Conference hydra::amiga_v1

    John,
    
    I'm glad your happy with the new Multisync.  I don't understand
    your surprise with the interleaved performance.  I would expect
    that a Multisync without a flicker fixer would perform no better
    than a Comodore monitor in interlaced mode.  In fact I've seen
    lot's of software run interleaved on a comodore monitor without
    flicker.  I think the fact that you're not seeing flicker with
    what you've done so far is co-incidence.  
    
    The best demo I ever saw was at a Boston computer show where the
    flicker fixer people had an Amiga 2000 driving 2 NEC Multisyncs
    at the same time.  One was hooked to the flicker fixer and the 
    other straight out of the monitor connector on the back of the
    2000.  With identical monitors you could see EXACTLY what a
    flicker fixer could do for you.  They had software running that
    continually showed graphics, animations, and game segments
    and I was was really surprized at the results.
    
    1. My first observation was that the majority of all the stuff
       they displayed didn't even have a flicker on the unfixed
       monitor.  At that point I questioned wether or not the flicker
       fixer was worth the $450 for the small amount of software I 
       might be using!
    
    2. When flicker did occur it was anywhere from "barely noticeable"
       to "oh my God! how could Comodore sell this".  
    
    3. The flicker fixed monitor had absolutely no flicker or jitter
       of any kind, in any picture.
    
    4. What flicker fixer also did was provide this beautiful matte
       finish with no signs of scan lines or retrace on the screen 
       at any resolution.
    
    5. That un-flicker fixed NEC Monitor (in my opinion) was no better
       than a 1084 and cost a lot more money.
    
    I think the need/want to go with a Multisync and flicker fixer is
    very subjective and certianly not "necessary".  In my case I went
    for it and I'm pleased with the decision but it cost a lot of money
    and I don't think it could be justified. It's just another toy and
    at the time I didn't want to spend $300 for the Comodore monitor
    knowing that I may someday want to upgrade, that's even more expensive.
    
    Frank
    

    I only just grocked what flicker is all about.  I used a ruler to
    count the raster lines on my screen.  It was one line per millmeter
    height on the amiga, and 2 lines/mm for bradcast television.
    This means that the amiga in interlace writes the two fields into
    the exact same position, instead of making the second one lower.
    My brother thinks you could make a circuit that suppress the vertical
    sync pulses and add them back in, making the second one longer.
    beats me.  The thinks that look worst in interlace are when there
    are thin horizontal lines that are only in one of the fields, so
    the line turns on and off 30 times a second.
    $450?????? Is is a circuit or a screen add-on.?
    Tom

    
    I'm not so sure about that.  I believe the second pass is shifted down
    one half of a normal (200 line) scan line.  I use SetLace all the time
    just so that these blank lines look a bit better.  The flicker fixer is
    a frame buffer card which fits inside the A2000.  The flicker is totally
    gone.  I'm sure there are other notes in this file discussing how it
    works.  It really does produce a gorgeous display.  But, I'm in no rush
    and I'm hoping the new graphics chips come out before long...
    
    - steve

>I'm hoping the new graphics chips come out before long...

But even when they do, they will not support flickerless versions
of all the current Amiga display modes, so the FlickerFixer is still
a useful gadget.

-jim

    
    Perception of flicker is really an individual thing.  30 hz verticle
    refresh rate seems to be the average threshold where individuals' eyes
    can perceive the flicker.  Some people can see 60 hz flicker! I was
    never too bothered by flicker, but I bought a FlickerFixer precisely
    because of the gorgeous 'filling in' of the scan lines.  This 'filling
    in' is achieved by doing the same trick that 'SETLACE' does in 200 line
    mode, except the FF video circuitry is much better than the Amiga's.
    
    A FlickerFixer used with any multisync monitor looks like laser
    printed text on a white sheet of paper.  You really have to see it to
    appreciate just how good it it.  The only display that comes close is a
    monochrome Atari ST (which to me looks MUCH better than even a Mac
    display).  In fact, I think that if the Amiga had been designed with an
    additional separate monochrome video circuit, even if it required a
    separate monitor, Commodore would have sold their millionth machine a
    long time ago.  I'm sure many people who bought Macs would have bought
    Amigas if a quality 400 line display mode was available.  I think this
    is STILL the Amiga's biggest, glaring flaw.
    
    .0 is correct in assessing the near flickerless Mitsubishi monitor. 
    I've seen a few Mitsus and they must be using a much longer persistance
    phosphor than most of the other Multisyncs.  It really is nearly
    flickerless, even with black/white horizontal lines.  Plus most Mitsu
    models have an NTSC composite input.
    
    Ed
    
    
    

Re: .2

>    I used a ruler to
>    count the raster lines on my screen.  It was one line per millmeter
>    height on the amiga, and 2 lines/mm for bradcast television.
>    This means that the amiga in interlace writes the two fields into
>    the exact same position, instead of making the second one lower.

