The related 8/15 modulation coding and decoding method for run-length (2, 12) of high-density CD comprises: from the 15-bit 400 codes accorded with limit, selecting the 273 codes with least significant digit as 0, then selecting 265 codes to form the code list; when cascade connection conflicts, converting the least significant digit to 1 and the nearby codes according to conflict type; when decoding, determining whether modify most significant digit according to conflict flag bit, and determining whether there is conflict through whether the lease significant digit is 1; for d-conflict or k-conflict, forward looking next code; converting the low significant digit, setting conflict flag bit, querying the converted code in list to obtain its address, and choosing the low 8 significant digits for decoding. This invention exceeds 6.67% to current EFM-PLUS code. |