Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: notesfiles - hp internal release 1.2; site orstcs.UUCP
Path: utzoo!watmath!clyde!floyd!harpo!seismo!hao!hplabs!hp-pcd!orstcs!stenerso
From: stenerso@orstcs.UUCP
Newsgroups: net.audio
Subject: Re: CD defect
Message-ID: <2900008@orstcs.UUCP>
Date: Thu, 9-Feb-84 12:47:00 EST
Article-I.D.: orstcs.2900008
Posted: Thu Feb  9 12:47:00 1984
Date-Received: Thu, 9-Feb-84 07:41:04 EST
References: <30200020@hpcnoa.UUCP>
Organization: Oregon State University - Corvallis, OR
Lines: 38
Nf-ID: #R:hpcnoa:30200020:orstcs:2900008:000:1870
Nf-From: orstcs!stenerso    Feb  2 09:47:00 1984


   The CD debate is now getting petty.  Getting a few bad CD's is no reason
to damn the whole CD process.  Just as with analog discs (LP's) you
tend to get a few rejects.  When this happens you simply return them to
where you purchased them for an exchange.  I would expect quality to go
up as quantity increases since any bugs should be eliminated or
reduced as the process of producing discs is 'perfected.'
   The error correction used is a Cross Interleave Reed Solomon (CIRC)
Code.  The maximum correctable burst length is 3500 bits (~2.4mm) and
the maximum acceptable burst (error correction + interpolation) is
12000 bits (~8.5mm).
   However, when Sony developed the CIRC code they made it possible to
use all of its power or part of it.  The idea being that more
expensive players would use all of the code and less expensive players
would only use part of it.  At this point I do not know how much of
the error correction capability is used in present players.
   I must admit that I do not own a CD player at present.  They are still
a bit spendy for a struggling EE student!  But I have listened to one
though a pair of Stax headhones and do plan on buying a player by the
end of the year.
   As it see it there are not any major problems with the following:
	1. sampling rate (band width)
	2. quantization (16 bits linear/channel)
	   (I do wonder why a nonlinear quantizer was not used though,
	    ie.  CCITT.)
	3. error detection and correction
	4. features (ie. direct access to any part of the disc)

   The major limitations are more concerned with the present
implementation then with the disc format.
	1. bad software (discs)
	2. the analog and digital filters could be a problem if not
	   designed properly.
   I will not give details on the above since they have already been
beaten to death on the net!
   Flames to /dev/null!

Roger Stenerson