Home Internet Jobs - All About DVD Part 1: DVD Format

Types of DVD and history of development

And instead of making conscious choice they just buy randomly without any knowledge of what exactly they are getting. "what kinds of DVDs are there" and many others still remain mystery for many users, "how come DVD is different from CD if they look so similar", answers to questions like "what sort of arcane symbols are printed on disk boxes". Most people don't seem to know what it is exactly, however. It's been a long time since DVD became common in our everyday life.

DVD-Video will get most attention as it is the most common type of DVDs. Along with its history and different types available on the market, we will examine DVD in details.

What is DVD?

Which is still used nowadays, another meaning for DVD acronym was introduced - Digital Versatile Disk, when DVD started to become popular for storage of all types of data, later. Thus its acronym was decrypted as Digital Video Disk. Initially DVD standard was designed for video storage only.

But DVD capacity would never reach more than 4.7 gigabytes if it wasn't possible to make DVD disks double-layered or double-sided. This storage increase is achieved by reducing laser wavelength. Depending on disk type, dVD is able to hold anywhere between 1 and 17 gigabytes, while CD disk can only contain between 650 and 800 megabytes. DVD differs from CD by its significantly larger capacity, first of all. DVD is the next generation of CD, generally.

Most video releases are printed on double-layered disks. While single-layered disk appears gold, it is easy to recognize double-layered disks - they have silver shade of working surface. Up to 9GB, this allows doubling the capacity. And then switches to the second layer, laser collects data from bottom layer first, during reading. Outer layer is made semi-transparent, to avoid interlapping. One side of double-layered disk can contain two layers of data.

This wasn't possible with CDs as they are thick enough already. It is not a problem to put additional layer instead of 0.6mm of plain plastic, of course. Single-sided DVD disks have additional plastic added to them to achieve 1.2mm thickness, in order to keep compatibility with older format, so. 0.6mm instead of 1.2mm, that is, the possibility of making double-sided disks arise from the fact that the protective layer for DVD is only half of that for CD. Both sides of DVD can be used to store data, apart from that.

DVD - the history of conflict

As CD technology was becoming less and less sufficient, in 1997 several large manufacturers of electronic equipment established organization called DVD-Forum (earlier known as DVD Consortium) in order to develop single standard for new generation of disks.

It was soon followed by DVD-Video standard. The final decision was made and DVD (with eight types of it) standard was established, despite many debates and lots of technologies claiming to be the best.

The most interesting part was the fact that different branches of formats were not compatible with each other. These companies founded their own coalition called DVD+RW Alliance. Several large companies started to push their own formats DVD+R and DVD+RW, when it came to standards for recordable and rewritable disks, however.

But it was compatible only with DVD-RAM devices, this standard was faster and more reliable. Panasonic also contributed to the mess by developing DVD-RAM standard, apart from that.

As they were forced to make a difficult choice of preferred technology, the ones who suffered the most from this mess were common users.

For that reason many people didn't rush for DVD and kept their data on good old CD-Rs and CD-RWs.

This was the beginning of the DVD era for PC users. Sony soon was followed by other manufacturers and the ability to read both types of disks soon became a standard for any DVD drives. This device instantly became popular even in spite of its double price compared with single-standard drives. Which made DVD drive capable of reading both DVD-RW and DVD+RW, the war of standards was ended by Sony.

At the moment both formats are not selling particularly well and are not known in some countries at all. This format was called Super Audio CD (SACD). But Philips and Sony didn't give up and released their own format without DVD-Forum support, toshiba won. And a standalone Toshiba's standard, two technologies compete for the title of Audio CD heir: a partially compatible with Audio CD technology from Philips and Sony. DVD-Audio, there also were lots of disagreements during development of single standard for digital audio, unfortunately.

Types of DVD

Which is denoted by the number in the name (value is rounded), the difference is in the capacity. DVD-10 and DVD-18, dVD-9, dVD-5, dVD-4, dVD-3, dVD-2, at the moment DVD comes in 8 flavors: DVD-1. DVD is the most common format nowadays. Let's move to DVD itself.

These disks are used for most software and video releases. DVD-5 holds 4.7 GB of data and DVD-9 is able to contain up to 8.5 GB. Respectively, these are single- and double layered single sided disks. The most common formats are DVD-5 and DVD-9.

This type of disk holds 12.32GB of data. Which is double sided disk with one side single- and the other one double-layered, another type of disk to mention here is DVD-14. All four formats mentioned above have same diameter of the disk - 12cm. This two types of DVD are much less common. DVD-10 is double sided single layered disk (9.4 GB) and DVD-18 is double sided double layered disk (17GB).

Are quite uncommon, except DVD-1, all these disks. 4.95 GB), 2.72 GB) and double sided double layered disk (DVD-4, double sided single layered (DVD-3, 2.48 GB), single sided double layered disk (DVD-2, 1.36 GB), as with full-size disks there are single sided single layered disk (DVD-1. Their diameter is 8cm but otherwise they are completely compatible with standard drives. DVD-3 and DVD-4 are miniDVD, dVD-2, dVD-1.

Types of DVD data

Store software (DVD-Data) and to listen to the music (DVD-Audio), dVD can be used to watch movies (DVD-Video). Each DVD disk is able to hold various types of data.

DVD-Data

But it is clear that CD versions soon will disappear. As not everyone has DVD drive yet, at the moment software is usually released on both CD and DVD. In case with DVD one or two disks are usually more than enough. Computer games and Linux packages often need more than 10 CDs, for example, most modern programs doesn't fit on single CD. However DVD-DATA is more convenient as a storage medium due to its large capacity. And it is used the same way as CD-ROM is, but with much bigger capacity, basically it is the same CD-ROM. DVD-DATA is used to store computer data on DVD.

