Method and apparatus for error processing in optical disk memories

Abstract

The present invention more efficiently retrieves and processes data stored on an optical disk in a DVD-ROM format. Generally, the retrieval and processing of data includes inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data. For this device, the sector of data is encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code. The device calculates an initial and an intermediate error detection value for data within the sector. The target for the error detection value is non-zero because the data within the sector are scrambled. If there is a match between the initial or intermediate error detection value, the sector can be presumed to be free of errors. Decisions as to whether error correction operations are to be made or how error correction operations are to be performed are then made on the basis of the knowledge that some or all of the sectors within a block of DVD-ROM are free of errors.

1 - 22 . (canceled)  
     
     
         23 . In a device adapted for the retrieval and processing of data stored on an optical disk in a DVD format, the retrieval and processing of data including inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data, the sector of data encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code, a method of correcting and detecting errors in the data, the method comprising: 
 passing the sector and a target error detection value through an error processing circuit to determine whether or not one or more error correction operations are to be performed on data wholly or partially within the sector, the determining performed on a sector by sector basis; and    subsequently descrambling the data within the sector and outputting the data within the sector.    
     
     
         24 . The method of  claim 23 , wherein the target error detection value is a non-zero value representative of scrambled data.  
     
     
         25 . The method of  claim 24 , wherein the target error detection value is one of sixteen different values used for sectors within an ECC block of DVD-ROM formatted data.  
     
     
         26 . The method of  claim 23 , wherein the error correction operations include both inner code and outer code corrections.  
     
     
         27 . The method of  claim 23 , wherein the error correction operations include inner code corrections.  
     
     
         28 . The method of  claim 23 , wherein inner code error correction is performed on the sector before passing the sector through a CRC generator.  
     
     
         29 . In a device adapted for the retrieval and processing of data stored on an optical disk in a DVD format, the retrieval and processing of data including inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data, the sector of data encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code, a method of correcting and detecting errors in the data, the method comprising: 
 calculating an initial error detection value for data within the sector;    performing an error correction operation on the data within the sector and determining an updated, intermediate error detection value responsive to the error correction operation;    using a target error detection value and one of the initial error detection value and the intermediate error detection value to determine that the sector does not include errors;    processing an outer code to provide a set of error patterns and error locations; and    determining if any of the error locations are for data within the sector and not correcting data corresponding to the error locations within the sector.    
     
     
         30 . The method of  claim 29 , wherein the data within the sector are scrambled so as to require descrambling before use by a host.  
     
     
         31 . The method of  claim 29 , wherein the target error detection value is representative of information used in scrambling the data within the sector.  
     
     
         32 . The method of  claim 29 , wherein inner code error correction is performed on the sector before calculating the initial error detection value.  
     
     
         33 . The method of  claim 29 , wherein the initial error detection value is calculated by a CRC generator.  
     
     
         34 . The method of  claim 33 , wherein the initial error detection value is calculated by a linear feedback shift register.  
     
     
         35 . The method of  claim 33 , wherein the initial error detection value is calculated by dividing an error detection codeword comprising the bits of the data within the sector by the polynomial g(X)=X 32 +X 31 +X 4 +1.  
     
     
         36 . The method of  claim 35 , wherein the initial error detection value is calculated by a linear feedback shift register.  
     
     
         37 . In a device adapted for the retrieval and processing of data stored on an optical disk in a DVD format, the retrieval and processing of data including inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data, the sector of data encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code, a method of correcting and detecting errors in the data, the method comprising: 
 generating a target error detection value according scrambling rule;    passing the sector and the target error detection value through an error processing circuit to determine whether or not one or more error correction operations are to be performed on data wholly or partially within the sector, the determining performed on a sector by sector basis; and    subsequently descrambling the data within the sector and outputting the data within the sector.    
     
     
         38 . In a device adapted for the retrieval and processing of data stored on an optical disk in a DVD format, the retrieval and processing of data including inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data, the sector of data encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code, a method of correcting and detecting errors in the data, the method comprising: 
 passing the sector and a target error detection value through a first error processing circuit to determine whether the sector is good or not;    error correcting for the sector;    passing the corrected data, the first error processing circuit output and a target error detection value through a second error processing circuit to determine whether the corrected sector is good or not; and    subsequently descrambling the corrected data and outputting the corrected good data sector.    
     
     
         39 . In a device adapted for the retrieval and processing of data stored on an optical disk in a DVD format, the retrieval and processing of data including inner and outer code error correction for a Reed-Solomon product like code and an error detection process for evaluating an extent of errors in a sector of data, the sector of data encoded within a plurality of inner codes and parts of plural sectors encoded within each outer code, a method of correcting and detecting errors in the data, the method comprising: 
 passing the sector and a target error detection value through a error processing circuit to determine whether the sector is good or not;    error correcting for the sector;    passing the corrected data and a target error detection value through the error processing circuit to determine whether the corrected sector is good or not; and    subsequently descrambling the corrected data and outputting the corrected good data sector.