CD and DVD formats
Only the French, characterized by a proverbial nationalistic spirit , have a habit of just translate all the computer terms in their native language . The other Europeans , the Italians in particular, often have to contend with the terms of Anglo-Saxon origin of the various computer products : monitor , mouse, scanner , just to name a few. A terminology that may complicate life for the less experienced and who has no special knowledge of English. This situation is compounded by the fact that the world of computing is really full of acronyms and sizes expressed with names often incomprehensible even to insiders . More than any other product , the world of optical media is characterized by a number of abbreviations and acronyms without equal .
Only part of their proliferation is due to lack of agreements between manufacturers. However when you walk into a store to shop , it should certainly arrive unprepared. Here is a concise guide to never lose the compass : we will consider the two large families (CDs and DVDs ) and their “derivatives” , pointing from time to time , at what particular use they are intended. Finally, we will take a look at the future that seems interesting surprises in store : the big launch of Blu-ray and HD- DVD .
Which CD or DVD is compatible with your PC?
To figure out which disks are compatible with your PC ( and its reader / writer ) may not be easy. If you’re buying a new computer, carefully examined the specifications or the list of features , which will be specified in the optical drive read / write and formats it can support. Otherwise, you should contact your dealer or the manufacturer. All units for burning CDs currently marketed can read CD -R and CD -RW discs , while all units for writing DVD currently marketed should be able to read format DVD-R/RW and DVD + R / RW as well DVDs and DVD -ROM standard . If you already have a PC , you look at the front of the computer .
Unit of writing various symbols are likely to be present : the logo Compact Disc, which often contains the words Recordable or Rewriteable (if the unit is able to offer these features ) and possibly one or more logos DVD . Be careful because the latter there could be as many as three : one to indicate the ability to read DVD-ROM , one for writing DVD + R / RW and DVD-R/RW one for writing . Please note that these abbreviations contain three different information : the type of disc, the size and capacity. For example, in the acronym DVD-R/RW : DVD specifies the type of disc, the dash indicates the format of ” less” and R / RW specifies that the drive can read and record many times the data on the disk.
What does the future hold ? The producers are convinced that even the DVD will be sufficient for future storage requirements and therefore have developed two competing formats that already now battle it out to become the new standard : Blu-ray and HD- DVD .
The Blu-ray standard was created by a group of electronics companies and computer science that have given rise to an association by the name Blu- ray Disc Association ( BDA) , which includes: Dell, HP , Hitachi, LG, Panasonic , Mitsubishi, Pioneer , Philips, Samsung, Sharp , Sony, TDK and Thomson. The Blu-ray Disc must use the name of a particular laser of blue color which allows to store a greater number of information compared to the DVD : the blue laser has a wavelength shorter than that of red laser used for DVDs and lets you encode the data into smaller spaces than in this format.
These supports can store up to 57 GB , while those in the HD-DVD format has a maximum capacity of 30 GB . The HD- DVD (High Density Digital Versatile Disc) is instead mainly been promoted by Toshiba, NEC and Sanyo and is also supported by four famous production houses in Hollywood. Both formats will be available to the general public as early as next year . Before the big launch of these supports manufacturers are trying to test the market with the intention of securing a commercial network adequate and whether it is worth agreeing to a possible compatibility of the two formats . If we compare it with its closest competitor , Blu -ray, however, has the disadvantage of being definitely more expensive, at least in this first period of market penetration .
This is also why the producers are particularly likely to seek an agreement for a single format . It is not excluded , however, that competition to push down prices , leading to the same competitive level the two formats and the benefit of the consumer.
CD (Compact Disc) Discs Optical on which you can store data, images, sounds, and movies . It has a capacity up to 750 Mb . Dual layer Literally ” Double layer ” , the technology used on DVD with a double capacity compared to that of a DVD normal . 8.5 Gb instead the traditional 4.7 Gb . DVD (Digital Versatile Disc, originally Digital Video Disc ) DVD is a storage medium of the optical type and the time is the best for record the movie: in this context we are talking about DVD-Video. More generally the DVD is a support for data logging , at first sight is like a CD-ROM, but can contain information on both faces and on two distinct levels (Double Layer) . Optical media are memories ( patented by Philips and Sony ) that can be read and written through a special laser beam positioned within peripheral known writers , are part of this all category products the CD and DVD formats . ROM ( Read Only Memory) Only memory reading , on it are recorded data that can only be read and not deleted. Unlike RAM , ROM maintains information stored even after PC shutdown
The ability of the various media
This table provides you with a detail of the historical evolution of the capacity of storage media for personal computers
1967 Floppy disk 51/4 0,36 Mb
1983 Floppy disk 31/2 1,44 Mb
1985 CD-ROM 750 Mb
1996 DVD 4,7 Gb
1996 DVD double layer 8,5 Gb
2002 Blu-ray 25 Gb
2002 Blu-ray double layer 50 Gb
2003 HD-DVD 15 Gb
2003 HD-DVD double layer 30 Gb
A comparison of the main features formats: CD, DVD, Blu-ray and HD-DVD
The table summarizes the most significant media and allows you to have a concrete idea of the differences between various formats.
|Capacity (Single Layer / Dual)|
Support for video
Data transfer rate Mb/s
Size of the track (μ)
Pit length (um)
Laser wavelength (uM)
Protective layer (mm)
Number of layers750 Mb / –
14,7 / 8,5 Gb
1 o 225 / 50 Gb
1 o 215 / 30 Gb
1 o 2
Size The size of the trace of the entire trail left by the laser. A major dimension of the track allows you to store less data on the disk.
Pit length The length of the single path traced by the laser being written. The shorter the groove, the greater the amount of data that may affect the support.
The wavelength of the laser The decrease of the wavelength (the distance between the maximum peaks in a specific wave) laser allows to write on the support a greater numberof data in less space.
A numerical aperture greater numerical aperture of the laser corresponds to a smaller distance between the tracks and thus to a higher data density on the disk.