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From: u-jmolse%sunset.utah.edu@utah-cs.UUCP (John M. Olsen)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: Message from designer of FlickerFixer
Message-ID: <5658@utah-cs.UUCP>
Date: 16 Aug 88 17:48:24 GMT
References: <3318@crash.cts.com>
Sender: news@utah-cs.UUCP
Reply-To: u-jmolse%sunset.utah.edu.UUCP@utah-cs.UUCP (John M. Olsen)
Organization: University of Utah, Computer Science Dept.
Lines: 40

In article <3318@crash.cts.com> haitex@pnet01.cts.com (Wade Bickel) writes:
>The cludge is needed to solve
>a problem that is otherwise unreasonably expensive to correct.
>...However I stand by the point that IDEALLY it
>should not be mixing mis-matched fields (which I can definitly see it doing).
>...buffer each
>video field (using video industry terminology) and then combine it with the
>subsequent field to form a frame (de-interlaced display).  Given this 
>methodology doesn't that mean that every other display update contains a
>Frame composed of mis-matched feilds?
>                                                        Wade W. Bickel
>
>UUCP: {cbosgd, hplabs!hp-sdd, sdcsvax, nosc}!crash!pnet01!haitex
>ARPA: crash!pnet01!haitex@nosc.mil
>INET: haitex@pnet01.CTS.COM
>Opionions expressed are mine, and not necessarily those of my employer.

This came up before, but I think that much of the discussion was in Email
(for a change :^).  When the machine is modifying the display at 60 Hz,
like redrawing a moving mouse pointer, there are no two correctly matched
fields to display that will not cause split images, and hence the Flicker-
fixer does the absolute best possible thing until the system forces all
software to update at a maximum of 30 Hz, which would be a Bad Thing.
Nobody likes having their animation speed cut in half.  The designers 
worked with what they had, and did the best they could.

To properly de-interlace an NTSC signal, you need to be able to tell which 
pair to match, but only if they are meant to be matched, which they
currently are not on the Amiga.  Under the current system, every pair of 
adjacent frames is technically mis-matched, but you only notice when things 
move.

It's a common problem for someone familiar with how TV NTSC works to see
a computer that sends an NTSC signal, and assume that the formats are 
similar.  You should know better than to trust a standard. :^)

 /|  |     /|||  /\|       | John M. Olsen, 1547 Jamestown Drive
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