Recording to CD: More than Meets the Ear
Part 1, by Lionel L. Dumond

 
There's a lot more to recording a CD than just pressing "record"! Ever wonder what really ends up on those shiny round discs? In Part I of this two-part series, you'll learn about the physical and logical workings of the medium, while being treated to a "written-in-plain-English" overview of data storage and retrieval, CD formats, encoding, error correction, subcodes, and more. As recording and mastering engineer Lionel L. Dumond shows, there's more to a recorded CD than meets the ear.

I recall my very first honest-to-goodness studio gig. It was an eight-track room with carpet on the walls, egg crates on the ceiling, and an ancient Tapco board. The year was 1980, back when a digital audio recorder cost more than a downtown building, "ADAT" was something your deaf grandfather would mutter whenever anyone said something to him, and the compact disc was just coming out of the laboratory.

Mostly, I recall the frustration of getting test pressings back that didn't sound anything like I expected they would. No bottom end, mushy highs, the dynamic range squashed. To me, they would just sound dead compared to the mix we had sent. Add to this the fact that these test pressings weren't even the real thing -- they were acetates, made of soft plastic that held up to about a half-dozen good spins if you were lucky!

You see, back in the day when vinyl was still king, producing a real "master" in a local recording studio just wasn't possible. Once we as producers and engineers had taken our best shot, the final step in preparation for pressing involved shipping the two-track reels to some mysterious, far-away place where a mastering engineer would take over. Part of the mastering engineer's job was to apply equalization and limiting -- not necessarily to make the music sound better, but so that a low-frequency passage wouldn't make the needle jump a groove, or a hot peak wouldn't blow the head off a cutting lathe. Depending on the skill and conscientiousness of the mastering engineer, the results could range from decent to disappointing. This was something we pretty much lived with at the time. Unless you owned your own record factory, you and your master were at the mercy of the man at those controls.

I remember wishing back then that I could get my hands on my own master cutting lathe!

Fortunately, thanks to modern recording technology, things are different today. With the advent of digital audio technology has come a revolution in the way music is recorded and distributed. The introduction of the compact disc removed the physical constraints of styli, turntables, and PVC from the playback medium, making the mastering of records much more an art than a mechanical process. And with the subsequent introduction of CD-R -- the recordable CD -- it became possible for the recording engineer, working in a regular facility, to actually receive a copy of a work (or create one himself) in an format virtually identical to the final product. No more cheesy acetates! Heck, this is better than owning a record-cutting lathe -- and all without the several tens of thousands of dollars it would have taken to buy one in the old days!

But of course, with this new technology came new issues to deal with and new things to learn. I soon figured out there's a lot more to recording a CD than pressing "record"!

The theory, techniques, and uses of recordable CD in audio production is a complex subject, and often a source of confusion for the uninitiated. It's important to remember that compact disc is, by its very design, a digital chameleon, which is what it's developers intended. A CD (and by extension, a CD-R) can contain audio, video, photographs, computer programs, data files of any type, or a combination of any or all of the above, contained in any number of different physical and logical formats. Of course, as the types of digital information stored varies, the recording methods used will vary as well.

In this article, we explore the subject of CD recording as it pertains to audio production. In Part I, we'll present a brief theoretical overview of CD data encoding, storage, and retrieval. In Part II, we'll tackle various hardware and interface options, and explore some of the more useful recording methods and technologies. We'll also define some of the most commonly-encountered technical terms as we go along.

How CDs Work -- An Overview
A compact disc nothing more than a physical medium used to store binary information. In this regard, it's no different than a floppy disk, the hard drive in your computer, or a DAT -- it's merely a way of storing a long list of ones and zeros. What makes a CD -- and for that matter, any other digital storage medium -- unique is the way in which the data is written, arranged and accessed. While a very technical explanation of how this is done would exceed the scope of this article, a simplified presentation is in order.

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