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Old 20 May 2009, 12:08   #721
exoticaga
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Originally Posted by NoX1911 View Post
Capture was done with saa7134 chip on 704x576@52µs (philips), cropped to 703 and resized to 768x576 (more here: PDF - Der Karl's Capture Cards aspect ratio for Dummies (on the bottom)).
Link correction: http://www.doom9.org/capture/par.html
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Old 20 May 2009, 16:03   #722
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I did some more testing and measured the Amiga display aspect ratios as accurately as I could on my LCD monitor. Aspect-ratio set to 5:4 to compensate for my 5:4 LCD monitor. KAR disabled. All tests were done with a PAL screen with PAL circle and NTSC screen with NTSC circle. Initially WinUAE was in FS mode, I made the measurements and then without making any changes to the Amiga side I simply hit F12 and enabled Auto-Scale and made the measurements again. Results below. 4:3=1.3333, 5:4=1.25. The aspect ratio should be 1.333 for all four tests.

FS:
NTSC 1.326 (round circle)
PAL 1.235 (stretched circle)

Auto-Scale:
NTSC 1.328 (round circle)
PAL 1.328 (round circle)

As you can see FS with PAL is the only one that has the wrong aspect ratio and wrong circle. There's a bug in FS PAL.
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Old 20 May 2009, 17:29   #723
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I was viewing the link hexxaae gave me on my PC, I don't do the internet with WinUAE. The monitor on my PC is a 5:4, and that's the problem with viewing his link.
I don't get it. When you use a 5:4 monitor you should select a 5:4 resolution like 1280x1024, then nothing gets stretched and everything is exactly the way it is on 4:3 monitors (with a little more vertical space). And in WinUAE you compensate by selecting 5:4 AS WELL as a 5:4 resolution, then you also get the same thing as 4:3 owners.

I have a 5:4 monitor, I'm using a 5:4 resolution and his screenshots look as they should (first three round, fourth squashed). There's nothing like "as accurately as I could", it's exactly the same when viewing screenshots. WinUAE is a different tale, but since 1280x1024 is much bigger than Amiga's native display, the difference after scaling is almost exactly close to zero.

Of course, you can also select 4:3 resolutions on a 5:4 monitor, but you have to disable hardware and driver stretching, so that you'll get black borders on top and bottom. Then it's no difference with 4:3 monitors.

Last edited by aidenn; 20 May 2009 at 17:38.
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Old 20 May 2009, 17:47   #724
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Note that also NTSC-checkbox in display panel affects how filtering works.

EDIT: if NTSC hardware: NTSC is "base" resolution. if PAL hardware: PAL is "base" resolution.

Last edited by Toni Wilen; 20 May 2009 at 19:51.
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Old 20 May 2009, 20:38   #725
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What i don't understand is why is the simple mathematical model invalid or unacceptable? The Amiga has DAR4:3 and 5:4 resolutions resulting in a PAR16:15 (or 640x512 -> 640x480 correction on square pixel/winuae). Everyone would scale the max CLI window (5:4) to a 4:3 display area on a real Amiga and that's what i would call the standard Amiga PAR 1.0666:1 as well.

There are ported games like bomberman that come from arcade machines or consoles with even more exotic PARs. These imported gfx are also completely wrong for Amiga displays. No one cared about it...

Regarding PPaint: To create a clean round circle on the Amiga you'd have to have (per definition) the same diameter/radius (distance) for x and y, right? To achieve that PPaint would need to compensate the non-square pixels. But it does not. Instead x and y have same pixelcount (for x and y) by different pixelsize so PPaint circles cannot be round by design on a typical Amiga environment.


Box size coords in top-right corner

Even if there is (technically) something like a reference signal (like the composite capture attempt) its meaningless since CRTs geometry wasn't static. That's why they put the geometry menu in the frontend of dedicated monitors.

Unless i'm somewhere completely wrong i'll drop the composite signal measurement. I don't think it leads to anything helpful.

If there was something intended by design than it was a 4:3 display. And that can be calced easily. My opinion...

