Error detection/correction and fault detection/recovery – Pulse or data error handling – Digital data error correction
Reexamination Certificate
1998-03-31
2001-07-10
Decady, Albert (Department: 2784)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Digital data error correction
C714S785000
Reexamination Certificate
active
06260169
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to error correction devices, and more particularly to error correction devices used in correcting data read from DVD media.
2. Description of the Related Art
In recent years, optical disc technology has gained popularity in computer and entertainment industries. For example, by providing superior digital sound quality, CD players and discs have effectively displaced phonographs in the music industry. In addition, CD-ROM technology has also become popular in the computer industry as well for recording and reading large amounts of information or data.
However, in response to an ever increasing demand for convenient storage devices with even greater storage capacity, a new optical media known as digital video disc or digital versatile disc (DVD) has emerged as a promising new technology. The DVD media technology provides many times the storage capacity of a conventional CD-ROM disc. For example, a DVD medium may store data, for example, between 4.7 Gigabytes up to 18 Gigabytes. In contrast, conventional CD-ROM discs are usually only capable of storing about 650 Megabytes of data. Of course, the capacity of a DVD medium may surpass 18 Gigabytes in the near future as technology improves.
Information in a DVD medium is stored in a similar manner as the traditional CD-ROM disc. Prior Art
FIG. 1A
illustrates a DVD medium
100
having a center hole
104
. In the DVD medium
100
, data is typically stored in units of sectors that are laid out in a continuous spiral
102
from the center hole
104
and extending through to the circumference of the DVD medium
100
. Sectors are laid out along the spiraling track
102
. For example, a portion
106
of the spiraling track
102
may include numerous sequential sectors.
Prior art
FIG. 1B
illustrates a more detailed layout of the portion
106
of the spiraling track
102
in the DVD medium
100
. The portion
106
includes five sequential sectors
110
,
111
,
112
,
113
, and
114
(i.e.,
110
through
114
). Each of the sectors
110
through
114
stores user data of 2064 bytes.
Each of the sectors
110
through
118
contains a header field
120
and a data field
122
. The header field
120
is typically assigned sixteen bytes. Of these sixteen bytes, the first four bytes store the sector number for identifying the sector, and the remaining bytes are used to store information related to error detection, copy protection, and payload error detection.
Often however, user data stored in or read from a DVD medium may become corrupted or contaminated. For example, contamination or corruption can occur for reasons such as scratches, dust, noise, and other imperfections. The contamination or corruption typically causes two types of errors: a random error and a burst error. The random error refers to a single bit of error. On the other hand, the burst error refers to an error involving a set of contiguous bits.
To protect against such random and burst errors, DVD technology typically implements an error correction code (ECC) block coding scheme. In the ECC block coding scheme, user data is organized and encoded in data sectors. A data sector contains 12 bytes of header, 2048 bytes of user data, and 4 bytes of EDC. The data sector is split into 12 rows of 172 bytes each. Each data sector is converted to a recording sector by adding 10 bytes of row check bytes (i.e., inner parity bytes) to each row and also adding 16 rows of column check bytes (i.e., outer parity bytes). The column check bytes are interleaved between 16 sectors of user data such that each sector is followed by a row of column check byte. Accordingly, each recording sector consists of 13 rows of 182 bytes each.
The recording sectors are converted to physical sectors by splitting each row of the recording sectors down the middle and adding a 1-byte sync code in front of each half-row. In addition, the data is processed with an 8-to-16 modulation (EFM plus), which replaces each byte with a 16-bit code. This conversion process results in the creation of 16 blocks of physical sectors within an ECC block. Each of the physical sectors consists of 4836 bytes. The physical sector data are then sequentially written out row by row to a DVD medium as channel data starting with the first sector in the ECC block. The first sector of the next ECC block immediately follows the last sector of the current ECC block.
Prior Art
FIG. 1C
illustrates a block diagram of a DVD data correction system
150
for correcting random and burst mode errors. In this system
150
, an EFMPlus decoder
132
receives a stream of physical sector data from a DVD disc
130
and decodes the data from a 16- to 8-byte format. A disc manager controller
134
receives the decoded stream of data from the EFMPlus decoder
132
and identifies sync bytes to convert the physical sectors back to recording sectors. The disc manager
134
then transmits the recording sector data to a buffer
136
. An error correction circuitry
138
reads the data in the buffer
136
and performs error correction on the sector data held in the buffer
136
. Using the data contained in the buffer
136
, the error correction circuitry
138
performs both row and column error corrections at this stage. In this process, the error correction circuitry
138
converts the recording sector data into the original user data for transmission to a host
140
.
In the prior art DVD data correction system
150
, the error correction circuitry
138
performs both row and column error corrections at the same stage of the data pipeline. Unfortunately, performing row and column error corrections at the same error correction stage can lead to a performance degradation. For example, when the header
120
in a desired sector
112
contains an uncorrectable error, sector
112
may never be identified during a search.
In order to address such a situation, conventional techniques typically read several sectors (e.g., 5 to 6 sectors) ahead of time. Then, if the sector
112
cannot be identified in the sequence of sectors, a pause in processing is required to enable one more revolution of the DVD media. This revolution of the DVD media will enable the same sectors to be re-read, including the sectors located around the un-identifiable header of sector
112
. For instance, a DVD drive may determine that it has missed the desired sector when it is only able to read a header associated with the next sector. At this point, the DVD drive will determine that it has failed to detect the desired sector. In order to read the undetected header, the DVD drive must make another revolution of the DVD media to re-read the group of sectors. This time the DVD drive reads the unidentified sector by assuming that sector
112
is located between the identifiable sectors directly before and after the undetected sector (i.e., sectors
111
and
113
, respectively).
By thus making another revolution around the DVD medium to re-read the undetected sector, the conventional system
150
results in significant performance and time penalties. Furthermore, since the conventional system
150
typically reads several sectors ahead of time, real time error detection and correction is not possible.
In addition, the conventional system
150
, which performs the row and column error corrections at the same stage, also delays the identification of a desired sector. This is because the header typically is not processed until both the row and column data have been transferred to the buffer
136
. In the conventional system
150
, once a block of data has been transferred to the buffer
136
, the row correction reads the entire data stored in the buffer
136
to perform the row corrections. Accordingly, the above described conventional techniques also tend to introduce delays associated with accessing and correcting the data in the buffer
136
.
In view of the foregoing, what is needed is a device and method that can reliably correct the row data including the header in a DVD data sector without reading back the entire dat
De'cady Albert
Galanthay Theodore E.
Jorgenson Lisa K.
Slater Steven H.
STMicroelectronics N.V.
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