Defeat of the copy protection of optical discs
View Patent ↗DVDs can be copy protected by incorporating regions which contain unreadable or subversive data within the data area ( 42 ). For example, such a region may be configured as a cell of a video object (VOB) ( 50 ) within a VOB file ( 51 ). Access to the region of subversive data is prevented during normal playback, for example, by ensuring that there are no pointers leading to the subversive region. To defeat such a copy protection method, the content on the copy protected optical disc is accessed by utilising the navigation provided for normal playback of the disc. Thus, the subversive regions are navigated around during copying of the disc. The accessed content is stored in a corresponding data area and, where subversive regions are identified, arbitrary data is incorporated within regions of the copy data area which correspond to regions of unreadable or subversive data in the original data area.
1. A method of copying a copy protected optical disc, the copy protected optical disc carrying content and control data in a data area, the content being arranged in one or more content files, and the control data providing access to the content, wherein at least one region of the content which contains subversive data is provided within the data area, and navigation is provided for normal playback of the copy protected optical disc, the navigation comprising navigation paths defined by said control data which can be used for access to the content on the copy protected optical disc, and wherein during normal playback of the content on the copy protected optical disc utilizing the navigation paths, access to the at least one region of subversive data is prevented, the method comprising:
mapping the navigation paths to identify regions of the data area which are not accessed by the navigation paths,
accessing the content on the copy protected optical disc by navigating to the content utilizing the navigation paths provided for normal playback of the copy protected optical disc, but avoiding accessing any region identified as not accessed by the navigation paths,
storing the accessed content in a corresponding data area, and
storing arbitrary data into any regions of the corresponding data area which correspond to any region identified as not accessed by the navigation paths.
2. A method of copying a copy protected optical disc according to claim 1 , wherein there are no navigation paths which provide access to the at least one region of subversive data.
3. A method of copying a copy protected optical disc according to claim 2 , wherein the method further comprising accessing the data in the data area in a linear manner.
4. A method of copying a copy protected optical disc according to claim 2 , the method further comprising playing the copy protected optical disc whereby the content on the copy protected optical disc is accessed in a manner determined by the navigation paths, and storing the content retrieved in the corresponding data area.
5. A method of copying a copy protected optical disc according to claim 1 , wherein there are navigation paths which lead to the at least one region of subversive data, but such navigation paths are such that they do not provide access to the subversive data during normal playback of the content on the copy protected optical disc.
6. A method of copying a copy protected optical disc according to claim 5 , wherein the method further comprising accessing the data area in a linear manner.
7. A method of copying a copy protected optical disc according to claim 5 , the copying method further comprising playing the copy protected optical disc whereby the content on the copy protected optical disc is accessed in a manner determined by the navigation paths, and storing the content retrieved in the corresponding data area to build up an image of the content and control data on the copy protected optical disc.
8. A method of copying a copy protected optical disc according to claim 1 , wherein the copy protected optical disc is played by an optical disc player to obtain the content of the copy protected optical disc, and wherein the content output by the optical disc player is stored.
9. A method of copying a copy protected optical disc according to claim 8 , further comprising commanding the optical disc player to play all of the content of the copy protected optical disc such that the copy of the content data is complete.
10. A method of copying a copy protected optical disc according to claim 1 , further comprising producing a different optical disc from the stored content.
11. A method of copying a copy protected optical disc according to claim 1 , wherein the at least one region of subversive data is formed within content files, as an additional content file, or as a gap between two adjacent content files, the method comprising accessing the content files to retrieve their content, and storing the content in corresponding content files.
12. A method of copying a copy protected optical disc according to claim 11 , wherein the content files are video object files and are composed of video objects (VOBs) which are divided into cells, and wherein the cells can be accessed by respective pointers in navigation paths defined by the control data.
13. A method of copying a copy protected optical disc according to claim 12 , wherein the at least one region of subversive data is formed as an additional cell within a video object, and wherein there are no pointers accessing the additional cell.
14. A method of copying a copy protected optical disc according to claim 12 , wherein the at least one region of subversive data is formed as an additional cell within a video object, and wherein there are pointers accessing the additional cell but the use of pre commands or cell commands ensures that the additional cell is not played during normal playback of the material.
15. A method of copying a copy protected optical disc according to claim 12 , wherein the at least one region of subversive data is inserted within a video object, and wherein there are no pointers accessing said region.
16. A method of copying a copy protected optical disc according to claim 1 , wherein the arbitrary data included in said regions of the data area comprises sectors of zeros.
17. An apparatus for copying a copy protected optical disc, the copy protected optical disc carrying content and control data in a data area, the content being arranged in one or more content files, and the control data providing access to the content, wherein at least one region which contains subversive data is provided within the data area, and navigation is provided for normal playback of the copy protected optical disc, the navigation comprising navigational paths defined by said control data which can be used for access to the content on the copy protected optical disc, and wherein during normal playback of the content on the copy protected optical disc utilizing the navigation paths, access to the at least one region of subversive data is prevented, said apparatus comprising:
a processor;
a memory accessible to the processor for storing content and control data;
an access module, executable by the processor, for accessing the content on the copy protected optical disc by navigating to the content utilizing the navigation paths provided for normal playback of the copy protected optical disc, said access module comprising a mapping module for mapping the navigation paths to identify regions of the data area which are not accessed by the navigation paths, and an access device for avoiding accessing any region identified as not accessed by the navigation paths;
a storage module, resident in the memory, for storing the accessed content in a corresponding data area; and
an incorporation module, executable by the processor, for storing arbitrary data into any regions of the corresponding data area which correspond to any region identified as not accessed by the navigation paths.
18. The apparatus for copying a copy protected optical disc according to claim 17 , wherein there are no navigation paths which provide access to the at least one region of subversive data.
19. The apparatus for copying a copy protected optical disc according to claim 17 , wherein there are navigation paths which lead to the at least one region of subversive data, but such navigation paths have been altered such that they do not provide access to the subversive data during normal playback of the content on the copy protected optical disc.
20. The apparatus for copying a copy protected optical disc according to claim 17 , wherein said access module for accessing the content on the copy protected optical disc comprises a receiver for receiving the output from an optical disc player, and wherein said storage module is arranged to retrieve the content from the output and to store the retrieved content in the corresponding data area whereby an image of the content and control data on the copy protected optical disc is stored.
21. The apparatus for copying a copy protected optical disc according to claim 20 , further comprising a command module for commanding the optical disc player to play all of the content on the copy protected optical disc such that the stored image of the copy protected optical disc is complete.
22. The apparatus for copying a copy protected optical disc according to claim 17 , further comprising a burn module for burning the accessed content and arbitrary data onto a different optical disc.