Last edited by NoX1911; 20 May 2009 at 20:50.
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Old 20 May 2009, 20:58   #726
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Quote:
Originally Posted by NoX1911 View Post
Regarding PPaint: To create a clean round circle on the Amiga you'd have to have (per definition) the same diameter/radius (distance) for x and y, right? To achieve that PPaint would need to compensate the non-square pixels. But it does not. Instead x and y have same pixelcount (for x and y) by different pixelsize so PPaint circles cannot be round by design on a typical Amiga environment.
As far as I can see PPaint DOES compensate PAL/NTSC pixel aspect when you draw circles in non 1:1 mode. Try yourself, PPaint is free: http://aminet.net/search?query=ppaint
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Old 20 May 2009, 21:04   #727
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It has nothing to do with PAL/NTSC vs Square. For me, DAR4:3 is reference area and 5:4 the resolution (640x512).

And on the picture i made (that is PPaint) you can clearly see in the upper right corner that the box size is 41x41 pixel. If this would have been PAR compensated it should be something like 41x44 Pixel to be round for your eyes.
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Old 20 May 2009, 21:07   #728
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Stop talking about theory. Real Amiga + real display device proof only accepted as usual
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Old 20 May 2009, 21:18   #729
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What do you consider as proof? A round circle manually measured on a CRT display? Not really...
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Old 20 May 2009, 21:23   #730
Toni Wilen
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Originally Posted by NoX1911 View Post
What do you consider as proof? A round circle manually measured on a CRT display? Not really...
Program that shows round circle on real display (see my above posts. type of device is important!) and does not show round circle on emulation.

I have stopped assuming long long time ago. It is never as simple as it should be..
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Old 20 May 2009, 22:13   #731
Toni Wilen
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http://files.winuae.net/beta/winuae.zip

NTSC hardware in PAL mode aspect ratio issue should be fixed now.
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Old 20 May 2009, 23:27   #732
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I already gave the proof that PPaint is working with square pixels internally and thus it only produces round circles on square pixel displays. No one should try to find these as round ones on real amiga equipment. If so, you're on PAR1:1 like winuae.

Whatever you do, i hope you also include/remain a 5:4->4:3 scaling option (x=x*16/15).

Last edited by NoX1911; 21 May 2009 at 00:36.
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Old 20 May 2009, 23:27   #733
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Quote:
Originally Posted by Toni Wilen View Post
http://files.winuae.net/beta/winuae.zip

NTSC hardware in PAL mode aspect ratio issue should be fixed now.
Now FS + KAR:<any> keeps the same aspect ratio when in Fullscreen/Fullwindow or Windowed and that's ok for both PAL and NTSC.

NTSC in FS + KAR:VGA now looks exactly as it was previous beta in KAR:TV and vice-versa now KAR:TV looks like previous KAR:VGA.
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Old 20 May 2009, 23:49   #734
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But is it correct?

I have limited test scenarios right now (only PAL games), but everything looks perfect with FS + KAR:VGA (TV is stretched but I assume that's how it should look). I have one problem with KAR and 5:4 though - the black border that keeps the ratio is only on top. Could the display be automatically centered with borders on top and bottom?
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Old 21 May 2009, 00:34   #735
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Here are two circles that are 5:4 prescaled. In my opinion these ones should be round on a real Amiga.

For 640x256 and 640x512 resolutions, IFF/ILBM, brushes for ppaint.
If possible maximize the working area as good as possible to the visible area of your display. The working area is the one the mouse pointer can move in.

@Toni Wilen:
Why not implement a 'PAR correction' option that offers input fields for PAR x:1 and y/z (as a calculator for x). Technically, you just need to multiply the x-axis (e.g. 640) with the PAR value and rescale with that relation (optionally add another local display PAR correction factor if necessary). Give it a 'save' and 'load' button and some templates (e.g. 16/15=5:4 to 4:3 conversion, 27/26=composite measurement, and so on). This way there's always the option to add more if necessary and you can go on with other development.
Attached Files
File Type: zip ppaint-round-circles.zip (2.3 KB, 124 views)

Last edited by NoX1911; 21 May 2009 at 17:29.
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Old 21 May 2009, 03:27   #736
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Hi mates,

there's one thing I don't understand: let's consider, for a moment, only those Amiga games/programs with circles which appear horizontally/vertically widened/shortened on a *real* 4:3 CRT display (with default from-fabric calibration, hence not 100% perfect) connected to a *real* Amiga.

Do you/we want to obtain a similarly widened/shortened circle in WinUAE (so that it would be as near as possible to the real thing), or would it be preferable to have it perfectly round "at all costs" (but different from the result on the real thing)?

