High Definition CD or HDCD - What is it exactly?

I have an Audio Aero Capitole MKII and always thought it had the ability to read HDCD's. I thought this until recently playing an HDCD on a friend's CEC CD player which has a small light that appears that tells you that it is reading the disc as an HDCD. The improvement and realism in the sound was awesome. The realism in sound reminded me of SACD in many ways, although I don't have much listening experience with either HDCD or SACD.

What exactly is HDCD and why can't the Aero Aero (at this price point) play/read these types of CD's?

One more thing...I burned a copy of the HDCD, but the CEC player did not recognize the copy as an HDCD.

Your comments are appreciated. Thanks,

Here is a web site with some information that you seek http://searchwebservices.techtarget.com/gDefinition/0,294236,sid44_gci843768,00.html as the article states HDCD decoding rquires a special chip and software to decode the information. I do not believe the Audio Aero has the ability to decode HDCD data. Only players that have this decoding capability can such as some Cary players. Usually a manufacturer will advertise their player as having HDCD decoding capability.

And as you have experienced your computer can not decode HDCD as well which explains why when you burned the CD you did not get the HDCD information.

I must admitt I do not know to much about HDCD as I have never had the need to since it is not very well supported/promoted by the industry.

If mastering engineers would stop compressing music (to make stuff sound good on boom boxes) then HDCD might be of more value. Unfortunately most recordings are compressed to a point where a regular CD has far more dynamic range than is actually needed.

Some of the best recordings are made for film soundtracks these days, as these are destined to be played on very costly systems at the cinema and the engineers have a large budget. Only a few film soundtracks are deliberately compressed (completely ruined) when re-mastered for CD.

HDCD is only part of the story...a good recording/mastering venue/studio and good sound engineers are even more important. Alas, music has become a mass market thing and HDCD is not necessarily the solution. (Some of the HDCD recordings are done on meagre budgets and although the "theoretical" sound should be better, often the venue/miking etc. falls behind what big budget productions can muster...)

just my two cents....
HDCD is a brilliant scheme which encodes extra audio information in the dithering signal present on all Redbook CDs.

The dither is put there to increase the number of bits in the lowest-level signals and thus improve resolution. On normal CDs it contains no signal information. The HDCD dither looks the same as the regular kind to a normal CD player. However to one equipped with a decoding chip, it delivers its information. This information can improve dynamic range, HF resolution and more.

The HDCD decoder chip must include very precise filters. These filters are sometimes better than those found on ordinary Redbook players. Consequently a CD player equipped with an HDCD chip may do a better job than a standard player on normal, non-HDCD-encoded CDs.

The only downside to playing a non-HDCD disc on a player with an HDCD chip is a slightly reduced volume level. Compensate by turning the volume up about 6 dB.

I own no stock in Microsoft, now the owner of HDCD. I just think the system, created by Pflash Pflaumer and Keith O. Johnson, is very elegant. It really can improve CD sound, too. Just too bad it's not in wider use for Redbook material. However if you have an HDCD-equipped player, you may get a surprise sometimes. With the occasional disc, the HDCD light comes on to show the extra info is there, even when there is no mention of HDCD on the disc wrapper.
The HDCD encoding is embedded in the audio data on the disc (low order bit modulation) and should survive a disc copy. If the CEC player failed to recognize the copy as an HDCD it means that your copy software did not make a bit-for-bit copy of the original disc.
Microsoft seems to have dropped this, but many performers insist of recording in HDCD. I have had two universal players that decode it properly. The first was the Lindemann 680D. I was shocked at the improved performance. My Exemplar/Denons also show a light with HDCD, but the performance jump is not as great.

If you can get the capability to play such disks as HDCD, go for it.

I have made copies of HDCD that do play as HDCDs.
I think Dusty Vawter of Channel Islands Audio eschews HDCD decoding in his DACS because the HDCD D-A chips don't sound as good as he wants them too.
I don't think I'm mis-paraphrasing him - Just another side of the coin to consider.
My HDCDs are the best sounding ones I have, on my compatable player.
Well thank God for Tobias (especially), Ghost, and Tbg -- y'all saved me from a lot of typing ;--) So I'll just add a couple of things:

First, I highly recommend Keith Johnson's newly ressurected Reference Recordings site: www.referencerecordings.com for both incredible HDCD recordings and info/links. As most of you know he co-invented HDCD.

Second, regarding HDCD decoding: The new(er) Levinson DACs and CDPs use a proprietary Levinson HDCD decoding chip, not the ones normally provided as OEM parts to most manufacturers. However, software-based DACs, such as my Wadia 27 and some others, do a perfectly marvelous job of decoding HDCDs. And even though you don't get the HDCD indicator light, some folks (like Steve Huntley @ GNSC) feel the Wadias do a better job than the HDCD implemented DACs.

I'll say one thing, I can usually tell (blind) if an unfamiliar disc is an HDCD or an XRCD (but not which is which ;--) Let's not do it here, but I'm going to start a thread for listing favorite HDCD/XRCD titles (if no one's done it yet ;--)

BTW, I agree that any bit-for-bit burner should copy an HDCD or an XRCD faithfully.

Tobias, that's the clearest explanation I've read.
I've been a big fan of HDCD for sometime. My first experience was with Joni Mitchell's "Blue," amazing depth and deail. I have noticed many unmarked cds are HDCD encoded with no indication on either the label or cd. There is a thread listing favorite HDCDs here and a rather lengty one at audiocircle.
One of my favorites is Stepen Stills "Manassas."
Alpass -- this site has the most extensive HDCD catalog I've run across. It's a Swedish site (I think) but has an English language option:


BTW, the HDCD license that the manufacturer needs in order to sell a player with an HDCD decoder requires that the player have an indicator for HDCD disks. It also requires that the level of non HDCD disks be 6db lower than HDCD disks. Some manufacturers put a defeat switch inside the player for this gain reduction - it doesn't violate the license if the end user disables the gain reduction.

For a long time Pacific Microsonics would not grant a license for a software implementation of HDCD (I.e. Wadia, Theta, Krell, etc) - you had to buy their decoder chip (PMD-100 or PMD-200). I think that stance has shifted since Microsoft bought them.

If you have windows media player (version 9.0 or above) and windows XP you can set up your computer to decode HDCD as long as you have a 24 bit capable sound card by doing the following. Go to tools-options-devices-speakers-properties-performance and check the box for 24 bit capability. Your computor will now decode HDCD.

Thanks Chuck. Will it say "HDCD" in blue letters across my screen? (Guess there's one way to find out ;-))


No, but the description pertaining to the 24 bit box mentions that you can now decode HDCD as long as you have a 24 bit card.

Czbbel - Interesting - the HDCD process only results in a 20 bit data stream, so I wonder why Microsoft wants a 24 bit card.

The only explanation that I was able to find states the while HDCD is a 20 bit stream as you mention most sound cards are either 16 bit or 24 bit and that you must step up to the 24 bits before the 20 bit HDCD can be used. Here is still more information http://en.wikipedia.org/wiki/HDCD

Great thread. Thanks to all for your insights and input.
I was impressed with the responses.