| Types of DVD and history of developmentIt's been | | | | DVD was initially designed for. Compared with VHS |
| a long time since DVD became common in our | | | | tapes DVD-Video is a giant leap into the future. |
| everyday life. However, most people don't seem to | | | | There are heaps of features there that most people |
| know what it is exactly. Answers to questions like | | | | have no idea about.First of all, DVD-Video is |
| "what sort of arcane symbols are printed on disk | | | | interactive - any place on the disk is instantly |
| boxes", "how come DVD is different from CD if they | | | | accessible and it is possible to have more than one |
| look so similar", "what kinds of DVDs are there" and | | | | ending for the movie. And parents can limit viewing |
| many others still remain mystery for many users. | | | | of naughty parts of movies for their children. Apart |
| And instead of making conscious choice they just | | | | from that disks can have additional bonus materials, |
| buy randomly without any knowledge of what | | | | such as interviews, promotion trailers, slides, text info |
| exactly they are getting.We will examine DVD in | | | | and even videogames. In addition to all this |
| details, along with its history and different types | | | | DVD-Video is capable to have multi angle view |
| available on the market. DVD-Video will get most | | | | option, when camera angle can be changed during |
| attention as it is the most common type of | | | | playback. However, this feature mostly used in porno |
| DVDs.What is DVD? Initially DVD standard was | | | | movies and live concert records.Video data on |
| designed for video storage only. Thus its acronym | | | | DVD-Video disks is compressed by using MPEG-2 |
| was decrypted as Digital Video Disk. Later, when | | | | compression. This compression algorithm allows |
| DVD started to become popular for storage of all | | | | shrinking video stream approximately ten times, |
| types of data, another meaning for DVD acronym | | | | without loss of picture quality. As a result, each disk |
| was introduced - Digital Versatile Disk, which is still | | | | is able to hold up to 4 hours of video with 720x576 |
| used nowadays.Generally, DVD is the next generation | | | | resolution at 24 frames per second (PAL) or |
| of CD. First of all, DVD differs from CD by its | | | | 720x480 at 30 frames per second (NTSC). The |
| significantly larger capacity. While CD disk can only | | | | streaming speed is usually between 3 and 10 MBit per |
| contain between 650 and 800 megabytes, DVD is | | | | second.Video can be recorded in different screen |
| able to hold anywhere between 1 and 17 gigabytes, | | | | ratios. For example, it can have ratio of 4:3, which is |
| depending on disk type. This storage increase is | | | | a standard television ratio, or widescreen - 16:9. |
| achieved by reducing laser wavelength. But DVD | | | | Widescreen image have two types: Letterbox and |
| capacity would never reach more than 4.7 gigabytes | | | | anamorphic. In the first case image is simply cropped |
| if it wasn't possible to make DVD disks | | | | at the top and at the bottom to achieve desired |
| double-layered or double-sided.One side of | | | | format. In anamorphic mode the image is initially |
| double-layered disk can contain two layers of data. | | | | recorded in stretched form and then shrinked to the |
| To avoid interlapping, outer layer is made | | | | desired size. This method is much more effective as |
| semi-transparent. During reading, laser collects data | | | | whole frame is used for useful data, while in |
| from bottom layer first, and then switches to the | | | | Letterbox large part of the frame is used to store |
| second layer. This allows doubling the capacity, up to | | | | black pixels only. As a result, anamorphic mode has |
| 9GB. It is easy to recognize double-layered disks - | | | | better details and sharper picture.Audio data can be |
| they have silver shade of working surface, while | | | | stored in various formats: LPCM, Dolby Pro Logic, |
| single-layered disk appears gold. Most video releases | | | | Dolby Digital, Dolby Digital EX and DTS.LPCM (linear |
| are printed on double-layered disks.Apart from that, | | | | pulse code modulation) is uncompressed stereo or |
| both sides of DVD can be used to store data. The | | | | mono soundtrack. It is usually used in musical video |
| possibility of making double-sided disks arise from the | | | | clips and movies where sound clarity is important. |
| fact that the protective layer for DVD is only half of | | | | Same format is used for generic Audio CDDolby Pro |
| that for CD, that is, 0.6mm instead of 1.2mm. So, in | | | | Logic is special type of soundtrack that can be split |
| order to keep compatibility with older format, | | | | into 4 channels for surround sound. Nowadays this |
| single-sided DVD disks have additional plastic added to | | | | format is uncommon.Dolby Digital (AC-3) is fully digital |
