Scandoubler recommendations

[Hyperspeed]

First things's first - An Amiga outputs 15Khz horizontal frequency to be compatible with a TV.

A scandoubler willdouble 15Khz to make 30Khz. PCs use 31Khz.

This means you will have to get a `Multisync' monitor or one with good range of frequency such as an NEC or Philips.

One with digital memories for different screenmodes would be very handy, maybe 10x different `channel's so you can play games that don't make use of overscan.

Another thing you need to remember is that if you have anything but an A1200 you can't use an internal scandoubler. How do you think a CD32 gets by? I reccomend everyone get an external Scandoubler WITH integrated flicker-fixer so that it can be easily swapped between Amigas.

I also reccomend you switch to NTSC as my external EZ-VGA Plus (From Eyetech) gives me faint vertical lines in 50Hz mode and it's quite flickery and dark compared to NTSC @ 60Hz. I got the impression too that 50Hz was giving me some sort of 8-bit colour limit as opposed to HAM8's 19-bit (?)...
 
My unit does get hot, particularly in the summer but it should survive most extremes of heat. Putting a fan on is optional but a good idea Doppie.

:-)

You can use an Amiga without a scandoubler/FF if you put the Multisync-Productivity driver in Devs/Monitors/ and since it doesn't use video signals like native modes you get a small, crisper mouse pointer. Albeit at the expense of ChipRAM slowdown.

One other thing to remember is that an external Scandoubler/FlickerFixer will hog the 23-pin video port so you may not be able to use a genlock. An internal one would provide it's own extra port.

[Hyperspeed]

Ahhh...     good point.

But you are still cutting it fine, on the borderline because you are
trying to get these VGA monitors down to 50Hz vertical refresh.

For example, I bought 2x NEC monitors of exactly the same batch and
model number. One had vertical roll syndrome and the other was fine.

Sometimes you can just miss the threshhold of luck!

:-D :-D

I wonder if an LCD would accept a scandoubled NTSC 60Hz screen at
640×480 overscan, thus keeping to the 1:1 optimum for these panels'
input resolution.

If a panel were designed for 1280x960 or 640x480 then NTSC would be
the best all-rounder for an AGA Amiga to get an LCD.

Multiscan would just slow you down and wouldn't have as high a refresh
rate as NTSC.

:-)

[Hyperspeed]

@Daedalus

So only external scandoublers have this 8:4:4 colour limit? I can't
say I notice it in NTSC but I did in PAL mode. I also got noticeable
vertical lines down the screen no matter how much I adjusted the
potentiometer on the back.

My picture quality is equivalent to S-VHS I'd say, not quite RGB as on
dotted areas I notice slight signal fuzziness but the whole picture is
crisp, vibrant and full colour with my EZ-VGA Plus in NTSC 60Hz.

If you're going to use your Amiga solely on a VGA monitor there's no
reason to stick with PAL anymore anyway.

I use a 724x482 Overscan screen which gives me an extra 84x82 pixels!

:-D

Can anyone remember the name of that PD program for creating custom
screenmodes? I wonder if it works with OCS/ECS/AGA so that Doppie can
make a custom 512x384 or 1024x768 screenmode to work at his LCD's
optimum resolution.

If LCD has no visible refresh flicker then there can't be much
harm in sacrificing refresh to get a few more pixels out of your
custom chips right?

:-)

[Hyperspeed]

I can't believe this!

So even DCE were selling these things knowing they were cut down and
saving themselves extra buffer chips? When I bought mine I complained
that I was getting 8-Bit colour but the shop just ignored me and told
me to live with it.

I'm curious about NTSC though, PAL was pretty rough but I seem to be
getting perfect display from NTSC/PAL 60Hz. I do notice a slight
banding on smoothe gradiants but I put this down to 19-bit HAM8 as
opposed to 24-Bit True-Colour.

So are you sure even the INTERNAL scandoublers/flicker-fixers were
limited to 8:4:4?

:-(

What about the Picasso-IV, I know Amiga Format rated that much more
highly than the CyberVision 64/3D's flicker fixing ability.

[Hyperspeed]

That was a good summary Doppie.

:-)

I was always suspicious about my colour palette in relation to 24-Bit
but it doesn't make much difference between 16-Bit and 19-Bit HAM8.

The reduction was more noticeable in PAL 50Hz than in PAL 60Hz for
some reason though.

So if the internal scandoublers have the same limit with colours as
external, what exactly are the benefits of an internal scandoubler?

1)Hassle to open up the Amiga
2)Can't use it on different machines like CD32/CDTV
3)Can't swap it between your Amigas in emergency
4)Could heat up your motherboard and hard disk


Why not the easy plug-in external one? In PAL 60Hz (/NTSC) you lose
next to no quality at all.

