Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!van-bc!rsoft!mindlink!a708
From: Gord_Wait@mindlink.UUCP (Gord Wait)
Newsgroups: comp.sys.amiga.graphics
Subject: Re: Single Frame recorders
Message-ID: <5253@mindlink.UUCP>
Date: 24 Mar 91 17:46:36 GMT
Organization: MIND LINK! - British Columbia, Canada
Lines: 24

The reason that 'still frame' recording isn't done (except in the 1 inch sony
2500 machine.. and others like it..) is the path that the video head takes over
the tape. To rehash, the video is recorded as 'green bean' slices along the
tape. In full play 1 times speed, the path that the head takes along the tape
is different than the path that the head wants to take when the tape is
stationary. To visualize, imagine the bean slice shape as the tape goes past
the head faster and faster.. The slices become longer and longer. (bean slices
like this:
\\\\) The reverse is true as you slow down the tape. (keeping the rotating head
speed constant by the way..) So in still playback and record on the sony 2500,
the playback and record heads are physically wobbled back and forth in time
with the head rotation, so as to keep the head aligned with the bean slice
shape that corresponds to the normal playback slice. In consumer decks, they
play magic tricks with partial or even full frame storage, and multiple tape
reads to maintain that nice clear image. Mucho complicated to do in record
mode, so they don't do it for the small number of us who would like it, and
like it cheap. Gord Wait
--
Gord Wait
Member of Technical Staff
ASIC Engineering
SMOS Systems
Vancouver Design Center
Gord_Wait@mindlink.UUCP