| them to achieve 1.2mm thickness. Of course, it is not | | | | sound compression format; it can be split into up to 6 |
| a problem to put additional layer instead of 0.6mm of | | | | independent channels. Unlike Dolby Pro Logic, each |
| plain plastic. This wasn't possible with CDs as they are | | | | channel is recorded on separate physical track.Dolby |
| thick enough already.DVD - the history of conflictIn | | | | Digital EX is more advanced version of Dolby Digital. |
| 1997 several large manufacturers of electronic | | | | Supports up to 8 independent channels.DTS (Digital |
| equipment established organization called DVD-Forum | | | | Theater System) is another digital audio compression |
| (earlier known as DVD Consortium) in order to | | | | format, introduced by Steven Spielberg as an |
| develop single standard for new generation of disks, | | | | alternative to Dolby Digital. DTS provides more quality |
| as CD technology was becoming less and less | | | | than Dolby Digital due to lower compression. That, of |
| sufficient.Despite many debates and lots of | | | | course, leads to bigger size of the soundtrack itself, |
| technologies claiming to be the best, the final decision | | | | which occupy more disk space. It also requires special |
| was made and DVD (with eight types of it) standard | | | | receiver to be decoded. Because of these reasons |
| was established. It was soon followed by DVD-Video | | | | DTS disks usually does not have any bonus materials |
| standard.However, when it came to standards for | | | | but have LPCM soundtrack. This soundtrack is |
| recordable and rewritable disks, several large | | | | included to allow users without special receiver to |
| companies started to push their own formats | | | | listen to the sound (stereo only, though). Because of |
| DVD+R and DVD+RW. These companies founded | | | | all these DTS disks are much less common compared |
| their own coalition called DVD+RW Alliance. The most | | | | to Dolby Digital. Usually DTS disks with improved |
| interesting part was the fact that different branches | | | | video quality (and without bonus materials) are called |
| of formats were not compatible with each | | | | SuperBit. Both DTS and Dolby Digital (EX) are also |
| other.Apart from that, Panasonic also contributed to | | | | used in cinemas.Some of the largest drawbacks of |
| the mess by developing DVD-RAM standard. This | | | | DVD-Video are its various copy protection measures, |
| standard was faster and more reliable, but it was | | | | which were added because of the pressure from film |
| compatible only with DVD-RAM devices.The ones | | | | companies. At first these measures provided lots of |
| who suffered the most from this mess were | | | | nuisance for users, but eventually every DVD |
| common users, as they were forced to make a | | | | protection was hacked. This process was also |
| difficult choice of preferred technology.For that | | | | assisted by equipment manufacturers who simply |
| reason many people didn't rush for DVD and kept | | | | didn't support most annoying protection |
| their data on good old CD-Rs and CD-RWs.The war | | | | measures.One of the most annoying of such |
| of standards was ended by Sony, which made DVD | | | | measures was "Regional Protection" . The world was |
| drive capable of reading both DVD-RW and | | | | divided into 8 zones, and each DVD player was |
| DVD+RW. This device instantly became popular even | | | | supposed to have information about its zone. The |
| in spite of its double price compared with | | | | same was made for DVDs, and thus DVDs from one |
| single-standard drives. Sony soon was followed by | | | | zone could only be played on players from the same |
| other manufacturers and the ability to read both | | | | zone. User was allowed to change zone for the |
| types of disks soon became a standard for any DVD | | | | player few times only, and the last of selected zones |
| drives. This was the beginning of the DVD era for PC | | | | was locked in the player forever.This trick was |
| users.Unfortunately, there also were lots of | | | | invented in order to be able to assign different price |
| disagreements during development of single standard | | | | in each region, depending on income level. Besides, |
| for digital audio, DVD-Audio. Two technologies | | | | movie might be released in different times in |
| compete for the title of Audio CD heir: a partially | | | | different countries. For example, in Africa the movie |
| compatible with Audio CD technology from Philips and | | | | might just hit cinemas and in USA it might already be |
| Sony, and a standalone Toshiba's standard. Toshiba | | | | available on DVD. So regional protection was |
| won, but Philips and Sony didn't give up and released | | | | supposed to stop people from buying DVDs in USA |
| their own format without DVD-Forum support. This | | | | and selling them in Africa.Unfortunately, this |
| format was called Super Audio CD (SACD). At the | | | | protection didn't bring anything but troubles. Many |
