All About DVD Part 1: DVD Format

Types of DVD and the history of the development

It 's been a long time since DVDs became commonplace in our daily lives. However, many people seem to know what exactly. Answers to questions like "what kind of arcane symbols are printed on boxes of records," "why DVD is different from a CD if they seem so similar," "what kind of DVD, there is" and many more mystery to many users. And instead of making a conscious choice to buy only at random, without any knowledge of what they are getting.

DVDs will examine in detail, along with its history and types available on the market. DVD-Video gives the most attention as the most common type of DVD.

What is DVD?

Initially standard DVD is designed for storing only the video. So its acronym has been deciphered as Digital Video Disc. Later, when the DVD began to become popular for storing all types of data, another meaning for the acronym was introduced DVD - Digital Versatile Disc, which is still used today.

In general, the DVD is the next generation of CD. First of all, DVD differs from the CD by the capacity considerably greater. While CD can only contain between 650 and 800 megabytes, DVD is able to take anywhere between 1 and 17 gigabytes, depending on the type of disc. This increase in storage is achieved by reducing wavelength laser. But the capacity of DVD would never have reached more than 4.7 gigabytes, if you can not do double-layer DVD discs or on two sides.

One side of the double-layer disc can contain two layers of data. To avoid interlapping, outer layer is made semi-transparent. During reading, laser collects the data from the first layer lower, and then passes to the second layer. This allows to double the capacity, up to 9GB. It 'easy to recognize dual-layer discs - Silver Shade have the work surface, while a single layer of the disc appears gold. Most of the video versions are printed on double-layer disc.

In addition to this, both sides of the DVD can be used to store the data. The possibility of performing two sides discs derive from the fact that the protective layer of DVD is only half that for CD, ie, 0.6 mm instead of 1.2 mm. Therefore, in order to maintain compatibility with the old formats, a single-sided DVD discs have additional plastic added to them to reach the thickness 1.2 mm. Of course, is not a problem to put additional layer, instead of 0.6 mm plastic flat. This was not possible with CDs because they are already quite thick.

DVD - the story of the conflict

In 1997 a number of electronics manufacturers large established an organization called the DVD Forum (formerly known as the DVD Consortium) to develop a single standard for next-generation discs such as CD technology was not always sufficient.

Despite the many debates and a lot of technologies that claim to be the best, the final decision was made and DVDs (with eight types of) standard was established. It 'was soon followed by DVD-Video standard.

However, when it was standard for recordable and rewritable discs, some large companies have started to push its DVD + R and DVD + RW. These companies have formed their own coalition called the DVD + RW Alliance. The most interesting is the fact that different branches formed were not compatible with the other.

In addition to this, Panasonic has contributed to the disaster through the development of DVD-RAM standard. This standard was faster and more reliable, but it was only compatible with DVD-RAM devices.

Those who have suffered the most out of this mess were common users, have been forced to make a difficult choice of preferred technology.

For this reason many people have no hurry to DVD and have maintained their data on the good old CD-R and CD-RW.

The standards war was ended by Sony, which made the DVD drive can read both DVD-RW and DVD + RW. This device has quickly become popular even in spite of its price twice the single standard unit. Sony was soon followed by other manufacturers and the ability to read both types of discs soon became a standard for all DVD drives. This was the beginning of the DVD for PC users.

Unfortunately, there were also a lot of disagreements during the development of a single standard for digital audio, DVD-Audio. Two technologies to compete for the title of heir Audio CD: a partially compatible with CD audio technology from Philips and Sony, and Toshiba's standard alone. Toshiba has won, but Philips and Sony does not give up and just published a model without the DVD-Forum. This format was called Super Audio CD (SACD). Currently both formats do not sell particularly well and are not known in some countries at all.

Types of DVD

Moving on to the DVD. DVD is the most common format today. Currently DVD is available in 8 flavors: DVD-1, DVD-2, DVD-3, DVD-4, DVD-5, DVD-9, DVD and DVD-10-18. The difference is in the ability, which is indicated with the number in the name (rounded value).

The most common format is DVD-5 and DVD-9. These are single and double-layer single-sided discs, respectively. DVD-5 contains 4.7 GB of data and DVD-9 can hold up to 8.5 GB. These discs are used for most of the versions of the software and video.

DVD-10 is double-sided single-layer disc (9.4 GB) and DVD-18 is of double-sided double-layer disc (17GB). These two types of DVDs are much less common. All four of the above formats have the same diameter of the disc - 12 centimeters. Another type of disk to be mentioned here is called DVD-14, which is double-sided disc with only one side and the other double-layer. This type of disc contains 12.32GB of data.

DVD-1, DVD-2, DVD and DVD-3-4 are miniDVD. Their diameter is 8 cm but otherwise are completely compatible with standard units. As in the case of full-size disks there are single-sided single-layer disc (DVD-1, 1.36 GB), disk single sided double-layer (DVD-2, 2.48 GB), double-sided single-layer (DVD-3 , 2.72 GB) and double-sided double-layer disc (DVD-4, 4.95 GB). All these discs except DVD-1, are quite rare.

Types of Data DVD

Each DVD disc is able to contain various types of data. DVD can be used for watching movies (DVD-Video), business software (DVD-data) and listen to music (DVD-Audio).

