JPH06150573A - Data decoder - Google Patents

Abstract

PURPOSE:To use data except the data occurring an error as the valid data by increasing/decreasing a data length within the range where an error flag detected by an error position detection means exists and reproducing the data. CONSTITUTION:When te stored data are started to be read from a magneto- optical disk 3, the regenerative data are read out intermittently based on the remaining amount of data in a RAM 10. Thereafter, by a magneto-optical disk reproducing device 1, the compressed data corresponding to the data several seconds before the audio data under reproducing presently are written by temporarily writing the compressed audio data in the RAM 10. At this time, the error flags occurring in the compressed data are fetched successively. By a system controller 9, when the length of a sector coincides with a prescribed length, a head address for transferring data is outputted to the RAM 10 to be transferred to a descramble circuit 11 successively. When the length of the sector is different from the prescribed length, the fluctuation of the time base is corrected.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problems to be Solved by the Invention (FIGS. 7 and 8) Means for Solving the Problems (FIGS. 1, 3 and 4) Operation (FIGS. 5 and 6) Example ( 1) Overall configuration of the embodiment (FIGS. 1 to 6) (1-1) Configuration of disk reproducing device 1 (FIGS. 1 and 2) (1-2) Configuration of RAM control circuit 8 (FIGS. 3 and 4) (2) Operation and effect of the embodiment (FIGS. 5 and 6) (3) Other embodiment Effect of the invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data decoding device, and is suitable for application to, for example, a device for reproducing an audio signal recorded on a magneto-optical disk.

[0003]

2. Description of the Related Art Conventionally, a disk reproducing apparatus and a disk recording / reproducing apparatus capable of reproducing information from both a magneto-optical disk and a compact disk and recording desired information on the magneto-optical disk as many times as possible have been considered. There is.

By the way, when this disk reproducing apparatus is used for reproducing an audio signal recorded on a magneto-optical disk or the like, it is likely to be used outdoors where it is susceptible to external vibrations. Therefore, even if a large vibration is applied. A technique for improving vibration resistance by using a semiconductor memory so as to prevent interruption of sound due to interruption of data reading is being studied.

This anti-vibration technology is compressed to about 1/5,
The audio data recorded after the error correction processing is read from the magneto-optical disk at a speed of 1.4 [Mbit / s], and the decoded audio data is once written in a random access memory (hereinafter referred to as RAM). Following this, the compressed audio data is stored in RAM
Further, the vibration resistance is improved by continuously reading at a speed of 0.3 [Mbit / s] and expanding the original data length. Incidentally, at this time, the audio data is read out intermittently from the magneto-optical disk.

In this way, by storing the audio data up to several seconds ahead of the audio data to be actually reproduced in the random access memory, even if it becomes impossible to take in the data due to a large vibration, the audio data will be reproduced again. By playing back the stored data until the reading is started, it is possible to prevent the occurrence of sound skip.

[0007]

By the way, in the magneto-optical disk used for reproducing the audio data, audio data divided into predetermined block units (hereinafter referred to as sound groups) are predetermined data units (hereinafter referred to as clusters). A data recording area for each recording and a lead-in area for storing table of contents information (TOC (Table Of Contents) data) other than music data, such as disk information and track information, are provided.

Of these, the data recording area is provided outside the recording area, and the lead-in area is provided inside the recording area. Writing and reading of data to and from this data recording area is performed by an integral multiple of one cluster.

Here, one cluster is composed of 36 sector data, and in the case of a magneto-optical disk for recording, the first 3 sectors are link sectors L as redundant sectors,
The next 1 sector is assigned to the sub data S, and the remaining 32 sectors are assigned to the compressed data (FIG. 7A).

Incidentally, one sector consists of a sync area of 12 bytes from the beginning, a header area of 4 bytes, a sub-header area of 4 bytes, and a compressed data area of 2332 bytes, of which the cluster number, sector number, Mode area is 2 bytes, 1 byte,
They are allocated byte by byte (Fig. 8).

Of these, in one sector of the compressed data area, there are 5 sound groups consisting of two left and right channel data and left channel data or right channel data and 5 sound groups.
A set of sound groups is assigned (Fig. 7
(B) and FIG. 7 (C)).

In this type of disk recording / reproducing apparatus, compressed data of 512 samples, that is, 424 bytes of one sound group is handled as one unit (FIG. 7 (D)).

