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AuthorTopic: The astonishing unpopularity of "dynamic-highres"  (Read 5801 times)

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Offline itix

Re: The astonishing unpopularity of "dynamic-highres"
« Reply #45 on: July 30, 2013, 01:28:30 AM »
Quote from: psxphill;743021
If you look on the diagram on the page I linked, you'll see that paula's slots are fixed and are always available.


However it requires CPU to initiate DMA transfer. While Paula has got it allocated slots it is possible it is just playing wrong note because CPU could not keep up.
My Amigas: A500, Mac Mini and PowerBook
 

Offline ChaosLord

Re: The astonishing unpopularity of "dynamic-highres"
« Reply #46 on: July 30, 2013, 01:54:24 AM »
If the CPU can't keep up then Paula would play whatever note it just played in a loop over and over until the cpu caught up.  It sounds really horrible and jarring and obvious when it happens.
Wanna try a wonderfull strategy game with lots of handdrawn anims,
Magic Spells and Monsters, Incredible playability and lastability,
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Offline blakespot

Re: The astonishing unpopularity of \
« Reply #47 on: October 24, 2019, 03:25:52 AM »
I just did a very quick interview with Rhett Anderson who made SHAM. He said the viewer slowed the system 10-15% but was not intensive. His first viewer was not multitasking friendly, and so people (including me) assumed it took loads of system resources. Apparently not. I am working on a post to detail the back and forth with the author.
:: http://www.bytecellar.com - The Vintage Computing Weblog
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:: Amigas: 1000, 2000, 1200 \'060, SAM440ep-Flex 733
 

Offline Amiga_Nut

Re: The astonishing unpopularity of \
« Reply #48 on: November 10, 2019, 12:08:59 AM »
Not in Digi-Paint, but in Digi-view 4.0 video capture software it was an option. I'm sure it was called Dynamic Hi-res (Dynamic HAM being 320x512 true HAM image with palette swap for HAM 16 base colours used on every scan line) but it's been decades since I've seen the box let alone used the software.

The problems with HAM fringing are not that bad if you use interlace AND you feed a very evenly lit and neutral/daylight temperature of lighting of image (or the TV output form a digital camera displaying a high quality JPEG is the most ideal today if you still have a Digi-view unit to use). Some images will be a problem of course but the fringing is also caused by bad lighting just as often.

It used to be a lot of fun, hopefully one day I will get a chance to mess about with it again as in my misspent hours of youth!

HAM has problems changing all three of the RGB components, if you get uneven lighting on the image then that means on every pixel the RGB has subtle changes to it at best, or totally inaccurate colours being seen by the camera at worst i.e. there was no need for the colour to change except due to poor uneven lighting of the original so you just make a clever shortcut in screen memory usage into an absolute nightmare of a compromise. HAM is supposed to be used on HSV values not RGB where the 'fringing' is less jarring due to the more subtle differences when HSV values are being manipulated on an image but Jay Miner decided it was better than nothing with RGB after seeing it in action on a Flight Simulator system.

Garbage in, garbage out as they used to say in 1980s computer courses heh!
 

Offline psxphill

Re: The astonishing unpopularity of \
« Reply #49 on: November 10, 2019, 05:07:52 PM »
HAM is supposed to be used on HSV values not RGB where the 'fringing' is less jarring due to the more subtle differences when HSV values are being manipulated on an image but Jay Miner decided it was better than nothing with RGB after seeing it in action on a Flight Simulator system.

The flight simulator is where he got the idea for HAM from, it wasn't an Amiga flight simulator. But when the Amiga output went from HSV to RGB as they pivoted from a games console to a desktop computer then they were going to take it out, but decided it would be extra work and they didn't have time to reuse the space for anything else anyway.

Photo realistic images was not even the goal, it was for fast horizontal line filling. Instead of setting each pixel to blue/red/green etc you could set the pixels where the color changes. I don't know if the HSV chipset worked better, but there doesn't seem to be a way of setting up memory with a NO-OP value. So it pretty much fails to be useful for the original intended use.