Is it possible to make a vga cable for the Amiga 1200

[thgill]

Originally Posted by ajk

@Zetr0

I accept that you don't see it (as you say, in your opinion), but won't accept that it is not there, unless you can explain how the 50 images are output as 60 images over the same period of time otherwise

You don't really need to bother though, since you are happy with it and I don't use one anyway. Also, as you say, Youtube and camcorders and the like are not useful for demonstrating such things; would need at least a good VGA capture card that does not drop any frames. I'm just interested in standards conversion issues due to dabbling in other video technology.

@seuden

If you show a fraction of a field, it means that the field changes in the middle of the screen (ie. "tearing"). This is generally much more undesirable than slight stuttering.

I have also noticed that its there as well.

In games, for the most part, its not as noticeable. Load up a Demo that has smooth scrolling text (which is pretty much all of them) and its apparent right away.


Too bad this device wouldn't pass 50Hz through instead of sampling it up or at least give an option for 50Hz. Might not do too much good with most LCDs, but would be a nice choice for CRT monitors.

[Zetr0]

@thgill

what demo did you use, I would like to try that here.

[Mark Wright]

WARNING! DIATRIBE AHEAD BUT I WANTED TO WRITE THIS...

I think it's amazing that, after all these years, there remains those among us (like me) who rightly notice the inevitable tearing/jerking of anything designed to scroll horizontally at 50hz (like 99.9% of Amiga demos/games) running on a non-50hz display.

And the others (seemingly the majority) who absolutely don't. And who can't be convinced of the issue no matter how much it's pointed out. And (frustratingly) don't seem to care either way anyway.

Which, I suppose, explains the effortless and unstoppable rise of LCD/plasma TVs, all of which (in my experience) exhibit this issue.

Which, again, I suppose is why TV broadcasters (certainly BBC/ITV in this country) insist that production companies don't run programme credits horizontally at the end of shows, but vertically or page by page (the closest thing we get to demo techniques in the broadcast world ;-) just to mask how awful it looks.

When I first started using UAE (DOS) and later Fellow (this would be 1997) I was astonished by how capable the emulators were, but immediately noticed the juddery scrolling. And with all of the massive advances of WinUAE over the past 15 years, this fact hasn't changed under Matthias Ortmann, Brian King or Toni Wilen. Because it can't. Figuring this problem out effectively remains an impossible holy grail.

Perhaps those who don't notice the issue weren't gobsmacked at how impressively silky-smooth and awesome an Amiga demo looked on a CRT TV or CBM monitor back in 1988/1989. Programmers used to battle to make their games and demos run at 50 frames per second, endlessly chasing raster time, just so the end product looked alive and vibrant.

I still can't find a way to recapture that using an Amiga with an LCD or WinUAE through HDMI or SVGA... even though my TV is supposedly 100hz. It's the same for many videotaped UK TV shows (even live broadcasts) that just don't have the same characteristics that they used to.

At this point, can I say: IS THERE REALLY A MAGIC BOX COSTING £25 THAT WILL MAKE THIS HAPPEN!?

For those still reading...

In 1997, it wasn't yet possible to watch movies/TV shows on a PC (DVDs didn't yet exist and online streaming (which was still in its Real Player infancy) was expected to look terrible) so UAE was all I had to go on and just assumed it was an issue with the emulation. Then I realised MAME was the same. And Frodo, and in fact anything that sought to emulate something intended to originally run on PAL/NTSC 50/60hz.

In 2003 I bought a 100hz monitor thinking that as it's 50hz divisible, WinUAE would finally look great - but it didn't. And nor did it running on a 100hz LCD TV a couple of years later. It still doesn't. And believe me, I've tried things like Powerstrip and also ruined an ancient monitor that was supposed to scan down to 15khz, etc.

* * *

And now, as my admittedly increasingly bizarre and rambling post draws to a close, we reach its point...

