Such webcams. How a webcam works Main characteristics that will help you gain respect

A digital web camera is a peripheral device that consists of a video camera (CCD matrix), a compression processor and a built-in web server. Typically, a webcam is used as a device for video recording, video conferencing, or video surveillance and video transmission over LAN/WAN/Internet. To operate a webcam, no special devices are required. personal computer. If properly configured, access to the video image captured by the web camera can be granted to all users of the network or to other authorized users.

Device and principle of robotic webcam

The current webcam is a digital device that can capture video, convert analog video into digital, compress digital video, and transmit video. computer network. The webcam includes the following components:

PZZ matrix,

lens,

optical filter,

video capture board,

video compression block,

central processor and web server,

flash memory,

edge interface,

subsequent ports,

alarm entry/exit.

How the photo sensor of most web cameras gets stuck PZZ matrix ( PZZ, CCD - charge-coupled device) - a rectangular light-sensitive conductor plate with 3:4 sides, which converts the light that falls on it into an electrical signal. The CZZ matrix is ​​composed of a large number of light-sensitive centers. In order to improve the light sensitivity of the CZZ matrix, it is often necessary to form a structure that creates a microlens in front of the skin center. The technical parameters of the webcam include specifying the format of the PZZ matrix (the maximum diagonal of the matrix in inches), the number of effective pixels, the type of projection (row or interrow) and sensitivity.

Lens - a whole lens system designed to project the image of a security object onto the light-sensitive element of the web camera. The lens is an invisible part of the webcam, so the correct choice and installation contains the content of the video image that is captured by the webcam. The webcam is often equipped with a lens. Lenses are characterized by a number of important parameters, such as focal length, lens aperture (F), depth of sharpness, mount type (C, CS), format.

Optical infrared filters , which are installed at the webcam, are optically precise plane-parallel plates that are mounted on the CZZ matrix. They operate as optical low-frequency filters with a frequency around 700 nm near the red color. The stinks appear in the infrared warehouse of light colors, ensuring the webcams correctly transfer colors. Prote, on most black-and-white webcams such filters are not installed, which is why monochrome webcams may be more sensitive.

Video capture fee Web cameras (digitization unit) convert an analog electrical signal generated by a CCD matrix into a digital format. The process of signal transformation consists of three stages:

Discretization,

Quantuvannya,

Koduvannya.

Discretization- Reading the amplitude of the electrical signal at equal intervals of an hour (period). This stage of signal transformation is characterized by the sampling frequency.

Quantuvannya- this is the process of presenting the results of sampling in digital form. The change in the level of the electrical signal during the sampling period is given in the form of a code word with 8, 10 or 12 bits, which gives a total of 256, 1024 and 4096 quantization levels. The number of quantization steps determines the accuracy of the signal in digital form.

Koduvannya. In addition to the information about the change in the level of the signal captured at the advanced stage, during the encoding process, beats are formed that indicate the end of the synchronization pulse and the start of a new frame, as well as additional beats for protection loc.

Compression block webcams compress the digitized video signal into one of the compression formats (JPEG, MJPEG, MPEG-1/2/4, Wavelet). I’m really embarrassed, the size of the video frame is getting shorter. This is necessary to save and transfer video over time. Since the local edge to which the webcam is connected may limit the bandwidth, then in order to avoid overloading of the edge traffic, it is necessary to completely reduce the traffic. transmitted information, reducing the frequency of frame transmission along the edge, or the separate number of frames. Most compression formats such as webcams provide a reasonable compromise between these two methods of overcoming the problem of video transmission at a time. Currently available formats and restrictions allow you to stream digitized streams with a small bandwidth of 64 KB - 2 MB (with such a smooth bandwidth, video streams can be processed in parallel with other data streams at intervals).

Video compression from a webcam can be provided either in hardware or in software. Software implementation of compression is cheap, and due to the high computational capacity of compression algorithms, it is ineffective, especially if you need to watch video from a webcam online. Therefore, most wired video cameras release webcams with hardware implementation of compression. For example, the skin-mesh camera from AXIS Communications is equipped with an ARTPEC compression processor, which provides high-quality compression of JPEG/MJPEG video.

central processor є computing core of the webcam. This operation involves the display of digitized and compressed video, and also corresponds to the associated functions of the built-in web server and other programs for web cameras.

Interface for Ethernet Used to connect a webcam to the Ethernet standard 10/100 Mbit/s.

For robots, a webcam can be used serial port to connect to a modem and work in dial-up mode within a day local measures. You can also connect to a peripheral webcam via the serial port.

