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