By the way, in this disk recording / reproducing apparatus,
When the reproduced RF signal has an error due to scratches or defects (disk) on the disk and fluctuations occur in the PLL etc., the number of frames apparently fluctuates in units of 24 bytes. I have something to do. That is, 2352 + α is between the sync signal and the next sync signal.
It looks like (α = 24, 48, 72 ...).

The data having this error can be detected by an error flag such as so-called C2PO (error pointer after C2 decoding). However, the descrambling applied to 2340 bytes of all data other than the sync signal is performed in units of a fixed byte.

For this reason, if the number of detected bytes fluctuates with respect to the original number of bytes, all sector data will become erroneous until the next synchronizing signal thereafter, and if such an error occurs, the error will occur. It was mute all the rest of the data in the sector. However, if this is done, other data in which no error has occurred will be wasted, so it is desirable to effectively use data in which no error has occurred.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a data decoding apparatus capable of removing only data in which a burst error has occurred and making other data valid. .

[0017]

In order to solve such a problem, according to the present invention, a second data group (5.5) including a plurality of first data groups (sound groups) each having a predetermined number of words is used.
In a data decoding device for decoding digital data in units of data groups (sectors), a sync detecting means for detecting a sync signal arranged at the head position of the second data group (sector), and a second data group ( (Sector), the error flag EF for each word is monitored, and the error position detection means 8B for detecting the range of the error occurring in the second data group (sector) and the second data group (sector) are sequentially arranged. When the number of words of the storage means 10 for storing and the second data group (sector) divided by the synchronization signal detected by the synchronization detection means is different from the predetermined number of words, the error position detection means 8B is used. Error flag E detected
Read control means 8 for increasing or decreasing the data length of the first data group (sound group) corresponding to the range in which F exists, and controlling the number of words of the reproduced second data group (sector) to a constant value, and a read operation. Descramble means 1 for descrambling the second data group (sector) output from the control means 8
1 and 1.

Further, in the present invention, data decoding for decoding digital data in units of a second data group (sector) including a plurality (5.5) of a first data group (sound group) having a predetermined number of words In the device, the second
Of the second data group (sector) for detecting a synchronization signal arranged at the head position of the second data group (sector)
Of the error data EF for each word forming the second data group (sector) and the error position value detection means 8B for detecting the range in which the error flag EF occurred in the second data group (sector). ) And the second data group (sector) divided by the synchronization signal detected by the synchronization detection means have a different number of words from a predetermined number of words, the error position detection means 8
The data length of the first data group (sound group) corresponding to the range in which the error flag EF detected by B exists is increased or decreased, and the number of words of the reproduced second data group (sector) is made constant. When the second data group (sector) read by the read control means 8 includes a word in which an error has occurred, the read control means 8 for controlling
Of the corresponding word in the data group (sector) of
The data group (sound group) of is muted.

[0019]

When the number of words of the second data group (sector) divided by the synchronization signal detected by the synchronization detecting means is different from the predetermined number of words, the error detected by the error position detecting means 8B is detected. The data length of the first data group (sound group) located in the range where the flag EF exists is increased or decreased to control the number of words of the second data group (sector) reproduced by the read control means 8 to be constant. By doing so, it is possible to use the error occurrence as valid data other than the data, and it is possible to further improve the data use efficiency.

By muting the first data group including the word in which the error has occurred, it is possible to use the data in which the error has occurred as valid data other than the data.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Overall Configuration of the Embodiment (1-1) Configuration of Disk Reproducing Device 1 In FIG. 1, reference numeral 1 denotes the entire reproducing device in the disk recording / reproducing device, which is a light rotatably driven by a spindle motor 2. A magnetic disk 3 is irradiated with a light beam from an optical pickup 4, and a reproduction signal, which is a received output of the reflected light, is amplified by a high frequency amplifier circuit 5.

The disk reproducing apparatus 1 supplies the amplified reproduction signal to the servo control circuit 6 and the decoder 7
Supply to. Here, the servo control circuit 6 controls the rotation speed of the spindle motor 2 on the basis of the reproduction signal, and also controls the tracking and focus of the optical pickup 4.

On the other hand, the decoder 7 outputs the reproduction signal to 2
After demodulating into value data, this is subjected to EFM decoding processing and error correction processing, and the corrected reproduction data is supplied to the RAM control circuit 8 as compressed audio data.

