clp@altos86.UUCP (Chuck L. Peterson) (05/08/89)
Okay, I finally found out how to turn on flicker -- by choosing interlace in the preference window, then rebooting. Boy, do I get flicker! Are these new Agnus chips supposed to fix this problem? Is it me, or is there something inherently wrong with a product requiring the purchace of an expensive 3rd party device (flicker fixer) to give acceptible output? The technology is obviously there, so what is the problem with the Amiga Hardware Dudes using it? Chuck L. Peterson ...!sun!altos86!clp
king@dciem.dciem.dnd.ca (Stephen King) (05/16/89)
In article <1082@altos86.UUCP> clp@altos86.UUCP (Chuck L. Peterson) writes: >flicker! Are these new Agnus chips supposed to fix this problem? As reported, the new Agnus will offer flicker-free hi-res mode in 4 colours, but you will need a multisync monitor to make use of it. >Is it me, or is there something inherently wrong with a product >requiring the purchace of an expensive 3rd party device (flicker fixer) >to give acceptible output? The technology is obviously there, >so what is the problem with the Amiga Hardware Dudes using it? It is not you, nor is there anything wrong with the product. The shortfalling exists with our television standard, NTSC, which specifies 30Hz interlaced frames (60Hz fields). The Amiga was designed to be TV compatible; this is one of the reasons it is so popular. Things will not get better with HDTV, either, as this (proposed or whatever) standard is also interlaced. -- << ... if I could walk that way I wouldn't need the talcum powder !!! >> Opinions courtesy of: ...!utzoo!dretor!king king@dretor.dciem.dnd.ca
dougp@sbphy.ucsb.edu (05/16/89)
In article <1082@altos86.UUCP>, clp@altos86.UUCP (Chuck L. Peterson) writes... >Okay, I finally found out how to turn on flicker -- by choosing >interlace in the preference window, then rebooting. Boy, do I get >flicker! Are these new Agnus chips supposed to fix this problem? No, the new agnus chip only allows you to use 1 meg of chip ram. >Is it me, or is there something inherently wrong with a product >requiring the purchace of an expensive 3rd party device (flicker fixer) There is nothing inherently wrong with the Amiga. When the Amiga was designed, they decided to use the NTSC brodcast standard. In matching that standard, they did a much better job than any other home computer that came before it (Apple II, Atari 800, Commodore 64, or Timex Sinclare 1000 to name a few names). For computer use, there is quite a bit wrong with the NTSC brodcast standard. Composit video, which is the NTSC standard output on the back of the A1000, limits the resolution of picture, and muddies the colors (this is where the joke about the initials comes from "Never The Same Color"). The A1000 gets arround this problem by using the RGB output. The amiga still has to contend with the scaning rate and interlaceing scheme of NTSC. Interlece was a scheme that the designers of television came up with to double the resolution of television without sending more information. They got away with this because in most pictures, the brightness does not change drasticly between scan lines. On a computer it is all too easy to create images with high contrast between scan lines. To get arround this problem, a non interlaced mode was provided. by cutting the number of scan lines in half, every scan line can be refreshed 60 times a second instead of 30 times a second, so even when there is a high contrast between scan lines it does not flicker. Anyway, I don't think multi-sync monitors were available when the Amigas custom chips were designed. >Chuck L. Peterson > ...!sun!altos86!clp Douglas Peale
bob@jacobs.CS.ORST.EDU (robert s. richardson) (05/16/89)
In article <1082@altos86.UUCP> clp@altos86.UUCP (Chuck L. Peterson) writes: >Okay, I finally found out how to turn on flicker -- by choosing >interlace in the preference window, then rebooting. Boy, do I get >flicker! Are these new Agnus chips supposed to fix this problem? >Is it me, or is there something inherently wrong with a product >requiring the purchace of an expensive 3rd party device (flicker fixer) >to give acceptible output? The technology is obviously there, >so what is the problem with the Amiga Hardware Dudes using it? > >Chuck L. Peterson > ...!sun!altos86!clp To understand the "problem" of interlace it is necessary to look at the history of the Amiga. The original chipset was designed with graphics applications in mind, but was optimized for rendering to NTSC video for such applications as videogames. NTSC video is interlaced. It is the very limitation business and CAD users point out in the Amiga (flicker) that makes it the popular machine suitable for video work without extensive modification. So you can look at it two ways: 1) Interlace flicker is what keeps the Amiga out of the business marketplace. (At least one of the reasons) or 2) NTSC compatibility is what brought the Amiga into business because of its usefulness in desktop presentations. And remember, the price of the FlickerFixer is less than that of a PC VGA card and less than that of many EGA cards. In the PC world buying a video card is a practical necessity, while it is just another option in the Amiga world, depending on your own preference and intended application. Question: Can someone fill me in on the layout of VGA? Does it use a blitter? I've seem some impressive graphics done of VGA, but the Amiga still seems to outstrip even a 386 in the area of real-time animation and sound capabilities. (Useful for presentation as well as games). What about the TARGA board, and how does one get that board to work in an Amiga 2000? And to Commodore 1.4 people: Is it conceivable to utilize the blitter as a math coprocessor with the proper code? Or is the 68000 faster in such areas? I know some simple binary operations could probably be implemented, but what about floating point? Thanks any and all. +---------------------------------------------------------------------+ | Bob Richardson (or, for you UNIX buffs: bob@jacobs.cs.orst.edu) | | 220 NW 21st, Corvallis, OR 97330 503-758-5018 "We Never Open" | +---------------------------------------------------------------------+ | PLEASE NOTE NEW NETWORK NAME ABOVE (was richarr@nikola). MAIL TO | | OLD ACCOUNT MAY NOT REACH ME. THANK YOU. | +---------------------------------------------------------------------+
phil@ux1.cso.uiuc.edu (05/16/89)
Flicker is an inherint characteristic of the fact that the real frame rate of standard television is about 30 hz in (North and South) American and Japan and is 25 hz in the rest of the world. Interlacing scans only half the lines the first time through, and the rest the next time. So although the sweep occurs 50 or 60 times a second, any ONE LINE is only updated half as often. The human eye notices the flicker if the brightness is different. The rods are sensitive to it, but the cones are much less so. There are combinations of colors that dramatically reduce flicker. I use a yellow on blue color combination that has relatively little flicker. Because of the low contrast, it is a little harder to read though. Broadcast television does not suffer from flicker because the change from one line (scanned in one cycle) to the next (scanned in the other cycle) is very little. Try the following with your Amiga. Find a program (such as MicroEmacs) that creates its own screen in interlace mode. Now open this screen up overtop a regular screen, and pull it down to the bottom. The CRT scanning rate is in interlaced mode, but the data on the regular screen is DUPLICATED for every line pair. You will see that there is much less flicker, but there is some apparent JITTER. This is what television is really like, but it also has smooth gradations of intensity so even the jitter is not there. High Definition Television, unfortunately, is continuing with the interlace system at about the same frame rate. Some TV sets do "super scanning" by storing the picture in a frame buffer as received, and scanning EVERY line out to the CRT at 60 hz or higher. If you are lucky enough to have one of these expensive units, you don't need a flicker fixer. The prices will come down some day.