Flash memory card Allows you to update other webcam programs and save corrupt HTML pages.

RAM Serve to save time data that is generated when installing certain programs and scripts. Many Internet cameras are called video buffers. The whole part of the OZP is reserved for recording and saving video frames captured by the web camera. The information in the video buffer is updated cyclically. new frame sign up to replace the oldest. This function is necessary if the webcam is a security video alarm, and allows you to update the steps that transmit and attack the alarm signal from security sensors connected to the webcam.

Alarm entries/exits serve to connect alarm sensors to the webcam. When one of the sensors is activated, an alarm signal is generated, as a result of which the webcam processor compiles a set of frames recorded in the video buffer before, after and at the time the alarm signal is received. This recruitment can be done using the specified e-mail address or FTP.

Connecting and installing a webcam

Typically, the webcam is connected to the Internet via a 10BaseT/100BaseTX/1000BaseTX Ethernet port or to an additional modem via a serial port. Afterwards physical connection Webcams are assigned IP addresses before they are broadcast. Most often, the webcam does not record IP addresses; It can be installed either using the additional functions of a standard web browser or using a DOS command, which is used for identification serial number webcam assigned by the publisher. In addition, the production companies are being fragmented special programs for web cameras, which will significantly simplify the procedure for assigning an IP address to a web camera (for example, IP Installer from AXIS Communications). Required software for web server, FTP server, FTP client, e-mail client, etc. The webcam connects directly to the LAN/WAN/Internet network and acts as an independent network device. This differentiates webcams from other digital cameras, which require a simple connection to a personal computer via a USB or LPT port. In addition, webcams can support the robot with scripts and JAVA applets.

To install a webcam on the street or in the vicinity of a lot of cameras, the design of the camera body has a special fastening designed for installation on walls, pedestals, brackets and rotating devices. The webcam decks can be equipped with rotating devices for installation on a horizontal or vertical surface.

Additional capabilities and functions of the webcam

Roc detector - tse software module The main task is to detect a web camera that moves into the field of view of the video surveillance object. The roc detector not only detects movement in the image field, but also the dimensions of the object and the fluidity of its roc. It is important to set the video alarm, adjust the web camera rogue detector to detect object movements by limiting the minimization of processing steps (by filtering out the code), set the processing logic alarms (alarm recording, integration with other security equipment).

Audio transmission In most cases, the connection to the webcam of the additional audio module is affected. For example, AXIS Communications company for expanding functional capabilities Webcams are produced by a special audio module AXIS 2191, which is compatible with most AXIS webcams.

Password protector serve to limit access to the webcam to persons who do not deny access rights.

You can watch the promotional video from the webcam from anyone edge computer, on which a standard web browser is installed, for example, Internet Explorer or Netscape Navigator. However, you can restrict a number of people from the rights to access the webcam by entering a password on the same page. Many webcams support extensive password protection for delineating access rights and administration.

Programs for webcams

As a rule, images from a webcam can be viewed using a standard web browser, such as Internet Explorer or Netscape Navigator. However, many software companies produce exclusive programs for webcams.

It combines the functions of a web browser and other software used for editing, adjusting and viewing images from a web camera (for example, AXIS Camera Explorer or another program from JVC Professional for the administration of line V. networks). I sleep the same way security software for departments edge systems video precautions that support the ownership of various video processors, such as Sphinx-DV from Digicore Systems.

Connecting a webcam before the meeting

Currently, a webcam can connect to a network in a number of ways, which are based on different data transfer standards.

10/100 Mbit Ethernet. This is the most popular method of transferring data from a webcam to a network. There are two standards for 10 Mbit Ethernet: 10Base2 (over coaxial cable cables) and 10BaseT (over twisted pair cables). 10Base2 rarely settles down due to the sensitivity of the coaxial cable to external transients. The 100BaseTX standard uses a twisted pair and ensures data transmission speed of 100 Mbit/s.

1000 Mbit Ethrnet, Gigabit Ethernet. The 1000BaseTX standard, which is being reviewed here, is a refined version of 100BaseTX. This standard is important for establishing highways and local networks.

Standard telephone modems. It's cheap and has more options for connecting a webcam to global measure. The main drawback of this connection method is low fluidity data transmission ( maximum fluidity data transfer – 56 kbit/s, maximum upload speed – 33.6 kbit/s). The webcam is connected to the modem via the serial port.

