Re: [stella] interlace

Subject: Re: [stella] interlace
From: Mark De Smet <de-smet@xxxxxxxxxxxxxxx>
Date: Wed, 21 Jun 2000 22:54:28 -0500 (CDT)
> >Fascinating, never knew that.  So the lines it draws are effectively
> >double the width(spaced out that way)?
> Double the height, not width.

Sorry, that's what I was thinking.

> >A regular NTSC signal flickers between frames because it is interlaced,
> >the only difference between that and frame flicker on the atari is that
> There is no frame flicker on the Atari that I'm aware of.  Only sprite
> flicker.

But sprite flicker is kinda the same thing.  Example, that polo demo(I
don't remember the name).  I can't find it(I don't remember if I have a
copy), but IIRC, it does flickered venitian blinds.  Isn't this the same
thing as the frame flicker of a tv image?  I mean it is every other line
drawn on oposite frames.  The only difference I see is that the lines on
the VCS are double height(in spaceing).  And the polo demo's flicker is

> The reason you don't notice NTSC flicker that much is because most shapes 
> in live action video are not aligned with an individual field's individual 
> scanline.  The thinner the line, the worse the flicker, too.

That is true, and the images are more continuous through the lines, but
what about the polo example?

> However, on the Amiga, for instance, if you run it in interlaced NTSC mode, 
> you'll see a LOT of flicker because you'll have many horizontal lines 
> perfectly aligned with individual field scanlines.  These lines will only 
> show up on alternate fields, thus flickering.

Really?  I mean in interlaced mode, shouldn't it be doing the same as a tv
signal?  I've use a character generator that had very obvious pixals, one
per line, and it does not appear to flicker.

> Certainly every VCS's RF out breaks broadcast standards.  It will get to 
> the TV okay, but try recording the VCS signal to tape and then freezeframe 
> it.  I couldn't get that to work right on my $1000 Mitsubishi SVHS VCR.

Nope, your right, it doesn't work.  Well, it doesn't hold the frame, it
scrolls quite abit...


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