Questions about the Jags Max Resolution

[Willard]

I know that Thunderbird and Jagware have each produced some hi-res demos featuring still images for the Jaguar... does anybody know what the max horizontal and vertical resolution is for a still image? Does this affect color depth? Has it been achieved?

 

Also, what is the max in-game resoluition (im guessing 320x240)?

[segasaturn]

From looking at online websites here's what I got......

 

Display:

- Programmable screen resolution. Horizontal resolution is dependent on the amount of scanline buffer space given to the "Tom" graphics processor. Maximum vertical resolution varies according to the refresh rate (NTSC or PAL). Reportedly, a stock Jaguar (without additional memory) running NTSC can display up to 576 rows of pixels.

- 24-bit "True Color" display with 16,777,216 colors simultaneously (additional 8 bits of supplimental graphics data support possible).

- Multiple-resolution, multiple-color depth objects (monochrome, 2-bit, 4-bit, 8-bit, 16-bit, 24-bit) can be used simultaneously.

 

If you want the website with LOTS of Jaguar spec's:

 

http://www.vgmuseum.com/systems/jaguar/

[Gorf]

From looking at online websites here's what I got......

 

Display:

- Programmable screen resolution. Horizontal resolution is dependent on the amount of scanline buffer space given to the "Tom" graphics processor. Maximum vertical resolution varies according to the refresh rate (NTSC or PAL). Reportedly, a stock Jaguar (without additional memory) running NTSC can display up to 576 rows of pixels.

- 24-bit "True Color" display with 16,777,216 colors simultaneously (additional 8 bits of supplimental graphics data support possible).

- Multiple-resolution, multiple-color depth objects (monochrome, 2-bit, 4-bit, 8-bit, 16-bit, 24-bit) can be used simultaneously.

 

If you want the website with LOTS of Jaguar spec's:

 

http://www.vgmuseum.com/systems/jaguar/

 

 

 

I have personally done 800 horizontal pixels across but the 240 vertical makes it less than a

reasonable ratio. To get a higher vertical res, you need to tricks and the Jaguar at higher

resolution will have serious performance problems depending on the amount of action you

intened to have in your game. 2D you might have a cold chance in hell, but I would not even

think about such a thing trying 3D in that high a resolution. To go even higher than using the

tricks for more vertical line, you need additional hardware.

Edited January 24, 2010 by Gorf

[kskunk]

A US Jaguar is capable of progressive output at 720x480p (using VGA timing). Interlaced, it can reach 1280x480i. In PAL you can get slightly more horizontal lines, 720x576p and 1280x576i. Either mode pushes the Jaguar to its limit. (The Jaguar chips can do higher res, but it's not supported in the console.)

 

It's possible to do 2D graphics in these modes at 60FPS. But Gorf is right, the sophistication of the graphics is limited at these resolutions. At best you can get a single scrollable background layer with some sprites on top (not too many). There could be enough bandwidth to do 24-bit color at these resolutions (with a little letterboxing) but there'd be no time or space left for a game. A 1280x576x16M image needs 2.88MB of DRAM and the Jaguar only has 2MB!

 

16-bit color fits in memory and bandwidth, with "only" 1.44MB needed per 1280x576 still image.

 

- KS

Edited January 24, 2010 by kskunk

[Zerosquare]

From an old topic :

If you want to display it on a TV (so 50 or 60 Hz, interlaced), 1400x486 @ 60 Hz and 1383x576 @ 50 Hz.

 

If you don't care about the refresh rate, then 1440x4096 interlaced... @ 9 Hz

Those numbers are for 16-bit color modes. For 24-bit, the maximum horizontal resolution is limited to 720 pixels by the line buffers' size. Edited January 24, 2010 by Zerosquare

[Gorf]

The fact is, even though a machine might display a high rez with higher color, it is best to use it

at it's strength's and get a great app rolling on it then to simply max it out for the sake of saying

you did so. Let's face it, though the game may 'look' great, the chances of it playing great when

you start to push it that hard become slim to none.

