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| Sep 24, 2008 - About DVD COPY Protection - 08. |
The first four forms of copy protection (Macrovision, CGMS, CSS, and CPPM) are optional for the producer of a disc. CSS decryption is optional for hardware and software playback manufacturers, although a player or computer without decryption capability will only be able to play unencrypted movies. CPRM is handled automatically by DVD recorders, although it's optional and many recorders don't support it. DTCP and HDCP are handled by DVD players with digital video outputs.
These copy protection schemes are designed only to guard against casual copying (which the studios claim causes billions of dollars in lost revenue). The goal is to "keep the honest people honest." The people who developed the copy protection standards are the first to admit they can't stop well-equipped pirates.
Movie studios have promoted legislation making it illegal to defeat DVD copy protection. The result is the World Intellectual Property Organization (WIPO) Copyright Treaty and the WIPO Performances and Phonograms Treaty (December 1996) and the compliant U.S. Digital Millennium Copyright Act (DMCA), passed into law in October 1998. Software intended specifically to circumvent copy protection is now illegal in the U.S. and many other countries. A co-chair of the legal group of the DVD copy protection committee stated, "in the video context, the contemplated legislation should also provide some specific assurances that certain reasonable and customary home recording practices will be permitted, in addition to providing penalties for circumvention." It's not at all clear how this might be "permitted" by a player or by studios that routinely set the "don't copy" flag on all their discs.
DVD-ROM drives and computers, including DVD-ROM upgrade kits, are required to support Macrovision, CGMS, and CSS. PC video cards with TV outputs that don't support Macrovision will not work with encrypted movies. Computers with IEEE 1394/FireWire connections must support the final DCPS standard in order to work with other DCPS devices. Likewise computers with HDMI (DVI) connections must support HDCP to output DVD-Video content. Every DVD-ROM drive must include CSS circuitry to establish a secure connection to the decoder hardware or software in the computer, although CSS can only be used on DVD-Video content. Of course, since a DVD-ROM can hold any form of computer data, other encryption schemes can be implemented.
The Watermarking Review Panel (WaRP) --the successor to the Data-Hiding Sub-Group (DHSG)-- of the CPTWG selected an audio watermarking system that has been accepted by the DVD Forum for DVD-Audio. The original seven video watermarking proposals were merged into three: IBM/NEC, Hitachi/Pioneer/Sony, and Macrovision/Digimarc/Philips. On February 17, 1999, the first two groups combined to form the "Galaxy Group" and merged their technologies into a single proposal. The second group has dubbed their technology "Millennium." Watermarking permanently marks each digital audio or video frame with noise that is supposedly undetectable by human ears or eyes. Watermark signatures can be recognized by playback and recording equipment to prevent copying, even when the signal is transmitted via digital or analog connections or is subjected to video processing. Watermarking is not an encryption system, but rather a way to identify whether a copy of a piece of video or audio is allowed to be played. New players and software are required to support watermarking, but the DVD Forum intends to make watermarked discs compatible with existing players. Reports were made that the early watermarking technique used by Divx caused visible "raindrop" or "gunshot" patterns, but the problem was apparently solved for later releases.
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