While DVDs and DVD recording is currently a hot issue, there is more and more demand for DVD backup software. DVDs are still vulnerable for scratches, children and pets and people are looking into solutions to create safety copies. In this article we will try to explain why you can't just simply copy a DVD and the processes you have to go trough. This article is in no way the answer to all your questions, but it should get you started and explain the basics of the process.
A DVD is currently generally a movie, therefore we will focus on making a copy of a DVD movie. This process includes several tasks that might be - or become - illegal in your country, because there is circumvention of copy protections involved. We strongly advice you to check if you are not violating any law in your country.
First we will introduce you to the DVD format, tell you why you can't just simply copy it and the processes needed in order to make a copy. After that we will discuss some useful tools to assist you in making your backup.
What's on a DVD?
If you have purchased a DVD that you want to copy, you can put it in your DVD-ROM drive to check out its contents. On the disc you will find several folders with files in it. Normally you should always see a VIDEO_TS and AUDIO_TS folder. The AUDIO_TS folder is used to store DVD Audio, the VIDEO_TS to store DVD Movies.
We will be focusing on a movie DVD, so we'll enter the VIDEO_TS folder. In this folder you will find .VOB .BUP and .IFO files. The VOB file contains the actual movie files. This is a MPEG-2 encoded file. Simplfied is MPEG-2 is a method of compression for movies, just like MP3 files are compress audio. The file contains also audio, normally this should also be a compressed format. Mainly it is an improved form of MP3, named AC-3. Besides that contain the .VOB files the subtitles and multiple camera angles.
The .IFO files are the information files, used by your DVD playing device. It gives the DVD player information on what .VOB files to load and when. E.g. when to start a new chapter. The .BUP files are simply a backup of the IFO files and generally have no use, they will only be used when an .IFO files become unreadable somehow.
Let's copy those files!
You would think it would be as easy as copying these files to a folder on your hard disk and then burn them to a recordable DVD, but unfortunately they didn't make it that easy. The files copied will contain useless data and your copy will not work,
DVD movies are protected with the Content Scrambling System (CSS), a protection developed and adopted by the Hollywood Studios. It simply protects them from pirates who want to make copies to sell. Simplified the protection encrypts the data on a DVD and requires a special key to decrypt it. DVD playing software developers have received such a key from the studios and therefore their software is able to read the information, but unfortunately the studios don't hand out keys to anyone else.
However the protection has proven to be weak and has been beaten by many applications. Most of them are based on the software DeCSS of which you might have heard due the many lawsuits that try to forbiod the software. The software is illegal in many countries. Removing the DeCSS protection and getting the movies to e.g. a hard drive is mainly referred to as ripping. Later on we will discuss the software available for ripping. Besides CSS movie sometimes also contain a protection developed by Macrovision, this is also on many VHS tapes, software that is able to remove CSS, will also easily remove this Macrovision protection.
Another problem is that if you are planning to record it to a recordable DVD, it simply won't fit. Why doesn't it fit? Currently DVD recordables can only contain about 4.7 (actually it's 4.38) Gigabytes of data, they are generally referred to as DVD-5 (4.7 ~ 5). The movie you have purchased might contain a lot more Gigabytes, many movies are released with up to about 9 Gigabytes of data (DVD-9), you will understand that a DVD-9 movie, will not fit on a DVD-5 disc. In order to make this happen there are three possibilities:
- Remove data
- Shrink data
- Split the data
Sometimes you will need to make choice between them, sometimes you can combine these techniques. On the next page we will show you the best solutions and show you where to go when you want to create a backup.