ISDN modem. The ISDN (Integrated services Digital Network) standard is being developed for the transmission of digitized graphics, audio and video information and other digital data over private or underground digital networks. telephone measures. The ISDN standard ensures data transmission from the web camera at speeds up to 128 kbit/s with two channels.

xDSL modems. DSL (Digital Subscriber Line) is a technology that ensures a wide range of transmission through simple copper telephone wires. The speed of data transmission from the webcam may vary depending on the company that provides this service. The average rate is 1 Mbit/s for data acquisition and 250 kbit/s for downloading.

Cable modems. A cable modem is a modem that provides access to the Internet over the Internet cable tower. Cable modems use asymmetric technology, which is best suited for Internet access. In this case, the maximum possible speed of receiving data from a webcam with such a modem can reach 40 Mbit/s (although it does not exceed 1 Mbit/s), and the speed of data transmission can be close to 10 Mbit/s.

Stilnikov modems. Using a steel modem, you can connect a webcam to the Internet via a wireless connection. The transmission speed should be set from 5 to 20 kbit/s.

Report technical information on specific models web cameras from Axis Communications and JVC Professional are presented on this site in the video camera section. Short technical characteristics Prices for webcams are listed in the ARMO-Systems online store.

How to gain access to your webcam via the Internet

How to gain access to your webcam via the Internet

Butt: Since you are already downloading images from your webcam to your computer, you believe that it would be impossible for you to access the camera via the Internet. For example, as a store manager, you want to control the activities in the store from your office, instead of having to work at work

Croc 1: System benefits

Scenario A)

If your device (where the camera is installed) is already connected via Ethernet to the Internet Service Provider (Internet service provider), simply set up oblikovy record, connect the security camera to the switch through the boundary output, and you must assign a dynamically assigned large IP address to the security camera. Enter the installation commands for the security camera. A special program or utility for the webcam will be used to identify the IP address.

The number of assigned IP addresses can be changed by your Internet service provider (via an exchanged IP address that is shared among clients), you can find out how you can assign an IP address to the cameras in Krok4 below .

Scenario B)

If your booth is not equipped with Ethernet access, then in most cases you may need the following devices:

Wideband modem for connecting an asymmetric digital subscriber line (whichever is delivered to your Internet service provider) or cable TV towers

a broadband router, which can also be called an Internet Gateway, (a broadband router allows local network users to seamlessly connect to the Internet. It also serves as an interface to the Internet, Wider and local network)

switch that allows various devices It allows devices to merge directly one by one and allows devices to work locally beyond an IP address),

NOTE: Most broadband routers come with a built-in switch function and don't need one.

merging chamber

local computer

computer for remote monitoring

Step 2: Assign an IP address for your camera

A wide-area router typically assigns automatic, local IP addresses for devices connected to a local network, such IP addresses may be subject to change. Static (fixed) IP addresses are recommended for the boundary camera. To identify a static IP address, find out the IP address range of the router, which, for example, can range from 192.168.0.2 to 192.168.0.35. If you want to use an IP address in the range, such as 192.168.0.100, as a static IP address for the camera, you will certainly not risk that your device will have conflicts with other devices, which will override the automatic address and.

Setting up an IP address for your camera can be divided into three in different ways, as listed in the camera's handbook. As soon as the IP address is assigned, set up a gateway and a gateway (this information can be retrieved from the router), and configure the camera setup parameters: password, account registration to ensure limited access to the camera.

Lesson 3: Port Forwarding

A wide-range router, as stated earlier, will provide an interface between the Internet, the Provider and the Local Network. The router finds the external IP address from the Internet service provider and supplies internal (local) IP addresses to devices on the local network.

To deny access to a security camera that is permanently located in the local network, you must identify the external IP address of your router (your router's personal name), and configure your router so that the external IP address is directed to a static one. local IP- addresses of the boundary chamber. This process is called the critical port; So, if you share the external IP address of the router with any security camera, the Internet recognizes the local location of your router and therefore redirects your request to the local IP address assigned to the security camera.

Launch a web browser and go to the router’s web page via Login to the router configuration pages.

Find the menu item "port forwarding" (or similar), with a table approximately as shown below:

Service name

Port cob

Port of Kintsya

Server IP addresses

Not adjusted

Not adjusted

Not adjusted

Since the camera transmits its video via HTTP, you must configure the HTTP service as follows:

Service name

Port cob

Port of Kintsya

Server IP addresses

Not adjusted

Unofficial port

Save the configuration on the router and exit the configuration page. Wicono configuration. Any requests that reach the external IP addresses of the router on port 80 will be sent to the IP camera address: 192.168.0.100.

