| 摘要 |
A copy-protected compact disc includes, within a single session, a table of contents (TOC) and a Video CD index (VI). Each track (T) is prefaced by unrecoverable data (UD) at a track start position (ATOC) indicated by the table of contents (TOC). However, the Video CD index (VI) indicates the actual position (AP) of the tracks. DVD players use the Video CD index (VI) to locate the tracks, while CD-ROM drives use the table of contents (TOC) and read the unrecoverable data (UD), which prevents them from reading the subsequent track (T). The unrecoverable data (UD) may be prefaced by data pointers (DP) which cause the CD-ROM drive to load a player program in response to the error condition. The player program can be used to play the tracks (T), but restricts copying. Subchannel data (P; DX) causes audio CD players to ignore the Video CD index (VI) and the unrecoverable data (UD), and to play the tracks (T) at their actual start positions (AP).
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