Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!elroy.jpl.nasa.gov!decwrl!fernwood!oracle!news From: jlange@oracle.com (Jim Lange) Newsgroups: comp.sys.amiga.graphics Subject: Re: Colorburst and Animation Message-ID: Date: 20 Mar 91 21:04:57 GMT References: <13948@life.ai.mit.edu> Sender: news@oracle.com Organization: Oracle Corp., Belmont CA Lines: 56 In-reply-to: rjc@geech.ai.mit.edu's message of 13 Mar 91 18:14:27 GMT In article <13948@life.ai.mit.edu> rjc@geech.ai.mit.edu (Ray Cromwell) writes: > A 320x200x24 screen is 192k > In one refresh frame the Amiga can send about 100k, and in 60 frames > this is the 5.5 megabytes figure we recognize. > The Colorburst has 1.5mb of onboard memory, this is enough to store > 8 lores 24bit screens. > The Amiga can send a full colorburst frame about every 2 vertical blanks > which gives us 30 frames per second assuming we had infinite chip ram or > no processor lock-out. > My solution? Preload the colorburst's memory with 8 frames, allocate > 572k of chip ram and stuff three frames in chip. Here's the procedure > to get 20fps 320x200x24 animation. > 1)display frame from colorburst's memory > 2)erase frame in colorburst's memory > 3)display next frame from colorburst's memory > 4)start transfering one colorburst frame amiga chipram (takes 1/30th second) > 5)TURN VIDEO DMA COMPLETELY OFF, and copy a colorburst frame from fast memory > to amiga chip memory (takes 1/15th second) > 6)turn dma back on, and go to step 2 > So it takes a total of 1/30th + 1/15th second to insure colorburst > gets a frame constantly. This amounts to 20fps which is acceptable. > On a 9mb Amiga this amounts to 3 seconds of animation. This however > does not take into account compression which can dramatically increase > the length of the animation. Given that Colorburst supports the trick of turning off DMA, it could even be used as a pure graphics "accelerator" by buffering 16 color hi-res images that are then used as input into DCTV (or HAM-E). Since DMA contention is one of the bottlenecks for realtime DCTV animation and the Colorburst allows selectable bitplanes/colors, it could display 16 color animations compatible with DCTV without the DMA lockout while fetching or decompressing the next frame. Plus several frames (or delta data) could be stored in Colorburst's 1.5 meg. If the Colorburst graphics processor can decompress delta information on its own, then the amiga would only need to send the next "chunk" of anim data to the Colorburst (from fast ram or even a hard disk). > A board that can display 24bits of true color, and in > addition 24bits of overlay, with 1.5mb of ram onboard, and works with > all Amiga's? And it only costs $400! The next comparable board costs $1600? > Colorburst is a great deal, even if it couldn't animate, which it can. Considering that you can own both DCTV and Colorburst for under $1000, it could be the best of both worlds--full 24 bit output for stills or limited animation AND high-speed NTSC color anims when frame rate is a priority. Anybody wish to speculate on the maximum realistic frame rate with Colorburst and DCTV working together? Jim Lange Oracle Corporation