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From: ts@cup.portal.com (Tim W Smith)
Newsgroups: comp.arch
Subject: Re: CD-ROM II standard?
Message-ID: <37606@cup.portal.com>
Date: 5 Jan 91 14:08:44 GMT
References: <009421D2.AF8D5120@KING.ENG.UMD.EDU>
  <1991Jan3.151718.3398@idayton.field.intel.com>
Organization: The Portal System (TM)
Lines: 21

< As far a DVI goes (which I know a bit about,too and I didn't get it all from
< books) a CD-ROM can hold up to 70 min. of full-screen, full-motion video with
< good quality stereo audio.  This is fine for almost all the applications

(I don't know anything about DVI - I had never heard of it until this
discussion, so forgive me if the following questions are stupid)

How does this work?  Assume 700 meg of data (for easy computing) and
we get 10 meg for each minute of video, or 170 KBytes per second,
or (assuming 30 frames per second) about 6 KBytes/frame.

And for the audio, if there are 16 bits per sample and 20,000 samples
per second (I'm trying to give a generous definition of good quality
stereo), we need 200 Meg for the audio, so that cuts the video down
to maybe 4 KBytes/frame.

So how do they get good video from this?  Compress the heck out of it?
How hard is this to decode?  Why don't CDV discs use this (they only
get something like 5 minutes of video on these)?

						Tim Smith