Digital Video Interactive (DVI):

Developed by RCA and now owned by Intel, Digital Video
Interactive is not a storage medium per se, but rather a storage
protocol that promises to be the technological successor to the
analog videodisc medium.  DVI is a hardware and software system
for the IBM PC-AT computer (or compatible) that constitutes an
interactive, multimedia environment in an all digital format.  It
accommodates real-time video (30 frame per second), still images,
computer animation, and stereo audio as well as text and tabular
data on an IBM PC-AT compatible microcomputer system.  As a
digital medium, the data quality and real-time video capability
mark its most significant attributes.  The key to this capability
is an image compression and decompression algorithm that reduces
image storage requirements to less than 1% of the original file
size.  An audio compression algorithm and a memory buffer permit
continuous audio playback.  With video data compression
approaching the ratio of 10,000 to 1, DVI permits approximately
one hour of video and multichannel audio on a 500 megabyte CD-ROM
(Compact Disk-Read Only Memory) disk.  Displayable resolution can
range from 256x240 to 768x480 pixels with 24 bit RGB color. 
Additional improvements in CD-ROM technology promise greater
storage capabilities, extending disk playtime and making a system
of higher resolution images feasible.  DVI also includes an
edit-level video feature which allows single frame image
compression ratios of 25-to-1 in one to two seconds on the PC-AT.
Compression ratios for highly detailed images or technical
graphics are limited to ratios of 2-to-1 or 3-to-1.  As
compression routines become more sophisticated and hardware
components become more powerful, compression ratios and speeds
will improve further.  DVI is compatible with a variety of
digital mass storage media such as magneto-optical and WORM
(Write Once-Read Many) systems.  

Advantages over competing systems include DVI's integrated
digital format (versus the computer controlled analog audio and
video of videodisc technology), and its extended real time video
capability as a result of the fast image data compression and
decompression algorithms.  Less efficient algorithms employed in
the Sony and Philips compact disk interactive (CD-I) system place
significant limits on its ability to display real-time video. 
However, CD-I, a hardware/software system that also integrates
CD-ROM with a computer controlled environment, does possess
higher quality audio than DVI.

<ffile41>   Data Storage
<cfile42>   Video Systems
<cfile62>   CD-ROM Storage