CRC code in a 12-byte reserve area for the first 512 bytes of data and a 12-byte reserve area for the latter 512 bytes of data. Data such as track number and C
The 16-byte additional information consisting of the RC code is 48 x 2
Insert all at the end of the last row of the matrix array of 2.

Then, as in the example of FIG. 1, for each row of this matrix array, a 52,48 Reed-Solomon code is generated and a 4-byte parity C ₁ is added. For each column of the matrix array, a 24,22 Reed-Solomon code is generated and a 2-byte parity C ₂ ′ is added.

In this case, if the configuration shown in FIG. 2 is used, the hardware for creating the 512-byte data structure shown in FIG. 1 can be used almost in common. However, this is different from the case where the second error correction code in the column direction is 512 bytes, but this is because the difference in data size between 512 bytes and 1024 (1K) bytes is used as the data size identification signal in the reserve area described above. By recording it, it is possible to cope with the difference between the error correction codes C ₂ and C ₂ ′ when reproduced.

The data size is not 512 bytes / sector or 1024 bytes / sector, but 52 bytes / sector, for example.
When 0 bytes / sector and 1032 bytes / sector are used, the data structure can be used as it is in FIGS. 1 and 2 by using a part of the reserve area of the additional information part as a data area.

[Embodiment 4] Block diagram of recording / reproducing system FIG. 4 shows an example of a recording / reproducing system for recording and reproducing information of various transfer rates in the sector format as described above by changing the disc rotation speed. It is a block diagram of.

Reference numeral 11 is a magneto-optical disk, and this disk 1
1 is recorded as a spiral track, but a recording / reproducing head (not shown) is subjected to tracking control so as to correctly scan a previously formed track. There is.

Reference numeral 21 is a disk drive motor for the disk 1
The motor 1 is rotationally controlled by this motor so as to rotate at a predetermined speed with a constant angular speed. That is, the drive motor 21 is provided with the frequency generator 22, and the frequency signal FG proportional to the rotation speed of the motor 21 is obtained from the frequency generator 22 and is supplied to the phase comparison circuit 23. On the other hand, the phase reference circuit 23 is supplied with the speed reference signal REF. This speed reference signal RE
As will be described later, F can be changed according to the transfer rate of the data to be recorded or reproduced, but the output FG of the frequency generator 22 when the disk 11 is rotating at the target rotation speed It is a signal equal to the frequency. Of course, a signal having a frequency obtained by dividing the output FG may be used, and in that case, the output FG is of course divided by the same division ratio and supplied to the comparison circuit 23.

The comparison output of the phase comparison circuit 23 is passed through the integration circuit 24 to be a speed error voltage, which is supplied to the motor 21 via the motor drive circuit 25,
The motor 21 is controlled to rotate at an angular velocity according to the speed reference signal REF.

Next, the recording section will be described. Reference numeral 31D is an input end of digital data. As digital data, analog audio data is sampled at various predetermined sampling frequencies in addition to computer data.
Each sampled value is sampled as a word having a predetermined number of bits, and digital data of various transfer rates is input.

Reference numeral 31A is an input terminal to which an analog signal such as an audio signal is supplied. Digital signal input terminal 3
When a digital signal is input to 1D, a signal indicating the transfer rate may be sent together with this digital signal. The signal indicating the transfer rate is input terminal 31.
Supplied to R.

Digital data from the input terminal 31D is supplied to the selector 33. The analog signal from the input terminal 31A is converted into a digital signal by the A / D converter 32. The sampling frequency of the A / D converter 32 is, for example, 32 kHz, 44.1 kHz.
It is possible to switch to various ones such as z and 48 kHz, and one sample can be switched and output as a word having various bit numbers such as 8 bits, 12 bits, and 16 bits.

The digital signal from the A / D converter 32 is supplied to the selector 33. The selector 33 is operated manually or by a control signal from the outside and the digital signal from the input terminal 31D and the A / D converter 3
3 or digital signal from 3 is selected.