DVD-Video

There are heaps of features there that most people have no idea about. Compared with VHS tapes DVD-Video is a giant leap into the future. The one that DVD was initially designed for, currently this is the most common type of DVD data.

This feature mostly used in porno movies and live concert records, however. When camera angle can be changed during playback, in addition to all this DVD-Video is capable to have multi angle view option. Text info and even videogames, slides, promotion trailers, such as interviews, apart from that disks can have additional bonus materials. And parents can limit viewing of naughty parts of movies for their children. DVD-Video is interactive - any place on the disk is instantly accessible and it is possible to have more than one ending for the movie, first of all.

The streaming speed is usually between 3 and 10 MBit per second. Each disk is able to hold up to 4 hours of video with 720x576 resolution at 24 frames per second (PAL) or 720x480 at 30 frames per second (NTSC), as a result. Without loss of picture quality, this compression algorithm allows shrinking video stream approximately ten times. Video data on DVD-Video disks is compressed by using MPEG-2 compression.

Anamorphic mode has better details and sharper picture, as a result. While in Letterbox large part of the frame is used to store black pixels only, this method is much more effective as whole frame is used for useful data. In anamorphic mode the image is initially recorded in stretched form and then shrinked to the desired size. In the first case image is simply cropped at the top and at the bottom to achieve desired format. Widescreen image have two types: Letterbox and anamorphic. Or widescreen - 16:9, which is a standard television ratio, it can have ratio of 4:3, for example. Video can be recorded in different screen ratios.

Dolby Digital EX and DTS, dolby Digital, dolby Pro Logic, audio data can be stored in various formats: LPCM.

Same format is used for generic Audio CD It is usually used in musical video clips and movies where sound clarity is important. LPCM (linear pulse code modulation) is uncompressed stereo or mono soundtrack.

Nowadays this format is uncommon. Dolby Pro Logic is special type of soundtrack that can be split into 4 channels for surround sound.

Each channel is recorded on separate physical track, unlike Dolby Pro Logic. It can be split into up to 6 independent channels; dolby Digital (AC-3) is fully digital sound compression format.

Supports up to 8 independent channels. Dolby Digital EX is more advanced version of Dolby Digital.

Both DTS and Dolby Digital (EX) are also used in cinemas. Usually DTS disks with improved video quality (and without bonus materials) are called SuperBit. Because of all these DTS disks are much less common compared to Dolby Digital. Though), this soundtrack is included to allow users without special receiver to listen to the sound (stereo only. Because of these reasons DTS disks usually does not have any bonus materials but have LPCM soundtrack. It also requires special receiver to be decoded. Which occupy more disk space, leads to bigger size of the soundtrack itself, of course, that. DTS provides more quality than Dolby Digital due to lower compression. Introduced by Steven Spielberg as an alternative to Dolby Digital, dTS (Digital Theater System) is another digital audio compression format.

This process was also assisted by equipment manufacturers who simply didn't support most annoying protection measures. But eventually every DVD protection was hacked, at first these measures provided lots of nuisance for users. Which were added because of the pressure from film companies, some of the largest drawbacks of DVD-Video are its various copy protection measures.

And the last of selected zones was locked in the player forever, user was allowed to change zone for the player few times only. And thus DVDs from one zone could only be played on players from the same zone, the same was made for DVDs. And each DVD player was supposed to have information about its zone, the world was divided into 8 zones. One of the most annoying of such measures was "Regional Protection" .

So regional protection was supposed to stop people from buying DVDs in USA and selling them in Africa. In Africa the movie might just hit cinemas and in USA it might already be available on DVD, for example. Movie might be released in different times in different countries, besides. Depending on income level, this trick was invented in order to be able to assign different price in each region.

Some movies were released in certain countries only, apart from that. Buying disks over the internet or from EBay also became a problem. Many travelers were not able to play disk purchased overseas. This protection didn't bring anything but troubles, unfortunately.

Chinese manufacturers basically abandon this protection at all. Many manufacturers considered these implications and started to provide means of switching off regional protection for their devices.

Simply copying the disk will make the copy completely useless. CSS basically encrypt all disks content and the key for decryption is available only for DVD-Player or special viewing program. Manufacturers included special CSS (content scrambling system) technology in DVD-Video standard, to prevent that from happening. Especially given the fact that digital information can be copied endlessly without any loss of quality, illegal copying was much bigger problem for them. But uncontrolled distribution of DVDs wasn't the only thing that movie makers were against.

Jon was declared not guilty and his program laid a foundation for many DVD copy utilities all over the world, finally. Activists even printed DeCSS code on t-shirts. This case sparked lots of support movements around the world, however, they wanted to stop DeCSS from spreading and put Jon in prison. Developers of CSS were enraged with that and sued Jon. Who wrote DeCSS program for Unix that easily bypassed CSS protection, this issue was solved by Jon Johansen. But manufacturers forgot to include support for Unix system and playback was available only for Windows and MacOS.

Has spread all over the world and almost replaced VHS tapes, despite some issues with regional protection, dVD format was successful and, in general.

Summary

It won't be a problem to switch to something new later, and if someone became familiar with underlying principles once. For example HD-DVD or Blue Ray, the answer to this lies in the fact that DVD provides foundation for most new technologies. Someone could ask why does he or she needs to be familiar with DVD if there is something new coming? DVD is not a new format anymore and there are actually new formats already that aim to replace it.