Patent ID: 7231576
Filing Date: 2007-06-12
Classification: G11B

Abstract:
1. A reproduction method for reproducing a composite coded data piece from a recording medium having the composite coded data piece recorded thereon, wherein: the composite coded data piece includes a first coded data piece which is error-correction-coded using a first error correction code, a second coded data piece which is error-correction-coded using a second error correction code having a lower degree of redundancy than that of the first error correction code, and a plurality of synchronization data pieces, the first coded data piece includes a plurality of first symbols, the second coded data piece includes a plurality of second symbols, at least one first symbol is provided between two adjacent synchronization data pieces among the plurality of synchronization data pieces, and at least one of the plurality of second symbols is provided at least between a synchronization data piece and a first symbol, the reproduction method comprising: a reading step of reading the composite coded data piece from the recording medium and outputting the first coded data piece, the second coded data piece, and the plurality of synchronization data pieces; 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 error location information generation 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; an erasure locator information generation step of generating erasure locator information which represents an erasure position of the second coded data piece, based on the error location information and the synchronization detection information; and an erasure error correction step of performing erasure error correction of the second 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 there is a synchronization data piece which is not detected and the error location information indicates that no error is detected in the first symbols immediately on both sides of the undetected synchronization data piece, determining at least one of the plurality of second symbols provided adjacent to the undetected synchronization data piece as representing erasure.