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Digital versatile disc, or DVD, is newer
technology that builds upon the strengths of CD-ROMs. DVDs share the
same physical size of a CD-ROM but can handle a much greater amount of
information. DVDs are used for movies and audio, as well as data. Depending upon the layering and single or double-sided disc, DVDs can
store close to 20 times the amount of information as a single CD. DVDs
are able to store more information because they provide a greater area
for data storage, use a higher density recording technique, and can
access multiple layers within the media. The two major markets for DVD
players are the home entertainment market and the computer DVD drive
market.
Many consumers have a DVD player as a component in their home theatre setup. This is due to the fact that movies recorded onto DVD media are digital reproductions with vivid colors, theatre style surround sound, and often contain other movie-related extras. Since the movie is recorded in a digital format, the quality of the movie is as close to the film quality as possible and will never deteriorate like VHS tapes. Home DVD players also offer various audio options featuring multiple audio channels including Dolby Surround, Dolby Digital 5.1, and DTS. As for extras, many studios include scenes removed from the movie's theatrical release, "making of" featurettes, commentaries, and previews of other titles. Computer DVD drives can also play movies and music as well as read data discs. Software manufacturers are beginning to offer their products on DVDs. These manufacturers can now place their entire program on a single DVD instead of multiple lower capacity CDs. Another benefit of DVD drives is that they are backwards compatible with CDs. A DVD drive can read DVDs and CDs while a CD-ROM drive can only read CDs. DVD players and drives are very similar to CD-ROM drives in design. DVD players are comprised of a drive motor for spinning the disc, a laser assembly for reading the DVD, a tracking mechanism for moving the laser assembly into the desired area, and communication circuits for moving the data to its destination. Other optional components include decoders. All home DVD players and some computer DVD drives have an MPEG-2 decoder for decompressing the video data into a format that can be shown on a television screen or monitor. Some DVD players and drives also contain audio decoders for either Dolby Digital 5.1 or DTS audio streams. These decoders decompress the audio data and separate the information into the proper discrete channels. DVD players and drives that do not contain these decoders may use other hardware (or software) to accomplish the decoding. The laser used in a DVD player is different from lasers used in CD-ROM drives. The laser in a DVD player must be able to focus on different layers of the media. While a single layer DVD has only a single reflective layer of material, a dual layered disc contains a semi-transparent layer over the top of a completely reflective layer. The laser must be able to distinguish between the two by focusing on the correct layer of material containing the desired data. When installing a DVD drive, follow the steps for a CD-ROM drive installation including all safety procedures. Slide the drive into an open bay, connect the communication cable (usually 40-pin IDE ribbon cable), connect the power supply, configure the drive jumpers, and connect any audio cables necessary. DVD drives usually have connectors for analog audio out as well as digital audio out cables. Finally, install the device driver and check by restarting the computer. |