In "An Introduction to DVD" SlapNutz discussed some of the basics of this amazing media format. Today he returns with a more detailed look at the underlying technology, and the benefits to adult content producers of using it:
What Makes DVDs So Much Better Than VHS Videocassettes?
Two words: data capacity. Although a DVD (short for "digital versatile disc" or "digital video disc") looks identical to a compact disc, the format uses much smaller and more compact digital "pits" in its physical structure. And compared to a CD, it is capable of storing up to 25 times as much digital information -- up to 17 gigabytes of data on a double-sided, dual-layered DVD (see the following heading for more on sides and layers). Most movies can easily fit onto a single-sided, single-layer DVD (which can hold 4.7 gigabytes of data), allowing ample room for additional soundtrack options, language tracks, filmmaker commentaries, and subtitles, as well as bonus features such as deleted scenes, featurettes, biographies, and interviews. And because DVD is an all-digital format, it offers superior sound clarity and picture resolution, which are enjoyable even on a modest budget but can be best appreciated on a state-of-the-art home-theater system.
What is A Dual-Layered DVD?
A DVD can hold digital information on both sides of the disc and in two sandwiched layers on each side. A dual-layered disc, for example, can offer a movie in both widescreen and full-screen (or pan-and-scan) formats, and your DVD player can switch from one layer to another with a barely perceptible interruption in playback. Dual-layered DVDs are also useful for holding longer films (such as Titanic and Saving Private Ryan) or video games that exceed the capacity of a single layer.
What's the Difference Between Widescreen and Anamorphic?
These terms are often confused, but they're not interchangeable. On a standard widescreen DVD, the disc is encoded with both the widescreen movie and the black bars (at the top and bottom of the picture) that are necessary to properly fit the movie onto a standard 4:3 ratio TV screen. (In other words, precious data storage is required to generate the black bars.) On an anamorphic DVD, the widescreen movie is compressed to fit a standard 4:3 TV screen, then decompressed by your player, which then generates the black bars to accommodate the widescreen image. Anamorphic widescreen is best appreciated by those who own widescreen (16:9) video monitors, because this allows the entire anamorphic image to fill the screen at full resolution, with no black bars. (Consequently, the issue of widescreen vs. anamorphic will become less important as widescreen video monitors become the accepted norm.)
What About the Pan-and-Scan and Full-Frame (or Full-Screen) Formats?
The pan-and-scan technique is used to fit widescreen movies onto a standard 4:3 TV screen, so named because the image is often cropped (sacrificing picture detail from the edges) and then "panned" across to reveal actors or details that don't fit into the narrower frame. Fortunately, this method has grown less common as DVD has offered more widescreen viewing options. The full-frame format is used for films (often but not exclusively older films) that were shot in the 4:3 ratio (or, more accurately, the 1.33:1 aspect ratio most common in Hollywood's golden age). On home video and DVD, these films actually include some frame detail that would normally be masked off in theatrical exhibition, but you're seeing essentially the same image shown in theaters. Full-frame can also refer to a film (for example, Stuart Little) that has been reformatted (often but not always with panning and scanning) from its theatrical format (typically 1.85:1) to fill a standard TV screen.
What's the Difference Between Dolby Surround, Dolby Digital 5.1, and DTS?
Dolby Surround (also Dolby Pro Logic) is the surround-sound format most commonly found on video cassettes and laser discs (and many DVDs). It refers to a non-discrete sound format in which four channels (left, right, center, and surround) are combined into two channels and decoded back (by Pro Logic receivers) into the original four surround channels of your home-theater speaker system.
Dolby Digital 5.1 is a discrete-channel surround-sound format consisting of five distinctly separate channels (left front, left rear, right front, right rear, and center), plus a subwoofer channel (the .1 in 5.1) to provide deeper, fuller bass. And while not all DVD movies offer a Dolby Digital 5.1 soundtrack, an increasing number of them do, and you will definitely notice and appreciate the difference. (Side note: Dolby Digital AC-3, a sound process introduced in the laser disc format, translates original two-channel stereo sources into simulated 5.1-channel output. It is less frequently used on DVD.)
DTS (Digital Theater Systems) is an impressive digital surround-sound system first introduced in theaters with the release of Jurassic Park in 1993. DVDs encoded with a DTS soundtrack require a DVD player and stereo receiver equipped with DTS-processing capability. Preferred by avid videophiles, DTS demands more data space on a DVD (often sacrificing bonus features), but many believe the audio quality to be superior to Dolby Digital 5.1-channel surround sound.
How Can a DVD Offer Parental Control Over Potentially Offensive Material?
DVDs encoded with the parental lock feature can be edited to skip over offensive or adult-oriented material during playback – sort of like turning an R-rated movie into a PG-13, and so on. If a DVD is encoded with this capability (check the packaging to make sure), your DVD player's internal rating system can be set to different levels of parental control, typically accessed via the player's set-up menu. (For example, the parental lock feature on DVDs can be used to automatically edit out use of mature language and a violent scene involving frightening aliens.) For adult content providers, this feature alone makes DVD a much better distribution format than VHS. Because DVD is subject to the same issues of piracy and market sharing that govern the entire video industry, region encoding was introduced to set geopolitical boundaries for compatibility of DVDs and players.
What's the Difference Between PAL and NTSC?
There are two television display systems in commercial use: PAL (common in Europe and parts of Asia) delivers a scanning / frame rate of 25 frames per second, while NTSC (used in the U.S. and Canada) delivers a scanning/frame rate of 29.97 frames per second. Currently there are no DVD players that convert from PAL to NTSC or vice versa. However, many PAL DVD players are able to display NTSC video on televisions that support what is known as the 60-Hz PAL system. For all DVD players in the U.S. and Canada, NTSC is the exclusive system in use.
What is Region Encoding?
Because DVD is subject to the same issues of piracy and market sharing that govern the entire video industry, region encoding was introduced to set geopolitical boundaries for compatibility of DVDs and players. For instance, a DVD encoded for Region 1 can only be played on a Region 1 (U.S. and Canada) DVD player.
Currently there are six global DVD regions, and DVD manufacturers can encode their product to play in any combination of regions. The vast majority of DVDs are Region 1 or 2 compatible, and many DVDs are "all-region" – suitable for playback on any player, anywhere. While numerous methods have emerged to illegally bypass region encoding with "hacked" DVD players capable of playing DVDs from any region, movie studios have also increased their efforts to protect their regional copyrights with advanced DVD security coding.
For smaller producers who burn ‘one-off‘ copies, the option of tailoring regional settings for your clients may provide a higher degree of security, since it could help prevent them from ‘sharing’ your copyrighted content.
I hope that these two articles have provided you with a better understanding of DVDs and a glimpse of the benefits of using them as a content distribution vehicle. For anyone who currently provides content via CDs or VHS, moving up to DVD is a logical choice that will streamline post-production and distribution expenses while increasing profits!