The physical DVD disc formats described previously determine how (and how much) data is stored on a disc. But a disc still is not useful for a specific purpose until the format of the data stored on it is defined. This is the domain of application, or logical, DVD formats: these determine the data structures and types, as well as specific compression formats, used to organize and store files of data on the disc. Put succinctly, the physical format allows the hardware to access the raw data, and the application format allows it to be understood and played back.
DVD-Video and DVD-Audio are the base DVD application formats, but some variants, competing formats, and related CD formats also exist:
DVD-Video is the DVD format for movies, supporting high-quality video, surround-sound audio, interactive navigation with menus and chapters, alternate video, audio, and subtitle tracks, and several content protection features.
DVD-VR/+VR (Video Recording) is a variant of the DVD-Video format developed for set-top DVD recorders. VR recorders essentially save meta-information on the disc so that its contents can be edited to record and delete segments. Unfortunately, dash and plus use different VR formats, and these have varying compatibility with standard DVD players.
Some DVD authoring tools provide the ability to create and edit the VR disc format, which is useful for sharing discs between the set-top and desktop, so you can record and/or edit the same disc from either platform. Encore focuses on creating fully compatible DVD-Video discs.
The high-end audiophile market is currently split by another format war, between two different approaches for providing higher-quality, multichannel, surround-sound audio for discriminating listeners:
DVD-Audio is a music audio format defined by the DVD Forum. It supports higher-quality surround sound than DVD-Video, plus options for menus, navigation, and some multimedia that can scale from TV displays to simpler car players. Most set-top DVD players do not support DVD-Audio format, and therefore many DVD-Audio discs also contain a DVD-Video version of the music.
Super Audio CD (SACD) is a competing audiophile music format developed by Sony and Philips, and requires a SACD-compatible player. SACD is based on CD technology, using double-layer discs to provide CD compatibility plus the higher-quality SACD content.
Although the technical merits of these two audio formats can make for wonderful debates, there is also a lifestyle difference between those who prefer to experience high-quality music with surround-sound speakers in the living room on a DVD player, or in the den on an audio system. Authoring these formats also currently requires higher-end professional tools.
CD-based video formats can be good options for consumers getting started with DVD authoring because they provide DVD-like experiences without the cost of a DVD burner. As a result, many entry-level DVD authoring tools now support Video CD format as an output format, but often not SVCD because it does not work on set-top players.
Video CD (VCD) is a simplified format designed to deliver video on inexpensive CD disks. Especially popular in Asia, VCD support is built into almost all set-top recorders and DVD player software, and is used for commercial discs such as music videos and movie shorts and trailers. VCD squeezes 74 minutes of video onto a CD by using lowerquality MPEG-1 video compression at 352 x 240 resolution. This is often described as “VHS-quality,” although blocky video compression artifacts are often visible.
Super Video CD (SVCD) is a newer format that increases the video quality by using the same MPEG-2 compression as DVD, but still at a lower 480 x 480 resolution. The trade-off for this “near-DVD quality” is that SVCD fits only around 35 minutes on a disc. SVCD also supports DVD-like interactive menus. However, most set-top DVD players do not support the SVCD format.
DVD on CD is not a formal disc format; it’s more of an observation that if a DVD production is short enough, it could be stored on a CD. If you author a DVD of less than around 18 minutes at reasonable quality, you can copy the DVD files to CD as a convenient storage medium. DVD on CDs are not playable on typical set-top players, but can be copied and played on computers.
Theoretically, no. Beyond the base DVD application data formats, the DVD-Video and DVD-Audio specifications also include several different mechanisms for content protection, designed to protect the DVD content by controlling its use. In a nutshell, these are:
Content Scrambling System (CSS) is the DVD-Video encryption technique used to protect the content as digital data. Authorized DVD player hardware and software then contains the decryption algorithm needed to decode and display the content.
Copy Generation Management System (CGMS) is the DVD-Video mechanism that limits copying of the digital data by specifying the number of permitted copies.
Macrovision Analog Protection System (APS) is the DVD-Video copy protection mechanism that addresses the issue of copying the analog signal out of a DVD player to a television. When enabled in the player, it adds distortions to the analog video output signal that cause VCRs to be unable to synchronize to the signal, while televisions can still display it properly. This also prevents routing a DVD signal through a VCR to a television, which is why DVD players must be connected directly to a television set.
If you’ve ever purchased a DVD from another country, you’ve probably run into another copy protection scheme called region codes. Basically what this means is that both DVDs discs and DVD players can be “branded” with a particular region (or set of regions). These region codes restrict the use of discs to those players that match. Region codes were invented to isolate certain DVDs to various areas of the world in an attempt to support staggered release dates for films in different markets. For example, DVDs from Region 1 will play only in Region 1 players, not in Region 2 players. This means that motion picture distributors can sell DVDs of a specific movie in the United States and Canada while the movie is still in theatrical distribution in Europe.
So goes the theory. In reality, many general-interest discs are “region-free” and will play in any player. In addition, you can (legally) purchase region-free players that will play any DVD. Some discs are actually designed with special logic to check for such players and refuse to run. You should be aware, however, that DVDs from different countries may not use NTSC for their encoding standard. Many region-free players output whatever signal the disc was encoded with. So, a PAL DVD from Region 2 will play fine in the player, but you must have a PAL television set to watch it.
Figure 2-5 shows the countries associated with each region code:
U.S., Canada, U.S. Territories
Japan, Europe, South Africa, and Middle East (including Egypt)
Southeast Asia and East Asia (including Hong Kong)
Australia, New Zealand, Pacific Islands, Central America, Mexico, South America, and the Caribbean
Eastern Europe (Former Soviet Union), Indian subcontinent, Africa, and North Korea
China and Tibet
Two additional codes are not shown on the map:
Reserved
Special international venues (airplanes, cruise ships, etc.)
