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From: es1@cunixb.cc.columbia.edu (Ethan Solomita)
Newsgroups: comp.sys.amiga.advocacy
Subject: Re: AMIGA
Message-ID: <1991May8.062658.14796@cunixf.cc.columbia.edu>
Date: 8 May 91 06:26:58 GMT
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In article <937@cns.SanDiego.NCR.COM> dltaylor@cns.SanDiego.NCR.COM (Dan Taylor) writes:
>In <1991May6.164821.8807@cunixf.cc.columbia.edu> es1@cunixb.cc.columbia.edu (Ethan Solomita) writes:
>>	I'm afraid your hard drive is a tad faster than mine. My
>>Quantum can read slightly greater than 1MB/sec I believe if it is
>>nice and contiguous, but if each frame is 32K then that makes
>>1920K/sec. However, 60fps is irrelevant. 30 and 24 are far more
>>meaningful. 
>
>Most Amiga animations are stored in a format that does NOT require a
>complete copy of EACH frame image, rather, deltas between frames are
>used whenever possible, usually within a "scene".  Between the CPU
>and the graphics coprocessors, it is easily possible to update the
>next frame, then use the "copper" to switch at vertical sync.  I think
>the real numbers are more like 60 "fields" per second, which is the
>30 frames per second you mentioned.
>
	Oh, I have no doubt that a blitter could do 60fps on a
low-res screen, or an 030 on a high-res screen. My question was
simply about getting it into memory. Do compressed ANIMs lend
themselves to off-disk loading? I hadn't thought it would be as
easy: frames aren't fixed size. If it is, how much compression do
you usually get? And how about on digitized images?

>Our disks can sustain near-megabyte per second throughput, but I haven't
>seen one, myself, that can sustain 2 mbs through the file system.  The
>original ZorroII, as in the A2000 family, has a (roughly) 4 mbs data
>rate, so it IS possible to run the 2 mbs of disk data, and handle the
>overhead.
>
	Maybe try a Wren drive. I've been told that they'll do
2M/sec, but the question would then be the realistic throughput
of the controller.

>Dan Taylor


	-- Ethan

"Brain! Brain! What is Brain?"