DVD-Data

DVD-DATA is used to store data on DVD. It is basically the same CD-ROM, but with much larger capacity, and is used in the same manner as CD-ROM is. However, DVD-DATA is cheaper as a storage medium, for his great ability. Most programs today do not fit on a single CD, for example, computer games and Linux packages often require more than 10 CDs. In case DVD with one or two discs are generally more than sufficient. Currently the software is usually released on CD and DVD, because not everyone has a DVD player yet. But it is clear that the versions of the CD will soon disappear.

DVD-Video

Currently this is the most common type of data DVD, what was initially designed for DVD. Compared to VHS tapes DVD-Video is a giant step towards the future. There are heaps of features there that many people have no idea.

First of all, DVD-Video is interactive - anywhere on the disc is instantly accessible and you can have more than one order for the film. And parents can limit the display of bad parts of movies for their children. Apart from that the disks may have additional bonus materials, such as interviews, promotional trailers, slides, text information and even video games. In addition to this DVD-Video can have more chances angle of view when the camera angle can be changed during playback. However, this function mostly used in porn movies and recordings of live concerts.

The video data on DVD-Video is compressed using MPEG-2 compression. This compression algorithm allows the video stream of the contraction of about ten times without loss of image quality. As a result, each disc can contain up to 4 hours of 720x576 resolution video at 24 frames per second (PAL) or 720x480 at 30 frames per second (NTSC). The flow velocity is generally between 3 and 10 Mbits per second.

The video can be recorded in different proportions of the screen. For example, it can have a ratio of 4:3, which is a ratio normal television set, or panoramic - 16:9. Image in widescreen format are of two types: letterbox and anamorphic. In the first case the image is simply cut into the top and bottom to obtain the desired format. In anamorphic mode the image is recorded initially in the form elongated and then crumpled to the desired size. This method is much more effective as a whole structure is used for useful data, while largely Letterbox of the frame is used to store only pixels blacks. As a result, anamorphic mode has better detail and sharper images.

Audio data can be stored in different formats: LPCM, Dolby Pro Logic, Dolby Digital, Dolby Digital EX and DTS.

LPCM (Linear Pulse Code Modulation) is uncompressed stereo or mono soundtrack. It is usually used in music videos and movies in which the clarity of sound is important. The same format is used for generic CD Audio

Dolby Pro Logic is a special kind of soundtrack that can be divided into 4-channel surround sound. Today this size is rare.

Dolby Digital (AC-3) is fully digital audio compression format, but can be divided into up to 6 independent channels. Unlike Dolby Pro Logic, each channel is recorded separately on physical evidence.

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

DTS (Digital Theater System) is another digital audio compression format, introduced by Steven Spielberg as an alternative to Dolby Digital. DTS offers more quality than Dolby Digital because of less compression. This, of course, leads to very large size of the soundtrack, which take up more disk space. It also requires special receiver to decode. Because of these reasons DTS discs usually do not have any bonus material, but LPCM soundtrack. The soundtrack is included to allow users without special receiver to hear the audio (stereo only, though). Because of all these DTS discs are much less common than Dolby Digital. DTS discs usually with better video quality (and no bonus materials) are called Superbit. Both DTS and Dolby Digital (EX) are also used in the film.

Some of the biggest drawbacks of DVD-Video are its many levels of copy protection, which were added because of pressure from film companies. At first the measures provided a lot of nuisance for users, but eventually all DVD protections have been violated. This process was also assisted by the equipment manufacturers simply do not support measures to protect the most annoying.

One of the most annoying of these measures was "regional protection". The world was divided into 8 zones, and each DVD must have information on his area. The same was done for the DVD, the DVD and then by a zone could only be played on players from the same area. User was allowed to change the time zone for only a few players, and the last of the selected zones has been locked in the drive for ever.

This trick was invented in order to assign different price in each region, depending on income level. Moreover, the film could be released at different times in different countries. For example, in Africa could also affect the film and cinema in the U.S. may already be available on DVD. Protection, so you should have regional stop people from buying DVDs in the U.S. and sell them in Africa.

Unfortunately, this protection has not brought nothing but trouble. Many travelers were unable to reproduce disk bought abroad. The purchase of discs on the internet or EBay has also become a problem. Besides this, some films were released only in certain countries.

Many producers considered these implications and has started to provide extinguishing regional protection for their devices. Chinese producers substantially abandon this protection.

But the uncontrolled distribution of the DVD was not the only thing that the directors were against. Illegal copying was a much bigger problem for them, especially given the fact that digital information can be copied endlessly without any loss of quality. To prevent this, the producers included special CSS (Content Scrambling System) technology in standard DVD-Video. CSS basically encrypt the entire contents of disks and the key for decrypting is only available for DVD-Player or special viewer. Just copy the hard copy will be completely useless.

But the producers forgot to include support for the Unix system and reproduction was only available for Windows and MacOS. This problem was solved by Jon Johansen, author of the DeCSS program for Unix that the CSS easily bypassed. CSS developers were angry with that sued and Jon. They wanted to stop the spread of DeCSS, Jon put in prison, however, this case has generated a lot of support movements around the world. The activists also DeCSS code printed on t-shirts. Finally, Jon has pleaded not guilty and his program laid the basis for many utilities to copy DVDs worldwide.

In general, the DVD format has been successful and, despite some problems with protection at the regional level, has spread around the world and almost completely replaced the VHS tapes.

Summary

DVD is not a new format and there are actually new formats already aiming to replace it. Some might ask why he does or she must be familiar with the DVD if there is something new coming up? The answer to this is that the DVD is the basis for most of new technologies such as HD-DVD or Blue Ray. And if someone familiar with the fundamentals once, will not be a problem to switch to something new later.