Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!cs.utexas.edu!asuvax!noao!ncar!gatech!mcnc!taco!hobbes!kdarling From: kdarling@hobbes.ncsu.edu (Kevin Darling) Newsgroups: comp.sys.amiga.graphics Subject: Re: Colorburst and Animation Message-ID: <1991Mar17.131751.2152@ncsu.edu> Date: 17 Mar 91 13:17:51 GMT References: <13948@life.ai.mit.edu> <1991Mar14.231042.26446@ncsu.edu> <14058@life.ai.mit.edu> Sender: news@ncsu.edu (USENET News System) Organization: North Carolina State University Lines: 45 In <14058@life.ai.mit.edu> rjc@geech.ai.mit.edu (Ray Cromwell) writes: >>> 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. >> >> [and I reply] -- >> Ooops :-). That totals 3/30th second, which is _10fps_ at 320x200x24. > > Double oops. I made a mistake. It's not 1/15th, it's 1/60th. [...] > Using movem's (copymemquick()) with video dma off, you can transfer > almost an entire colorburst frame to chip in 1 screen. [ = 15fps] Better make that triple oops :-). I was being generous letting you say 192K can be moved in only 1/15th second. Considering that an impossibly best case transfer (no waits, totally zero overhead) with a 68000 will take 4 cycles to read 16-bits, and 4 cycles to write those 16-bits back out, I'll let you do the calcs yourself for the full memory updates/second: (amiga 68K cycles/sec) / (96,000 words/frame * 8 cycles/word) So even 10fps is unlikely for fullscreen 24-bit animation in the situation we were talking about, unless perhaps you have the A3000 32-bit CHIP access, or full memory DMA, etc. Otherwise, continuous 7fps transfers, maybe. > Now that I think about it, HAM-E and DCTV are going to have more of a > problem animating than Colorburst. Depends on the resolution, width, etc. But first a comment: someone inadvertently claimed that HAM-E/DCTV would have the same 80% CHIPRAM lockout as the Colorburst. Obviously for 320x200 this is untrue. The Colorburst at 320x200x24 requires extra CHIP bandwidth to send the larger data (24-bit) as quickly as possible. But at 320x200x8, the others' continuous lockout will "only" be about 55%. Still, some rough figuring indicates that the Colorburst (by cutting down the video DMA when needed) could, even at 12-bits, keep up with the 8ers. At 8bits/pixel, it can be twice as fast; at 24, twice as slow as them. > You could easily reduce Colorburst > to 12bit mode and get 4096 colors out of 16.7 million and do animation. Now _that_ is impressive. You're saying that it has enough fast palette RAM to hold 4096 24-bit colors?! Decent! Or is another technique used? Thx! kevin