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