Copy-protected compact disc and method for producing same
View Patent ↗The present application relates to a copy-protected compact disc and a method for producing the optical disc and preventing unauthorized copying. The contents of at least one of the lead-in items in the optical disc are altered so that it is no longer uniform, thereby making a copied disc effectively corrupted and unplayable.
1. A method for determining the location of a table of contents (TOC) being read by an optical disc player, comprising: reading a calibration disc to determine the location of the TOC, being read by the optical disc player, of a plurality of TOCs on the calibration disc by reading the calibration disc a plurality of times using the optical disc player and determining the average, minimum, and maximum logical block addresses of the TOC being read to determine the location of the TOC.
2. An optical disc having a plurality of subcoding blocks comprising a continuous repetition of table of contents (TOCs), wherein each of said table of contents (TOCs) is different from at least one of the other continuous repetition of table of contents (TOCs), the absolute-time minutes (PM), absolute-time seconds (PS), and absolute-time frame (PF) fields of at least one of the three lead-out pointer items of at least one of said continuous repetition of TOCs is different from at least one of other three lead-out pointer items, and the PM, PS, and PF fields are equal to the track-time minutes (MI), track-time seconds (SE), and track-time frame (FR) fields bf one of said lead-out pointer items.
3. The optical disc according to claim 2 wherein the PM field is encoded with the minute and frame of the lead-in frame.
4. The optical disc according to claim 3 , wherein PM=(frame/3)+((minute−97)*25).
5. The optical disc, according to claim 2 , wherein the program area comprises a multitude of zones each of said multitude of zones having a predetermined time period.
6. The optical disc, according to claim 5 , wherein each of said pre-determined time period is encoded as a series of modulated tones.
7. A method for protecting an optical disc from unauthorized copying, said method comprising the steps of: reading a calibration disc to determine the location of a table of contents (TOC), being read by a specific player, of a plurality of TOCs on the calibration disc by reading the calibration disc a plurality of times using the specific player and determining the average, minimum, and maximum logical block addresses of the TOC being read; and altering a TOC on the optical disc at the determined location, whereby the altered TOC has a different value from a corresponding item in at least one other of a plurality of TOCs on the optical disc.