Digital devices for information processing digital devices. Generations of digital information processing devices

What is this digital devices information processing? Digital devices are devices for processing information presented in a computer-accessible form. It: touch screens scanners cameras camcorders mobile phones web cameras document cameras projectors wireless data transmission devices video surveillance systems

Camcorders Camcorder electronic filming apparatus, device for obtaining optical images of the objects being shot on a photosensitive element, adapted for recording or transmitting moving images to television. Usually equipped with a microphone for parallel audio recording.

Webcams A webcam (also a webcam) is a digital video or photo camera capable of capturing images in real time for further transmission over the Internet (in programs such as Instant Messenger or in any other video application).

Projectors A projector is a light device that redistributes the light of a lamp with concentration luminous flux on a small surface or in a small volume. Projectors are mainly optical-mechanical or optical-digital devices that allow using a light source to project images of objects onto a surface located outside the device screen.

Bluetooth wireless communication devices enable the exchange of information between devices such as handheld and portable devices. personal computers, mobile phones, laptops, printers, digital cameras, mice, keyboards, joysticks, headphones, headsets on a reliable, inexpensive, universally available radio frequency for short-range communications.

GPRS (General Packet Radio Service) wireless data transmission devices common use) an add-on over the GSM mobile communication technology, which carries out packet data transmission. GPRS allows the network user cellular communication exchange data with other devices in the GSM network and with external networks, including the Internet. GPRS assumes billing based on the volume of transmitted / received information, and not the time spent online.

Wireless transmission devices Allows you to deploy a network without laying a cable, can reduce the cost of deploying and expanding the network. Locations where cable cannot be laid, such as outdoors and in buildings of historical value, can be serviced wireless networks... Unlike cell phones, Wi-Fi equipment can work in different countries Worldwide. Wi-Fi (English Wireless Fidelity "wireless accuracy") is a standard for Wireless LAN equipment.

Video surveillance Video surveillance (closed Circuit Television, CCTV closed-circuit television system) is a process carried out using optoelectronic devices designed for visual control or automatic image analysis (automatic recognition of faces, state numbers).

Digital information processing devices Author: Dmitry Tarasov, 2009

SECTION 2. DIGITAL ELECTRONIC CIRCUITS

Basic concepts of digital electronics

The purpose of electronic devices, as you know, is to receive, convert, transmit and store information in the form of electrical signals. Signals operating in electronic devices, and accordingly the devices themselves, are divided into two large groups: analog and digital.

Analog signal - a signal that is continuous in level and in time, i.e. such a signal exists at any time and can take any level from the specified range.

Quantized signal - a signal that can only take certain quantized values \u200b\u200bcorresponding to the quantization levels. The distance between two adjacent levels is the quantization step.

Sampled signal a signal, the values \u200b\u200bof which are set only at the moments of time, called sampling moments. Distance between adjacent sampling points - sampling step
... With constant
the Kotelnikov theorem is applicable:
where is the upper cutoff frequency of the signal spectrum.

Digital signal - signal quantized in level and time-sampled. The quantized values \u200b\u200bof a digital signal are usually encoded with a certain code, with each sample selected during the sampling process replaced by a corresponding codeword, the symbols of which have two values \u200b\u200b- 0 and 1.

Typical representatives of analog electronics devices are communication devices, radio broadcasting, television. The general requirement for analog devices is minimal distortion. Striving to meet these requirements leads to complications electrical circuits and device designs. Another problem of analog electronics is the achievement of the necessary noise immunity, because in an analog communication channel, noise is fundamentally unavoidable.

Digital signals are formed by electronic circuits, the transistors in which are either closed (the current is close to zero) or completely open (the voltage is close to zero), so they dissipate insignificant power and the reliability of digital devices is higher than analog ones.

Digital devices are more immune to interference than analog ones, since small extraneous disturbances do not cause erroneous operation of devices. Errors appear only with such disturbances in which a low signal level is perceived as high or vice versa. Digital devices can also use special codes to correct errors. There is no such possibility in analog devices.

Digital devices are insensitive to the spread (within acceptable limits) of the parameters and characteristics of transistors and other circuit elements. Digital devices that are error-free do not need to be tuned, and their characteristics are completely repeatable. All of this is very important in the mass production of devices using integrated technology. The cost-effectiveness of the production and operation of digital integrated circuits has led to the fact that in modern radio electronic devices, not only digital, but also analog signals are digitally processed. Digital filters, regulators, multipliers, etc. are common. Before digital processing analog signals are converted to digital using analog-to-digital converters (ADC). Reverse transformation - recovery analog signals by digital - performed using digital-to-analog converters (DAC).

With all the variety of tasks solved by digital electronics devices, their functioning takes place in number systems operating with only two digits: zero (0) and one (1). By the type of coding of binary digits with electrical signals, elements of digital technology are divided into potential (static) and impulse (dynamic).

