Error correction method and reproduction apparatus

Abstract

A reproduction method includes a step of performing error correction of the first coded data piece and generating error location information which represents an error location of the first coded data; a step of generating erasure locator information which represents an erasure position of the second coded data piece, based on the error location information; and an erasure error correction step of performing erasure error correction of the second coded data piece based on the erasure locator information. The erasure locator information generation step includes the step of, when the error location information indicates that no error is detected in the Nth first symbol and the (N+2)th first symbol and that an error is detected in the (N+1)th first symbol, determining at least one of the plurality of second symbols provided adjacent to the (N+1)th first symbol as representing erasure.

1 . A reproduction method for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols,    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces, and    the plurality of synchronization data pieces include an Nth synchronization data piece, an (N+1)th synchronization data piece, and an (N+2)th synchronization data piece, where N is an integer,    the reproduction method comprising:    a reading step of reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation step of detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation step of generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction step of performing erasure error correction of the coded data piece based on the erasure locator information,    wherein the erasure locator information generation step includes the step of, when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, determining at least one of the plurality of symbols provided adjacent to the (N+1)th synchronization data piece as representing erasure.    
   
   
       2 . A reproduction method according to  claim 1 , wherein the erasure locator information generation step further includes the step of, when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, determining at least one symbol provided adjacent to the (N+1)th synchronization data piece, among at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure; and determining at least one symbol provided adjacent to the (N+1)th synchronization data piece, among at least one symbol provided between the (N+1)th synchronization data piece and the (N+2)th synchronization data piece as representing erasure.  
   
   
       3 . A reproduction method according to  claim 1 , wherein the erasure locator information generation step further includes the step of, when the synchronization detection information indicates that neither of the two adjacent synchronization data pieces are detected, determining all the symbols provided between the two undetected synchronization data pieces as representing erasure.  
   
   
       4 . A reproduction method for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least two of the plurality of symbols are provided between two adjacent synchronization data pieces of the plurality of synchronization data pieces,    the reproduction method comprising:    a reading step of reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation step of detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation step of generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction step of performing erasure error correction of the coded data piece based on the erasure locator information,    wherein the erasure locator information generation step includes the step of, when the synchronization detection information indicates that a synchronization data piece adjacent to a detected synchronization data piece is not detected, determining at least one symbol adjacent to the undetected synchronization data piece, among at least two symbols provided between the detected synchronization data piece and the undetected synchronization data piece, as representing erasure; and determining at least one symbol provided adjacent to the detected synchronization data piece as not representing erasure.    
   
   
       5 . A reproduction method according to  claim 4 , wherein the erasure locator information generation step further includes the step of, when the synchronization detection information indicates that neither of the two adjacent synchronization data pieces are detected, determining all the symbols provided between the two undetected synchronization data pieces as representing erasure.  
   
   
       6 . A reproduction method for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols,    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces, and    the plurality of synchronization data pieces include an Nth synchronization data piece and an (N+1)th synchronization data piece, where N is an integer,    the reproduction method comprising:    a reading step of reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation step of detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation step of generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction step of performing erasure error correction of the coded data piece based on the erasure locator information,    wherein the erasure locator information generation step includes the step of, when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, determining at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure.    
   
   
       7 . A reproduction method according to  claim 6 , wherein: 
 the plurality of synchronization data pieces include an (N+2)th synchronization data piece, and    the erasure locator information generation step further includes the step of, when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, determining at least one symbol provided between the (N+1)th synchronization data piece and the (N+2)th synchronization data piece as not representing erasure.    
   
   
       8 . A reproduction method for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces of the plurality of synchronization data pieces,    the reproduction method comprising:    a reading step of reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation step of detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation step of generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction step of performing erasure error correction of the coded data piece based on the erasure locator information,    wherein the erasure locator information generation step includes the step of, when the synchronization detection information indicates that any two or more data pieces from undetected synchronization data pieces and synchronization data pieces detected with a positional offset are consecutive, determining at least one symbol provided between the consecutive synchronization data pieces as representing erasure.    
   
