| A Digital Video Disc or DVD is one of the | | | | Producing DVDs requires certain |
| most popular forms of storage media nowadays. | | | | authentication. Also, certain processes and |
| It is an optical disc and mainly used to | | | | rules are needed to be followed to handle |
| store videos. However, data in any form can | | | | their production. Present day markets are |
| be stored on a DVD. The dimensions of a DVD | | | | full of illegal and fake DVDs. Especially in |
| are generally the same as a common compact | | | | Asia, Africa and Brazil. So, certain security |
| disc but the amount of data that can be | | | | measures are applied to check this illegal |
| stored is six times greater. | | | | business. Copy prevention techniques are used |
| | | | that prevents illegal replicating of the |
| The different variations of DVD are based on | | | | original disk. |
| the way data is being stored on it. A DVD-ROM | | | | |
| has pre-written data that can only be read. A | | | | A DVD-Video is standard for storage of video |
| DVD+R and DVD-R are the ones on which the | | | | content on the media. Typically the format in |
| data can be written only once; and on a | | | | which video is stored in the DVDs is MPEG-2, |
| DVD+RW the data can be written and erased | | | | 16:9 aspect ratio videos. The resolution used |
| more than once. The lasers used to read DVDs | | | | are 720*576 (PAL) or 720*480 (NTSC) at 25 or |
| are typically of 650 nm wavelength. | | | | 29.97 FPS. The audio on the disc is stored in |
| | | | DTS (Digital Theatre System) or AC-3 (Dolby |
| The terms DVD-Audio and DVD-Video discs are | | | | Digital) formats. However, a number of other |
| DVDs with suitably structured and formatted | | | | resolutions and formats are also supported. |
| audio and video content respectively. Other | | | | Other features like selectable language in |
| types of DVDs are called DVD-data discs. | | | | subtitles, menus, multiple audio tracks and |
| | | | more than one camera angle is also supported |
| The term `DVD` is used for an unofficial full | | | | by DVD-Video. |
| form `digital video disc`. However, it was | | | | |
| officially announced that it stands for | | | | The DVD-Audio format is used to deliver |
| `digital versatile disc`. | | | | high-quality audio content. A number of |
| | | | channel configuration choices (like from mono |
| A typical DVD has a 4.7 GB storage capacity. | | | | to 5.1 or 7.1 surround sound) at a number of |
| These discs are one sided and single layered | | | | sampling frequencies are offered by the |
| i.e. the data is stored only on one side of | | | | DVD-Audio. The higher storage capacities |
| the disc and only at one level. The size is | | | | enable it to store a considerable higher |
| enough for a high quality 133-minute movie. | | | | amount of music or a much higher audio |
| The double sided and dual layered DVDs can | | | | quality. |
| store about 17 GB of data in any form. The | | | | |
| capacity dwarfs a compact disc easily. | | | | Although the DVD-Audio has higher technical |
| | | | specifications, the debate on whether the |
| The writing speeds on a DVD vary from 1350 KB | | | | audio enhancements that are being included |
| s (1 x) to 26 MB/s (18 x to 20 x). For a CD, | | | | are actually distinguishable or not in a |
| the speed 1 x means only 153.6 KB/s. | | | | typical listening environment is still on. |
| | | | |
| Initially, the burning or the duplication of | | | | There are a number of possible successors to |
| DVD was an expensive work and required | | | | the DVD. The strongest being the Blu-Ray |
| skilled persons to do it. Today, the process | | | | Disc. Others are Maxell`s HVD (Holographic |
| of writing on a DVD has become a piece of | | | | Versatile Disc) and the 3D optical storage |
| cake and any one with a little knowledge of | | | | discs that are being developed actively. |
| computers can do it at a click of the mouse. | | | | |