IN potential elements zero and one correspond to two sharply different voltage levels. In this case, the voltages can be both positive and negative with respect to the case, the electric potential of which is taken as zero. There are elements that work in positive and negative logic. In elements with positive logic, the transition from 0 to 1 occurs with increasing potential. In negative logic, a more negative voltage is taken as logical 1.

IN impulse elements, a logical unit corresponds to the presence, and a logical zero corresponds to the absence of an impulse.

The operation of digital devices is usually clockeda sufficiently high frequency clock generator. During one clock cycle, the simplest micro-operation is implemented - read, shift, logical command, etc. Information is presented as a digital word. Two methods are used to transmit words - parallel and sequential. Serial coding is used in the exchange of information between digital devices (for example, in computer networks, modem communications). Information processing in digital devices, as a rule, is implemented using parallel information coding, which ensures maximum performance.

The element base for building digital devices is made up of digital integrated circuits (ICs), each of which is implemented using a certain number logical elements (LE) - the simplest digital devices that perform elementary logical operations.

All digital devices can be classified into one of two main classes: combinational (without memory) and sequential (with memory). Combinationalare called devices, the state of the outputs of which at any moment in time is uniquely determined by the values \u200b\u200bof the input variables at the same moment in time. These are logical elements, code converters (including encoders and decoders), code distributors (multiplexers and demultiplexers), code comparators, arithmetic logic devices (adders, subtractors, multipliers, ALU itself), read-only memory (ROM), programmable logic matrices (PLM).

Output state consistent of a digital device (finite automaton) at a given moment in time is determined not only by logical variables at its inputs, but also depends on the order (sequence) of their arrival at previous moments in time. In other words, state machines must necessarily contain memory elements that reflect the entire history of the arrival of logical signals, and are executed on triggers, while combinational digital devices can be entirely built only on logical elements. Sequential digital devices include triggers, registers, counters, random access memory (RAM), microprocessor devices (microprocessors and microcontrollers).

Before studying various digital devices, let's get acquainted with the elements of the mathematical apparatus used in their construction. Him constituent parts are the concept of number systems and methods for describing and transforming logical functions.

9. Mathematical foundations of digital electronics

9.1. Positional number systems

Number system is called the way of displaying an arbitrary number by a limited set of characters, called numbers. The position number that determines the weight with which this digit is added in the number is called discharge, and the number systems with the noted property are positional.

In general n- positive bit Nin an arbitrary radix ris represented by a sum of the form

(9.1)

where a k - individual digits in the number record, the values \u200b\u200bof which are equal to members of the natural series in the range from 0 to ( r– 1).

When performing calculations by digital electronic devices, elements with two stable states are used. For this reason, the positional binary number system (with base 2) has become widespread in digital technology. In each binary digit, called bit, can be 1 or 0. The very same number notation (binary code) is a sequence of ones and zeros. To distinguish a binary number from a decimal number, we will supplement it on the right with the suffix IN(Binaire), as is customary in special machine-oriented programming languages \u200b\u200bcalled assemblers.

The weights of the adjacent digits of the binary code of the number differ by two times, and the rightmost digit (least significant) has weight 1. Therefore, for example

101101B \u003d 1. 2 5 + 0. 2 4 + 1. 2 3 +1. 2 2 + 0. 2 1 + 1. 2 0 \u003d 45.

The four adjacent bits are called notebook, a group of 8 bits is called byte, and from 16 bits - machine word... The aggregate of 1024 (2 10) bytes is called a kilobyte, of 1024 kilobytes - a megabyte, of 1024 megabytes - a gigabyte.

1 GB \u003d 2 10 MB \u003d 2 20 KB \u003d 2 30 bytes .

Modern personal computers can store digital information tens of gigabytes in their memory on hard magnetic disks.

Arithmetic operations in binary system reckoning is extremely simple and easy to implement in hardware. However, when entering and outputting information into a digital device, it must be represented in a more familiar decimal number system. The desire to simplify the procedure for converting binary numbers to a decimal equivalent led to the use bcdcode. In this code, to write individual digits of the digits of the decimal number, they use the tetrads of their binary

Lesson topic:"Digital information processing devices: digital camera"

The purpose of the lesson:

Create conditions for the formation of students' understanding of the types and purpose of digital devices for information processing;

Develop skills in information processing using various devices;

To foster a respect for computer technology, compliance with the rules of safe behavior.

Students should know:

Possibilities of using digital cameras.

Lesson provision:

presentation "Digital Camera";

multimedia projector and screen;

digital camera;

DURING THE CLASSES:

Organizing time.

Greetings, organizing students for joint effective activities.

Explanation of the new material.

Vopr. What are the most common digital information processing devices you know ?:

Today we will take a look at digital cameras. You will study the material as follows: each of you will draw out a card with an assignment and study the material. Then, according to the numbers of the cards, you will form into groups (pairs), discuss the material together and choose a way to convey it to the others. At the end of the lesson, you and I should form an idea of \u200b\u200ba digital camera as a means of processing and transferring information to a computer according to the following plan:

General view, components.

