CD Duplication 101

If you've been shopping for blank CDs or blank DVDs recently, you may have found yourself a bit confused by all of the choices - CD-R, CD-RW, DVD+R, DVD-R, DVD-RW, and DVD+RW. Trying to figure out the abbreviations between them can be a bit mind racking indeed.

To make matters worse for those who aren't up on the lastest marvels of technology is the rate at which the industry of technology is evolving. Just when you think you've caught on to the concepts of MP3s and burning CD and DVD media, new twists on blank media hits the market and you found yourself confused more than you were to
start with.

The "R" found in CD-R and DVD+/-R media stands for recordable. It will tell consumers that these disks are blank recordable media. You can record movies, data, music, and photos on the disc, but the discs cannot be erased.

The "RW" on CD-RW and DVD+/-RW media stands for rewritable. This lets you know that media with RW on them can be recorded and erased several times. Even though the prices for blank CD and DVD media is inexpensive, you can expect to pay a bit more for RW type media.

The biggest source of confusion stems from DVD-R and DVD-RW and how they are different from DVD+R and DVD+RW media. In order to avoid a long technical speech on the differences, you simply need to know that each DVD types can record movies just like the next type.

DVD+R and DVD+RW are a newer more expensive technology that offers a few technical advantages over DVD-R and DVD-RW. None the less, DVD-R has greater compatibility with more DVD players than any other format of blank DVDs.

If you have a newer DVD player or if you use your computer to play back media, you should have no problems with DVD+R/DVD+RW media. Some say that they provide a better range of quality, although the quality is indeed similar.

Keep in mind that all recordable CD and DVD media do the same thing regardless of their particular brand or extension. Because there is not an industry standard that involves DVD technology, not every DVD player is compatible with each and every format you see on retail store shelves.

For this very reason, you should always check with DVD player manual to see which type of recordable media it will play back. This way, you'll know what to buy the next time you go shopping for blank CD or DVD media.

Differences Between CD and DVD Media

Even though both CD and DVD disks have the same media size and shape, the things they have in common ends there. There are many different things between the two, such as what they hold and how much they hold.

Data pits and lasers

A disc has microscopic grooves that will move along in a spiral around the disc. CDs and DVDs both have these grooves, with laser breams applied to scan these very grooves.

As you may know, digital information is represented in ones and zeroes. Inside of these discs, very tiny reflective bumps known as lands and non reflective holes known as pits, which can be found beside the grooves, reflect both the ones and the zeroes of digital information.

By reducing the wave length of the laser to 625mm or more infrared light, DVD technology has managed to write in smaller pits when compared to the standard technology of CD. This will allow for a greater amount of data per track on the DVD. The minimum length allowed for a pit in a single layer DVD-R is .4 micron, which is obviously more than the .0834 micron that a CD offers.

The tracks of a DVD are narrower as well, which allows for more tracks per disc, which also translates into more capacity than a CD. The average single layer DVD holds 4.5 GB of data, while a CD holds a mere 700 MB.

Layers

As stated above, a DVD has smaller pits and the lasers need to focus on them. This is actually achieved by using a thinner plastic substrate than in a CD, which means that the laser needs to pass through a thinner layer, with less depth to reach the pits. It's this reduction in thickness that's responsible for the discs that were only 0.6mm thickness - which is half that of a CD.

Data access speed

DVDs will access data at a much faster rate than a CD can. The average 32X CD-ROM drive reads data at 4MB a second, while a 1X DVD drive reads at 1.38MB a second. This is even faster than an 8X CD drive.

Universal data format

The recording formats of CDs and DVDs are quite different, as DVDs use UDF, or the Universal Data Format. This format allows data, video, audio, or even a combination of all three to be stored in a single file structure. The advantage to this is any file can be accessed by any drive, computer, or even consumer video. CDs on the other hand aren't compatible with this format.