The presentations made at the March 5, 2003 meeting of the ARDG are now posted on the ARDG website. Presentations from the second day (March 6) have not yet been posted.
On the first day, Jim Burger reviewed the history of the Data Hiding Study Group (DHSG), a group chartered back in 1997 to examine the state of the art in watermarking technologies. Jim is an attorney with the DC law firm of Dow, Lohnes and Albertson who represents the Computer Industry Group at ARDG. His presentation was a useful reminder that the "analog hole" is not a new problem, although its unfortunate moniker is of recent vintage. Although the DHSG issued an interim report in 1998, the task of selecting a watermarking technology was ultimately taken over by other entities and stalled amid inter-industry disagreement.
Adam Goldberg, from Sharp, offered a short presentation aimed at defining the scope of the ARDG's efforts.
Michael Epstein, from Philips, gave a very interesting presentation regarding a reference model that combined fragile watermarks with "play control". Content protection is accomplished by frustrating a user's efforts to display content that shows a "broken" watermark (for example, if it has been through a round of "lossy compression"). Broken watermarks could be detected by displays equipped with watermark detectors. This represents an interesting approach because it places less emphasis on preventing copying, focusing instead on reducing the value of unauthorized copies by making them unplayable on devices that include watermark detectors.
Brad Hunt, from the MPAA, gave a 3-slide presentation aimed at defining the analog reconversion problem and offering a "reference architecture" within which it might be addressed. More about the interesting questions raised by Brad's presentation in a later post.
Day Two (March 6) included presentations about two analog rights signaling systems that are already widely deployed: CGMS/A and Macrovision. Neither presentation has been posted yet.
CGMS/A is an analog "broadcast flag" meant to indicate the protected status of analog over-the-air broadcasts, as set out in the EIA/CEA 608-B standard. The flag is carried on line 21 in the "vertical blanking interval" (VBI) and is able to signal four possible states: no restriction; no more copies; one more generation; and no copies permitted. CGMS/A support is currently required by DVD-CCA license for some products, and is voluntarily supported in some DVD recorders and D-VHS recorders. Computer-based products have traditionally ignored CGMS/A flags, although Microsoft's new Media Center products offer limited CGMS/A support.
The Macrovision presentation outlined the protection systems most widely encountered on analog VHS recorders, known as Automatic Gain Control and Colorstripe Process. In addition to providing a mechanism for blocking analog VHS recording of protected content, these systems are also supported by certain digital devices, which detect the "trigger bits" associated with Macrovision protected content, and thus can operate to control redistribution in certain circumstances.
Posted by fred at March 19, 2003 05:34 PM