Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!mcnc!ece-csc!ncrcae!ncr-sd!hp-sdd!ucsdhub!jack!man!nu3b2!rwhite From: rwhite@nu3b2.UUCP (Robert C. White Jr.) Newsgroups: comp.graphics Subject: Re: Why not streaming video recorders? Message-ID: <794@nu3b2.UUCP> Date: Fri, 10-Jul-87 21:29:39 EDT Article-I.D.: nu3b2.794 Posted: Fri Jul 10 21:29:39 1987 Date-Received: Sun, 12-Jul-87 14:18:45 EDT References: <17110@glacier.STANFORD.EDU> <2328@dciem.UUCP> Organization: National University, San Diego Lines: 41 Summary: How it works. Since the veido recording head spins on its axis and it's axis is on a bias [slanted with respect to] to the direction of tape travel a veido tape is "always in motion" even if the tape is not traveling. Each image is a diagonal stripe on the tape so seccuessive frames are dropped in anad apear as: frame #: 1 2 3 4 5 6 7 8 --------------------- \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ ... \ \ \ \ \ \ \ \ \ \ --------------------- on a segment of tape. The problem is that the jog [forward|backward] until sync is dificult to maintain/produce. Even good consumer level VCR's have some problem keeping an acceptable "still frame" [stop the tape and keep the head engaged and spining] Multiple "heads" on a single "head drum" are used to catch the slack and skew. Extreemly good veido tape editors have a "multi head" drum and two extra little arms which travel the tape in increments of millimeters. The controll circuts which preform this act are extensive and expensive. Beacuse a computer would be more upset than a human eye about the loss of bits most vedio/data medimum write seccuessive frames of identical data. A system could easily be designed to "still frame" data but TWO sets of "travel arms" would be required 1) alignment on amilimeter basis, and a data-frame-by-frame set to account for/remove startup skew and tracking. Such a device is easily possible, but quite expensive without quantity purchases [thousands]. It can't really be added on to an existing VCR. Further Details Available. [I know a lot about veido from my high school minor] Robert. Disclaimer: My mind is so fragmented by random excursions into a wilderness of abstractions and incipient ideas that the practical purposes of the moment are often submerged in my consciousness and I don't know what I'm doing. [my employers certainly have no idea]