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Video:What is a DVD-R?

with Zoya Popova

DVD-R is a blank recordable disc that is able to have new information written on to it for storage. Learn more about the technology behind DVD-R discs.See Transcript

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Transcript:What is a DVD-R?

Hi, I'm Zoya Popova for About.com, and today I'm going to talk about DVD-R.

Most people know DVDs as the pre-recorded discs with movies on them that we get at the store and watch on DVD players or computers. But that is only part of DVD technology. So let's look more into it.

Lasers Read DVDs' Information

DVDs are optical discs, and by optical, we mean that the data stored on the disc is read by a laser. All DVDs are made up of two polycarbonate discs with a reflective metal layer sandwiched inbetween. In a mass-produced pre-recorded DVD, one of those discs has a track of microscopic pits and lands that were stamped onto it at the factory. This track is much similar to the track on a vinyl record. It starts at the center of the DVD and spirals outward.

As the laser follows the track, it bounces off the reflective layer, and depending on whether it hits a pit or a land, signals a 1 or a 0. This binary sequence is your data—the digital representation of the grooves on the DVD.

Lasers Encode New Date on Blank DVD-Rs

Now, as you may know, factory-produced movie DVDs are read-only. Once those pits and lands are etched in the surface, this disc can only be used to read the pre-recorded data. Conversely, DVD-R is a blank recordable disc. Between the 2 polycarbonate discs that compose it, DVD-R has a dye layer in addition to a reflective layer. In order to record data onto the disc, the laser will move along the spiral groove incorporated into one of the discs, burning the dye layer as it goes.

Depending on whether it needs to encode a 1 or a 0, the laser beam will change its intensity, changing the reflective properties of the dye layer. This results in an optical equivalent of a pit or a land. Of course, in order to be able to do record onto DVD-R, you will need DVD-burning software, and your computer must an appropriate DVD drive.

Because a single-sided, single-layer DVD-R has a capacity of around 4.7GB, it is a great solution for storing large amounts of data, such as software and video files.

DVD-R Can Only Be Written Once

One thing to remember, though, is that, unlike rewritable DVDs, DVD-R is a write-once-read-many type of disc. Once the disc capacity is filled, the dye “pits and lands” cannot be written over. So the data you decide to store on DVD-R should be something you intend to keep for a long time. This makes DVD-R a good fit for archiving music, photos, and documents. And this is it for DVD-R, thank you for watching, and for more information, please visit us at About.com.

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