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
One of the reasons that I still keep my old EAD 7000Mk3 DAC is because it decodes HDCD. To my ears, HDCD is a very nice and easily heard improvement over the standard Redbook.
I actually believe that HDCD can still compete today with some of the higher rez formats. IMO, HDCD has a certain 'analog' sound to it that seems to do away with some of the digital nasties, that are to my ears always present in digital reproduction. 
@daveyf Yep, I am really liking my transcoded tracks, but I liked them a lot before. PM did nice things. :)

Yeah, the HDCD "license" holders actually had to buy little DIP chips with HDCD printed on them. I'm sure it's all in software now.
PCM HDCD and DXD/DVD-A rules when converted through a well implemented R2R Multibit converter with either PMD100 or the last to my ears better PMD200 HDCD chip.
Especially the 24bit pcm hdcd recordings from "Reference Recordings" done by the hdcd master Keith Johnson. Far better than any DSD crap, unless it’s native then it’s good, but sadly there’s no good music/artists for me on native dsd.

Cheers George
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