HDCD rescue - it's possible, but man...


I spent the better part of today sick, but working on finding a way to decode music I might have that is HDCD encoded.

As a refresher, HDCD was an enhanced CD format. In some ways the predecessor to MQA. HDCD was an engineer's toolbox, allowing the mastering engineer to select a number of features. This would then be decoded by a matching chip on a CD player or DAC. The most famous feature of HDCD was bit-compression. Getting a 24 bit signal encoded in a 16 bit music file.

As an aside, the Pacifics Microsonics AD converters were highly prized by engineers for their sound quality. Anyway, the format got bought by Microsoft and died.

Of the 670 CD's I have ripped only about 11 were HDCD encoded. But man, what a pain. I ripped everything to FLAC, but the HDCD decoder only does WAV. I had to download source, compile it, then write a script to go through every CD and decide if it's HDCD or not. Once found, I have to convert from FLAC (44/16) to WAV, decode the WAV file (now 24 bits) and convert back to FLAC to compress again.

The discovery process was pretty fast.  About 10 minutes to go through them all by cheating. :) More time was spent figuring out how to pass apostrophe's in file names than finding the files.  Nathalie Merchant was one author who consistently used HDCD by the way.
erik_squires
Wow, you packed a lot in that first sentence, @georgelofi Not sure what you meant.

AFAIK, the HDCD chip, was purely digital domain. The DAC implementation was left up to the licensees.

Interesting about Reference Recordings. I wonder if they are using any of the bit-compression or just the transient filters.

As far as I knew, there were no longer any HDCD ADC's available, so you had to use vintage gear, although I soppose you could do it purely in software, but then what's the point??
AFAIK, the HDCD chip, was purely digital domain.
Yes I know, I never said they were in the analogue domain, they were magnificent, especially when partnered with with well implemented Multibit d/a converters (I/V stages and buffers that weren’t just text book installed opamps) as many are.

Cheers George
So I've poked around Reference Recordings. I've not heard them, so I have no idea what they sound like, but I must say that their site is VERY light on technology. Big on adjectives.

Again, it may be fantastic, but I personally would love to understand which set of HDCD features they are taking advantage of.

Best,

Erik
Professor Keith Johnson who was the design man behind HDCD in 1996 also founded Pacific Microsonics Developments (PMD). And is now also the Technical Director, Recording Engineer and partner in Reference Recordings.

http://www.goodwinshighend.com/music/hdcd/hdcd_development.htm

http://referencerecordings.com/about.asp

http://www.stereophile.com/content/keith-o-johnson-reference-recordings#sbudxxeHz73RTH26.97

Cheers George
I've never heard one, but the owners "say" the Pacific Microsonics Model Two A-D/D-A Converter is the end game for listening to pcm with. And worth a small fortune s/h.
https://forum.audiogon.com/discussions/Pacific%20Microsonics%20Model%20Two%20A-D/D-A%20Converter

 Cheers George