From: sethb@fid.morgan.com (Seth Breidbart)
Subject: Re: Sony Mini-Disc Questions/Debate
Organization: my opinions only
Date: Tue, 25 Aug 1992 21:34:44 GMT

In article <MARC.92Aug21091602@mamba.es.ele.tue.nl> marc@es.ele.tue.nl
(Marc Heijligers) writes:
>
>In article <24809@castle.ed.ac.uk> sss@castle.ed.ac.uk (S S Sturrock) writes:

>I don't know who did the review, but when I heard DCC myself yesterday, I can
>only state that the recorded sound sounded exactly the same as the original
>sound did.

Really?  What kind of microphones were used, and what setup?  I'd love
to be able to produce *any* kind of recorded sound that sounds
"exactly the same as the original sound".  Unfortunately, nobody has
ever achieved that goal.

Or do you mean that the DCC sounded the same as the CD it was made
from?

Even so, wasn't there some problem with a whine that lots of listeners
missed until somebody (from Sweden? I seem to recall) pointed it out
to them?

>It is not ordinary chrome tape.

One of the selling points for DCC was that it was ordinary tape, which
could be produced cheaply.

> The information on the tape is 'digital' (in
>fact it is analogue ofcourse), which means that a degradation of the tape can
>hardly be noticed (a degraded '1' has to degrade very hard to become a '0').

If it's that hard to degrade, why does dat use half of its real estate
for error correction?

[quoting someone at Philips]

>1. audio inputs: DCC players (at least for some time) will have both an analog 
>and a digital input. The digital input format complies with the IEC958 standard,
>commonly called 'AES/EBU interface', since it was approved by these two 
>organisations (Audio Engineering Society and European Broadcasting Union).
>The digital interface that many of you will find on your CD player is also in 
>AES/EBU format, or better a subset of it, called SPDIF = 'Sony / Philips 
>Digital Interface'.

S/PDIF is not a "subset" of AES/EBU; it operates at a different
voltage level, and some of the bits have different meanings.  There is
no place in the AES/EBU specs for SCMS, for instance.

> (How many of you, more 'mature', listeners
>can still hear the 15.625 kHz tone normally generated by PAL television sets?)

I don't know about PAL, but I can easily hear the whine from US
television sets, which is about the same frequency.  I can actually
hear well above that.  I'm 38, and have lived in New York City most of
my life (not exactly a quiet place).

>Since bandwidth is expensive, for the applications mentioned above the small
>pay-off in sound quality (only noticed by a limited group of listeners) was 
>considered subject to the significant reduction in transmission bandwidth.

ie: Your quality is less important than our money.

> You must realise, however, that every time 
>you make a digital copy, data reduction is applied another time. Since the 
>reduction is non-bit-true (the bits coming out of the DCC digital output at 
>playback are not the same as the bits put in the digital input digitally at 
>recording) a slight degradation is possible. Tests, however, have shown that 
>only for the first copies this is slighlty noticeable, and after, say, 5 
>generations, no more degradation is perceived.

So he admits that DCC does degrade the sound.

> Copies were made up to more 
>than 80 (...) generations, but the audio quality remained very high.

In dat, 100 generations are indistinguishable from the master.

>As a final remark, from a technical point of view (confirmed by tests), with
>prerecorded tapes, DCC in some cases can have a *higher* perceived sound 
>quality than CD, since its dynamic range is far greater than that of CD.

Tests have shown that adding *noise* can cause a recording to have a
*higher* **perceived** sound quality.

>6. Your auditory system: the point above describes some results of listening
>tests, because that what we at Philips are interested in. However, take a listen
>to DCC with your own ears as soon as you can: never let anybody tell you what
>*you* hear.

Or what you don't hear.

Seth		sethb@fid.morgan.com