Edited January 24, 2010 by Gorf

[kskunk]

If you want to display it on a TV (so 50 or 60 Hz, interlaced), 1400x486 @ 60 Hz and 1383x576 @ 50 Hz.

 

If you don't care about the refresh rate, then 1440x4096 interlaced... @ 9 Hz

Thanks, your numbers are much more precise than mine! I compared your timings to CCIR 601 and you're dead on.

 

Those numbers are for 16-bit color modes. For 24-bit, the maximum horizontal resolution is limited to 720 pixels by the line buffers' size.

You're correct, if you use the chip as intended. You can squeak out more horizontal resolution by running the OP more than 2 times per scan line. This is possible by banging the video block registers -- the registers are not locked during video so you can, Atari 2600 style, modify them at strategic times to get as many horizontal (or even vertical) pixels as you desire. Once nice feature is that the video block only reads from the registers as it reloads internal counters, allowing you to be pretty sloppy with the timing if you were to try something this crazy.

 

Bandwidth is a problem though. Even though the Jaguar technically has enough bandwidth to support 24-bit color at max resolution, there's an OP bug that limits it to 66% of peak. So you'd need some letterboxing on the sides.

 

- KS

[Willard]

Here is an old topic that features a hi-res image demo that I was referring to:

 

http://www.atariage.com/forums/topic/87202-a-688576-picture-on-jaguar/

 

I have a few more questions that will likely exploit how little I know about TV resolution, but anyway: If I'm not mistaken, the max resolution of a CRTV is 1024X768, so the Jaguar can produce an image that exceeds that? Also, the standard video cables for the Jag are S-video, Composite and RF are limited to:

 

S-Video: 720X480 (640X480 Display Resolution)

Composite: Similar

RF: ?

 

If this is true, how do the cables handle images that are a higher res than their maximum capability?

 

Anyway, if I understand right the Jag can produce an image with a higher vertical res than 240 but anything higher severely restricts game interactivity. Also, hi-res images on the Jag are more suitable for a CD project than a cartridge project as they take up way too much space.

[Zerosquare]

You're correct, if you use the chip as intended. You can squeak out more horizontal resolution by running the OP more than 2 times per scan line.

Yep, I had been thinking about doing something like that (never actually tried it, though)

I don't want to think about the bandwidth and processor power that would be required

 

If I'm not mistaken, the max resolution of a CRTV is 1024X768

CRT TVs (those without digital processing, that is) don't really have a resolution : although the vertical number of lines is defined, the signal for each line is analog and continuous, it is not divided into discrete pixels. Of course the sharpness isn't infinite either, it is limited by other factors (pitch, focus, video amplifiers bandwidth...)

So, no contradiction here

 

Also, the standard video cables for the Jag are S-video, Composite and RF are limited to:

 

S-Video: 720X480 (640X480 Display Resolution)

Composite: Similar

RF: ?

 

If this is true, how do the cables handle images that are a higher res than their maximum capability?

It's a bit more complicated than that. The standards actually limit the video bandwidth ; from that you can calculate the theoretical maximum resolution they could achieve without loss. (BTW, the actual numbers are lower that those you quoted, especially for composite and RF). But since it's analog, if the original signal has a higher resolution, it basically means that the small details won't be reproduced accurately.

I recommend using an RGB (SCART) cable (with a compatible TV or monitor) to view those demos, since the effect will be partly lost with RF, composite or S-video

[Willard]

You're correct, if you use the chip as intended. You can squeak out more horizontal resolution by running the OP more than 2 times per scan line.

Yep, I had been thinking about doing something like that (never actually tried it, though)

I don't want to think about the bandwidth and processor power that would be required

 

If I'm not mistaken, the max resolution of a CRTV is 1024X768

CRT TVs (those without digital processing, that is) don't really have a resolution : although the vertical number of lines is defined, the signal for each line is analog and continuous, it is not divided into discrete pixels. Of course the sharpness isn't infinite either, it is limited by other factors (pitch, focus, video amplifiers bandwidth...)

