🚀 go-pugleaf

I have been reading the various discussions of CD capacity
lately and I figured that it's about time to add my two cents.

Just as Jim Fister is more experienced with DVI than CD-I, my bias is with
CD-I, although I have worked on the standardization committees for CD-ROM XA
as well as CD-I.

This is the general story:

CD-ROM/CD-I/DVI  all use the same carrier.  They all store data within the
context of the ISO 9660 standard for storing data on an optical disc.  This is
the same optical disc that is used to store music (CD-DA) although of course
music discs don't have directory structures on them.

CD-I and CD-ROM XA (and perhaps DVI) store audio in an ADPCM format which
*may be* streamed directly into an audio processor. CD-I allows you to also
read that data into memory for buffering and later playback.

CD-I allows four levels of audio:

	CD-DA  (16 bit PCM - 44.1 KHz)	  72 minutes
	Hi-Fi  (8 bit ADPCM - 37.8 KHz)	  stereo - 144 minutes  mono - 288 minutes
	Mid-Fi (4 bit ADPCM - 37.8 KHz)	  stereo - 288 minutes  mono - 576 minutes
	Lo-Fi  (4 bit ADPCM - 18.9 KHz)	  stereo - 576 minutes  mono - 1152 minutes

At Lo-Fi mono, this gives appx 19 hours of audio.  Most music sounds pretty good
at MidFi Stereo and most people's stereos cannot reproduce the difference
between Hi-Fi and CD-DA.

CD-ROM XA has included the Lo-Fi and Mid-Fi modes.  I do not know anything about
DVI audio.

Now for video.  A CD, played start to finish, holds 72 minutes of data
at 75 sectors per second.  Data (text) sectors hold 2048 bytes.  Video sectors
hold 2324 bytes because they don't contain extra EDC/ECC.  Therefore:

	(72 * 60 * 75 * 2324)/1024 = 735  Meg of video data

					or

	(72 * 60 * 75 * 2048)/1024 = 648  Meg of text/program data

Full Motion Video on CD-I or DVI uses the full bandwidth of the disc, thus
appx 72 minutes of FMV on a CD.

CD-I and DV-I systems can use hard disks as well as optical discs for their
data storage.  In fact, most good hard discs are faster than CDs and there
are now some quite affordable HDs that hold more than CDs.

CD-I players can read CD-DA, CD-ROM and CD-ROM XA discs.  In addition, it
takes only a small amount of extra circuitry to handle CD+G or CD+Midi.
Several manufacturers are planning these extensions from the beginning.

Finally, CD-I is being used today.  There are several companies around the
world using CD-I for data archival, training, Point-of-Info or Point-of-sales.
Although it is *primarily* intended as a consumer technology and it will be
hard-pressed to fight the IBM/Mac lock on business systems, it will find
some uses in dedicated systems used by businesses.

The Wall Street Journal recently carried an article about the Tokyo Electronics
Show in Japan where 33 exhibitors were showing CD-I players or software.  Over
10 companies are manufacturing players including a hand-held model by Sony that
uses a 5" LCD screen or connects to your favorite TV.

Personally, I will feel better going out to buy a system that has competition
from ten manufacturers than one that is offered only by Intel or Commodore.
There will certainly be a much greater force to lower prices and add features.

I don't know if I have actually cleared up the discussion at all, but I feel
like this was information that needed to be presented.  


Eric Miller                         *  If this is paradise, I need a lawn mower.
Manager, New Media Systems          *
Microware Systems Corp              *    - David Byrne