PLEASE *DO NOT* GUARANTEE OR RECOMMEND SOMETHING THAT PURPORTS TO DO THE IMPOSSIBLE based on your own experience - use the facts! I have been looking for a way to consistently achieve what is being claimed in this thread for so many years that (as you have seen) I am particularly passionate about this subject.

For those who essentially claim. "yeah, it looks just like an Amiga used to back in the days of CRT TVs and it's 100% perfect, etc." Just run an intro before game and examine the scrolling before you left-click. Or a demo that horizontally scrolls text (I can't think of any examples there - but there must be at least one!) and... and.. and..

<uses inhaler>

I probably should go to bed now.

[spanner]

Well all I care about is if it works on mine and it looks better then a RF and AV signal and works on my flatscreen..

I don't play demos anyway..

[thgill]

Originally Posted by Zetr0

@thgill

what demo did you use, I would like to try that here.

Honestly...take your pick.

A good example is any of the Kefrens Multi MegaMix music disk releases (all 3 are quite good too).

http://www.pouet.net/prod.php?which=4708
http://www.pouet.net/prod.php?which=4709
http://www.pouet.net/prod.php?which=4713

All 3 are also available in WHDLoad versions.

The bottom of all 3 has your typical scroller with greets and such. First view them on a RGB CRT and then view them through the GBS8220 onto any VGA monitor. LCD or CRT doesn't matter.


Its very VERY noticeable. And this isn't just for these 3 either. Anything with silky smooth 50Hz scrolling suffers the same. But with scrolling Text it almost hits you like a hammer in the face at the difference.

Originally Posted by spanner

Well all I care about is if it works on mine and it looks better then a RF and AV signal and works on my flatscreen..

I don't play demos anyway..

Whats the saying? Ignorance is bliss?

I understand that you are happy that its better than RF and AV and don't view demos, but neither doesn't change the fact that you can not achieve smooth scrolling with this device. End of story. Some may not notice or even be bothered by it. Good for them, I wish I could say the same.

However others, such as ajk, Mark Wright and myself its a different story. It stands out like a sore thumb and destroys the experience for us.

[desiv]

Originally Posted by Mark Wright

PLEASE *DO NOT* GUARANTEE OR RECOMMEND SOMETHING THAT PURPORTS TO DO THE IMPOSSIBLE based on your own experience.

Yes, please for the love of <insert deity or lack thereof here> please don't express your own opinion on a public forum!!

Won't someone please think of the children!!!!!



desiv

[Thorham]

Originally Posted by Mark Wright

I think it's amazing that, after all these years, there remains those among us (like me) who rightly notice the inevitable tearing/jerking of anything designed to scroll horizontally at 50hz (like 99.9% of Amiga demos/games) running on a non-50hz display.

It's just the way the human eyes work. Anyone who uses some device to convert signals who doesn't see this, probably has a converter/monitor combination that can handle 50 hertz (regardless of what the specs say, I've seen 50 hertz rated VGA monitors do less than 50 hertz, for example).

[ajk]

Sorry if this is going too far off topic, but just to illustrate the phenomenon I have made up a graphic:



Now, assuming the animation has loaded completely and runs properly, what you should see in the first panel is Superfrog gliding along smoothly at even intervals, two "pixels" or so at a time. This is what the original 50 Hz output should look like (obviously slowed down a lot here).

The second panel tries to illustrate what happens when the output is 60 Hz instead. As the frames have to be sent out quicker, every now and then there is nothing to send, as a new frame has not come in yet. Therefore the current frame has to be sent out again, and this leads to small stops or stutter in the movement. This is most likely what all of these scan converter boxes, Indivisions etc. do in the situation.

Another option sometimes used in PAL-NTSC video conversions is to blend the frames in the appropriate ratio. So for example if the output frame is best represented by 30% of the previous frame and 70% of the current frame, such a blend is created. This can look decent in the case of television, but the ghosting is pretty obvious if you look closer, particularly with sharp content such as video games.

