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Multimedia

the Science and technics
 
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Thanks to huge progress in the technician personal computers all become more powerful. They support now a sound and read out the information from compact discs, and high-speed chips used in them allow to move promptly under the program. So there was a platform for multimedia.

The Word "ьѕыі=шьхфшр" last years at all in language. In the bare kind, it only use more than one means for information representation. The most simple case - the image in the book, more difficult - the computer program in which sound fragments and videoclips, and also the text are stored.

Interactive means of multimedia allow users to supervise a way of representation of the information. It means that they can move ahead in search of any information necessary for them on an own way.


CD-ROM Disk

CD-ROM Disk the Most widespread method of storage of the similar information - CD-ROM disk. CD-ROM is deciphered as "яюё=ю ээюх a memory on ъюьяръ=-фшёъх" and it means that the information on a disk can be read out, but it is impossible to bring changes in it. Compact discs are widespread way of representation of multimedia programs as on them information (Mb) - approximately as much can be stored about 650 mbytes, how many you could store on 500 flexible disks 3,5".

CD-ROM operates in many respects the same as also a sound compact disc. Actually, many disk drives of compact discs are capable to reproduce sound compact discs though return compatibility thus is not present. The disk is usually made of polycarbonate with the layer put on it from an aluminium alloy which, in turn, has a covering from the plastic, protecting from a dust and fingerprints. The information is stored on a disk in the form of a number of the smallest deepenings (pitov) in an aluminium layer.

Disk drives Applied now read compact discs, using the laser generating beams in red area of a spectrum, but possibility of use of dark blue lasers which would allow to increase volume of the information stored on a compact disc is already studied. Now on a compact disc it is possible to write down a maximum of 75 minutes of video, and at transition to a dark blue beam - three times it is more.

Time, which is required to the computer to find the information on a disk, is called as access time. Usually it is measured in milliseconds (msek). The access time, the faster the computer is shorter answers your commands. Today average time of access for a compact disc makes approximately 200 msek that somewhere ten times more than for the majority of hard disks. In process of perfection of technology access time will decrease, of course.

The Information can be read out, as soon as the laser will be positioned over a demanded part of a disk. Speed from which the information is transferred to the computer, is called as speed of data transmission. It is measured by volume of the information which can be read out for one second. Early models of disk drives for compact discs handed over the information with a speed approximately 150 kilobytes (kb) in a second. Two-high-speed drives work twice faster. The above speed of an information transfer, the faster it is displayed on the monitor.

Multimedia computer systems are usually equipped by the disk drive for compact discs, stereophonic system of sound reproduction with dinamikami and a sound card. The sound card is established on a system payment. She analyzes the maintenance of sound files and reproduces them through dynamics or ear-phones. She will allow you to write down a sound from a microphone or any other source of a signal. After that the computer will present sound waves in a digital form - that is will transform them to a line of binary numbers which he is capable to distinguish - and will keep on a disk.


Sound images

Two various types of sound files - wave (WAV) and not wave, or MIDI-files can create and reproduce the Majority of sound cards. The sound is, in general, waves extending in air which force to vibrate an eardrum. In a snail, in an ear labyrinth, these fluctuations will be transformed to signals which the brain interprets as sounds. In wave files the actual wave picture of a written down sound remains, but signals are transformed in clear to the computer a binary code. At first sound waves will be transformed by a microphone to the changing electric signals named the analogue. Then the sound card registers force of these signals some times for a certain time interval. Frequency from which this registration is made, is called as frequency of digitization. Precisely to display initial sounding, the computer should possess frequency of the digitization equal to several thousand once a second.

Frequency of digitization is measured in kilohertz (kgts). The lowest frequency of digitization used in sound cards, is usually equal 11 kgts, otherwise, every second a payment registers 11 000 vyborok. With increase in frequency of digitization quality of a sound improves. Some sound cards make registration with frequency 44 kgts, however the majority provides a sound of high quality and at frequency of digitization 22 kgts.

Files MIDI, on the contrary, store not a wave spectrum, and, more likely, commands for a reconstruction of sounds. They can be used only for music storage: MIDI the interface musical шэё=Ёѕьхэ=ют" is deciphered as "чш¶Ёютющ; and these files contain the information for reproduction of notes. Such commands are sent to a synthesizer (to the electronic device, capable to form sounds), and already it reproduces music. MIDI files are especially useful in the event that there are problems with a memory size as they it is much less, than wave - occupy at the same duration of reproduction less than one percent of the size of the last.

