I read an article yesterday which discussed the technologies that support DVD Media. Beyond the technical jargon about how data is stored on the physical medium and what standards have been set up for interoperability, the parts that really interested me was the efforts to maintain copyrights.

There is a problem with illegal copying of original works, and it is getting worse because of the Internet. Well, not because of the Internet per se, but from the ability to spread and disseminate information, to pass along digitized copies easily, without loss of content. And the fact that so many youngsters are using this facility, kids who don't really have the sophistication to know that what they're doing is wrong.

The DVD Video industry has done a good job so far. A standard for encrypting information is in place. All DVD players have to be able to detect illegal copies and not play them. And although the decryption was recently hacked, there are still some good ideas being passed along, as well as some disturbing ideas.

First you have to get used to the idea that protection depends on making *every* player compliant. To make a player you need the decryption codes and to get those you have to sign an agreement so that your player follows the security rules. Every DVD player is compliant, from standalone players to computer DVD players.

To make sure you can't just tape a DVD broadcast, the player adds interference in the video stream, which doesn't affect NTSC play- back, but degrades recording on VHS. Clever. Another protection is to make sure that DVD blank discs have a small area glossed out, so that you can't just copy the encryption data when duplicating a disk. You can still duplicate a disk, but compliant players won't play it.

I once read an article about digitial watermarking. This was back when the concept was new. Add digitial data to a video/audio stream to mark it. If you copy the stream, the watermark goes along with it. The watermark is imbedded so that it can't be separated from the stream. At the time it was seen as a way to protect copyright notices in a work, so that people couldn't copy it and claim it as their own.

But the DVD companies want to take that concept a step further. Watermark control codes into a stream. These control codes specify not only the copyright, but whether you can make a copy of a stream or not. Maybe you can only make one copy, in which case the copier changes the control code such that the copy can't be used to make further copies. Quite clever.

The only problem I have with this is the ability to do what you want with the copy that you own. Things like time-shifting and media-shifting (taping something to be watched later or converting from one media type to another) may be prevented by the producer. Sure, I support copy protection and I do try to not use copyrighted material without the proper permission.

People want to do stuff like take a video capture and use it as a screensaver. Or compose other works. Personal use has already been established as not infringing copyright. I would not like to see those user rights taken away.