   
       9 . A reproduction method for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces,    the reproduction method comprising:    a reading step of reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation step of detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation step of generating at least first erasure locator information and second erasure locator information which represent an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction step of performing erasure error correction of the coded data piece based on at least one of the first erasure locator information and the second erasure locator information,    wherein the erasure error correction step includes the step of, when there is an error which cannot be corrected based on the first erasure locator information, performing erasure error correction of the coded data piece based on the second erasure locator information.    
   
   
       10 . A reproduction method according to  claim 9 , wherein: 
 the erasure locator information generation step includes the steps of:    when all the errors can be corrected based on the first erasure locator information, generating erasure locator information for erasure error correction of another coded data piece using an identical method as the method used for generating the first erasure locator information, and    when all the errors can be corrected based on the second erasure locator information, generating erasure locator information for erasure error correction of another coded data piece using an identical method as the method used for generating the second erasure locator information.    
   
   
       11 . A reproduction method according to  claim 9 , wherein: 
 the plurality of synchronization data pieces include an Nth synchronization data piece, an (N+1)th synchronization data piece, and an (N+2)th synchronization data piece, where N is an integer, and    the erasure locator information generation step includes the step of, when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, determining at least one of the plurality of symbols provided adjacent to the (N+1)th synchronization data piece as representing erasure.    
   
   
       12 . A reproduction method according to  claim 9 , wherein: 
 the plurality of synchronization data pieces include an Nth synchronization data piece and an (N+1)th synchronization data piece, where N is an integer, and    the erasure locator information generation step includes the step of, when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, determining at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure.    
   
   
       13 . A reproduction method according to  claim 9 , wherein the erasure locator information generation step includes the step of, when the synchronization detection information indicates that any two or more data pieces from undetected synchronization data pieces and synchronization data pieces detected with a positional offset are consecutive, determining at least one symbol provided between the consecutive synchronization data pieces as representing erasure.  
   
   
       14 . A reproduction apparatus for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols,    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces, and    the plurality of synchronization data pieces include an Nth synchronization data piece, an (N+1)th synchronization data piece, and an (N+2)th synchronization data piece, where N is an integer,    the reproduction apparatus comprising:    a reading section for reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation section for detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation section for generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction section for performing erasure error correction of the coded data piece based on the erasure locator information,    wherein when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, the erasure locator information generation section determines at least one of the plurality of symbols provided adjacent to the (N+1)th synchronization data piece as representing erasure.    
   
   
       15 . A reproduction apparatus according to  claim 14 , wherein when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, the erasure locator information generation section determines at least one symbol provided adjacent to the (N+1)th synchronization data piece, among at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure; and determines at least one symbol provided adjacent to the (N+1)th synchronization data piece, among at least one symbol provided between the (N+1)th synchronization data piece and the (N+2)th synchronization data piece as representing erasure.  
   
   
       16 . A reproduction apparatus according to  claim 14 , wherein when the synchronization detection information indicates that neither of the two adjacent synchronization data pieces are detected, the erasure locator information generation section determines all the symbols provided between the two undetected synchronization data pieces as representing erasure.  
   
   
       17 . A reproduction apparatus for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least two of the plurality of symbols are provided between two adjacent synchronization data pieces of the plurality of synchronization data pieces,    the reproduction apparatus comprising:    a reading section for reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation section for detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation section for generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction section for performing erasure error correction of the coded data piece based on the erasure locator information,    wherein when the synchronization detection information indicates that a synchronization data piece adjacent to a detected synchronization data piece is not detected, the erasure locator information generation section determines at least one symbol provided adjacent to the undetected synchronization data piece, among at least two symbols provided between the detected synchronization data piece and the undetected synchronization data piece, as representing erasure; and determines at least one symbol provided adjacent to the detected synchronization data piece as not representing erasure.    
   
   
       18 . A reproduction apparatus according to  claim 17 , wherein when the synchronization detection information indicates that neither of the two adjacent synchronization data pieces are detected, the erasure locator information generation section determines all the symbols provided between the two undetected synchronization data pieces as representing erasure.  
   