Other factor influencing quality of a sound, is a quantity of the bits accessible to storage. Bit - the least unit hranimoj on the information computer. The more bits it is used for each sound, the its quality is better. Sound cards usually are 8 or 16-bit. The 16-bit payment can register and write down the most thin shades of a sound. If you use frequency of digitization 44 kgts the 16-bit payment is necessary to you.

There are special software packages which allow to edit a sound and considerably to improve its quality.


Visual display

Visual display completely to take pleasure in multimedia, your personal computer should be able to display accurate and colourful images. The monitor reproduces any colour images by means of a combination of three primary colours - red, dark blue and green. Three electronic guns in its back part fire at the screen the most thin bunches elektronov. The image on the screen is made of thousand the tiny points named in pixels. Each pixel, in turn, consists of group of points which at hit in them of an electronic beam are shone by red, dark blue or green colour. Changing intensity of a beam, it is possible to receive various colours. The more on the screen, the the image is more accurate than pixels.

As each volley elektronov exists instants to support the image on the monitor, constant replacement elektronov the new is necessary. By frequency of regeneration measure speed from which the monitor replaces vertical and horizontal lines. Most important how vertical lines are quickly replaced. In the majority of monitors it occurs approximately 76 times a second, i.e. They possess frequency of regeneration of 76 Hz. Than above frequency of regeneration, the image displayed is especially steady.


Application of multimedia

The Combination of motionless and moving images, the animations, the written and sounding words, music and other sounds makes strong impression. The good multimedia program uses all these means in their unity. Giving too much attention to one of them (for example, to the video image), it is possible to spoil cumulative effect. Representing the information in very attractive and simple way for understanding, video takes a lot of place on disk space, and its loading and reproduction can slow down program work. Easy access to the information on a disk is extremely important also. For way instructions to the related information hyperlinks are used: to click a mouse on one of them as the user will pass to the following screen of the essential information enough. Hyperlinks are especially important in multimedia as give to the user freedom: it can supervise both volume of a studied material, and speed of mastering. Well thought over programs of multimedia give the chance to the user, having pressed the button, one jump to return to the screen with an initial hyperlink. One more way of detection of the information in a multimedia application is connected with use of the built in possibilities of search. Search is based on the text. Even appendices which allow you to search for video or sound files, find it under the text description.

There are three basic search engines - on a keyword, on a theme and text-through. Keywords are applied to representation more the general themes or questions. For a certain portion of the information the developer appoints a keyword. Advantage of search in keywords consists in its speed as it is not necessary to ransack under all text, and to be limited to only built in list of keywords.

Subject search, as a whole, tries to find coincidence, touching headings of heads or sections. Besides, after end of operation the appendix displays the list of files in which there is an interesting theme.

Text-through search goes much more slowly therefore it is carried out under all appendix. On its end the appendix will display the list of all articles which contain the reference about search.

Multimedia applications are not limited to games and encyclopaedias. There is very wide choice and other appendices. It can be methodical grants for the household or professional purposes: for example, there are the disks explaining how to improve skills of dialogue or to make in the house repair. They find the application in an education sphere at training of kiddies of the account or reading, adults - to a foreign language. There are the tourist directories offering to the user before going to any city, to see and "ѕёы№°р=і" it to plunge into its atmosphere. There are disks for fans to prepare, repair cars. Without multimedia do not manage and at office, successfully applying it, for example, in the field of marketing.


Multimedia resources

The kind of multimedia resources Most habitual today is "-ёхьшЁэр  ярѕ=шэр" or the Internet. The user types the Internet address necessary to it (beginning usually from letters "www") to connect the computer to the multimedia resource which is on other computer - it is possible, for thousand kilometres. Having connected, the user can "яѕ=х°хё=тютр=і" on an offered resource in the same way as though this resource has been loaded into its computer from CD-ROM. Unique notable difference that access time is limited in the speed from which the data can be loaded through the Internet.

Many users design own web sites by means of design packages of multimedia programs. A ready web site place then on the special computer ("§юё=х" or the owner), connected to the Internet.


Whether

you Know?

In the name "ьѕыі=шьхфшр" there is nothing not clear: "ьѕыі=ш" means "ьэюую" and "ьхфшр" - plural of a Latin word "ёЁхфр, эюёш=хыі" (in this case - a way to which the information is presented). On CD-ROM disks such means, as the text, a sound, motionless images, animation and video are most widely used. CD-ROM disks allow to store much more information, than flexible disks.