The "holy grail" of standards conversion would be perfect motion interpolation of the content. 100/120 Hz TV's with "pure motion" etc. technology sort of do this, they estimate an in-between frame to simulate more fluid motion. While this can work reasonably well, it's much more difficult to make an arbitrary conversion. In a 50->60 conversion most output frames would have to be synthetic ones, rather than just every other one. Also even the best algorithms tend to fall apart when there is complex motion, such as things passing in front of each other and so on.

Now again, for anyone who is not bothered by such inaccuracies in motion, this does not matter. But I'm pretty sure the problem itself has not been overcome in any device yet.

[Mendel]

Thanks ajk. This thing that you represent in your superfrog animation on the right is what is happening to me. I wondered what this is and didn´t quite get it. I thought it was some sort of interlacing artifact but then it also happened in progressive resolution so I was a bit puzzled. Also wondered why I can´t see stuttering. This would explain it all.

This effect that slightly blurs the game character is actually sligtly distracting to me, it appears to be worst with Fury of the Furries game out of the games I´ve tried.

Definitely beats actually using 50Hz with a CRT though as that causes headache and eye pain to me

[spanner]

Oh I wanted to ask has anyone got one they could sale me cos I know I can get from ebay but I will have to wait for it up to one month and the cable would be allready made for the Amiga(And I would rather get it from one of you guys)..??

On my mointor if you look at the specs I posted it says:

Vertical Refresh Rate 75 Hz
Horizontal Refresh Rate 60 kHz

And it say:

Native Resolution 1024 x 768 at 75.0 Hz

So mine goes up to 75khz then can it do 60khz..?

Here is a pic of it:

[Zetr0]

@thread

Sorry guys, understand that I do think the world of you. but I really don't have the time to make stuff up and or recommend something that doesn't do as I explained.

I will test out some Demos tonight that thgill posted up and we shall see.

[spanner]

Here is a site that will help you setting up the video conveter GBS-8220 to the Amiga..

http://amigamodblog.blogspot.ca/

[spanner]

Why is Indivision AGA MK 2 so dear..Its was a lost cheaper thats that before...

[desiv]

Originally Posted by spanner

Here is a site that will help you setting up the video conveter GBS-8220 to the Amiga..
http://amigamodblog.blogspot.ca/

Looks nice, but careful..
That blog is telling you to pull power for the GBS from the Amiga video port, which doesn't have the required AMPerage on it for the GBS..

Sounds like a bad idea to me...

desiv

[Zetr0]

indeed it is.

I found the the GBS can be quite a hungry little beast and I would suggest using a good quality 5volt @ 2-3 amps DC power supply.

[thgill]

Originally Posted by Zetr0

@thread

Sorry guys, understand that I do think the world of you. but I really don't have the time to make stuff up and or recommend something that doesn't do as I explained.

I will test out some Demos tonight that thgill posted up and we shall see.

Have you had a chance to test those demos yet?

[spanner]

Originally Posted by Zetr0

indeed it is.

I found the the GBS can be quite a hungry little beast and I would suggest using a good quality 5volt @ 2-3 amps DC power supply.

Can you point me to a good one please,and can I use the connector from a external disk drive on it.is the video port the same size as the disk port..?

I am going to buy the GBS tomorrow..

I was thinking will it work on a xbox(not xbox 360 i have a lead for that,its a special vga lead)

A video on how to install the Indivision AGA MK 2 is on my site now..
http://cbmborg.rumpigs.net/videos.htm

[spanner]

I just bought a GBS 8200 for £14..

Has anyone made a case for one of theses..?

[johnim]

can I use the connector from a external disk drive on it

yes you can the port on the back of floppy is correct

14 from where, link please i want another

[spanner]

Originally Posted by johnim

yes you can the port on the back of floppy is correct

14 from where, link please i want another

Sorry there was only one on ebay..

http://www.ebay.co.uk/itm/1708680052...#ht_546wt_1270

Whats the 2 white connectors on the right,one of them is near the power input..?

There are some going from £21.99 on ebay..

http://www.ebay.co.uk/itm/3006830156...ht_5714wt_1037

I just updated the first post cos most of the posts on here are about this card