In other words, is it preferable to enhance/correct these programs' behaviour or let them run (with defects) as they were on the real machines with their "old" displays, not geometrically perfect?
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Old 21 May 2009, 04:18   #737
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The goal is to get the real thing as near as possible in winuae. The problem is the definition of 'real thing'. I say its the working area (640x512 or SAR5:4) maximized to the visible area of the display (DAR4:3) resulting in PAR=16/15 (16:12 / 15:12).

SAR = storage aspect ratio (ratio of resolution, 640:512 or 5:4)
DAR = display aspect ratio (ratio of display dimensions or visible area, typically 4:3)
PAR = pixel aspect ratio (PAR = DAR / SAR)
PAR2:1 means pixels are twice in width against the height. A box of 8x16 pixel is square on such displays.
PAR1:1 is square pixels.

The value in question is the DAR of CRTs. Old CRTs change their geometry over time (temperature impact, component "drifting"...). They are strictly speaking not 4:3 anymore. That's why i consider measurements with rulers on CRTs as unreliable. Even if you calibrate the edges the linearity across the axis is lost and too complex to compensate (even with pin cushion, trapezoid, bow, parallel and whatever options).

A completely different and not yet mentioned point is the power of Denise (Display Encoder Chip). I'm not sure if output timing of Denise could be changed individually. If so it's theoretically possible to create custom resolutions with all kind of PARs in the PAL/analog world. If developers used that it would need accurate emulation of Denise to get proper results.

Last edited by NoX1911; 21 May 2009 at 06:09.
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Old 21 May 2009, 04:41   #738
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Quote:
Originally Posted by NoX1911 View Post
The goal is to get the real thing as near as possible in winuae. The problem is the definition of 'real thing'. I say its the working area (640x512 or SAR5:4) maximized to the visible area of the display (DAR4:3)
Ok, but... why maximize the working area to ALL the visible area of the display?
Why not leaving untouched the empty/unused area in the lower part of the screen (as it is on real machines. Quite a lot for NTSC Amigas, almost nothing for PAL Amigas) ?

Sorry if this sounds as a stupid question...

Quote:
The value in question is the DAR of CRTs. Old CRTs change their geometry and wear out over time (temperature impact, component "drifting" and so on). That's why i consider measurements with rulers on CRTs as unreliable.
I agree. Then wouldn't it be relatively simpler for Toni to assume an "ideally set" CRT display? Mmmm, I suppose this is what Toni did.

Last edited by Supamax; 21 May 2009 at 05:17.
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Old 21 May 2009, 06:02   #739
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Ok, but... why maximize the working area to ALL the visible area of the display?
That's just for illustration/mathematical purpose (or in case of CRT scaling to get a approximate 4:3 area). We are working with relations only so it doesn't matter. Once we have the PAR factor we can scale the picture like we want (with fixed proportions) to also see the overscan area for example.

Quote:
Originally Posted by Supamax View Post
Why not leaving untouched the empty/unused area in the lower part of the screen (as it is on real machines. Quite a lot for NTSC Amigas, almost nothing for PAL Amigas) ?
The black bottom border with NTSC is only visible on PAL machines. On true NTSC environments it should be fullscreen (like PAL) as well. That's why the PAR differs a lot between those two standards.
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Old 21 May 2009, 06:35   #740
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For calculating standard PAR for amiga, shouldn't everyone be using something like approx 768x576 like NoX1911 did? Or 704x576 or 720x568 or whatever.... In other words whatever the max PAL/NTSC amiga resolution (or PAL/NTSC TV standard) in a 4:3 ratio == Amiga standard PAR (which is essentially what I think NoX is saying). Which is just a mathematical equation rather than empirical evidence. 640x512 is only part of the Amiga's display. There is full overscan and the PAL (and NTSC) standard to consider.

Although I think Toni would know the Amiga's maximum display resolution capability in PAL/NTSC modes with overscan (due to WinUAE code) and how that compares with the PAL and NTSC standards.

Just my opinion. Carry on

EDIT: The flip side may be that e.g. for PAL 320x256 on a 4:3 display was considered standard display res that everyone used so that should be used to calculate the PAR.

EDIT2: Disregarding all this scaling stuff, if you use a 768x576 (4:3) screenmode and then run WinUAE with that with a 1:1 pixel ratio, would that not give you the correct PAR for Amiga PAL modes on square pixel PC monitors, considering that PAL max = 768x576.

Last edited by Calgor; 21 May 2009 at 06:42.
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