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From: bryan@cs.utexas.edu (Bryan Bayerdorffer @ Wit's End)
Newsgroups: comp.sys.amiga
Subject: Re: Commodore De-interlacer
Message-ID: <240@mohawk.cs.utexas.edu>
Date: 7 Nov 90 01:30:01 GMT
References: <5463@crash.cts.com> <239@mohawk.cs.utexas.edu> <565@cbmger.UUCP>
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In article <565@cbmger.UUCP> peterk@cbmger.UUCP (Peter Kittel GERMANY) writes:
=-
=-It has already been answered by one of the chip guys. The reason is the
=-definition of an interlaced TV screen where the Amiga sticks to. In this
=-norm one half picture starts in the upper left, but the other half picture
=-starts with a half line at the top in the middle. And they obviously did
=-their best to manage this also on the Amiga.

	Fine.  That's what the interlaced output looks like.  Now tell me why
the DEinterlaced output has to look like that.  It's not going to an NTSC
monitor, after all.

=-So the question arises: What does flickerFixer put in there?
=-
=-To get an understanding for this half line, you must imagine that during
=-a horizontal scan the vertical scan already and also is running, but
=-much slower. So all lines are bent a little downwards (if you don't
=-twist the tube). So for the second half picture to match perfectly
=-inbetween the lines of the first half, they (TV norm definers) chose to
=-start at the very top but offset by half a line horizontally. When you
=-draw this on paper you will see, that this way you get a perfect
=-interlacing of the two half pictures. And Amiga is dedicated to follow
=-TV norms.
=-

	I'm not sure I see your point here.  To get rid of the flicker all you
have to do is suppress the RGB signals that light up the dots on the screen 
during the first scan line of the odd field.  You don't have to touch the synch 
signals, which are what you're describing.  All you're doing in this case is
throwing away some information that's useless anyway because of the flicker.