Digital Video Disk or Digital Versatile Disk (DVD) can hold movies
and/or much more data
than a CD ROM. Current media is double sided and holds 2.5GB per
side. That means a single DVD ROM can hold over 7.5 CD ROMs. And
like the CD read and write drives, DVD drives come in read and read and write
models. Movie
video is typically Motion Picture Electronics Group (MPEG). MPEG is a
compressed digital video format specification. MPEG can be
decompressed/decoded with special hardware or by software. Hardware
decompression/decoding use to require special adapter boards for both video and
audio. Today, video card manufacturers are incorporating hardware assist
or full video and/or audio decoders right on the primary video card along with
3D hardware. The software decompression/decoding requires lot's of CPU
bandwidth and early implementations of DVD software players utilized Pentium II
specific code and were not totally compatible with all DVDs. The new
specification for audio/video compression/encoding is MPEG4. This new
format can be decoded with software. There are three types of DVD
media, DVD-R, DVD+R, and DVD-RAM. The two Recordable write once medias +R
and -R are not compatible. Basically two different consortiums of DVD
Recordable media tried to corner the market with their own proprietary standard.
Although today you can find PC drives and home theater devices that that support
both standards. DVD RAM is like the CD-RW media. | 