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  PC911 > How-To > Miscellaneous > Burn Baby Burn!

Burning CDs

So you finally managed to convince yourself, your parents (or bribed your significant other) into letting you buy the CD burner. You got it in the mail yesterday, and 10 minutes later, it was added to your already exorbitant arsenal of computer gadgetry. So now what? How exactly do you burn things? And why is it called burning anyway? It sounds so destructive. Well, have no fear, because this article will guide you through the world of CD burning in a step-by-step fashion. Before you know it, you'll be burning like a pro.


How it all works

One of the questions that everyone inevitably asks is "why is it called burning?" To answer that question, let's step back and take a look at how a CD actually works. Remember that all computer data, regardless of what type, is stored as zeros and ones. The computer then interprets the zeros and ones to make sense out of the madness. We used to have punch cards that did the trick. Now we have hard drives that store data in magnetic form. CDs are no different. On a CD, the "roughness" of the CD's surface represents the zeros and ones. This may come as a shock to you, since a CD's surface appears seemingly smooth to you. But make no mistake about it, there are incredibly small pits and grooves etched on the surface of the CD. Each pit represents a bit of data. (So the more pits you can pack into a CD, the more data it can store. Currently, normal CDs store about 650MB of data, or 74 minutes of audio.) When a CD is inserted into the CD-ROM drive, a small laser inside the CD-ROM drive is shot onto the surface of the CD. After the laser hits the surface, it will be reflected off the CD's surface. The reflected light is then intercepted by a series of mirrors and sensory devices, which analyzes the light and determines the bit the light represents. The digital signal processor in the CD basically analyzes the brightness of the reflected light. If the brightness is above a certain threshold, it is interpreted as a one. Otherwise, it is a zero. The brightness of the reflected light is directly related to the pits and grooves on the CD. If the light reflected off a huge pit in the CD, then the reflection would not be very bright. (because of scattering. Just as your image, viewed in a worn down mirror, will not be very clear.) Thus, a large pit is interpreted as a zero. Conversely, a smooth area on the CD, called lands, would reflect very well, and thus is interpreted as a one.






So now that we have a basic understanding of how CDs actually work, it's time to take a look at how CD writers perform their magic. If you've ever seen the backside of a brand new, unwritten, CDR disc (So yes, there are blank CDs. You can buy them at most of your major computer retailers, like Comp USA, or Best Buy.), you would notice that it is surprisingly reflective. A blank CD, in fact, has no pits (for the experts reading this article, I am of course making a oversimplification by ignoring the pre-grooved spiral track layer used to guide the burning laser). So if your computer were to scan the CD, it would read all zeros. When you actually write data on to the CD (and we'll be getting to that a little bit later in the article), the laser inside the CDR drive (from this point on, I will be referring to all types of CD writing drives as CDR) actually heats the surface of the blank CD up so that the chemical coating of the CD will react and form a pit. That is why most people refer to CD Copying as CD burning. In essence, you are burning a pit into the CD. Once the CD is written, you will notice that the backside is no longer as reflective as it used to be. The pits are now on the CD, and they don't reflect as much light as the smooth surface. There you have it - the magic behind CD writing.

Learning the Language

Right about now, you are probably really impatient and ready to burn your first CD. My answer to you: Not so fast! Before you start burning anything, let's make sure you understand some of the basic terminology used in CD writing. Because if you don't, you'll find yourself knee deep in coasters. And there is our first term - coaster. A coaster refers to a CDR that was not written correctly. This could happen either because of user error, or hardware/software error. In the bad old days, most coasters were the result of software/hardware error. But today, things are much improved. Most of today's coasters are caused by user error.

Having said that, let's take a look at some of the basic terminology used in CD burning. The most common terms used in CD burning are:

  • Session

  • Multi Session

  • Lead In

  • Track

  • TOC

  • CDDA

  • ISO-9660

  • Joliet

  • Mixed Mode

These terms may seem daunting. But trust me, they are really quite simple. First, data on a CD is organized into tracks. You probably know that from your music CDs. Each song on a music CD is stored on a separate track. You can think of tracks as the basic unit for organizing different types of data on the CD. What exactly are different types of data? We'll get to that in just a little bit. So just remember that every time you write stuff to a CD, you are writing it to a track.

The next term to look at is session. The definition is not too far off from that of a recording session in the music industry. A recording artist goes into the studios to modify her album. Every time she does that, she is in a recording session. The term means the exactly the same in CD writing. Every time you write something to a CD, you are adding another session to the CD. So if you wrote multiple times to the same CDR disc (so for example if you burned Windows 2000 to the CD on Monday, and added Half Life to it on Wednesday), then you've created a multi session CD.

Also related to the word session is the term Lead-In. Lead-In refers to an area at the beginning of a session that stores the session's information, such as where on the CD the session data starts, where it ends, what it contains. It is basically a table of contents for the stuff recorded in the session. For the technical minded, a lead-in takes up 4500 sectors on a CD, which is roughly 9 megabytes of data. That means you cannot create an infinite number of sessions.

A week later, you've got about 7000 files burned onto a CD. You are pretty proud of yourself. But now you wonder... How does the CD keep track (no pun intended) of all those files? The answer lies in the TOC, or Table of Contents. Just as the name may imply, the TOC keeps a long list of every file that's on the CD, their location on the CD, size, etc. Without the TOC, even if the CD is burned full of data, the computer will still think it is blank. If you've dabbed in hard drive partitioning before, the TOC on a CD is the equivalent of your FAT on a disk partition. If you've never heard of FAT before, don't despair. It's not that important. What is important is to understand that the table of contents tells the computer what the CD contains.

Remember a little bit up in the article I mentioned something about different types of data? Well, that's what the last few terms are. They are different data types. What will be covered here is somewhat technical in nature. It is interesting to know, but not necessary for CD burning.

First up is CDDA. CDDA refers to CD Digital Audio. It is the file format used to store audio data, like the music on your Backstreet Boys album. Sony and Phillips jointly developed the standard back in October of 1982. This standard is also known as Red Book. Another term is ISO 9660. This is the file format used to store data files on a CD, such as directories, word documents, MP3 files, etc. The one major limitation of this international standard is that its file names had an 8.3 limit, reminiscent of the bad old DOS days. However, in today's Windows 9x driven world, 8.3 filenames are no longer acceptable. Hence, a new file format has been created to fill the gap created by ISO 9660. That file format is Joliet. The biggest improvement Joliet has over ISO is that it allows for long filenames and directory names. And finally, a Mixed Mode CD is a CD that contains both data files and audio files. Typically, all the data is stored as the last session on the CD, and all the audio is stored as the first session (more on why later in the article).

There are of course many other terms. But the intention of this section is not to inundate you with every possible vocabulary word. Rather, the main purpose of this section is to get you familiar with the most basic terminology. In the following sections I will gradually introduce you to some of the other terms as the time becomes appropriate.

Starting The Fire

Now that we have a basic understanding of how CDRs work, it's time to burn our first CD. This section will be divided into three parts. Part I will discuss the procedure for burning Audio CDs. Part II will talk about data CDs. And finally, Part III will discuss the procedure for creating mixed mode CDs. Realize that there are many different programs you can use to write data to a CD, but the general process is the same. This article will be using Adaptec's Easy CD Creator, as it is one of the most popular CD writing programs. More advanced users may opt to use Nero or CDRWIN. For tutorials on those two programs, please refer to the Advanced CD Burning Guide.

Page 1: This page - Basics of CD Burning
Page 2: Compiling music CDs
Page 3: Writing data CDs






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