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From: jimf@idayton.field.intel.com (Jim Fister)
Newsgroups: comp.ivideodisc
Subject: Re: How much on a CD?
Keywords: CD-I DVI
Message-ID: <1990Nov29.142631.16491@idayton.field.intel.com>
Date: 29 Nov 90 14:26:31 GMT
References: <3931@mindlink.UUCP> <1990Nov28.220134.25186@iwarp.intel.com>
Distribution: na
Organization: Intel Corp./ Dayton Sales Office
Lines: 59

pweiss@iwarp.intel.com (Paul Weiss (pweiss@iwarp.intel.com)) writes:

>Hi.  "How much {picture,sound} time can ya fit on a CD?" is a
>deceptively complicated question.  CD-I and DVI use the same
>underlying medium (as do CD-DA and CD-ROM, fundamentally) but make
>different choices about how to use the bandwidth.  The disc can hold
>about 640Kb of "stuff", in any case.  As far as video goes, DVI uses
>fancy (and very proprietary) compression/ decompression to allow
>sustained full-screen, full-motion pictures.  I think the compression
>factor varies in some way with the material, from a low of 10:1 to a
>high of about 100:1.  (Can anybody do a better job on that?  Please
>followup!)  Although decompression can be done in real time, with
>Intel's 2-chip set, compression is a mainframe mega-cycles kind of
>proposition, with supercomputer-class machines ideal.

Not to be picky, but it's 640Mb of data on a CD ROM.  I'm not to sure
about CD-I, but DVI can do about 70 min. of full-screen, full-motion
video.  Compression on the high end, using the mainframe is about 120:1
now.  DVI can also do real-time compression.  The capture board on the
two-board set does about 80:1 right now, and it'll only get better.
It looks to be about standard VCR quality, if you want a reference.

>CD-I does a much better job on audio.  It supports 4 or 5 different
>encodings, ranging from CD-DA tracks on a CD-I disc, to an encoding
>which uses half that space and bandwidth, giving twice the time, all
[stuff deleted for BW]
>taken up with visual data.  CD-I's audio encoding doesn't have nearly
>the compute-time requirements as DVI's video encoding, and has been
>done successfully on PC-class authoring stations.

>For slide-show styled titles, using a combination of still video
>images, computer-generated box-and-arrow markup, cartoon graphics
>animation, and voice-over, CD-I will be a terrific medium.  For things
>which want a lot of whizzy full-motion video, DVI will probably do a
>better job.

I'm not so sure, but I don't have the info to argue.

>...DVI
>shares the same platform-dependence as CD-ROM, at least in theory, but
>the new 2-chip set should make the appearence of dedicated DVI players
>economically possible.  CD-I was designed from the start as
>mass-market consumer technology.

DVI can handle any transfer media with a BW of 150Mb/s or greater.  Our
office has successfully transferred RTV over a network, along with stills.
Platform dependance is true not, but not necessarily in the future.

Just my two cents.  I'd say more, but my lack of info on CD-I would only make
me seem more of an idiot than I'm normally accused of being.  Any CD-I hacks
out there?

Oh, the fact that the door outside the office says "Intel" doesn't mean that
I say what they mean, or that I mean what they say, right?  Other standard
disclaimers apply.

Greetings from the rocking metropolis.

JimF


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