The only downers about the external one are:

1)Protrudes 3" from 23-pin port
2)Blocks 23-pin from RGB Scart/Genlock/Grafitti card
3)Slight loss of picture quality (only noticeable on mesh patterns)

:-)

Would it be fair to say then, that the Picasso-IV is the SUPREME
scandoubler/flicker-fixer with full 24-bit pass-thru of AGA in HAM8?

[Hyperspeed]

The scandoubler I refer to is an Eyetech EZ-VGA Plus
scandoubler/flicker-fixer.

It's a metal case that's about 4 inches long and half inch thick with
a bit of paper on top for the logo.

This one has a red and green light to signify pass-thru of 31Khz modes
and a green to show it's scandoubling/flicker-fixing 15Khz modes.

The Eyetech one has a potentiometer screw on the back to tune exactly
to your Amigas clock signal. This may have deferred from motherboard
revisions.

I think it would appear that the internal scandoubler would offer the
best quality, but still inferior in colour rendering to the
Picasso-IV's which I assume to be full 24-Bit.

I must say again though, if you use your external one in NTSC or PAL
60Hz you won't notice it from 24-Bit RGB. Just give it a minute to
warm up on a cold day.

:-D

[Hyperspeed]

Wow, I tried that just now...

I use an Eyetech EZ-VGA Plus (3" long metal box on A1200 video port)

I created a 256-colour range from left to right in Deluxe Paint 5 and
it appears that my Scandoubler/Flicker-Fixer displays twice as many
tones in green as it does in red/blue. You have to turn off dithering
(Right-click the paint can/fill-tool in Deluxe Paint) so that
individual colours are seen as bars and not blended into each other.

Would this be RGB=4/8/4?

If this is correct then each increment should be just 3x pixels
across whereas my colour increments are closer to 33x pixels across in
red/blue!

What I mean is:
724(horizontal res) ÷ 22(colour increments) = 33(pixels per increment)

No wonder my HAM8 looks grittier than it should be! HAM8 theoretically
should be 4x smoother than 16-bit graphics since it's 256,000 colours
and 16-bit is 65,536.

If 4-bit is 16 colours then 16x256x16 (RGB 4-bit/8-bit/4-bit) =
65,536. This means that the power of AGA HAM8 is being degraded to
16-Bit PC quality as opposed to 19-Bit Amiga quality. We're
effectively getting only twice the Super-NES colour palette...

Grrrrr!

I would say that this is a serious breach of Amiga users trust that
years after purchase we are finding out we were sold scandoublers with
inferior hardware (so the manufacturers could save a few bucks).

Interesting to know what other people see in this experiment, be it on
DCE/Eyetech or Cybervision/Picasso!

:-(

[Hyperspeed]

Hold it...

If the Amiga brochures say AGA can handle 262,144 colours then HAM8
must be 18-bit.

I agree that HAM8 would be 6-bit on each of the RGB guns for a 64
colour gradient, however my eyes can't count that without getting
lost.

Since PAL is a little gritty on my EZ-VGA Plus I decided the only way
to be able to see the difference between gradients was to use NTSC.

I managed to count RGB colours as 22/44/22... which makes 4.5/5.5/4.5
as opposed to 4/8/4 or 5/6/5.

Since my eyes had trouble making this out accurately, this rough
calculation surely means I have a superior 5/6/5 16-Bit configuration
and not the crazy 4/8/4 scenario (or worse - 8/4/4 you mention).

However, if it left my HAM8 alone I would have 6/6/6 (the sign of the
devil!)

Oh well, if you love your colours I suppose the only option is to put
up with flicker on a 15Khz monitor or get a Picasso-IV.

Any PIV users here able to do this test on an AGA screenmode for us to
see?

:-D

[Hyperspeed]

What about finding (or making) a female->male extension lead. It could
fit in the obstructed port and trail out, then screw into a spare gap
in the other slot areas.

On another note, since the EZ-VGA Plus disables itself when it detects
Multiscan Productivity then on this particular screenmode I must be
getting a full 18-bit HAM8 palette!

Multiscan appears a little lighter than PAL/NTSC and is very crisp. It
doesn't appear to lose the quality of a 15Khz signal being converted
to composite and back (during the flicker fixing stage I think).

Multiscan Productivity is pretty slow as it eats up the ChipRAM
bandwidth but you get a perfect RGB 640x480 (4:3) resolution along
with a true 1:1 ratio mouse pointer which looks the business!

Maybe I'll set up a mode for every occasion!

:-D :-D :-D

[Hyperspeed]

Yes, I'd love a GFX card but I want a Picasso-IV and whilst it's
possible it doesn't look straightforward to add one to an A1200.
Particularly a desktop A1200!

:-D :-D

I think this thread is useful to A500, A500+, A600, CDTV and CD32
owners since the external EZ-VGA Plus can be just slotted onto their
standard video out ports. I've never heard of GFX cards for those
machines which is a shame really.

The biggest shame for A1200 owners was never getting a small GFX card
add-on but as has been explained to me in another thread - it was only
until the BlizzardVision that this was possible in an effective way.