When the RAM control circuit 8 receives the compressed audio data, the RAM control circuit 8 sequentially transfers the compressed audio data to a predetermined address of the RAM 10 designated by the system controller 9 configured by a micro computer (hereinafter referred to as MPU). Further, the RAM control circuit 8 reads compressed audio data from a predetermined address of the RAM 10 designated by the system controller 9 and supplies it to the descramble circuit 11.

Incidentally, the RAM control circuit 8 uses the error flag E
The F is also read / written from / to the RAM 9. Further, the RAM control circuit 8 extracts a header and a sub-header from the compressed audio data supplied to the descramble circuit 11 and supplies them to the system controller 9, and sorts out error information regarding the compressed audio data transferred to the descramble circuit 11. It is designed to be given to the system controller 9.

In the case of this embodiment, the storage area of the RAM 10 is 1 [Mbit], and it is divided into 44 sectors of main data, 6 or more sectors of TOC (Table Of Contents) data, and an error flag. It is designed to be stored (Fig. 2).

The descramble circuit 11 releases the scramble applied to the data after the sync signal in units of a predetermined byte and outputs it to the data decompression circuit 12, and when a burst error occurs. , Data with burst error is designed to be muted.

At this time, the data expansion circuit 12 outputs 0.3 [M
from compressed audio data that is read in [bit / s] 1.4 [M
When the bit / s] voice data is demodulated, it is supplied to a digital / analog conversion circuit 13 (hereinafter referred to as D / A conversion circuit 13) and converted into a voice signal.

Further, the system controller 9 controls the operation state of the entire disk reproducing apparatus 1 and adds various control data to the header area and the sub header area of each sector constituting the reproduced compressed audio data, and the RAM 1 is added.
It is designed to be stored at 0.

That is, the system controller 9 writes a track number in a mode area which is undefined when reading out from the magneto-optical disk when writing compressed audio data in the RAM 10, and an error in the sector in the sub header area. The end position of audio data in units of information or sound group is added and written (FIG. 8).

When the compressed audio data is read from the RAM 10, the control information such as time information of each sector is stored in the RAM.
At the same time, the control circuit 8 reads out the data, the reproduction time and the remaining time are displayed on the display 15 according to the instruction of the key operation unit 14, and the reproduction situation is managed. Further, when the data length of the sector has increased or decreased with respect to 2351 bytes due to the occurrence of the burst error, the system controller 9 reads the data by aligning the number of bytes based on the error data provided from the RAM control circuit 8. It is designed to let you.

(1-2) Configuration of RAM Control Circuit 8 In the case of this embodiment, the RAM control circuit 8 is constructed as shown in FIG. 3, and when the compressed voice data and the error flag are inputted, this is inputted to the system controller. 9 is sequentially transferred to a predetermined address of the RAM 10 designated by the RAM 9 via the RAM interface 8A.

The RAM control circuit 8 includes an error flag monitor section 8B consisting of a 3-byte read register (CMS23 to CMS00) and an in-sector byte counter 8C for counting the in-sector byte value with the head position of the header being "0".
The error flag monitor unit 8B reads out the state (number of error flags, start position, and final position) of the error flag EF for the immediately preceding sector data (header, data, sync) in the current sector. ing.

At this time, the error flag monitor section 8B is adapted to store the number N of error flags by 4 bits of the registers CMS23 to CMS20. If the number represented by these 4 bits is X, then the number of error flags N is

[Equation 1]

[Equation 2] 4 is established, and this is shown in a table as shown in FIG.

The error flag monitor unit 8B is adapted to represent the first position of the error flag EF in the registers CMS19 to CMS08 by 12-bit binary data. Here, the head position of the error flag is a value when the head byte position of the header is counted as 0th.

Incidentally, the most significant bit MSB of the 12-bit binary data is the register CMS19, and the least significant bit LSB is the register CMS08. If the sector does not include an error, the error flag monitor 8B sets all the data values of the registers CMS19 to CMS08 to "0".

Further, the error flag monitor 8B uses the registers CMS07 to CMS00 to detect the error flag EF.
It is designed to represent the last position where the standing. Here, from register 0 to register CMS07 to CMS00, 2
Out of the 12-bit address data representing the address 351 the upper 8 bits are stored and the lower 4 bits are omitted. If the sector does not include an error, the error flag monitor unit 8B determines that the registers CMS07 to CMS00.
All the data values of are set to "0".