Dignity.

Additional features.

Information storage methods

Communication with PC and other devices.

Card number 1

General view, components:

Basically, the digital camera device repeats the analog design. Their main difference is in the photosensitive element on which the image is formed: in analog cameras it is a film, in digital cameras it is a matrix. Light through the lens enters the matrix, where a picture is formed, which is then written into memory. The camera consists of two main parts - the body and the lens. The body contains a matrix, a shutter (mechanical or electronic, and sometimes both at once), a processor and controls. A lens, removable or hard-wired, consists of a group of lenses housed in a plastic or metal housing.

Card number 2

Advantages

Visibility and efficiency. When shooting with digital, you see the result immediately after pressing the shutter button.

Profitability. The price of a digital camera is reduced to the level of a conventional film. You also need to consider the cost supplies (films, reagents, etc.)

Compactness. The small size of a camera is one of the most important criteria for an amateur photographer.

Independence, reliability, easy storage. No reliance on photo printing wizard, longer shelf life.

Additional features. Modern digital cameras often have a number of additional features that are fundamentally inaccessible to their film counterparts. Among them, for example, video recording, panorama shooting mode or audio commentary recording. In addition, special image processing algorithms implemented in camera software can partially replace traditional photographic tools such as light filters and films for different types of lighting.

Digital processing.

Printing. Almost all modern digital cameras and printers support the PictBridge protocol, which provides for direct data exchange between the camera and the printing device.

Card number 3

Additional features

High-speed shooting. High-speed shooting is a mode in which the camera shoots frames not one by one, as usual, but in series - in the hope that at least one frame in a series will be successful.

Bracketing (bracketing) autofocus (exposure, white balance, flash). This is a special mode in which the camera takes several (usually 3) pictures in a row with a variation of one parameter or another.

Shooting panoramas ("stitch assist"). This function serves to facilitate panoramic shooting. A panorama is a series of shots taken with some horizontal or vertical displacement, and subsequently "glued" on a computer into one large image.

Macro photography. The macro function (macro mode) is a special autofocus mode that makes it possible to focus on very close subjects.

Orientation sensor. Many cameras have a so-called position or orientation sensor. The essence of its work is simple: at the time of shooting, the sensor determines in what position the camera is - in a normal or portrait position (rotated 90 degrees). If the portrait position is fixed, then after the shutter is released, there are two options (depending on the manufacturer of the device). Either the file is recorded "as is", but a special note about "portraitity" is made in its header, or the necessary rotation by 90 degrees is performed by the camera's processor, and the frame is immediately written, "as it should.

Voice comments for pictures. Some cameras allow you to accompany the just captured footage with short voice comments. For all the seeming pretentiousness, this is a pretty useful feature. For example, during a tour of an unfamiliar city, the photographer can mark which landmark he has just photographed, and in the future this will greatly facilitate the analysis of the footage.

Video. Almost all digital cameras (except for DSLRs) on the market allow video recording.

Special effects. Almost all devices have a set of special effects (or so-called filters) as an additional feature. Among them there are usually discarding color information (monochrome image), "sepia", increasing or decreasing color intensity, etc.

Card number 4

Information storage methods.

a) Built-in memory of the camera (usually very small, allows you to store up to 10 photos)

b) Flash memory or memory cards

At the moment, there are three undisputed leaders among flash memory formats - Secure Digital, CompactFlash and Memory Stick.

Secure Digital is a standard created by an alliance of SanDisk, Matsushita Electric (Panasonic) and Toshiba. The physical dimensions of the module are quite small and amount to 24x32x1.4 mm, which makes it possible to use this type of memory in super compact cameras. In addition, the standard provides protection against unauthorized copying (which allows you to release books in this format), as well as protection against accidental overwriting (there is a mechanical switch on the memory module). As of 2004, Secure Digital is the most popular format on the market.

Secure Digital memory module

SanDisk's CompactFlash standard provides two types of modules (Type I and Type II), differing in thickness. The dimensions of the cards are 42.8x36.4x3.3 mm and 42.8x36.4x5 mm, respectively. CompactFlash is the least compact of all formats, but in addition to memory, it produces a huge number of various peripherals for pocket computers: modems, GPS modules, WiFi and Bluetooth adapters, etc. In addition, miniatures are produced in this format. hard drives IBM / Hitachi Microdrive and Sony Microdrive from 2GB to 4GB (6GB from Western Digital is also expected). However, the advisability of purchasing compact hard drives (in light of the collapse in prices for flash memory) is rather doubtful.

