Ham mode

[hammer]

Originally Posted by albino

Hi everyone, just wondering what additional hardware the Amiga 500 would have needed to exploit this mode for video games use?

[ Show youtube player ]
Running Quake in Amiga 500's HAM mode with PiStorm-Emu68 accelerator.

[ Show youtube player ]
Amiga 500 with 14Mhz 68000 playing a youtube video playback. This video playback capability is useful when there is a powerful CPU generating frames for real-time HAM mode video playback.

[TEG]

Originally Posted by hammer

[ Show youtube player ]
Running Quake in Amiga 500's HAM mode with PiStorm-Emu68 accelerator.

I'm suspicious of this one because of so few (none?) HAM typical colors artefacts.

[pixie]

Originally Posted by hammer

[ Show youtube player ]
Running Quake in Amiga 500's HAM mode with PiStorm-Emu68 accelerator.

[ Show youtube player ]
Amiga 500 with 14Mhz 68000 playing a youtube video playback. This video playback capability is useful when there is a powerful CPU generating frames for real-time HAM mode video playback.

I imagined something like a continuous stream online, like a tv channel you could watch over the internet on the Amiga! xD

[AestheticDebris]

Originally Posted by TEG

I'm suspicious of this one because of so few (none?) HAM typical colors artefacts.

Quake has a somewhat samey colour palette, so maybe it just optimises better than you'd imagine compared to very generic imagery. And probably YouTube's own compression artefacts are helping hide the quirks too.

[Karlos]

Back in the day, I had an idea that I never tried, but perhaps the Emu68K/OCS makes it feasible. The idea was to use HAM6 interlace 320*400 for a 320*200 display in which each logical pixel is split into two physical pixels vertically.

The point of this was to try and take 15-bit RGB logical pixels and during conversion to HAM planar (12-bit colour) diffuse the least significant bit of each channel into the two half pixels. The "brighter" half pixels would alternate in a checkerboard parttern and invert every frame too.

It would probably be a flickery mess. I dunno.

[Aladin]

Without Ham mode, quake could not run on OCS. Quake has 256 colors. the exe is in the zone.

[robinsonb5]

Originally Posted by Karlos

The point of this was to try and take 15-bit RGB logical pixels and during conversion to HAM planar (12-bit colour) diffuse the least significant bit of each channel into the two half pixels. The "brighter" half pixels would alternate in a checkerboard pattern and invert every frame too.

It would probably be a flickery mess. I dunno.

It's certainly possible to get some nice results with that kind of mix of spatial and temporal dither - I've done something similar to smooth out gradients in a chequerboard floor effect on ECS. it'd be interesting to see how it interacts with the constraints of HAM mode.

(When working on the Minimig core for Turbo Chameleon 64 I use a DE10lite since its FPGA is the same tech level but twice the size - and that board only has four bits per gun on its VGA output. I use a similar dither to what you describe to gain two bits, as well as two bits from an LFSR to gain another two - the result's surprisingly good. One trick I do use, though, is to use one dither matrix for red and blue, and its inverse for green, to reduce the intensity change from frame to frame and make the flicker less noticeable. http://retroramblings.net/?p=1419 )

[Karlos]

Cool. I guess the idea had legs then.

[hammer]

Originally Posted by TEG

I'm suspicious of this one because of so few (none?) HAM typical colors artifacts.

It depends on the artwork's color range. HAM mode is good for natural color range but anime artwork can show HAM artifacts. [ Show youtube player ]

[PortuguesePilot]

Originally Posted by hammer

[ Show youtube player ]
Running Quake in Amiga 500's HAM mode with PiStorm-Emu68 accelerator.
(...)

If this is true, it is EXTREMELY impressive.

[Bruce Abbott]

Originally Posted by TEG

I'm suspicious of this one because of so few (none?) HAM typical colors artefacts.

Hard to tell because the video is so washed out, but I think we have to believe it. What impresses me is how fast and smooth it is. My A3000 with 66MHz 060 and RTG card couldn't get anywhere near that - it was barely playable. That you can do this good on an A500 is amazing! Perhaps I will rethink my reticence to buy a PIStorm.

Originally Posted by hammer

It depends on the artwork's color range. HAM mode is good for natural color range but anime artwork can show HAM artifacts. [ Show youtube player ]

The color fringing on the left edge shows that this video was badly encoded, but apart from that it looks pretty good, especially for a chipset from 1985!

[Thorham]

Originally Posted by Bruce Abbott

The color fringing on the left edge shows that this video was badly encoded, but apart from that it looks pretty good, especially for a chipset from 1985!

Seeing how that video is in HAM8, a better algorithm could've produced much better quality, even with a fixed palette. Check out meynaf's HAM8 image viewer to see what can be done with a fast algorithm already. With a dynamic palette and a slower algorithm it should be even better.

[BSzili]

Originally Posted by PortuguesePilot

If this is true, it is EXTREMELY impressive.

It is true, I implemented the same algorithm by Samuel Devulder in my Build ports. It works surprisingly well, but unfortunately very memory intensive due to the large lookup tables it requires. On 68060 processors it cuts the framerate in half. Here's a video of Blood running in HAM mode:
[ Show youtube player ]

[pixie]

This can be the HAM Renaissance! xD

[Karlos]

Have you guys seen the HAM8 raycaster demo?

[Reynolds]

Originally Posted by Aladin

Without Ham mode, quake could not run on OCS. Quake has 256 colors. the exe is in the zone.

I've ran Quake way back on my A2000 with 030, FPU and Fast ram. It was slow as hell, and had definitely less colour than on AGA, but it worked.

[Karlos]

Originally Posted by Reynolds

I've ran Quake way back on my A2000 with 030, FPU and Fast ram. It was slow as hell, and had definitely less colour than on AGA, but it worked.

I am pretty sure that C2P using EHB modes are a thing.

I remember running quake on my 040/AGA back in the day and just marvelling that it was possible at all. It was a total slideshow, but still.

[Seiya]

Originally Posted by hammer

[ Show youtube player ]
Running Quake in Amiga 500's HAM mode with PiStorm-Emu68 accelerator.

Amiga 500's HAM games run on Workbench 1.3, 68000@7 Mhz and 1 MB RAM, or 2 MB.
What kind of idea of HAM you can have with testing games that require FPU, Fast Processor, AmigaOS 3.x and lot or RAM?

[Karlos]

Originally Posted by Seiya

Amiga 500's HAM games run on Workbench 1.3, 68000@7 Mhz and 1 MB RAM, or 2 MB.
What kind of idea of HAM you can have with testing games that require FPU, Fast Processor, AmigaOS 3.x and lot or RAM?

Anything that wants to use HAM as alternative to 256 colours or highcolour display.

[Seiya]

Understood.
I thought this topic was to test ham mode on real or emulated A500 with classic configuration: kick 1.3 and 68000@7 Mhz