Analog Storage (Videodisc):

A videodisc is an analog medium that holds up to 54000 single
video frames on each side of a 12 inch disk.  Each video frame is
randomly accessible and can be viewed as a still frame.  If the
frames are shown at a continuous playing speed of 30 frames/sec,
one half hour of real time video is possible per side.  As with
the CD-ROM technology, standard videodisc productions must be
preprogrammed, and the production of a "master" disk is required.
Nonstandard videodisc formats do exist which offer analog "write
once-read many" systems that are similar in concept to the
digital WORM technologies. 

The videodisc has two channels of audio tracks to permit the
production of stereo sound as an accompaniment to the video
display or as a separate audio record.  Alternatively, each track
can be programmed separately to permit single track audio
programs in two languages.  A videodisc system can also be
developed with the capability for still frame audio programming. 
This capability enables an audio segment to be played while a
still frame is displayed on the screen.  This is accomplished by
special hardware that has the capability to retrieve
approximately 10 seconds of audio information from each video
frame (see Section 3.2.4).

As with the CD-ROM medium, the standard videodisc format is a
read-only medium, and production of a "master" disk is required. 
Similarly, ensuring an accurate replication of the data to be
encoded on the videodisc is a relatively expensive, tedious
process.  However, copies of the master disk can be produced
rapidly and cheaply, making the videodisc an appropriate medium
for the distribution of image libraries to a broad user audience.
The current hardware and software costs for a fully configured
videodisc based system are relatively inexpensive (under
$5000.00).  However, for tailored applications, a significant
cost is incurred in assembly of archival data and the production
of the master videodisc.

<cfile61>   Optical Disk Storage
<ffile42>   Analog