Deciphering DVD and CD
DVD and CD alphabet soup
Did you ever wonder what RW, +R, -R or DVD+RW
mean? What is the difference between a DVD and CD? This article
explains it all in clear and simple terms.
CD stands for compact disk which is a plastic disk
which was originally developed to store music and voice in a digital
format. DVD stands for Digital Video Disk which generally looks the
same as the CD but can contain much more data and deliver it much
faster. The disks use optical disk technology and data is written to
the disk and read from it by laser light.
The majority of the suffixes such as R and RW,
whether preceded by a plus or a minus, indicate whether the disk is
read only, write once and then read only, or rewrite able so that data
can be modified or added at will. The pluses or minuses in the name are
largely historical and indicate that a particular type of technology
was used to allow for the writing or multiple rewriting capability.
This used to matter in that some equipment supported one technology and
other equipment supported another. The minus was for a type of disk
that only Pioneer, Toshiba, Hitachi, Matsushita Electric (Panasonic)
equipment would support and Philips, Sony, Hewlett-Packard, Ricoh,
Yamaha supported only the plus type of drive. Most current DVD drives
can read and write to the disk regardless of the method by which the
data is actually stored on the disk so the plus and minus don't matter
The following table summarizes the meaning of the
||Created by some external agency for use on
||Write once and read many (WORM).
Data that is written to this disk is
permanent and the space used for it can't be overwritten or reused. The
primary intended use is to write whatever is desired in one session.
After this session it can be read but not written to.
|The user can write to this disk until it is
finalized. It may be readable by some drives before it is finalized but
is not readable by all drives until complete. The DVD can be finalized
so that it can be read by any drive even after only a very small amount
of data has been written to it.
||The user can rewrite to this disk many
times. Data written to it can also be deleted.
||Sometimes needs a caddy, which is a special
type of tray that holds the disk that is inserted into the drive, to
hold the disk
||A double layer of storage material is used
on each side of the disk, providing more storage capacity.
||Data is stored in a special format (which
is not a standard PC file format) which was developed to deliver audio
||CD or DVD players can play these disks, but
they hold much less data than file formats such as MP3 and WMA.
||Data is stored in a special format which
was developed to deliver video
||This format is intended for feature-length
motion pictures that can be played by a DVD player.
||Blue Ray disk or HD-DVD
||This is the next level of optical disk
storage which will provide huge capacities.
CDs can hold 74 to 80 minutes of audio or 700
megabytes of data. DVDs can hold from 4.7 gigabytes of data up to 17
gigabytes depending on the number of sides and the number of layers per
side used for storage. Blue Ray disks can hold up to 50 gigabytes, but
the drives needed to use them are much more expensive than standard DVD
drives. Standard DVD drives will run around $50 while Blue Ray will
cost around $600.
CD and DVD Speed
When CD and DVD disk speeds are discussed they are
referring to the speed at which information can be stored on the disk.
The speed at which the information can be read depends on the
particular DVD drive that you are using. Most of the time you will not
notice a difference. However, it should be noted that DVD disk speeds
are slower than hard disk access.
Detailed information about DVD and CD speed can be
DVD Speed Details
CDs and DVDs have long been known as the medium
used to deliver commercial software.
DVDs are used for playing music and movies. DVDs
have much more bandwidth than VHS tape and can provide a much more
robust video and audio experience than these tapes.
They are also used for transfer of data from one
computer to another.
Backing up your data is an important step in
safeguarding your data. If the data can be taken offsite it provides an
extra level of security. Since DVD disks are estimated to have a life
span of 25 years and are very portable, they are effective media for
storing backups of your data.
DVD and CD Burners
In order to gain the maximum advantage from this
technology, one should purchase a drive that supports reading and
writing of all formats. These drives are quite cheap and are generally
supported by inexpensive or free software such as Nero Express.
Sometimes to save a small amount of money, drives
that only write to CD but read or write from DVD are offered. The
saving is so minimal that these drives should be avoided.
If you have an older drive check the formats that
it supports before purchasing CD and DVD media.
LightScribe is an innovative technology that uses
a special disc drive, special media, and label-making software to burn
labels directly onto CDs and DVDs. This is a lot more readable and
prettier than magic marker scribblings on the CD.
See also Lightscribe Site
With LightScribe enabled DVD drives using
LightScribe ready CDs or DVDs (these are standard CDs except that the
non recording side of the cd is treated to allow computer generated
text and images) the user can make professional looking labels for the
disks they create.
There are programs available that allow you to
play audio and video content such as Cyberlink PowerDVD. However,
Windows Media Player which is supplied with Windows XP can also do this.
DVD and CD burning software such as Nero Express
and Roxio Easy DVD Creator provide the tools to record information.
They allow you to copy data to the disk and even create a bootable CD
or DVD. You can also create audio and video disks that are playable by
auto or home players from MP3 or other audio or video file input. DVD
and CD copying are also supported unless the source disks are copy
protected by content protection schemes. Commercial software, music and
video are generally copy protected.
These software tools generally also provide the
software necessary to create the LightScribe labels.
For those interested in an exhaustive, in depth
discussion of all details of this technology see;
DVD Details 2
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