Copy protection of optical discs

Abstract

Generally the more effective is the copy protection provided on an optical disc, such as a DVD, the greater is the likelihood that the copy protection will adversely interfere with legitimate uses of the optical disc. It is therefore proposed to include at least one region of subversive data within the content in the data area of an optical disc, and then to prevent access to each such region of subversive data during normal playback of the disc. For a DVD, the subversive data may be incorporated within video objects and/or may be in gaps between files in the DVD_Video zone. It is arranged that there are no navigable paths to the regions of subversive data.

1 . A 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 unreadable or subversive data is provided within the data area, and wherein access to the or each region of unreadable or subversive data is prevented during normal playback of the content on the disc.