(2) Operation and effects of the embodiment With the above configuration, when the magneto-optical disk reproducing apparatus 1 starts reading the stored data from the magneto-optical disk 3, the remaining amount of data in the RAM 10 is controlled according to the control of the system controller 9. Based on this, the reproduction data is read out intermittently.
At this time, the magneto-optical disc reproducing apparatus 1 reproduces the reproduced data.
When the data is read at a transfer rate of 1.4 [Mbit / s], it is input to the decoder 7, and decoding processing (parity deletion and deinterleave processing) for error correction and EFM (8
-14 modulation) Demodulation processing and the like are executed.

After that, the magneto-optical disk reproducing apparatus 1 writes the compressed audio data into the RAM 10 through the memory interface 8A once to write the compressed data which is a few seconds ahead of the audio data currently being reproduced. At this time, the error flag monitor 8
B sequentially takes in the error flags generated in this compressed data.

Here, the error flag monitor 8B obtains the position and number of error flags generated in the sector corresponding to the immediately preceding sector with respect to the current input, and stores this in the register CMS.
23 to CMS00. For example, as shown in FIG. 5B, "0123 (H)" is set as the start address and "023 (H)" is set as "0".
The case where 448 error flags EF having “2FF (H)” as the end address are set will be shown.

At this time, the number of error flags EF is "448".
Is a value obtained by subtracting 8 from 2 to the 9th power, and therefore the error flag monitor / status generation circuit 8B is
20 indicates "9" in 4 bits. Since the error start position is “0123 (H)”, the error flag monitor unit 8B sets “12” in the registers CMS19 to CMS08.
3 "is shown in 12 bits.

Similarly, the end position of the error is "0123.
(H) ”, the error flag monitor unit 8B writes“ 2F ”in the registers CMS07 to CMS00.
As a result, the data written in the 3-byte registers CMS23 to CMS00 by the error flag monitor unit 8B becomes "91232F".

When the system controller 9 fetches the error data from the plurality of registers, the compressed audio data of the corresponding sector contains an error, and if it contains the error, the length of this sector is a predetermined length ( (2352 bytes) based on the interval between the sync signals, and if they match a predetermined length, the head address for data transfer is output to the RAM 10 to sequentially output the descramble circuit 11.
Transfer to.

On the other hand, when the length of the sector is different from the original length, the position where the error flag is present is regarded as the joint of valid data, and the total length becomes 2352 bytes. Correct the fluctuation of.

That is, when the length of the data between the sync signals is longer than 2352 bytes from the address of the sync signal in the sector read from the RAM 10 and the address of the sync signal in the immediately preceding sector, the system controller 9 determines the length of the data. The fluctuation is assumed to have occurred during the period when the error flag EF is set.

The system controller 9 is a RAM
As read addresses of 10 bytes, k bytes from the header start address of the header to the start address of the error flag and data of (2352-k) bytes forward (reverse to time direction) from the end address of the sector are stored. specify.

As a result, a large number of sound groups containing valid data whose time axis has been corrected are transferred to the descramble circuit 11. In the case of this embodiment, the system controller 9 sends the control data to the descramble circuit 11 because the reproduced sound is distorted when the data having the error flag EF is reproduced, and the data having the error flag EF is muted. It is transferred to the expansion circuit 12. After that, it is converted into an audio signal by the D / A conversion circuit 13.

As a result, the magneto-optical disk recording / reproducing apparatus 1
Therefore, it is possible to mute only the sound group in which the error is included in the sector data to be reproduced, and the reproduced data can be effectively used.

According to the above configuration, the error flag monitor section 8B monitors the error flag EF to detect the position of an error occurring in the compressed audio data D sequentially written in the RAM 10 and give it to the system controller 9. When the corresponding compressed audio data D is read, the data length of the sound group in which the error occurs is adjusted based on the start address, the end address of the error flag and the number of error flags. Data can be increased further.

By muting the data of the sound group containing the error, it is possible to effectively avoid the possibility that an unnatural reproduced sound obtained by the data unrelated to the original data is reproduced.

(3) Other Embodiments In the above embodiments, the case where the descramble circuit mutes a sound group containing an error has been described, but the present invention is not limited to this, and the data expansion circuit is used. After extending the data length, the sound group containing the error may be muted.

Further, in the above-mentioned embodiment, the case where the end position of the error is represented by the address whose head byte position of the header is 0 is described, but the present invention is not limited to this, and the error start position is It may be represented by the number of error flags from this head position.