CompactFlash memory module

The Memory Stick format is attributed to Sony. This format has two basic types of enclosures - Memory Stick and Memory Stick Duo. The first has dimensions of 50x21.5x2.8 mm, the second - 31x20x1.6 mm. In the same form factors, there are also high-speed modifications with the ability to address more than 128 MB. They are designated by the index Pro (Memory Stick Pro and Memory Stick Pro Duo, respectively).

Memory Stick Pro

Secure Digital and CompactFlash are open standards free of any royalties. Memory Stick is a proprietary and licensed standard, so it hasn't gained much acceptance outside of Sony products. Modules of this format cost almost twice as much as the others, since license fees (royalties) are included in their price.

There are also other types of memory on the market (for example, the xD standard, developed not so long ago by Olympus and Fujifilm), the outdated MMC and SmartMedia standards, etc. However, they are much less common, and we will not dwell on them in detail.

Card No.5

Interface with computer and printer

The camera is connected to the computer to copy the footage from the flash memory and, if necessary, to update the software (“firmware”) of the camera. The connection to the printer is obviously necessary for direct printing from the camera using the PictBridge protocol.

The vast majority of cameras are connected to a computer or printer via the USB (Universal Serial Bus) interface. For this (from the camera side) either a standard mini-B connector or a non-standard proprietary connector is used. Obviously, the first option is somewhat preferable, because "in case something happens" you can easily buy a standard cable in any store for symbolic money, while you will have to run after a branded one (and it will cost much more).

At the moment, there are two versions of the USB standard: 1.1 and newer 2.0. The first provides a throughput of 12 Mbit / s, the second - 480 Mbit / s. Accordingly, if you are using a fast enough flash memory, USB 2.0 will be preferred. However, you can always remove the memory from the camera and use an external device for reading flash cards - the so-called card reader (the memory module will be presented as a medium with the FAT16 / 32 file system).

The simplest connector - RCA AV-out - to put it simply, "tulips" - is adapted for connection to any television equipment, and provides viewing of images on a TV screen.

To familiarize students with the material and discussion is assigned 10 minutes ... Students then give presentations followed by a teacher presentation.

Generalization of the material and summing up
Questions to the class:

1. What new have you learned in the lesson?

   Was the information helpful? What is its use?

   If you were to choose a camera, what parameters would you pay attention to?

Workshop on working with a digital camera.

Note: During the lesson, you can photograph the main stages. At the end of the lesson, transfer the footage to the computer in different ways.

Homework: set by groups:

1 group - the main elements of the video camera

Group 2 - the advantages of digital video cameras

3 group - devices for recording information in a video camera

4 group - transfer of information from a video camera to a computer

5 group - webcams

Lesson topic: "Digital information processing devices: digital video camera"

The purpose of the lesson:

create conditions for the formation of students' ideas about the types and purpose of digital devices for information processing;

continue to develop skills in processing information using various devices;

continue to foster respect for computer technology, compliance with the rules of safe behavior in the office

DURING THE CLASSES:

1. Organizing time.

2. Review of the material from the previous lesson:
1) what device did we talk about in the last lesson?

2) What are the main elements of the camera you can name?

3) What are the advantages of digital cameras?

4) Where are the images stored in the camera?

5) How is the transfer of images from the camera carried out?

3. Learning new material.

For today's lesson, you have prepared messages about digital camcorders - devices that greatly expands capabilities modern computers... We will conduct our acquaintance with this device according to the same plan as the acquaintance with a digital camera, i.e.

1 - the main elements of the video camera

2- advantages of digital video cameras

3– devices for recording information in a video camera

4 - transfer of information from the video camera to the computer

5– webcams

Let's give the floor to representatives of the groups.

(students make messages, if necessary, accompany the story with illustrations)

Material that can be offered to students is in Appendix 1.

4. Workshop on transferring video to a computer

Just like in the last lesson, you can shoot fragments of students' speeches, their activities in the lesson. In practice, show how to transfer a video (as a last resort from a camera). The form of work is individual.

5. Editing a video about the study of Digital Information Processing Devices

Working with video editorMoveMaker (frontal):

2. Upload video images - Record video - Import video.

3. Upload Photos - Record Videos - Import Images

4. Arrange video clips and photos on the storyboard panel (drag and drop)

5. Add transitions: Editing a movie - Viewing video transitions - Select a video transition - drag it to the storyboard panel in the area between frames.

6. Add effects: Editing a movie - Viewing effects - Select an effect - drag it to the storyboard panel directly onto the frame. To enhance the effect, it can be used several times.

7. Adding shooting galleries and captions: Editing a movie - Creating titles and captions - Select a caption or caption effect - enter text, set formatting - click the "Finish" button.

8. Add music: Record video - import sound and music - drag and drop the fragment to the storyboard panel.

9. Saving the movie in formatWMV - Finish making the movie - Saving the movie to your computer - Confirm the save movie wizard's requests

Give this algorithm to students as a memo. We do the work all together, the teacher shows everything the same on the screen.

