From: danaf@vccsouth28.its.rpi.edu (Frank R. Dana Jr.)
Subject: Re: Interlace video (Was Re: PC (OS/2) / Amiga debate)
Reply-To: danaf@rpi.edu
Organization: Rensselaer Polytechnic Institute, Troy, NY.
Date: Mon, 7 Sep 1992 18:02:48 GMT

In article <18clmuINN65b@matt.ksu.ksu.edu>, nan@matt.ksu.ksu.edu (Nan Zou) writes:
|> danaf@bray1b.its.rpi.edu (Frank R. Dana Jr.) writes:
|> >nan@matt.ksu.ksu.edu (Nan Zou) writes:
|> 
|> [...]
|> >>I think you're wrong on that one.  Standard VGA use 31.5 KHz horizontal
|> >>syncing frequency and 60 Hz vertical non-interlaced refresh.  And I don't
|> >>think EGA and CGA is interlaced either.
|> 
|> >I said DISPLAYS, which was not the best choice of words. I should have used
|> >a word like "screens" or "monitors"... I meant interlaced monitors.
|> 
|> My point still stands.  Most VGA monitors will do at least 60 Hz non-
|> interlaced display.  You may be referring to some SVGA monitors, which can
|> not handle high resolutions without resorting to interlacing.  The NEC 3D
|> for example, is non-interlaced at 800x600 but interlaced at 1024x768,
|> simply because the monitor can't sync up to frequency that high, 48 kHz.
|> 
|> For me, I'd sooner drop down to lower resolution than looking at a
|> flickering high res interlaced display, I value my eyes too much.

Then, of course, you can do the same thing on the Amiga. As I mentioned in the
LAST post I made, you can always shunt down a video mode if you want non-inter-
laced video. Direct quote: "It's not like every display on the Amiga is inter-
laced."

|> >>But let's face it -- interlaced video is bad for the eyes, the fact that it
|> >>facilitates video work is irrelevant.
|> 
|> >NOT TRUE! The Amiga is a machine targeted primarily toward the video market. 
|> 
|> Which part is not true?  It's bad on the eyes or...  If you think interlace
|> is just fine, why did you buy your flicker fixer?  You have too much money
|> to burn?  
|> 
|> As I said, I didn't mean to trivialize the importance of video or the Amiga's 
|> superiority in this area (or maybe I did).  I was talking about the quality 
|> of interlaced video in an objective manner.  So interlaced display may be
|> necessary for video work, it STILL looks worse on the eyes than a non-
|> interlaced one, OK?  You may not notice anything.  But accroding to studies
|> the mean at which people can detect flicker is around 65 Hz, with standard
|> deviation of around 5 Hz, this is a normal/Gaussian distribution, which
|> means half the people will notice flicker if the refresh is below 65 Hz.
|> All of the current PC video cards support at least 70 Hz or 72 Hz vertical
|> refresh, I run my ET4000 at 800x600 with 72 Hz refresh on my Sony Trinitron
|> monitor and the picture is rock solid.  The equivalent refresh rate in
|> interlaced mode will have to be 144 Hz, can your Amiga generate that high a
|> refresh?
|> 
|> >The fact that it has an interlaced display shows that focus. The display is
|> >certainly not "irrelevant"
|> 
|> It is irrelevant when I'm talking about picture quality.
|> 
|> So Amiga is tailored for the video market, this is a good thing.  But when
|> one's not doing any video work, the interlacing becomes a disadvantage.
|> 
|> >>No, there's nothing wrong with a interlaced display -- unless you have to
|> >>look at it in close range for long periods of time, then there's a problem.
|> 
|> >I see no problem. You really do get used to it. I owned an Amiga for over four
|> >years before I bought my flicker-fixer, and had no eye trouble. At one point,
|> >over a summer when I could not find a job, there were days when I would use
|> >the thing 10, 12 hours... up to 8 hours STRAIGHT. I'm still sighted.  9)
|> 
|> Each person will of course see things differently, but wouldn't you agree
|> the display looked BETTER after you put the flicker fixer in?
|> 
|> >>>and it is NOT a "low-end" alternative to a steady display. It has MANY, MANY
|> >>>applications in the real world, at levels the IBM machines cannot touch. 
|> >>
|> >>Yes, the video aspect, but how many use their computers for video?
|> 
|> >Uhm... in the Amiga community? 10-20% professionally/semiprofessionally, and
|> >about 30-40% "fool around". (Okay, okay... I just made up those numbers. But
|> >we'll ask Dave Haynie, someone who should have the market research to prove it.
|> >Dave? How close was I? I may have even UNDERESTIMATED.)
|> 
|> As long as we are throwing around numbers, let's say 80% of the Amigas are
|> in Europe, and most of these are owned by gameplayers with a one floppy
|> A500, how likely do you think they are to "fool around" with video
|> production?
|> 
|> And EVEN if there's a large number of people doing video work, do you think
|> they bought their computers for nothing other than video?  At some point
|> they'll want to write a letter, call a BBS, is interlacing still beneficial
|> in these situations?

Well, actually, there are people who buy Video Toaster workstations who never
even see the Amiga O/S... 8)

But, as I have REPEATEDLY stated, if you want to do something like write a
letter, you just drop to a NON-INTERLACED DISPLAY MODE. There are plenty.

I refuse to repeat this one more time. Read through that statement, S-L-O-W-L-Y
and carefully. THE AMIGA SUPPORTS NON-INTERLACED DISPLAY MODES AS WELL AS 
INTERLACED ONES.

|> >>Believe me, the flicke4qring is very noticable, I've looked at an interlaced
|> >>PAL display and I will go blind if I have to look at it for long periods of
|> >>time.
|> 
|> >AHA! Well, that's half of the problem, then. PAL video has its own flicker,
|> >especially when shoved onto an NTSC screen. Anytime I run my palbooter, I
|> >go half-crazy from that damn flashing screen. If you are looking at a PAL
|> >screen, you have a better chance of going blind from the PAL than from the
|> >interlacing!
|> 
|> I've also looked at an interlaced display on my own monitor, the flickering
|> especially with a bright background, can give me a spliting headache real
|> quick.
|> 
|> >>Idealy, interlaced video mode should only be used when doing video work,
|> >>all other times it'll just put unnecessary strains on the eyes.
|> 
|> >So, then you jump down a video mode! What's the big deal? It's not like every
|> >display on the Amiga is interlaced. We get up to 724x482 (?) non-interlaced, 
|> >which is fine for 90% of the applications people want to run. 
|> 
|> Interlacing or non-interlacing doesn't tell the whole story, vertical
|> refresh rate is the ultimate factor.  Of course, interlaced refresh will
|> have to be twice that of non-interlaced to be equivalent.  So, what's the
|> refresh rate of that 724x482 screen?

Hooo-boy. Okay, here we go. My display is a rock-steady, non-interlaced, 60 Hz
display. It is an overscanned 724x482 resolution, and it DOES NOT FLICKER.

|> 
|> -- Nan

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