Further, in the above embodiment, the case where the number of error flags is represented by 4 bits has been described, but the present invention is not limited to this and may be represented by 5 bits or more.

Further, in the above-described embodiment, the start position, the end position, and the number of error flags of the error flag are respectively obtained for the EFM-decoded audio data after being read from the magneto-optical disk, and a part is obtained based on the error information. The case of avoiding the possibility of invalidating even valid data due to an error occurred in the data has been described, but the present invention is not limited to this, and is also applied to digital data other than audio data subjected to other decoding processing. You can

[0056]

As described above, according to the present invention, the second division is made by the sync signal detected by the sync detecting means.
If the number of words in the data group of is different from the predetermined number of words, the data length of the first data group in the range in which the error flag detected by the error position detecting means exists is increased or decreased and reproduced. The number of words of the second data group read from the read control means can be controlled to be constant. As a result, data other than the data in which an error has occurred can be used as valid data, and the data usage efficiency can be further improved.

By muting the first data group including the word in which an error has occurred in the data read from the storage means, the error occurrence can be used as valid data other than the data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a data decoding device according to the present invention.

FIG. 2 is a schematic diagram showing a memory map of data stored in a random access memory.

FIG. 3 is a block diagram showing a configuration of a random access memory control circuit.

FIG. 4 is a schematic diagram for explaining a display of the number of error flags generated in the same sector.

FIG. 5 is a signal waveform diagram for explaining the operation of the random access memory control circuit.

FIG. 6 is a schematic diagram for explaining error information generated in an error flag monitor.

FIG. 7 is a schematic diagram showing a data structure of a cluster.

FIG. 8 is a schematic diagram showing a data structure of a sector.

[Explanation of symbols]

1 ... Disk playback device, 2 ... Spindle motor, 3
... Magneto-optical disk, 4 ... Optical pickup, 7 ... Decoder, 8 ... Random access memory control circuit, 8A
...... Memory interface, 8B ・ ・ ・ Error flag monitor, 8C ・ ・ ・ Sector byte counter, 9 ・ ・ ・ System controller, 10 ・ ・ ・ Random access memory,
11 ... descramble circuit, 12 ... data expansion circuit.

Claims (5)

[Claims] 1. A data decoding device for decoding digital data in units of a second data group including a plurality of first data groups each having a predetermined number of words, wherein the digital data is arranged at a head position of the second data group. A synchronization detecting means for detecting the generated synchronization signal, and an error position detecting means for monitoring an error flag for each word forming the second data group and detecting an error range occurring in the second data group. When the number of words of the second data group divided by the storage means for sequentially storing the second data group and the synchronization signal detected by the synchronization detection means is different from a predetermined number of words, The first corresponding to the range in which the error flag detected by the error position detecting means exists
Read / write control means for increasing / decreasing the data length of the data group and controlling the number of words of the second data group to be reproduced constant, and descramble the second data group output from the read control means. A data decoding device comprising: a descrambler. 2. A data decoding device for decoding digital data in units of a second data group including a plurality of first data groups each having a predetermined number of words, wherein the digital data is arranged at a head position of the second data group. Synchronization detecting means for detecting the generated synchronization signal, and an error position detecting an error flag occurring in the second data group by monitoring an error flag for each word forming the second data group. A value detecting means, a storage means for sequentially storing the second data group, and a word number of the second data group divided by the synchronization signal detected by the synchronization detecting means is a predetermined word number. When different, the first flag corresponding to the range in which the error flag detected by the error position detecting means exists
Reading control means for controlling the number of words of the second data group to be reproduced constant by increasing or decreasing the data length of the second data group, and adding the read data to the second data group read by the reading control means. A data decoding device, wherein when a word in which an error has occurred is included, a first data group including the corresponding word in the second data group is muted. 3. The second means provided by the descrambling means.
2. The data decoding apparatus according to claim 1, wherein after the data group of 1 is descrambled, the first data group including the word in which an error has occurred is muted from the second data group. 4. The error range detected by the error position detecting means is an error flag given on the basis of the head position of the first data group following the sync signal arranged at the head position of the second data group. The data decoding apparatus according to claim 1, wherein the data decoding apparatus is set according to a start position and an end position of the. 5. The data decoding device according to claim 4, wherein the end position is specified by the number of error flags for the start position.