Path: utzoo!news-server.csri.toronto.edu!cs.utexas.edu!uunet!samsung!think.com!mintaka!wookumz.ai.mit.edu!rjc From: rjc@wookumz.ai.mit.edu (Ray Cromwell) Newsgroups: comp.graphics Subject: Re: IFF, 24-bit color, displays, Amiga Message-ID: <1991Mar12.193951.634@mintaka.lcs.mit.edu> Date: 12 Mar 91 19:39:51 GMT References: <1991Mar11.223827.21988@ncsu.edu> <1991Mar12.014550.25284@mintaka.lcs.mit.edu> <1991Mar12.082113.16351@ncsu.edu> Sender: daemon@mintaka.lcs.mit.edu (Lucifer Maleficius) Organization: The Internet Lines: 108 In article <1991Mar12.082113.16351@ncsu.edu> kdarling@hobbes.ncsu.edu (Kevin Darling) writes: >rjc@geech.ai.mit.edu (Ray Cromwell) writes: >>> kdarling@hobbes.ncsu.edu (Kevin Darling) writes: >>> Most of those products have large palettes, yes. But few are true 24-bit >> Wrong. Both Firecracker24 and Colorburst are TRUE 24bit display devices., > >What "wrong"? The original implication I got was that all the devices >mentioned were 24-bit. I said a few were. That's still correct. I had the feeling that you were implying that there are no true 24 bit devices on the Amiga. There's three that I know of now. >> Colorburst costs $499 and is a 48bit display device that works on ALL >> Amigas. It is the only true 24bit card that can do animation. >> in 48bit the Colorburst uses another 24bits for overlay information >> and special effects. [...] >> What is the price of a comparable product on the Mac/IBM. > >I personally don't care, since I own neither (I do own an A1000). >Mac/IBM/Amiga wars don't interest me. As a techie tho, I admit >to not being one to ignore hype, missing info, and misuse of terms, >no matter what the machine is. WHat misuse of terms? 48bit? It does use up to 48bits of information for each pixel. 24bits of that are color, the rest is extra information to be interpreted in anyway the video coprocessor sees fit. >Yes, the Colorburst has a dual 24-bit display mode, where two 24-bit images >(of res's which can fit within its 1.5M memory) can be switched pixel by >pixel. But that's not "48-bit", no matter what you read from their ads. >Another thing to consider: I read that its RAM is loaded by sending the >R,G,B components as separate images from the Amiga video output lines. >In the highest res mode, that would take 6 Amiga display frames to do. 48bit color would be useless since we can't see anywhere near that amount of color, but Why isn't it '48bit'? Haven't you ever heard of alpha channel?If the colorburst can internally maintain 48bits of information per pixel, regardless of what that extra info is used for(color, overlay, zbuffer, cycling, whatever) it's 48bit. The Colorburst transfers data at 5.5 megabytes/sec through the db23 port. A lo-res screen is 40bytes widex200 lines deep x 24 bits. That's 192k, at 5.5mb/sec gives up 30 frames per second. At 400 lines deep, we get 15fps, and in hires(640x400) we get 7.5fps. The onboard VLSI processor can be used to decode compressed data, so its possible to shunt anim5 type data through it. If you want faster animation you can always drop back to 21bits deep, or 18 with not much loss in quality. If you don't belive this, go see Colorburst in action at this Friday's AmiEXPO in New York, or call MAST's BBS and talk to the engineer who created colorburst. Don't judge Colorburst by the marketing hype some marketroid put in the adds, go download the technical specs and developer source code for the colorburst from MAST's bbs. >> [HAM-E device] In this mode it can do 18bits (with error) >> by using the HAM trick of specifying delta's from the base color to >> be changed. This time, instead of a base of 16 colors with a single >> delta gun, HAM-E has a base of 240 colors, it then (like HAM) specifies > >Close. It can on-the-fly select one of four base banks of 59 colors each, >from which the next pixel can then do its extended HAM delta stuff on. Tell me more, what is the exact format of the bits(which bits in the pixel designate what) and what is the 'magic cookie' that they use to trigger the HAM-E mode. >> DCTV is an NTSC composite device which allows 4million colors, with >> whatever amount normal Television allows simultaneously to be >> displayed. If you like Television, you'll like this. >> DCTV also comes with a digitizer. > >It doesn't currently work with a genlock tho, which might be >crucial info to someone working with TV, and shouldn't be left out. Hmm, that's strange Digital Creations recently reported on Bix that the versions shipping now do work with a Genlock, or so I heard. The Toaster can accept DCTV input, so that solves that problem regardless. >> HAM-E works will all normal Amiga software with no patches, > >A nice way of saying that all the others require custom software :-). DCTV works with any display software too. That's because the Amiga doesn't know DCTV is a different screen, it just thinks it's a normal hires screen. Same goes for HAM-E. >I do think that people like being kept up to date, but it'd probably be >more interesting if we all waited until someone's actually used all these >cards instead of relying on ads. cheers - kev HAM-E's have been shipping for a long time now. On compuserve there are tons of pictures produced with HAM-E along with animations. Most of the people say HAM-E works as advertised, ditto for DCTV. Once again, call their bbs's and talk to the people who bought the devices, they all seem quite happy with the results. Really, from a hardware standpoint, the concepts are dctv and ham-e are simple. Since they are using normal hires screens, (and we all know the Amiga can animate hires screens), animation will definately work as advertised. MAST distributes a video of colorburst in action doing animation, so it must work. By a simple computation, you can see that animation is possible. The Amiga's max frame resolution is 768x240(non interlace). This is 96 bytes wide, 240 lines high, 4 bitplanes deep. This comes to about 92,160 bytes transmitted every frame. In 60 frames, it's 5,529,600 bytes a second. I've already shown above that 15 frames per second animation can be gained without compression. Neverless, it's an extremely good deal for $400, since the closest competitor, Firecracker24, costs $1600 and it can't animate.