So, no contradiction here

 

Also, the standard video cables for the Jag are S-video, Composite and RF are limited to:

 

S-Video: 720X480 (640X480 Display Resolution)

Composite: Similar

RF: ?

 

If this is true, how do the cables handle images that are a higher res than their maximum capability?

It's a bit more complicated than that. The standards actually limit the video bandwidth ; from that you can calculate the theoretical maximum resolution they could achieve without loss. (BTW, the actual numbers are lower that those you quoted, especially for composite and RF). But since it's analog, if the original signal has a higher resolution, it basically means that the small details won't be reproduced accurately.

I recommend using an RGB (SCART) cable (with a compatible TV or monitor) to view those demos, since the effect will be partly lost with RF, composite or S-video

 

Thanks to all for the information, have to really read up on some of the terms you mention when I get time to completely understand it all.

 

I now know what the maximum resolution is that the Jag can produce, so now I have another question derived from some of your answers:

 

What is the maximum resolution (ballpark if not precise) that an S-Video cable can display without quality loss? From your answers above, I'm guessing that the RF and Component can display the same image, only WITH quality loss?

[Zerosquare]

The vertical resolution is always 486 pixels for NTSC and 576 pixels for PAL.

 

Except for component (RGB or YUV), the horizontal resolution is difficult to evaluate, it depends on the quality of the source and the TV. A good margin would be 320 to 640 pixels, with usually RF and composite in the lower range, and S-video in the higher range. BTW, this resolution is the one for luminance ; the color resolution is much lower.

Edited January 24, 2010 by Zerosquare

[kskunk]

The fact is, even though a machine might display a high rez with higher color, it is best to use it

at it's strength's and get a great app rolling on it then to simply max it out for the sake of saying

you did so. Let's face it, though the game may 'look' great, the chances of it playing great when

you start to push it that hard become slim to none.

This is a good point. This thread made me try to think of games that could benefit from a high resolution.

 

Just like the Nintendo Wii, the Jaguar is capable of 720x480 progressive anamorphic wide-screen output. You have to use RGB to do it, but the quality is really good, even on an HDTV.

 

I was thinking you could do a nice looking pinball game at these resolutions, where the pinball playfield was a scrolling 256 color background with only a few sprites on top.

 

As another thought, a program specially designed for component video could support "standard" YCbCr-style component cables by driving the RGB lines in the YCbCr color space. YCbCr color has interesting properties when driven via the Jaguar's CRY converter -- now you have a fixed palette of 256 color/luminance combos that can be separately smooth shaded.

 

Any other game genres that have relatively static high-res graphics?

 

- KS

Edited January 25, 2010 by kskunk

[Zerosquare]

A breakout clone ?

[Pocket]

strategy games, turn based ones

[Atari_Owl]

pinball?

point and click adventures?

[Gorf]

Those suggestions are fine for an Atari ST but for the Jaguar? I guess if you must. I suppose the pinball

one is not too bad. Now if you are making an arcade perfect clone of a game, yeah. That's never a bad thing.

But a Breakout clone would not need such high color nor high resolution. Of course you can make a BreakOut

plus like game.

[philipj]

I guess anything other then 2D would be too much for the Jag to handle at a high resolution of 720x480.

[Gorf]

I guess anything other then 2D would be too much for the Jag to handle at a high resolution of 720x480.

 

 

Oh it could handle it...at a low frame rate.

[kskunk]

I guess anything other then 2D would be too much for the Jag to handle at a high resolution of 720x480.

Flat shaded polygons are doable at high framerates at those resolutions -- STUN Runner or Hard Drivin' style. This would use CLUT mode to keep the framebuffer and number of colors very small, and the blitter texture rate as high as possible.

 

Also wireframe 3D would be blazing fast. The Jaguar is very good at drawing lines.

 

- KS

[Austin]

Flat shaded polygons are doable at high framerates at those resolutions -- STUN Runner or Hard Drivin' style. This would use CLUT mode to keep the framebuffer and number of colors very small, and the blitter texture rate as high as possible.