6. Homework: In the next lesson, students will be doing a movie project. To do this, they will have to think over the subject of the project, what fragments and photographs they will use. During the lesson, they will have to shoot footage and edit a short film. (The topics are varied: My school, My class, Our computer science room, Our teachers, etc.) The work is supposed to be in groups of 2-3 people.

Appendix 1. Camcorders

Camcorders are primarily divided into digital and analog. Here I will not consider analog cameras (VHS, S-VHS, VHS -C, Video-8, Hi-8) for obvious reasons. They have a place in a thrift store, or on the top shelf in the closet (what if someday it will become a rarity), but the processing of analog video will definitely be considered, since, I think, everyone has a lot of cassettes. So, modern household video cameras differ in the type of video information carrier, in the method of recording (encoding) video information, in the size and number of matrices, and, of course, in optics.

1.1.1. By the type of storage medium, cameras are divided into:

HDV cameras: the newest and most likely future format. Frame size up to 1920 * 1080. Imagine, each frame is a 2 megapixel photo, and you will understand what the quality of the video is. Strictly speaking, HDV is a recording format, since there are HDD cameras that work in the HDV format. But I deliberately put this format in this row, since most of the existing HDV-cameras record on cassettes. If money is not a problem for you, these cameras are for you.

DV cameras: The main format for consumer digital video cameras. Frame size 720 * 576 (PAL) and 720 * 480 (NTSC). The recording quality largely depends on the optics and the quality (and quantity) of matrices. DV cameras are divided into DV (mini-DV) cameras and Digital -8 cameras. Which one to buy depends on you, on the one hand mini-DV cameras are more common, on the other hand, if you had a Video-8 camera before, it makes sense to pay attention to Digital-8 cameras, since these cameras record freely on any cassettes of 8 format (Video-8, Hi-8, Digital-8 (they can, of course, swear, they say, Video-8 is rather weak for me, but they write on them easily)), in addition, recording on cassettes of better quality (Hi -8, Digital -8), you will get a longer recording time than mini-DV.

DVD cameras. I am not a fan of this type of camera. Their recording quality is lower than that of DV-cameras, and even a disc with the best quality for them is enough for 20 minutes. But! If you are not pretentious about quality (especially since the difference is not so noticeable on the screen of an ordinary TV) and you do not want to bother with making a film, then encoding it into DVD format, you can easily use a DVD camera. Moreover, you can quickly assemble a full-fledged DVD from the resulting files onto a 1.4 GB DVD (used in DVD cameras) using specialized programs (for example, CloneDVD and DVD -lab).

Flash cameras. Recording is performed on a flash card in MPEG 4 and MPEG 2. The duration depends on the size of the card, the selected frame size and encoding quality. MPEG 2 is preferable as the quality is higher, but it takes up more space. But neither the one nor the other format, when processing video information by a camera for recording on a card, will not be able to provide quality, even slightly close to DV. Therefore, we can recommend such cameras for a gift to children or for filming in extreme conditions, since the indisputable advantage of these cameras is their compactness and the absence of mechanical parts (the exception is a zoom lens).

HDD cameras. Recording is made to the built-in hDD... Recording can be done in all formats from HDV to MPEG 4 (depending on model). Perhaps, like flash cameras, this is the future of household camcorders, but unlike the latest HDD cameras, they can already provide excellent HDV quality, or up to 20 hours of good quality MPEG 2 recording on a 30 Gb disk. But let's look at this splendor on the other hand, recording 1 hour of DV format takes up 13-14 Gb on a hard disk, and after making some simple calculations, tell me that it is easier to rearrange a cassette or rewrite video to a computer after 2.3-3 hours of recording (to good quality you get used to it quickly).

1.1.2. Any digital video camera uses compression (compression) of digitized video, because at the moment there is simply no media capable of withstanding uncompressed video (one minute of uncompressed PAL 720 * 576 video without sound takes about 1.5 GB on the hard disk, simple calculations allow you to see which is 90 GB for one hour). And it is also necessary to process this huge amount of information, even a simple rewriting of 90 GB will take about five hours. Therefore, video camera manufacturers simply need to use compression of the digitized video. Modern video cameras use the following types of compression: DV, MPEG 2, MPEG 4 (DivX, XviD).

DV is the main form of video compression in modern digital camcorders; it is used by HDV, miniDV, Digital 8 and some HDD cameras. The high quality of this type of compression, I think, will be leading among other formats for a long time.

MPEG 2 is the format used for dVD burner ... Although it has a slightly worse recording quality compared to DV, depending on the bitrate (roughly speaking, the number of bytes allocated per second of video), using this type of compression, you can get a video of a fairly high quality (remember licensed DVDs).

MPEG 4 - to be honest, manufacturers of digital equipment (photo and video) have seriously "tarnished" their reputation this format... To "squeeze" everything possible out of this format, you need to use a sufficiently powerful computer and spend a decent amount of time. Therefore, it turns out that the final video in MPEG 4 format on camcorders and cameras is of low resolution and low (to put it mildly) quality. What DivX or XviD is used is not so important, the difference (small), again, can be seen only when processing video on a computer.

