A Brief Discussion on DVD Protection

DVD shorten for Digital Video Disc or Digital Versatile Disc was published at the beginning of 1996 and dominated the multimedia market until now. All the film publishers choose to sell their movies on DVD after cinema. And to keep from piracy, they add protection on their DVDs. This article we will talk about what is DVD protection and how to remove it.

Before we talk about the DVD protection, I will first introduce you the structure of a DVD. A DVD is made up of 1 to 99 titles and all the titles are distributed in the Video Title Set(VTS). Each title has their chapters, which work with a program. The Program is composed of cells. A number of programs make a Program Chain (PGC). And when a Chapter works with its program, the number of PGC and program were determined at the same time.

A DVD movie disc contains a VIDEO_TS file, where the file related to the movie was found. You can find 3 types of file in VIDEO_TS file, including *.IFO(index file of a DVD), *.BUP(DVD index backup file) and *.VOB(DVD content file).

Now we know what is in the DVD disc, but how to add a protection on it? There are many ways to add protections on a DVD. Content Scramble System(CSS) and ArccOS are two ways widely used by DVD movie publishers.

Content Scramble System(CSS) adds protection in *.VOB file and when playing the DVD movie, a key is needed for decrypting *.VOB file. The key used to decrypt the *.VOB file is DVD disc. So people can not copy the DVD movie to another blank DVD disc by using physical file copy. Unfortunately, in 1999, Jon Lech Johansen and other two guys found a way to decode the CSS. As a result of that now CSS is not a big deal if you want to copy a DVD movie using CSS protection.

Nowadays, ArccOS is more and more popular than CSS. It has the following features:

A. Bad Sector

One of the features of ArccOS is that bad sector was set in the DVD disc. When your player is reading the bad sector, the player will crash right away. To those players which follow the rule of DVD, a command in the DVD disc will tell the player how to avoid bad sector and play the DVD movie correctly.

B. Titles

DVD in this kind of protection has as many as 99 titles. Movie content is divided and stored in each title disorderly. To those players which follow the rule of DVD, a command in the DVD disc will tell the player how to play the DVD movie as the movie actually goes.

So as we can see from above, bad sector and disorderly content become the two key point of decoding this kind of protection. In the market of DVD Ripper and copying software, there are many software that can only kill the first kind of protection (CSS), so they can not rip or copy many DVD movies released recently. Because they are protected by ArccOS. Some of them can decode the ArccOS but not perfectly. The output video has one problem or another. Most of them can not provide a perfect solution for ripping DVD movies.