 

Also wireframe 3D would be blazing fast. The Jaguar is very good at drawing lines.

 

- KS

 

Yeah, wouldn't a vector-based game be fine? No crazy colors and fill effects like Tempest 2000, of course, just straight-up wires.

 

Also, as far as higher than the low, normal resolutions for consoles in the early/mid '90s, Last Gladiators Pinball on the Saturn is a good example of a pinball game done at a higher resolution. Not sure if that would work as well on the Jag, but it might be remotely feasible.

[Gunstar]

I guess anything other then 2D would be too much for the Jag to handle at a high resolution of 720x480.

Flat shaded polygons are doable at high framerates at those resolutions -- STUN Runner or Hard Drivin' style. This would use CLUT mode to keep the framebuffer and number of colors very small, and the blitter texture rate as high as possible.

 

Also wireframe 3D would be blazing fast. The Jaguar is very good at drawing lines.

 

- KS

 

sorry double post

Edited January 31, 2010 by Gunstar

[Gunstar]

I guess anything other then 2D would be too much for the Jag to handle at a high resolution of 720x480.

Flat shaded polygons are doable at high framerates at those resolutions -- STUN Runner or Hard Drivin' style. This would use CLUT mode to keep the framebuffer and number of colors very small, and the blitter texture rate as high as possible.

 

Also wireframe 3D would be blazing fast. The Jaguar is very good at drawing lines.

 

- KS

 

Nothing to do with the Jag's High resolutions, but just wanted to point out or remind people that the CD version of Hover Strike has a wireframe cheat code (same as the change texture cheat on the cart, but on the CD it reduces the game to wireframe). The framerate exponentionally increases when this is done and it really does turn the game into a 'BattleZone 2000' type of game. Great stuff if you only hate HS becuase of relative slow and choppy frame-rates.

[kool kitty89]

I have a few more questions that will likely exploit how little I know about TV resolution, but anyway: If I'm not mistaken, the max resolution of a CRTV is 1024X768, so the Jaguar can produce an image that exceeds that? Also, the standard video cables for the Jag are S-video, Composite and RF are limited to:

 

S-Video: 720X480 (640X480 Display Resolution)

Composite: Similar

RF: ?

 

If this is true, how do the cables handle images that are a higher res than their maximum capability?

I believe the Jaguar outpurs RGB as well, which could either be at SDTV compatibile frequencies (so work on some high-end NTSC multimedia monitors, old ST/Amiga RGB monitors, or some early VGA monitros with CGA/EGA support, or SCART on PAL sets) which would limit it to 240p/480i 60Hz or 288p/576i 50 Hz. (horizontal res not having a hard limit) Given what was mentione dbefore, it can also support other timing, so higher res should be possible via an HDTV/VGA monitor via RGB.

 

But as for max horizontal resolution of various transmition methods for SDTV, that depends somewhat on the monitor (the sharpness/calibration of the scan and dot pitch of the phosphor screen of a CRT). Really good RF can be virtually indistinguishable to Composite video usually with slight interferance still visibel (most noticable on solid color screens) ranging to aweful noise with poor modulators on crappy TVs. (RF is also directly dependent on the composite video quality)

Composite video will depend on the quality of the video encoder used as well as the TV/monitor's comb filter, but will be worse than S-video and the luma signal will be degraded to soem degree compared to S-video (or YPbPr component video), you probably won't be able to clearly discern pixels in a display greater than 320 pixels wide via composite video though, not that higher values won't provide a better looking or smoother picture even in composite. (anything over 512 pixels wide is probably getting a bit wastefull in composite)

S-video has limited chroma (color) resolution, soemwhat better than composite I believe, but not a whole lot better (same color carrier, PAL being superior to NTSC in this respect), luma is separate though, so will not suffer degradation and should be identical in quality to YPbPr component video an dsimiler to RGB. (so with a black and white immage -or color turned off on the TV/monitor, it's great, the color is th ellimiting factor -plus the monitor itsself -scan, dot pitch and such)

Even via RGB or component video, once you get to 640-720 pixels wide, it's hard to distinguish individual pixels on any SDTV regardless of transmition method (maybe a multimedia monitor with fine dot pitch) and anything over 720 probably wouldn't give any advantage either. (probably why they stop at that value for SDTV format -sometimes 704 pixels)

 

Do note that th eluma signals used for composite, S-video, and YPbPr component video are all compatible, in fact you get a nice, crisp grayscale immage if you plug the Y/luma connector (green) into a composite video port on a TV.