1.1.3. An important, but rather basic, effect on the final result is exerted by the quality of the matrix used to digitize the optical signal passing through the lens of the video camera. The bigger it is, the better. When choosing a video camera, do not be too lazy to look into the specification and see the number of effectively used pixels ("points" on the matrix). For example, the specification for the Sony XXXXXXX camcorder says that with a frame size of 720 * 576 (0.4 Megapixels), 2 Megapixels of the matrix are used for video. Naturally, this has a positive effect on the final result, since with any encoding (compression) the law is rigidly applied: the better the source material, the better the result, and the more light falls on the matrix, the less digital noise will be, the darker the time it will be possible to use a video camera, etc. All of the above in triple size refers to three matrix cameras, among other things, the system of three matrixes can significantly reduce color noise due to the fact that the separation of light into RGB color components (a prerequisite for obtaining a video signal) is not performed electronics, but an optical prism, then each matrix processes its own color.

Indirectly, the size and quality of the matrix can be judged by the digital camera built into the camcorder, the higher its resolution, the better.

1.1.4. With video camera optics, everything is simple: the more, the better. The larger the lens diameter, the more light will enter the sensor. The greater the optical zoom of the lens ... However, it is worth dwelling on this in more detail. The first thing I want to say: NEVER look at the proud inscriptions on the side of the video camera (X120, X200, X400, etc.). You only need to look at the optical zoom of the lens (either on the camera (optical zoom) or on the lens itself). Of course, digital zoom can be used, but do not forget that digital zoom is a limitation of the number of effectively used matrix pixels (see figure). And just a 2x digital zoom (for example, with a 10x lens, this will be a 20x total magnification) will reduce the effective pixels on the matrix by 4 times!

Well, it would be nice to have an optical stabilizer, since cameras with a digital stabilizer do not use the entire matrix area.

Webcams

Webcams are inexpensive networked fixed devices that transmit information, usually video, over wireless or cross-linked Internet and Ithernet links. The main purpose of "room" webcams is to use them for video mail and teleconferencing. Such cameras are widely used in "baby-siting" - they perfectly cope with the role of video nannies, transmitting the image of a child left to himself. "Street" anti-vandal webcams act as security video observers. The ability to capture images in camcorder or still camera mode is an additional feature of webcams. Expect high quality from recorded videos or digital photo in this case not worth it. Because it makes no sense to equip webcams with high-quality optics and expensive electronics - transferring video data in real time requires incredibly high compression, which inevitably leads to a loss in image quality. Although it is fundamentally impossible to get a gorgeous picture using webcams, it is the quality of the resulting image that is the main characteristic that allows you to subjectively compare and choose cameras of this type. However, preference can also be influenced by an interesting design, software package and various options such as support for skins and additional communication interfaces... All webcams are equipped with a motion detection function and an audio input that allows you to transmit audio information, they are also often equipped with connectors for connecting various external sensors and devices such as lighting fixtures and alarms. World practice shows that the main manufacturers of webcams are becoming companies that manufacture computer peripherals (Genius, Logitech, SavitMicro) or network equipment (D-Link, SavitMicro), and not video or photographic equipment, which once again emphasizes the difference in the technologies used.

Video image compression formats

As an initial step in image processing, the MPEG 1 and MPEG 2 compression formats split the reference frames into several equal blocks, which are then subjected to a diskette cosine transform (DCT). Compared to MPEG 1, the MPEG 2 compression format provides better image resolution at a higher video bit rate through the use of new compression and de-redundancy algorithms and coding of the output data stream. Also, the MPEG 2 compression format allows you to choose the compression level due to the quantization accuracy. For video with a resolution of 352x288 pixels, the MPEG 1 compression format provides a bit rate of 1.2 - 3 Mbps, and MPEG 2 - up to 4 Mbps.

Compared to MPEG 1, the MPEG 2 compression format has the following advantages:

Like JPEG2000, the MPEG 2 compression format offers scalability to various levels of image quality in a single video stream.

In MPEG 2 compression format, motion vector precision is increased to 1/2 pixel.

The user can select an arbitrary discrete cosine transform accuracy.

Additional prediction modes are included in the MPEG 2 compression format.

The MPEG 2 compression format used the now discontinued AXIS 250S video server from AXIS Communications, the 16-channel VR-716 video storage from JVC Professional, DVRs from FAST Video Security and many other video surveillance devices.

Compression format MPEG 4

MPEG4 uses a technology called fractal image compression. Fractal (contour-based) compression means extracting outlines and textures of objects from the image. The contours are represented in the form of the so-called. splines (polynomial functions) and are encoded by reference points. Textures can be represented as spatial frequency transform coefficients (for example, discrete cosine or wavelet transform).

