HDCD

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2 total messages Started by donr@harpo.wh.at Thu, 10 Aug 1995 00:00

#3809

Author: donr@harpo.wh.at
Date: Thu, 10 Aug 1995 00:00

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> From: "Steve Marshall@CONTINENTAL INSURANCE COMPANY
> (SMARSH1 @ CDCNOTES)" <uscdcbk3@ibmmail.com>

> > Anyone out there is aware of the new HDCD standard? CD made using this
> > process sound really good. They are true 20-bit CDs.
> >
> i have not heard of this.
> The only one I've heard is the new Neil Young CD, & (to quote Neil on
> this one)
> it sounds like a "piece of crap" quality-wise...

Sorry my reply is about 2 weeks late....

HDCD ("High Definition Compatible Digital") was invented by Keith
Johnson (recording engineer for the audiophile label "Reference
Recordings") and members of Pacific Microsonics - a small California
electronics design company.

It was born of Johnson's frustration with even the present "state-of
the art" digital recording process.

It is **NOT** a true 20-bit CD. Only the loudest sample uses all 16
bits in a digital sample. The lower the level, the more unused bits
there will be in a particular sample. What HDCD does is to use these
unused bits to provide more high frequency detail.

How they do this is anybody's guess because Pacific Microsonics is
understandably non-committal about their patented technology.

Even standard playback of an HDCD-encoded disc is said to be superior
to a non-encoded one. But the full benefit can only be realized with
HDCD decoding, as well.

Up to very recently, only Reference Recordings CD's have been encoded,
due to a lack of available encoders for other CD manufacturers. HDCD
decoding equipment has been available for approximately 6 months or
more, with more companies offering it as time goes by.

The audiophile publication "The Absolute sound" has conducted its
first listening tests of HDCD CD's. 3 reviewers were involved.  One
was wildly enthusiastic, one was mildly so, and one (the Editor Harry
Pearson) was somewhat skeptical.

What needs to be done is to manufacture a CD with both standard and
HDCD encoded tracks of the same recording. Only then can the true
measure of the process be known.

I agree with TAS Editor Pearson's statement that (paraphrasing): 'HDCD
is only a band-aid, at best. It may provide some improvement but true
high-fidelity CD playback will only occur with a larger digital word
(20 to 24 bits) and a MUCH higher sampling rate.'  (In effect, the CD
equivalent to 1/2 speed mastering for vinyl).

I hope this explanation helps...

Don Roderick

Re: HDCD

#3990

Author: gabe@panix.com (
Date: Mon, 14 Aug 1995 00:00

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In article <40et9i$qhb@agate.berkeley.edu>, Donald J Roderick
 <donr@harpo.wh.att.com> wrote:

>How they do this is anybody's guess because Pacific Microsonics is
>understandably non-committal about their patented technology.

How they do this can be learned by anyone who wishes to go and get a
copy of the published PCT document, available as a matter of public
record, to anyone taking the time to order it.

>Even standard playback of an HDCD-encoded disc is said to be superior
>to a non-encoded one. But the full benefit can only be realized with
>HDCD decoding, as well.

Playing back an HDCD-encoded disc on a non-HDCD deocder results in
markedly inferior sound quality, mainly caused by the reduced dynamic
range resulting from HDCD's audio compression.

>The audiophile publication "The Absolute sound" has conducted its
>first listening tests of HDCD CD's. 3 reviewers were involved.  One
>was wildly enthusiastic, one was mildly so, and one (the Editor Harry
>Pearson) was somewhat skeptical.

The only listening test that will be of any value will be a comparison
of a) a live microphone feed to b) an HDCD system, c) a
state-of-the-art non-HDCD 24-bit A/D + noise shaping.

>What needs to be done is to manufacture a CD with both standard and
>HDCD encoded tracks of the same recording. Only then can the true
>measure of the process be known.

Precisely.  Funny, isn't it, how PM has not done this.  Perhaps they
know something we don't? :-)

>I agree with TAS Editor Pearson's statement that (paraphrasing): 'HDCD
>is only a band-aid, at best. It may provide some improvement but true
>high-fidelity CD playback will only occur with a larger digital word
>(20 to 24 bits) and a MUCH higher sampling rate.'

If we do ever raise the sampling rate, the added benefit will probably
come not so much from frequency response, but rather from dynamic
range.  Whereas now we use noise shaping to place the dither into
regions of the bandlimited spectrum where our ears are less sensitive,
with a higher sampling rate we should be able to place the dither into
regions where our ears are completely insensitive.  In other words,
move dither out of the audible passband altogether.

Gabe Wiener  Dir., Quintessential Sound, Inc. |"I am terrified at the thought
Recording-Mastering-Restoration (212)586-4200 | that so much hideous and bad
PGM Early Music Recordings ---> (800)997-1750 | music may be put on records
gabe@panix.com     http://www.panix.com/~gabe | forever." --Sir Arthur Sullivan

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