| 摘要 |
PURPOSE:To improve the reliability of a reproducing signal by setting the length of each index part within one frame in an optical disk in which at least one index part is provided on each track, and performing the multiplex recording of information on the index part. CONSTITUTION:The index part 42 on which the index of the number of a track 41 is recorded is provided at least at one position on each track 41. Meanwhile, a symbol included in each frame on the optical disk is separated to two frames after decoding. Therefore, when the error of only one symbol is generated in one frame on the optical disk, the error is generated in one frame after decoding, and when the error of 2-32 symbols are generated in one frame on the optical disk, the errors are generated in two frames usually after decoding. By setting the length of the index part 42 within one frame on the optical disk, the number of frame errors after decoding can be suppressed at 3 at maximum even when the error is generated in the information multiplex- recorded on the index part 42, thereby, it is possible to suppress aggravation for the reliability of the reproducing signal. |
