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Topic: 'HDCD' Detected? (Read 4704 times) previous topic - next topic
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'HDCD' Detected?

Hi all,

This was a surprise to me - when I play what appears to be a regular CD with windows media player a little button shows up 'HDCD detected'.
I say appears because on the packaging there is no mention of it being a HDCD.

When I play with foobar, it shows up as regular 44.1 material.

So either this a mislabelled 'hybrid' HDCD and I need a decoder for foobar, or its incorrectly tagged.

Any ideas?

'HDCD' Detected?

Reply #1
Could be an HDCD without the labelling.

Install the foobar2000 HDCD component, then see what the status bar reads when playing back the disc. Also try the context menu entry (right-click the track) Utilities -> Scan for HDCD tracks.

'HDCD' Detected?

Reply #2
Will give that a go, thanks.

'HDCD' Detected?

Reply #3
What's the CD?

'HDCD' Detected?

Reply #4
What's the CD?


Hi it's this one - random purchase.

http://en.wikipedia.org/wiki/Gabriel_%26_Dresden_%28album%29
I used the HDCD scanner and no results of it being one.


Some good info here: http://www.audioasylum.com/audio/digital/m.../15/156241.html
"ANY disc made with the PM A/D converter will light up the "HDCD" light (a metaphorical one in the case of Foobar). The PM inserts the hidden code whether or not it needs to."

'HDCD' Detected?

Reply #5
BTW -  HDCDs are still sampled at 44.1 kHz,  but one of the 16 bits of each sample isn't "normal" audio data but HDCD data that can be decoded to provide an effective 20 bits of resolution.

'HDCD' Detected?

Reply #6
My understanding is that it does not increase resolution (in fact it reduces it). What it increases is dynamic range.

'HDCD' Detected?

Reply #7
Hmm... I went looking for more detailed information and the best I could find is:
Quote
HDCD encodes the equivalent of 20 bits worth of data in a 16-bit digital audio signal by using custom dithering, audio filters, and some reversible amplitude and gain encoding; Peak Extend, which is a reversible soft limiter and Low Level Range Extend, which is a reversible gain on low-level signals.


The wording does make it sound like there is no *real* increase in bit-depth, but that it allows peaks higher than full-scale to be recreated.  Personally, I think it'd be a better idea to just cut the loudness-war-volume down by 6 dB and use that 16th bit for straight audio data

I know there have been similar techniques to this used with some success - Dolby NR on cassettes, SBR in HE-AAC, various digital sound restoration tools. But those are all specific solutions for specific problems. Has it ever been demonstrated that an HDCD gives better sound than the equivalent normal CD? I did have an HDCD once, but that's long gone, so I can't personally do any.

'HDCD' Detected?

Reply #8
There's some useful info in the foo_hdcd thread, especially [a href='index.php?act=findpost&pid=836350']here (click)[/a]. There are other posts in that thread along the lines of "HDCD is a useless gimmick".

'HDCD' Detected?

Reply #9
Personally, I think it'd be a better idea to just cut the loudness-war-volume down by 6 dB and use that 16th bit for straight audio data

Indeed. Particularly since basically cutting off the peaks during playback on a non-HDCD player may very well give audible distortion. Not a very efficient way of making things louder. It's an interesting approach to combining higher levels for the masses + optimum SQ for audiophiles though. IIRC the process also uses noise-shaped dither, which still was kinda novel at the time (but could be used on any ordinary CD nowadays).
Has it ever been demonstrated that an HDCD gives better sound than the equivalent normal CD?

Well, chances are they aren't actually equivalent. I happen to have two Joni Mitchell albums recorded within a short time of each other and presumably on similar or the same equipment, Hejira (1976) on an original CD issue (1987, I think) and Don Juan's Reckless Daughter (1977) on an HDCD remaster. The former sounds a bit lifeless when compared to the latter. This is nothing I'd attribute to HDCD though - rather bass and highs would seem to have been tweaked during remastering. A better ADC certainly didn't hurt either, though that again would benefit any format.

In sum, I'd say HDCD is an interesting historical footnote, and that's about it.

'HDCD' Detected?

Reply #10
There's some useful info in the foo_hdcd thread, especially [a href='index.php?act=findpost&pid=836350']here (click)[/a]. There are other posts in that thread along the lines of "HDCD is a useless gimmick".


It's worse than that -- in [a href='index.php?act=findpost&pid=731764']this thread[/a] they came to the conclusion that it's definitely possible to ABX an HDCD that hadn't been decoded against one that had, even if you can't ABX the resulting 20-bit stream against a properly-downsampled 16-bit version.

So HDCD actually seems to do active harm to the audio data unless you decode it properly, so while the production team probably should've dismissed HDCD as a useless gimmick, as consumers we now have to deal with its existence.

 
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