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From: rjn@hpfcso.HP.COM (Bob Niland)
Newsgroups: comp.ivideodisc
Subject: Re: MEMORY CAPACITY OF A VIDEO DISK
Message-ID: <11050006@hpfcso.HP.COM>
Date: 14 Jan 91 15:14:11 GMT
References: <11678@j.cc.purdue.edu>
Organization: Hewlett-Packard/FSY Ft.Collins,CO,USA
Lines: 15

re: > Does anyone know the mechanism of storing pictures in video disk?

The video is analog.  The composite video signal is used to modulate an FM
carrier over the range 7.6 MHz (sync tip) to 9.3 MHz (white level).  The
resulting sine wave is amplitude modulated by the two analog FM audio
subcarriers and the combined digital audio subcarrier, then clipped.  The
resulting square waves are recorded as pits and lands more or less as is.

Crudely put, the analog video signal is represented in the frequency of the
pit stream, and the various audio channels are represented by duty-cycle
modulation of the pit stream.

Regards,                                              Hewlett-Packard
Bob Niland      Internet: rjn@hpfcrjn.FC.HP.COM       3404 East Harmony Road
                UUCP: [hplabs|hpfcse]!hpfcrjn!rjn     Ft Collins CO 80525-9599