Now that you understand DVDs better, let’s get started deconstructing some DVDs. The Planet Earth series of DVDs that we’ll start with is subtitled “Visions of the Earth from Space.” The content is based on NASA space imagery of planet Earth: oceans, seas, islands, and coastlines. Each disc is organized by geographic region, with more than an hour of video panning over different areas accompanied by a thematic music track. The discs also include hundreds of detailed information screens linked to the videos. The Planet Earth series is designed to span seven titles. The first three Planet Earth discs are Oceania, Australia, with the Great Barrier Reef and New Zealand, and North America, covering Canada, the United States, and Mexico.
Let’s look at the cover to understand the features on this specific disc, and also take a look at the disc contents on our PC to see the data files stored on it. The front of the cover is shown in Figure 2-6.
Special features are often described on the back of the DVD case, along with a profusion of logos, as shown in Figure 2-7. Depending on the publisher, these are described in varying detail with phrases such as “Special Features” or “Technical Specs,” and are also indicated by the row of tiny logos arrayed at the bottom of the cover.
The logos on the bottom of the back cover represent, from left to right:
AlphaDVD, the disc producer and authoring company
DVD International, the disc distribution company
DVD Video format, suitable for play on set-top DVD players
DVD-ROM content, readable on PCs
DTS audio, containing optional soundtracks
Dolby Digital audio soundtrack
InterActual Player, with WebDVD features
These typical DVD features and logos are described in the following sections.
As we mentioned earlier, a manufactured movie on DVD is a DVD-ROM physical disc with content stored in DVD-Video format. So, at least one logo there should be very familiar.
- (3) DVD-Video
The DVD-Video logo, present on nearly every commercial DVD, identifies a DVD disc that is designed to be compatible with DVD players, both set-top devices and computer DVD-ROM drives and software.
The DVD-Video specification supports multichannel sound with a variety of audio formats. The most basic format is PCM, or pulse code modulation, which is the relatively uncompressed digital audio format also used on audio CD. Professional DVDs typically use compressed Dolby Digital audio format, which leaves more space on the disk for additional material.
- (6) Dolby Digital AC-3
A compressed audio format, also known as Dolby Digital 5.1 for full surround sound (http://www.dolby.com). The “5.1” name is a bit of a misnomer; it’s actually six channels: three front and two rear speakers, plus an additional channel, “.1”, for low-frequency effects which are typically sent to a subwoofer.
- (5) DTS (Digital Theater Systems)
An optional surround-sound audio format for DVD-Video, familiar from its use in movie theaters (http://www.dtstech.com). With the appropriate equipment, the user can select the optional DTS audio stream and have the DVD player feed it out to an external DTS decoder.
Encore DVD and other similar DVD authoring tools can create audio in three DVD formats: PCM, Dolby Digital (stereo), and MPEG. Although DVDs can contain audio tracks in multiple formats, NTSC DVDs must contain at least one PCM or Dolby Digital track.
Besides the content and formats designed for playback on set-top DVD players, DVDs also can contain additional data content designed only for access from a computer.
- (4) DVD-ROM
Technically, a commercial disc is a DVD-ROM because it is a manufactured read-only disc. But in this context, DVD-ROM means that, besides the movie, the disc also contains additional data files that can be accessed from a PC.
- (7) InterActual Player (also known as PC Friendly)
InterActual Technologies (http://www.interactual.com), now part of Sonic Solutions, provides PC-based software for integrating DVD playback with an interactive Web experience (also known as WebDVD). The InterActual Player is included on many DVDs from major motion picture studios to provide an enhanced experience when playing the DVD on a PC.
DVD authoring tools are independent of InterActual and other WebDVD technologies. WebDVD features typically are used after DVD authoring to integrate the DVD production and content with PC- and Web-based applications and materials. For the moment, WebDVD requires special players and tools. In the future, we can hope that the promise of WebDVD can be more generally realized by being integrated into all players and all authoring tools, and even set-top players.
The next set of DVD features identifies the type of television format that it is designed to play on, and the layout of the picture.
- NTSC and PAL television formats
The DVD specification supports both the NTSC television scan format used primarily in the United States and Japan and the PAL format used primarily in Europe. The DVDs that you create in Encore will be in one of these formats. Note that NTSC discs typically can be played on PAL DVD players, but not the reverse.
- Widescreen Anamorphic video
On the front of the DVD case, at the very bottom, are the words “Widescreen Anamorphic.” This means that the DVD video has a wide aspect ratio, similar to a movie in a theater, and is best displayed on a widescreen monitor with a 16:9 (1.78:1) aspect ratio. Video in this format typically originates from a film or high-definition video camera. On a standard television, widescreen video is usually displayed letterboxed at full width with black bars at the top and bottom (see Figure 2-9).
- Fullscreen video
The DVD video is stored at standard resolution, more square like a TV set or PC monitor at a 4:3 (1.33:1) aspect ratio. The video was originally shot with a standard video camera, or, if the original material was a widescreen film, the wide film frame was cropped to the standard aspect ratio. The screen then pans left and right across the widescreen image, depending on what is important, using a process known as pan and scan.
You can use Encore DVD to author DVD-Video content in either standard-resolution or widescreen video.