 

Anyway, if I understand right the Jag can produce an image with a higher vertical res than 240 but anything higher severely restricts game interactivity. Also, hi-res images on the Jag are more suitable for a CD project than a cartridge project as they take up way too much space.

For standard definition TVs, you can only get 240p/480i lines at 60 Hz or 288/576 lines for PAL, again horizontal res is variable.

 

There's also overscan to consider, most TVs have a good bit of both vertical and horizontal overscan, horizontal resolution can be compensated for assuming most TVs have the same amount of overscan (a wider horizontal resolution is output and then clipped to the desired visible resolution -with blank overscan or unnecessary graphics in overscan -as with safe frames in video), for vertical overscan you're going to lose lines as they're fixed, for both PAL/NTSC ~16/32i lines tend to go into overscan (so 224/448i lines 60 Hz and ~272/544i lines in 50 Hz), this can either be clipped or simply allowed with necessary visible objects withing the normal viewing area. (NES games for example, all use the full 240 lines) Some things don't compensate at all (even in a safe frame manner) and you lose graphics to overscan. (I've especially noticed this in some newer games, moreso for horizontal overscan than vertical)

 

Thus, it would likely be preferred to clip the display to 224/448i lines for anything intended for NTSC on the Jaguar. (to save precious DRAM usage) interlace also limits you to 30/25 frame per second maximum (for 60/50 Hz) or suffer combing artifacts.

 

Note:You can manually calibrate a TV to show overscan, either by adjusting pots on old TVs (sometiems accessible externally) or via a service menu accessed with the remote)

 

Flat shaded polygons are doable at high framerates at those resolutions -- STUN Runner or Hard Drivin' style. This would use CLUT mode to keep the framebuffer and number of colors very small, and the blitter texture rate as high as possible.

 

Also wireframe 3D would be blazing fast. The Jaguar is very good at drawing lines.

 

- KS

 

Yeah, wouldn't a vector-based game be fine? No crazy colors and fill effects like Tempest 2000, of course, just straight-up wires.

Oh, how about an arcade perfect (rasterized) Star Wars/Empire Strikes back conversion. That would have been awesome though.

Plus you could have hidden line removal, not just simple wireframe models.

 

But an actual Hard Drivin' (or Race Drivin') port to the Jaguar would have been nice to see as well, particularly given it was an Atari Games release, maybe even with some enhancements with 2D scaled scenery -it that fit, the Saturn port did that.

Edited February 1, 2010 by kool kitty89

[kskunk]

But an actual Hard Drivin' (or Race Drivin') port to the Jaguar would have been nice to see as well, particularly given it was an Atari Games release, maybe even with some enhancements with 2D scaled scenery -it that fit, the Saturn port did that.

My vote's for S.T.U.N. Runner! It uses the same basic hardware as Hard/Race Drivin'/Steel Talons. And in all those games, the main gameplay runs on a 68K with basic DSP assistance. To me, they always seemed like a good fit for the Jaguar, although I'm sure the games were considered pretty old fashioned by 1994.

 

As an aside, hidden line removal is really computationally intensive. It's almost equal work to do flat shaded polys, at least on the Jaguar. Plain old wireframe without line removal is definitely faster though.

 

- KS

[philipj]

The "Stun Runner Hardware" use Texas Instrament DSP that runs a little faster then the Jags DSP's. However I'm sure the Jags blitter can make up for whatever would be lacking if use properly.