What Is DVD Technology?|
DVD-ROMs offer improvements on the best features of other popular classroom resources, such as VHS videotapes, laser discs and CD-ROMs. They provide high-quality, full-motion video and audio; easy searching, navigation and branching (guidance from each element to related elements); and access to a wide variety of resources.
A DVD disc is sometimes compared to a compact disc (CD) because of its similar size and appearance. But the DVD disc can hold seven times as much information as a CD.
This greatly increased capacity of DVD technology is a result of how discs are constructed and how data is compressed on the disc. A DVD disc has two sides, and each side can hold two layers of data. A single-sided DVD disc holds up to 4.7 GB (Gigabytes) of information in one layer; adding a second layer almost doubles that capacity to 8.5 GB. A two-sided, dual-layered DVD disc has the potential of holding over 17 GB of information. (Because a two-sided disc must be turned over for full access, most DVD-ROMs are single-sided.) In contrast, a CD can hold approximately 680 to 740 MB of information.