The range of data rates supported by the MPEG 4 video image compression format is much wider than that of MPEG 1 and MPEG 2. Further developments are aimed at completely replacing the processing methods used by the MPEG 2 format. The MPEG 4 video image compression format supports a wide range of standards and baud rate values. MPEG 4 includes progressive and interlaced scanning techniques and supports arbitrary spatial resolutions and bit rates ranging from 5 kbps to 10 Mbps. MPEG 4 has an improved compression algorithm that improves quality and efficiency at all supported bit rates. Developed by JVC Professional - VN-V25U webcam included in line network devices works, uses the MPEG 4 compression format for processing video images.

Video formats

The video format determines the structure of a video file, how the file is stored on a storage medium (CD, DVD, hard disk or communication channel). Usually different formats have different file extensions (*. Avi, *. Mpg, * .mov, etc.)

MPG - A video file that contains video encoded with MPEG1 or MPEG2.

As you can see, usually MPEG-4 movies have the AVI extension. The AVI (Audi o-Video Interleaved) format was developed by Microsoft for storing and playing video clips. It is a container that can contain anything from MPEG1 to MPEG4. It can contain 4 types of streams - Video, Audio, MIDI, Text. Moreover, there can be only one video stream, while there can be several audio streams. In particular, AVI can contain only one stream - either video or audio. The AVI format itself does not impose absolutely any restrictions on the type of codec used, neither for video nor for audio - they can be anything. Thus, any video and audio codecs can be perfectly combined in AVI files.

RealVideo is a format created by RealNetworks. RealVideo is used for live TV broadcasting on the Internet. For example, CNN was one of the first to broadcast on the Internet. It has a small file size and the lowest quality, but you will be able to watch the latest TV news release on the website of your chosen TV company without overloading your communication channel. Extensions RM, RA, RAM.

ASF - Streaming Format from Microsoft.

WMV - Video file recorded in windows format Media.

DAT - File copied from VCD (VideoCD) \\ SVCD disc. Contains MPEG1 \\ 2 video stream.

MOV - Apple Quicktime format.

Connecting to a PC or TV

The simplest connector - RCA AV-out - to put it simply "tulips" - is available in any camcorder, adapted for connection to any television equipment, and provides analog video transmission with the greatest loss in quality. The presence of such analog inputs in digital video cameras is much more valuable - this allows you to digitize your archives of analog recordings if you had a digital video camera before. In "digital" their storage period will be extended, and it will also be possible to edit them on a computer. Camcorders of the Hi8, Super VHS (-C), mini-DV (DV) and Digital8 formats are equipped with an S-video connector, which, unlike RCA, transmits color and luminance signals separately, which significantly reduces losses and significantly improves image quality. S-video input in digital models gives the same advantages to owners of Hi 8 or Super VHS recordings. The built-in infrared LaserLink transmitter in Sony camcorders, using the IFT-R20 receiver, allows you to watch footage on the TV without connecting to it with wires. Just place the camcorder next to the TV at a distance of up to 3 m and turn on "PLAY". The more advanced Super LaserLink transmitter, which is equipped with all the latest models, works at a greater distance (up to 7 m). The presence of mounting connectors in the camcorder allows for line editing by synchronizing the camcorder with VCRs and an editing deck. In this case, on all devices connected to each other, the tape counter readings and all the main modes are monitored synchronously: playback, recording, stop, pause and rewind. In Panasonic camcorders, the Control-M connector is used for this purpose, in Sony camcorders - Control-L (LANC). Their specifications are incompatible, so we recommend that you check the conformity of the interface with the VCR and the video camera.

RS-232-C connector ("digital photo output")

Connector for connecting a video camera to the serial port of a computer for transferring still frames in digital form and controlling the video camera from a PC. In "sophisticated" models, instead of RS-232-C, an even faster "photo output" - USB interface is built in. All mini-DV and Digital8 camcorders are equipped with a DV output (i. LINK or IEEE 1394 or FireWire) providing fast transfer lossless digital audio / video signal. To do this, you need to have another device with support for DV-format - DV-VCR or computer with DV-card. Of course, camcorders that have, in addition to the output, also a DV input, are more valuable. Some firms produce the same model in two versions: the so-called. "European" (without entrances) and "Asian" (with entrances). This is due to the high customs duties in Europe on the import of digital video recorders, which can fairly include a video camera with DV input. IEEE-1394, FireWire and i. LINK are three names for the same high-speed digital serial interface that is used to transmit any kind of digital information... IEEE-1394 (IEEE - Institute of Electrical and Electronics Engineers) Refers to an interface standard developed by Apple Corporation (branded as FireWire). Designation adopted by the American Institute of Electrical and Electronic Engineers (IEEE). Most mini-DV and Digital8 camcorders are equipped with an IEEE-1394 interface, through which digital video information is sent directly to a computer. The hardware includes an inexpensive adapter and a four or six wire cable. Allows to transfer data at speeds up to 400 Mbps.

i. LINK

Digital input / output based on IEEE 1394 standard. Allows you to transfer footage to your computer. Camcorder models with i. Link increases flexibility through online editing, electronic storage and distribution of images.