The digital signal obtained from the selector 33 is supplied to the ECC encoder 34, and one sector data is formed every 512 bytes as described above. At this time, if one word is 8-bit digital data, 5
One sector of data is formed for every 12 words.
In the case of digital data in which 1 word of 2 bits, 16 bits, etc. is not 8 bits, 1 is an integer word in FIG.
In some cases, a row cannot be constructed and one word extends over two rows or even two sectors, but by setting the number of bytes in the row direction to an appropriate value in the data structure of the sector format of FIG. Can be prevented.

The data from the ECC encoder 34 is supplied to the recording process circuit 35, subjected to appropriate modulation, and then supplied to the head in bit serial to be recorded on the magneto-optical disk 11. The rotation speed of the disk 11 at this time is synchronized with the transfer rate of digital data recorded as follows.

That is, during this recording, the switch 26 is switched to the terminal REC side, and the speed reference generating circuit 36
Is supplied to the phase comparison circuit 23 as the speed reference signal REF.

The digital signal to be recorded is the input terminal 31D.
If the digital signal is a digital signal from the
Data is supplied to the speed reference generation circuit 36,
A clock is extracted from this data, the transfer rate is detected from this, and a speed reference signal corresponding to the detected transfer rate is output therefrom.

When the digital signal from the input terminal 31D is not a so-called self-clock signal but a signal indicating the transfer rate, such as a clock, is sent separately from the data, this is sent through the input terminal 31R to the speed reference generation circuit 36. And a speed reference signal corresponding to the transfer rate detected from the signal indicating the transfer rate is output therefrom.

When the signal to be recorded is a signal obtained by sampling an analog signal from the input terminal 31A, the switch 37 is switched according to the selected sampling frequency and the number of bits for one sample, and the transfer is performed. A speed reference signal corresponding to the rate is obtained from the speed reference generation circuit 36.

When the transfer rate of the digital signal from the input terminal 31D is known and the signal indicating the transfer rate is not sent, not the self-clock data, the switch 37 sets the transfer rate. The corresponding reference signal can be selected.

The speed reference signal according to the transfer rate thus obtained and the frequency signal FG from the frequency generator 22.
The motor 21 is driven so that and coincide with each other in phase (frequency coincidence), and the disk 11 rotates at a rotation speed synchronized with the transfer rate.

Then, in this case, the signal which identifies the transfer rate from the speed reference generation circuit 36 is supplied to the ECC encoder 34, and the identification signal of this transfer rate is the data identification information ID of the additional information part of the data structure of FIG. Recorded as part of the. The sampling frequency and the number of bits of the data word are also recorded as a part of this identification information ID.

It should be noted that the digital signal supplied to the input terminal 31D has E added with parity and other redundant bits.
If they are CC-encoded, they are once decoded to obtain only the original digital data.

However, since the magneto-optical disk has a large capacity, it may still contain redundant bits. However,
At that time, the transfer rate will be slightly different. The identification signal indicating the transfer rate of the recorded data may be recorded in the directory of the reproduction start area at the innermost circumference or the outermost circumference of the disc.

Further, the sampling frequency in the A / D converter and the number of bits of the data word may be written in this directory and used during reproduction. The relationship between the practical use, the transfer rate, and the disk rotation speed is shown below.

[0055]

[Table 1]

Although the rotation speed changes as described above,
Since the head is tracking-controlled so as to scan on the same track, the total number of bits as one disk does not change. That is, the recording time varies depending on the transfer rate.

As is apparent from this table, various standard rates of digital communication, 1.536 Mbps, 6.14.
It can be adjusted to 4 Mbps, 2.048 Mbps, etc. It is also possible to record the sound of the digital audio tape recorder as it is. Such a kind of recorded data, that is, an identification signal such as computer data, audio data, or image data may be recorded as the identification information ID of the reserve area.

Next, the time of reproduction will be described. The digital signal reproduced by the head from the disk 11 is supplied to the reproduction process circuit 41, demodulated, and bit-synchronized reproduced to be a digital signal. The output of the process circuit 41 is supplied to the decoder 46 of the identification information ID, the signal indicating the transfer rate recorded in the additional data portion of each sector is decoded, and the decoded output is supplied to the speed reference generation circuit 47. Then, a speed reference signal corresponding to the decoded transfer rate is obtained from this, and is supplied to the phase comparison circuit 23 through the reproduction side terminal PB of the switch 26, and the disc rotates at the number of revolutions synchronized with the recorded data transfer rate. To rotate.