No, the Amiga does offset the second field of data.  The fine black lines
between scan lines in 200 line mode disappear when in interlace mode.  Thus,
the Amiga (in interlace mode) acts exactly like the television signal.
This is why the Amiga has been a professional success in the TV and
cable industry for generating graphics.

>    The thinks that look worst in interlace are when there
>    are thin horizontal lines that are only in one of the fields, so
>    the line turns on and off 30 times a second.

That is true, but it isn't because the dark line and light lines are being
drawn exactly on top of each other.  The problem is a combination of
how long the screen phosphors hold their image and how long the cells
in you eye holds an image.

When the electron beam hits the phosphor, the phosphor glows.  When the beam
moves on, the phosphor will continue the glow for a short period of time.
A long persistence phosphor will glow for longer than a short persistence
phosphor.

When light (from a phosphor, say) hits the cells in your eye, the cell will
"fire" signaling that you see light.  The eye cell will hold that signal
for a certain length of time (determined by heredity and the number of
carrots you eat).

In non-interlaced mode, the Amiga repaints the entire screen 60 times a
second.  This is fast enough that almost no one can see the
effect of phosphors being hit by the electron, glowing brightly,
and then starting to fade to black.

In interlace mode, the Amiga outputs twice the amount of data at the same
rate.  Thus, the Amiga only refreshes the screen 30 times a second (the
phosphors have twice as long to fade to black).  This it slow enough that,
depending on the individual's eyes and the amount on contrast in the images,
that most people can see flicker.

When the images has a great deal of contrast, like text or other fine
lines on a screen, almost everyone can see flicker.

When the image is a smoothly shaded picture, flicker may be cut down
or even eliminated.  For example, a HAM picture often has such smooth
transitions that I can not see any flicker in it at all.  (Well, I
can see flicker on the edges of the picture at the transition from
background border to picture.)  This lack of flicker seems to be true
of most digitized pictures.   Ray-traced HAM images seem to show more
flicker (they usually have sharper boundaries, lack anti-aliasing, or
have more lurid colors).

The Amiga in interlace mode is prone to the same amount of flicker,
no more, no less, than a television set.  People usually don't notice
the flicker in TV because of the smooth shading and the lack of
sharp boundaries (you don't see much text displayed on TV in 1/8 inch
letters!).

> [Of the FlickerFixer:] $450?????? Is is a circuit or a screen add-on.?

The FlickerFixer is a frame buffer and video output board.  It has
enough high speed static memory to store the previous field of 
Amiga video output and combine it with the current field of the 
video output and spit out the result at twice the frame rate.  It's
the high speed memory on the board (256K, I believe) that makes it
so expensive.

    < Note 2414.6 by TLE::RMEYERS "Randy Meyers" >
                                  -< Flicker >-

>Re: .2
>
>>    I used a ruler to
>>    count the raster lines on my screen.  It was one line per millmeter
>>    height on the amiga, and 2 lines/mm for bradcast television.
>>    This means that the amiga in interlace writes the two fields into
>>    the exact same position, instead of making the second one lower.

>No, the Amiga does offset the second field of data.  The fine black lines
You seem to be ignoring the fact that I made a MEASUREMENT with a 1/2
    meter steel rule!  Go make the same measurement yourself on
    yourmonitor.  The The even field is not being offset on my monitor.
    I studied it some more over the weekend.  The black&white composite
    signal from the amiga is interlaced fine.  It's the RGB signal that
    does not get properly interlaced; the fields aren't really dead on top
    of each other, but they almost are; I can see slight movement from
    the top of the scan line to the bottom when I pull a window size.
    The fine black lines are still there between scan lines.  The composite
    sync wire ohmed out oK.  Perhaps I should try to use vertical and
    horizontal sync signals if the monitor accepts them.
    
    >between scan lines in 200 line mode disappear when in interlace mode.  Thus,
>the Amiga (in interlace mode) acts exactly like the television signal.
>This is why the Amiga has been a professional success in the TV and
>cable industry for generating graphics.>

>>    The thinks that look worst in interlace are when there
>>    are thin horizontal lines that are only in one of the fields, so
>>    the line turns on and off 30 times a second.>

>That is true, but it isn't because the dark line and light lines are being
>drawn exactly on top of each other.  The problem is a combination of
>how long the screen phosphors hold their image and how long the cells
>in you eye holds an image.

    
    I know what flicker fusion is; I wrote a report on it in the 6th
    grade, thank you.
>When the electron beam hits the phosphor, the phosphor glows.  When the beam
>moves on, the phosphor will continue the glow for a short period of time.
>A long persistence phosphor will glow for longer than a short persistence
>phosphor.
My goodness you're so smart!  You know the things that 10 years olds
    know!
    Tom

    Try adjusting the vertical hold.  This seems to affect the scan line
    separtion slightly.
    