| moment both formats are not selling particularly well | | | | travelers were not able to play disk purchased |
| and are not known in some countries at all.Types of | | | | overseas. Buying disks over the internet or from |
| DVDLet's move to DVD itself. DVD is the most | | | | EBay also became a problem. Apart from that, some |
| common format nowadays. At the moment DVD | | | | movies were released in certain countries only.Many |
| comes in 8 flavors: DVD-1, DVD-2, DVD-3, DVD-4, | | | | manufacturers considered these implications and |
| DVD-5, DVD-9, DVD-10 and DVD-18. The difference | | | | started to provide means of switching off regional |
| is in the capacity, which is denoted by the number in | | | | protection for their devices. Chinese manufacturers |
| the name (value is rounded).The most common | | | | basically abandon this protection at all.But uncontrolled |
| formats are DVD-5 and DVD-9. These are single- and | | | | distribution of DVDs wasn't the only thing that movie |
| double layered single sided disks, respectively. DVD-5 | | | | makers were against. Illegal copying was much bigger |
| holds 4.7 GB of data and DVD-9 is able to contain up | | | | problem for them, especially given the fact that |
| to 8.5 GB. These disks are used for most software | | | | digital information can be copied endlessly without |
| and video releases.DVD-10 is double sided single | | | | any loss of quality. To prevent that from happening, |
| layered disk (9.4 GB) and DVD-18 is double sided | | | | manufacturers included special CSS (content |
| double layered disk (17GB). This two types of DVD | | | | scrambling system) technology in DVD-Video |
| are much less common. All four formats mentioned | | | | standard. CSS basically encrypt all disks content and |
| above have same diameter of the disk - 12cm. | | | | the key for decryption is available only for |
| Another type of disk to mention here is DVD-14, | | | | DVD-Player or special viewing program. Simply |
| which is double sided disk with one side single- and | | | | copying the disk will make the copy completely |
| the other one double-layered. This type of disk holds | | | | useless.But manufacturers forgot to include support |
| 12.32GB of data.DVD-1, DVD-2, DVD-3 and DVD-4 | | | | for Unix system and playback was available only for |
| are miniDVD. Their diameter is 8cm but otherwise | | | | Windows and MacOS. This issue was solved by Jon |
| they are completely compatible with standard drives. | | | | Johansen, who wrote DeCSS program for Unix that |
| As with full-size disks there are single sided single | | | | easily bypassed CSS protection. Developers of CSS |
| layered disk (DVD-1, 1.36 GB), single sided double | | | | were enraged with that and sued Jon. They wanted |
| layered disk (DVD-2, 2.48 GB), double sided single | | | | to stop DeCSS from spreading and put Jon in prison, |
| layered (DVD-3, 2.72 GB) and double sided double | | | | however, this case sparked lots of support |
| layered disk (DVD-4, 4.95 GB). All these disks, except | | | | movements around the world. Activists even printed |
| DVD-1, are quite uncommon.Types of DVD dataEach | | | | DeCSS code on t-shirts. Finally, Jon was declared not |
| DVD disk is able to hold various types of data. DVD | | | | guilty and his program laid a foundation for many |
| can be used to watch movies (DVD-Video), store | | | | DVD copy utilities all over the world.In general, DVD |
| software (DVD-Data) and to listen to the music | | | | format was successful and, despite some issues with |
| (DVD-Audio).DVD-Data DVD-DATA is used to store | | | | regional protection, has spread all over the world and |
| computer data on DVD. Basically it is the same | | | | almost replaced VHS tapes.SummaryDVD is not a |
| CD-ROM, but with much bigger capacity, and it is | | | | new format anymore and there are actually new |
| used the same way as CD-ROM is. However | | | | formats already that aim to replace it. Someone could |
| DVD-DATA is more convenient as a storage medium | | | | ask why does he or she needs to be familiar with |
| due to its large capacity. Most modern programs | | | | DVD if there is something new coming? The answer |
| doesn't fit on single CD, for example, computer | | | | to this lies in the fact that DVD provides foundation |
| games and Linux packages often need more than 10 | | | | for most new technologies, for example HD-DVD or |
| CDs. In case with DVD one or two disks are usually | | | | Blue Ray. And if someone became familiar with |
| more than enough. At the moment software is | | | | underlying principles once, it won't be a problem to |
| usually released on both CD and DVD, as not | | | | switch to something new later.Artem Chlegov is a |
| everyone has DVD drive yet. But it is clear that CD | | | | editor and writer for - a DVD software review |
| versions soon will disappear.DVD-VideoCurrently this is | | | | website. |
| the most common type of DVD data, the one that | | | | |