difference between a CD disk and a DVD disk?

Question

can anyone tell me the difference between a blank DVD disk and a blank CD disk, I already know that a blank DVD disk can hold several times the amount of information that a blank CD can, but why is this - if you put them side by side they both look the same to me, so what makes the DVD disk different and allows it to hold so much more data than a CD

hey guys all I really want to know is HOW a dvd disk can hold more than a cd disk

I already know that DVD disks are used mostly for movies, but that doesnt explain how it is able to hold more data than a cd disk, also someone said a dvd disk is more dense what does that mean

Answer 1

DVD technology writes in smaller 'pits' to the recordable media than CD technology. Smaller pits mean that the drive's laser must produce a smaller spot. DVD technology achieves this by reducing the laser's wavelength from the 780nm infrared light used in standard CD drives to 625nm to 650nm red light.

Due to the smaller pit size DVD media uses a thinner plastic substrate than do CDs. This reduces the depth of the layer that the laser must pass through to reach the pits to record or read data.

Answer 2

I know a few...
- At the readable part of a two disks, the colors are different. The CD is silky silver, and the DVD is silky blue
- They have different storage quantities. A CD can hold usually up to 700mb and the DVD can hold about 4gb
- Each accepts different kind of files... meaning, you can't burn a DVD with something you would be able to burn a CD with or visa versa

That's about all I know... Another thing I know is that there -R's are the ones you can't remove data from once you put it in and the -RW's are working just like floppy disks or USB storage devices :)

Answer 3

CD or compact disk came well before the DVD, and at the time, the pits could not be so dense we did not have the proper technology nor could we use dual layering and a DVD or Digital Versitile disks where designed to be able to hold more information, its the way things go

CD=700 Mb or 0.7 GB

DVD=4700MB or 4.7GB

no need to guess which is bigger

Answer 4

Barkley has the best answer so far - new technology has allowed smaller pits to be developed that allow more of these pits to be put onto the DVD. CD's in a lot of ways are 'old technology'.

In addition to this, error correction technology has increased, and there is a lot of error correction data on a CD which is not on a DVD - the newer error correction data is far more efficient and smaller.

Also DVDs quite simply tend to use (again, partially due to technology) more of the physical space on the disc.

DVD are basically an improvement in data efficiency and physical-space use efficiency.

Answer 5

Both kinds use lasers to read little tiny holes burnt into the disc. On CDs the hole can only be one depth (it's either there, or it isn't.) But on a DVD, the hole can be several different depths, and the DVD laser can tell the difference. So a cd can only say one thing with one hole, but a dvd can say about 8 different things because the hole can be 8 different variations of depth.

p.s. You know what, I think I might be describing what makes Blu-Ray and HD-DVD better than DVD. Hound Barkeley might actually have the correct answer.

Answer 6

The reason a blank CD disk can not compare to a blank DVD disk, is because of a DVD disk is supposed to hold hours of videos where as a CD disk is at the max supposed to hold about 60 minutes to an 1,30 minutes...

Answer 7

The only real physical difference is that a dvd is thicker than a cd by a slight amount. Also the "metal"coating on the playable side is chemically a bit different but not much.

Answer 8

A CD is normally silver and the DVD is a pink ISH colour on the side that the drive burns on. and the DVD can store much more DATA.

Answer 9

Yeah, it's just the density of the writeable area of the disk (the more dense, the more storage capacity) CD's and DVD's can be used to store the exact same things, just like flash drives, and hard drives, for example, it's just storage capacities

Answer 10

As to the physical makeup of the actual disks, I am not sure. But the players use different lasers that use different spectrum's of light to read and write data onto the medium.