DVD
An acronym for Digital Versatile Disc, an optical-disc technology developed by the DVD Consortium. There are five specified DVD disc varieties. DVD-ROM, DVD-Video, DVD-Audio, DVD-R (recordable), DVD-RAM (eraseable). A standard for storing MPEG-2 compressed audio and video information on a high density disc the same physical size as a normal audio CD for storing large amounts of data, especially high-resolution audio-visual material.
DVD Conversion Explained
DVD Conversion refers to the process of converting DVD's MPEG-2 video and digital audio to another format, usually a lower quality one, in order to be able to store the movie on a CD media (or on your hard-drive), rather than on DVD. As you probably know, DVDs are encoded in an MPEG-2 format and encased in a file called a VOB (Video Object) file. For those interested in backing up their DVDs, it is almost impossible to do a 1:1 copy due to the un-availability of writable DVDs and the small sizes of CDs (650MB vs 8000 MB for DVDs). Conversion, therefore, is needed if you plan to backup your DVDs to CDs.
This guide briefly introduces some techniques to convert these very large VOB files to a format less space consuming, like VCDs, SVCDs and DivX, using the many software and techniques available.
Note, this guide is fairly advanced and is purely optional for those who seek to explorer more into the world of digital video editing and conversion. And also, please respect the copyright laws in your country.
CSS encryption : This is the encryption method used in DVDs. This encryption does allow files to be copied off the DVD, but the resulting files will contain garbage data that will be useless. Not all files on the DVD are encrypted though, and different files may use a different decryption key.
Rippers : A ripper is a program that allows you to break this encryption and "rip" out the files from the DVD, without it being turned into garbage data. Basically, it allows you to copy files from the DVD to your hard-drive successfully. This is not to be confused with CD ripping, which is the ripping of digital data off the audio CD - DVD ripping is really just DVD copying (to the hard-drive). Note that DVDs, unlike audio CDs, do not have a special "audio track" - the audio information is stored in a VOB file (see below) and are much like other digital video formats (eg. avi,mpg,rm).
VOB Files : VOB files are the default format of DVD movies. This files may contain several streams of audio/video "multiplexed" together (eg. chapters/language selections). These files, once ripped, can be played back with any soft-DVD player that supports the file opening feature (presently, only the Ravisent/Elsa player does not). VOB files have a naming standard :
vts_xx_yy.vob
xx - Title number
yy - Section number
The whole movie is usually contained within 1 title (usually vts_01), while the rest of the titles may be for things such as extras, trailers ... Video_ts.vob usually contains the main menu information. Each section of the title (eg. vts_01_1.vob) cannot exceed 0.99GB in size. Normally, the title that contains the actual movie is located in a title that has many 0.99GB sized files - the last one in the title set may not be this size.
IFO/BUP Files : IFO files contain the formatting information of the VOB files, which tells the DVD player exactly how the DVD should be played (eg. aspect ratio, subtitles, languages, menus ...). BUP files are backups for IFO files, which are needed if the IFO files gets corrupted. If you rip the DVD without IFO files, then the VOB files may not play correctly, or may not even play at all. Similarly for conversion, IFO files are essential since video converters like FlasKMPEG (which supports IFO parsing) will need them if you want to encode videos, or fix multi-angle ripping problems (see below). Whenever in this guide I refer to "ripping the entire DVD", I mean ripping all the VOB files and the IFO/BUP files as well.
Macrovision / Region : Region and Macrovision (copy protection) are encoded onto VOB files. Some rippers offer you the ability to rip out Region and Macrovision protection during normaing ripping. Once ripped this way, the files will play in any DVD player, and will not have Macrovision or region protection problems.
Multi-angle ripping : DVDs like The Matrix feature special content such as "Follow the White Rabbit" feature, which overlays a white rabbit on screen during certain special effect scenes, and if you highlight the white rabbit and press enter, you can access 8 hidden special effects features. Ripping of DVDs that contain these features, or others (eg. seamless branching titles like The Patriot, T2 : Ultimate DVD Edition, The Abyss) can be diffcult, if you don't rip the IFO/BUP files (remembering the IFO/BUP files contain the information to tell the player/ripper how to playback these DVDs). Newer rippers have special options that allow you to rip these types of VOB files successfully.
Merging : Some rippers allow you to merge the VOB files during ripping. This is not recommended. Merging VOB files will most likely damage their file structures (much like how if you merge 2 ZIP files, you won't get a big ZIP file that contains all the contents of the 2 smaller ZIP files). If you ripped the IFO/BUP files, then it is these files that will tell the player/converter to play/convert the multiple VOB files in series (with no gaps in between), and even without the IFO/BUP files, FlasKMPEG (a conversion tool) can still convert files with the same title number (see VOB files above).
Choose your format
Choosing which format you'll want to convert the DVD to will require you to know how exactly you plan to use the converted movie. The table below lists the properties that a converted 2 hour movie (at their typical resolution) will have depending on which format you choose. Note that the stated "low, medium, high and best" values are relative to the original DVD quality (with "low" meaning low quality, while "best" means same quality as the original DVD). Hopefully, the table below will help you choose which format you'll want. Once you have decided which format you want to use, please use the "INDEX" below to skip to the section you want.
| |
DivX (MPEG-4) |
VCD (MPEG-1) |
SVCD (MPEG-2) |
MiniDVD (DVD-on-CD) |
| Video Resolution |
560x240 (Widescreen - variable) |
352x240 (NTSC) |
480x480 (NTSC) |
720x480 (NTSC) |
| Video Quality |
Low-High (SVHS) |
Low (VHS) |
Medium-High (SVHS) |
Best (SVHS) |
| Audio Resolution |
Stereo, 16bit, 48kHz (MP3 - variable) |
Stereo, 16bit, 44kHz |
Stereo, 16bit, 44kHz |
Dolby Digital (AC3) |
| Audio Quality |
Low-Best |
Medium |
Medium |
Best |
| File Size (2 hour movie) |
300 - 1000+ MB |
1000+ MB |
800+ MB |
3000+ MB |
| Play on Standalone? |
No |
Yes |
Maybe * |
Maybe ** |
| Why this format? |
Widely available on the net. Variable quality/file size. |
Proven and reliable format. Playable on standalone. |
Playable on standalone. |
Same quality as original DVD. |
* - Most DVD players made for the Asian market will support
this (official) format. Features limited interactivity (1
menu with play button).
** - Only 1 or 2 (Aiwa, Affrey - more details here) DVD players
will play this (non-official) format. Full DVD interactivity. |
