Cracking HDCDs

HDCD stands for High Definition Compatible Digital not, as it would first appear, High Definition CD. If you have a middling to substantial collection of CDs (or lossless rips) the odds of you having one are quite high. If one of your CDs bears the logo, then good news. First of all, it means that the analog to digital converter employed in creating the digital signal on your CD is either the Pacific Microsystems Model One or Model Two, reputed to be some of the best converters ever made. From that standpoint, HDCD is a mark of quality.

Second, it means that on your disc or lossless file there may be features which have remained hidden. The most notable of these features is Peak Extension: a way of increasing the dynamic range of the recording by making the bulk of it quieter, increasing the bit depth (so that there is more room for different gradations of loudness), and then reversing the compression of some of the music's peaks.

More after the jump.
It's pretty hard to account for the real differences caused by decoding but if the feature's there , then why not use it?

These are the HDCDs I've identified in my collection: some Tom Petty and the Heart Breakers CDs from the 00s and the Flaming Lips' The Soft Bulletin. Though I haven't been through all of my Tom Petty CDs, I'm pretty sure they don't use peak extension. The same is true for the seminal Soft Bulletin. As I said previously, HDCD is still a mark of quality, but no real need to decode. I can keep these in my file format of convenience, Apple Lossless.

Perhaps more excitingly is my collection of Neil Young HDCDs. My copies of Neil Young with Crazy Horse' Everybody Knows This is Nowhere, and Neil Young's Neil Young,Harvest and On the Beachcan all be decoded and that all important Peak Extension utilized. It's my understanding that pretty much every CD in Neil's Archives project and Digital Masterpiece Series has had the peak extension treatment.Not only those, but the Beach Boys' Pet Sounds also makes use of Peak Extension. There's also Beck's Sea Change, which I've currently only got in mp3 format--my CD is in London, no decoding that for now.

Using Foobar with the HDCD Decoder Plugin by Kode54, I've been able to decode these albums so long as they are in FLAC (Apple Lossless can't currently be decoded because of the way Foobar plays it). When I tried with the CDs a while ago it didn't really work but don't let that stop you. Because Foobar is a little fiddly, it's taken me a long time, on and off, and a lot of tries to finally be sure I've got it working, read this thread and pay particular attention to the issue of the status bar. The real thing that pushed me over the top and got things working was transcoding from ALAC to FLAC as ALAC cannot currently be decoded using Foobar and the Decoder.

So how does it sound? The HDCD features are subtle and I probably do not have a sufficient listening rig to properly evaluate. That said, listening to Pet Sounds where I found (fairly minor) metering differences to the loudness, I felt I could detect a hint more dynamic range in the lead vocal at times. I feel there were subtle improvements to the Neil Young tracks too, often echo on the vocals. It strikes me as a bit of a gimmick really, but when listening to the music in a quiet setting I feel that if you can easily access that dynamic range then why ever not? I'm going to claim what I've done as an improvement on the basis that it cost me no money and I had fun while doing it.