   
       19 . A reproduction apparatus for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols,    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces, and    the plurality of synchronization data pieces include an Nth synchronization data piece and an (N+1)th synchronization data piece, where N is an integer,    the reproduction apparatus comprising:    a reading section for reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation section for detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation section for generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction section for performing erasure error correction of the coded data piece based on the erasure locator information,    wherein when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, the erasure locator information generation section determines at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure.    
   
   
       20 . A reproduction apparatus according to  claim 19 , wherein: 
 the plurality of synchronization data pieces include an (N+2)th synchronization data piece, and    when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, the erasure locator information generation section determines at least one symbol provided between the (N+1)th synchronization data piece and the (N+2)th synchronization data piece as not representing erasure.    
   
   
       21 . A reproduction apparatus for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces of the plurality of synchronization data pieces,    the reproduction apparatus comprising:    a reading section for reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation section for detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation section for generating erasure locator information which represents an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction section for performing erasure error correction of the coded data piece based on the erasure locator information,    wherein when the synchronization detection information indicates that any two or more data pieces from undetected synchronization data pieces and synchronization data pieces detected with a positional offset are consecutive, the erasure locator information generation section determines at least one symbol provided between the consecutive synchronization data pieces as representing erasure.    
   
   
       22 . A reproduction apparatus for reproducing a coded data piece from a recording medium having a plurality of synchronization data pieces and the coded data piece which is error-correction-coded recorded thereon, wherein: 
 the coded data piece includes a plurality of symbols, and    at least one of the plurality of symbols is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces,    the reproduction apparatus comprising:    a reading section for reading the plurality of synchronization data pieces and the coded data piece from the recording medium;    a synchronization detection information generation section for detecting states of the plurality of synchronization data pieces and generating synchronization detection information which represents the detection result;    an erasure locator information generation section for generating at least first erasure locator information and second erasure locator information which represent an erasure position of the coded data piece, based on the synchronization detection information; and    an erasure error correction section for performing erasure error correction of the coded data piece based on at least one of the first erasure locator information and the second erasure locator information,    wherein when there is an error which cannot be corrected based on the first erasure locator information, the erasure error correction section performs erasure error correction of the coded data piece based on the second erasure locator information.    
   
   
       23 . A reproduction apparatus according to  claim 22 , wherein: 
 when all the errors can be corrected based on the first erasure locator information, the erasure locator information generation section generates erasure locator information for erasure error correction of another coded data piece using an identical method as the method used for generating the first erasure locator information, and    when all the errors can be corrected based on the second erasure locator information, the erasure locator information generation section generates erasure locator information for erasure error correction of another coded data piece using an identical method as the method used for generating the second erasure locator information.    
   
   
       24 . A reproduction apparatus according to  claim 22 , wherein: 
 the plurality of synchronization data pieces include an Nth synchronization data piece, an (N+1)th synchronization data piece, and an (N+2)th synchronization data piece, where N is an integer, and    when the synchronization detection information indicates that the Nth synchronization data piece and the (N+2)th synchronization data piece are detected and the (N+1)th synchronization data piece is not detected, the erasure locator information generation section determines at least one of the plurality of symbols provided adjacent to the (N+1)th synchronization data piece as representing erasure.    
   
   
       25 . A reproduction apparatus according to  claim 22 , wherein: 
 the plurality of synchronization data pieces include an Nth synchronization data piece and an (N+1)th synchronization data piece, where N is an integer, and    when the synchronization detection information indicates that the (N+1)th synchronization data piece is detected with a positional offset, the erasure locator information generation section determines at least one symbol provided between the Nth synchronization data piece and the (N+1)th synchronization data piece as representing erasure.    
   
   
       26 . A reproduction apparatus according to  claim 22 , wherein: 
 when the synchronization detection information indicates that any two or more data pieces from undetected synchronization data pieces and synchronization data pieces detected with a positional offset are consecutive, the erasure locator information generation section determines at least one symbol provided between the consecutive synchronization data pieces as representing erasure.