    -steve

    
    Steve is right.  When using line-doubling (via SETLACE) or 400 line
    interlace, a slight tweak of the verticle hold will shift the even and
    odd fields vertically with respect to each other.
    
    Ed.

    OK I'll try the vertical hold, although the B&W was interlaced oK.
    Also, I fixed my scope a week ago by replacing the uA733 video amp
    on the trigger conditioning circuit, so I can look at the rgb sync
    relationships.
    Tom

    Re: .10

    Please tell us more about your exciting lifestyle! And my 5 year old
    would like to know more about how you fixed your scope. Perhaps you
    could enter it as a separate note.    Also, I fixed my toaster/oven
    this morning by replacing the lower heating element, so now I can
    eat breakfast and get to work on time! I'll let you know how it all
    works out...

    Pete (who's truly sorry for the flame, but dearly appreciates any
          replies by Mr. Meyers, no matter what level they are on.)

    Adjusting vertical helps, but makes the screen flip.  I'll probably
    have to adjust every time I turn it on.
    Tom

>    Pete (who's truly sorry for the flame, but dearly appreciates any
>          replies by Mr. Meyers, no matter what level they are on.)

I agree.  .7 did seem a bit uncalled for.  Randy was only trying to volunteer
his knowledge on the subject.  If you disagree or have conflicting info, by all
means feel free to chime in with it, but remember your notesfile etiquette. 
Biting remarks and insulting digs detract from the purpose and spirit of this
notesfile, and they will, I'm certain, meet with a very unwelcome reception. 


					John

BTW, Sorry to sound like 'Mom'.  I just hate to see notesfiles get so insulting
that folks are afraid to offer info on the chance that they might get verbally
assaulted.  Even 'obvious' things aren't so obvious to some of us.  :-)

    
    I too thought that .7 was a bit, er sharp.  I truly enjoy reading
    anything Randy Meyers has to say in this conference.  Randy has
    consistently been one of the most informative participants in this
    conference.
    
    The problem is that we have guests here who have never touched a
    computer before as well as those who have won the Nobel Prize in TV
    repair.  We sometimes repeat ourselves for the benefit of the
    newcomers.  
    
    Ed.
    

I agree.  There's no need for bashing anyone! Especially those who take
the time to try to help others in need. If you ask a question, be gratefull
that someone tries to help, replies like .7 will only keep others from
*wanting* to help you.

Randy Meyers has certainly contributed a significant amount of GOOD technical
information to this conference and I always take time to read his replies. If
it's something obvoius to me or really basic, it's much easier to hit next 
unseen.


John

    re .14/.15 about   .7

    Got my vote - I'm relatively new to the amiga myself and like many
    folk in this conference dont get time to read EVERY NOTE and EVERY
    REPLY. Mr Meyers has helped me out on several occasions and I dont
    like seeing the poor guy verbally bashed for trying to help a 
    fellow digit...

    Mabye a "re-phrase" or apology would be appropriate now...
        

    Flame on!!!
    
    I think that the comments in .7 are part of living in this society.
    People in this conference have it nice, easy and freindly. I just
    read it and it restores my faith in humanity and its diversity.
    
    Once while driving down the road , I stopped to let a woman in a
    car get into traffic so she can be on her merry way! Nice guy right?
    Well, she didn't think so! She flipped me the finger!
    
    I have't stopped letting people go in front of me and I trust Randy
    won't let this bother him!
    
    A differnt Tom
    

    I just want you to know that I love and respect all of you tremendously
    for the position you've taken on my reply in .7, and am grateful
    for the encouragement you have offered.  This kind of unselfish
    support of a victim is the reason I love conferencing.  
    Tom

    I don't think anyone (me anyways) wanted to discourage you from
    reading/contributing to this conference, it's just that your
    comments in .7 were a bit harsh considering what Randy had said.
    Just do a DIR/AUTH=MEYERS (and/or RMEYERS) and you'll see why
    people have a great deal of respect for the man. Oh, don't forget
    to read some of those notes pointed to by the latter; you'll
    learn alot about the Amiga (among other things) which is the whole
    point of this conference (*no* sarcasm intended). Please don't feel
    victimized; at least *you* got a response to your entry! 8^)

    Patheticly Pungent Pete

    Randy, Ed and many others have helped this novice more than they
    can imagine...
    
    Hey Guys - if your ever down this end of the world
    
    THE BEERS ARE ON ME!

    Just because you have a bad experience while doing a good deed should
    not make you stop from being a good samaritan, and at the same time
    lowering yourself to the level of people who need your example.
    Keep doing good, keep giving advice to the best of your ability,
    you will feel good doing it and people will respect you for it.
    
    (I should have been a preacher)
    
    Jean
    

    She flipped you the bird?  Sounds like my wife.

    - Z