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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

Showing 2 responses by dtc

dtc's avatar
dtc
1,047 posts
 
As I understand it, Microsoft bought the rights to HDCD and they elected to not do anything with it other than have decoding in Windows Media Center. As far as I know, they still own it.

I am pretty sure that all the current implementations are just the software implementations that dBpoweramp, foobar and others use. That was a reverse engineering project by an individual who posted it on doom9 forum and was discussed in detail on the hydrogenaudio forum. foobar uses that code to decode HDCD as does dBpoweramp. JRiver looked at implementing it but never did.

The software does the bit compression part but I do not think it implement the various filters. At least, that is my understanding. Not sure I could point to any documentation on that however. It has been a while since I looked for the source code. Pretty sure it is out there somewhere. I used dBpoweramp to rip my HDCDs.

There is a list of HDCD recordings on headfi and that also has a pointed to musicbenz.

http://www.head-fi.org/t/65414/hdcd-list

http://musicbrainz.org/search?query=format%3Ahdcd&type=release&limit=25&method=advanced


dtc's avatar
dtc
1,047 posts
 
Erik - You have to be a little careful of the hydrogenaudio comments. Many on there are so caught up on their methodologies and rules that I wonder sometimes whether they actual listen to music. I only have a few HDCD, but they are very good quality and I do believe the HDCD decoding improves the sound.

As to  disks that are not labeled as HDCD - no idea. Many of them may be a mistake, but it seems like an honest mistake since they were never labeled to be HDCD.  I just know the labelled ones I have I like.

RR is holding onto an old technology. WIth high rez available (including 24/44), I see no reason to continue with HDCD given the lack of proper decoders and the cheapness of disk space.
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