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