The speed reference signal for controlling the rotation of the disk at the time of reproduction can also be obtained by reading the data indicating the transfer rate recorded in the directory of the disk before the reproduction.

Further, if the transfer rate of the data recorded on the disc can be known by a memo or the like, the manual switching can of course be performed. In this way, the data reproduced at the number of revolutions synchronized with the data transfer rate is supplied to the ECC decoder 42 through the reproduction process circuit 41, subjected to error correction processing for each sector unit, and then the redundant bits are removed. Only the original data is made, and when it is digital data, it is led to the output terminal 45D by the multiplexer 43, and when it is a digitized analog signal, it is returned to the analog signal by the D / A converter 44 and then output terminal. 45A.

The sampling signal frequency and the number of bits of the data word in the D / A converter 44 are known in advance by decoding the identification information ID or by reading the data recorded in the directory, and the D / A conversion corresponding thereto is performed. It can be performed.

In this case, the identification information ID of the additional information portion is a part of the product code data and has a high error correction capability. Therefore, at the time of reproduction, the transfer rate of the recorded data, the sampling frequency, and the number of bits are correctly obtained. It is easy to do.

The above is the case where the disk is rotationally controlled so that the rotational angular velocity is constant, but it is needless to say that it is applicable to the case where the disk is rotationally controlled so that the linear velocity is constant.

[0064]

As described above, according to the present invention, a product code having a high error correction capability is formed for data and transmitted. When forming the product code, not only the data but also the data are related. Since the product code is formed by including the additional information, the additional information is resistant to an error, and the additional information can be effectively used on the data receiving (reproducing) side.

In this case, the reserved area of the additional information is shown in FIG.
Although it may be possible to arrange the data before the data on the matrix array as shown in FIG. 2, when the data is packed in the front and the additional information is arranged after the data as in the present invention, the first data is transferred in the first order. Error correction code C ₁ encoding and C
An RC code generation operation can be performed, and the number of accesses to the buffer memory of the ECC encoder can be reduced.

When the reserved area is before the data in the matrix array as shown in FIG. 5, the memory address controller for writing and reading the data in the buffer memory needs to add an offset to the memory address. However, in the case of the present invention, such an offset is no longer needed and the address controller is mod. It can be composed of 48 counters, and address management becomes easy.

Further, since the additional information section is attached later,
When the data size is changed from 512 bytes to 520 bytes, for example, a part of the additional information part can be easily used as a data area. That is, even when the additional information part is attached in front of the data, a part of the additional information part can be used as the data area, but in this case, the length of the additional information part is changed, so that Whereas the address offset value at the address controller will change, requiring more complex control, the present invention does not require such.

Further, when the data with additional information is sent from the host computer, when the additional information area is before the data as shown in FIG. 5, and when the additional information is sent after the data, Although the data cannot be encoded until the transmission of the data is completed, this problem does not occur in the present invention because the additional information area is after the data.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a product code used in the method of the present invention.

FIG. 2 is a diagram showing another example of a product code used in the method of the present invention.

FIG. 3 is a diagram showing a sector format of a magneto-optical disk to which the method of the present invention is applied.

FIG. 4 is a diagram showing an example of a disc recording / reproducing apparatus to which the present invention is applied.

FIG. 5 is a diagram showing an example of a data structure of a possible product code.

FIG. 6 is a diagram illustrating a data recording / reproducing system using a hard disk device.

[Explanation of symbols]

D _{0 to} D ₅₁₁ data C ₁ , C ₂ Parity in row and column directions

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H04L 1/00 H04L 1/00 B

Claims (1)

[Claims] 1. A data reproducing apparatus for reproducing data from a disk-shaped data recording medium in which data is recorded together with a signal indicating the transfer rate at different transfer rates, wherein a digital signal is reproduced from the data recording medium. A demodulation process circuit, an ECC decoder that performs error correction processing on the reproduced digital signal for each sector, and a multiplexer that separates the error-corrected signal by the ECC decoder into digital data and other signals. A data reproducing apparatus, which has information of a transfer rate of recording data from the digital data, and reproduces the data at a transfer rate at the time of recording according to the information of the transfer rate.