Firewire

Registered trademark of Apple, which was actively involved in the development of the standard. The name FireWire ("fire wire") belongs to Apple and can only be used to describe its products, and in relation to such devices on a PC it is customary to use the term IEEE-1394, that is, the name of the standard itself;

Memory card

On this card you can store in in electronic format photos, videos, music. With it, you can transfer the image to your computer.

Memory Stick

Sony's proprietary Memory Stick is capable of simultaneously storing recordings of image, speech, music, graphics and text files... Weighing only 4 grams and not exceeding a gum plate in size, the memory card is reliable, has protection against accidental erasure, 10-pin connection for greater reliability, data transfer rate - 20 MHz, write speed - 1.5 MB / s, read speed - 2.45 Mb / s Digital still frames capacity on a 4 MB card (MSA-4A): JPEG 640x480, SuperFine mode - 20 frames, Fine - 40 frames, Standard - 60 frames; in JPEG 1152x864, SuperFine - 6 frames, Fine - 12 frames, Standard - 18 frames. MPEG Movies capacity on 4 MB card (MSA-4A): Presentation mode (320x2.6 x 15 seconds; Video Mail mode (160x1.6 x 60 seconds.

SD Memory Card

SD Card - A new standard postage stamp memory card that can store any kind of data, including a variety of photo, video and audio formats. Currently available SD cards are 64, 32, 16 and 8 MB. By the end of 2001, SD cards with a capacity of up to 256 MB will be on sale. One 64 Mb SD card contains about the same amount of music as one CD. Since the transfer rate to the SD card is 2 Mb / s, it will take only 30 seconds to rewrite from a CD. Since the SD Memory Card is a semiconductor storage medium, vibration does not have any effect on it, that is, it is impossible to skip in the sound, which occurs with rotating media such as CD or MD. Maximum audio recording time on an SD card 64 Mb: 64 minutes of high quality (128 kbps), 86 minutes of standard (96 kbps) or 129 minutes in LP mode (64 kbps).

During the development of digital technology, computers of various types were developed. Many of them have long been forgotten, but some have had a strong influence on the development of modern computing systems. Here we will give a brief overview of some of the stages in the development of computing machines to show how human thought came to the modern understanding of computer technology.

Devices that facilitate counting or storing its results have been known for a long time, but we will only be interested in computing devices that automatically execute programs embedded in them, therefore we do not consider such devices as counting, mechanical adding machines and electronic calculators.

The first stored program calculating machine was built by a French scientist Blaise Pascalin 1642. It was mechanical with a hand drive and could perform addition and subtraction operations. German mathematician Gottfried Leibnizin 1672 he built a mechanical machine that could do the same operations of multiplication and division. For the first time a machine working according to the program was developed in 1834 by an English scientist Charles Babbage... It contained a memory device, a computing device, a punched card input device and a printing device. The commands were read from a punched card and performed data reading from memory to a computing device and writing the calculation results into memory. All devices of Babbage's machine, including memory, were mechanical and contained thousands of gears, the manufacture of which required precision unavailable in the 19th century. The machine implemented any programs written on a punched card, so for the first time a programmer was required to write such programs. The first programmer was an Englishwoman Ada Lovelace, in honor of which the programming language Ada was named in our time.

In the 20th century, electronics began to develop and its capabilities were immediately adopted by the developers of computers. The countdown of generations of digital computers begins with the construction of computers, the basic system of elements of which was built on electronic components. Note that the division of the period of development of digital technology into stages is mainly associated with the transfer of the basic system of elements to new technologies for the production of electronic components.

The first generation - vacuum tubes (1945-1955)

The basic system of elements of this generation of computers was based on vacuum tubes. Their use determined both the advantages and disadvantages of digital devices. Electronic tubes provided a high switching speed of logic elements, which increased the speed of computation compared to attempts to create a computer, the basic element of which was built on the basis of an electromechanical relay. Vacuum tubes were durable enough to provide reliable computer operation. Unfortunately, lamp computers also had a lot of shortcomings. Firstly, vacuum tubes operated with voltages of tens of volts and consumed a lot of energy, in addition, the size electronic tubes, according to modern concepts of microelectronics, was huge - several tens of cubic centimeters. Thousands of logical elements were needed to build a computer, so the size of tube computers in terms of the occupied area was tens of square meters, and the power consumption ranged from units to tens or even hundreds of kilowatts. This power led to overheating of the lamps, which were placed rather compactly, and set the task of effectively cooling the electronic components of the machine. The processing speed of information in tube machines ranged from several hundred to several thousand operations per second.