If you want to make more than one security camera accessible via the Internet, then you must use the additional (unofficial) ports of the router, type 80xx, and connect them to border address IP cameras.

Lesson 4: What can you learn if your Internet service provider often changes the Dfi external IP address

Create a cloud record with the DNS service that serves and registers domain names(for example, www.nic.ru, etc.) and link it to an external IP address. For a domain like www.web-kamera.ru, it’s easy to remember, and you can assign your cutaneous device to the skin domain, then. yogo IP address. Of course, if the IP addresses of the router are changed, it will be automatically registered by the DNS service to update your IP address in such a way that one and the same address will not be able to reach your security camera.

Most broadband routers support similar DNS support like www.dyndns.org.

Another alternative: you can buy or rent a static external IP address from your Internet service provider.

It’s easy to send your money to the robot to the base. Vikorist the form below

Students, post-graduate students, young people, who have a strong knowledge base in their new job, will be even more grateful to you.

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ENTRY

The first webcam in history was launched in 1991 and showed the boiler near the Trojan Room at the University of Cambridge. It doesn’t work, it was turned off on September 22, 2001. The remaining photographs taken by this camera can still be viewed on it home page on the Internet. The global web has only just begun to move around the planet. A group of apprentices, about 15-20 people, was working on a project from Galusi Merzhevyh Technologies. Mind you, the robots were spartan, and the whole team had only one pot, because it couldn’t please the entire team. Most of the work was carried out in the laboratory, the personnel live in one’s cabin, but in another part. In order to encourage the rational process with a cup of water to spoil, the participants in the scientific project were often excited to open a corridor where, located on top of the place where the cauldron was brewing, was brewing. More often than not, such campaigns ended in failure, and a few colleagues began to dispute the Omrian cause. The situation called for a non-standard solution, and it was found.

One of the computers in the laboratory has a frame grabber. Previously, they connected a camera, aimed directly at the security object. That same computer plays the role of a web server behind a shell of specially written software. It is important to know what it is, you must run a client software program on your computer that connects to the server /3/. As a result, on to a remote computer At the end of the little one a black and white image was displayed, which turned out to be trichy on the hvilina. A note about this plant complex was published in the Comm-Week magazine on September 27, 1992. Not much time has passed since the first prototypes of IP cameras appeared, but they have already been transformed into a whole new class of devices that make everyday life simpler, more convenient and more fun.

Similar to the wealth of advanced technologies, webcams and video chats have gained massive popularity. The need for “live” video images has given rise to web cameras that can communicate via the Internet in a video stream format, which eliminates the need to manually update images; but not for bar, unnecessary in current browsers special plugins have become available.

1. SEE THE WEB CAM

A webcam is a small-sized digital video or photo camera designed to capture images in real time, intended for further transmission over the Internet (in programs such as Skype, Instant Messenger or any other video app). It uses a web server, a edge interface, and connects directly to the LAN/WAN/Internet. Many edge cameras have additional functions such as: rogue detectors, sending notifications by e-mail, working with a modem, connecting external sensors and /1/. Users can access the camera using a standard web browser. If properly configured, access to the video captured by the web camera can be granted to all members of the network or to other authorized clients.

Web cameras that deliver images via the Internet upload images to the web server either on demand, continuously, or at regular intervals. This can be achieved by connecting the camera to the computer or depending on the capabilities of the camera. Some current models have hardware and software that allows the camera to independently operate as a web server, FTP server, FTP client, and/or send images via email.

Webcams used for video conferencing are usually simple camera models that are connected to a computer running a program such as Instant Messenger. Camera models that are used for security purposes can be protected additional extensions and functions (such as roc detectors, connecting external sensors, etc.) video chat interface detector camera

There are three types of webcam groups: desktop, portable and universal. Desktop webcams are most often used for desktop personal computers, portable ones for laptops, and universal ones, obviously, for laptops and computers. Webcams are also divided into drone-free and dart-based ones.

A drone-free video camera is a recording device that transmits audio and video signals to a receiver without a cable connection. Such cameras are often installed on objects, and for various reasons it is difficult to lay a cable line. The main advantages of droneless cameras are the absence of the need for long and laborious work in laying the cable, high resistance to faults, and reliability.

Drillless cameras must be manually used as cameras that are used with caution, because daily bulky cable harnesses. Such a mini-camera allows you to create the appearance of security at the site /2/. Also, a portable video camera is a micro-camera, which can also be used to record video in a variety of devices. In your heart, dartless cameras divided into two types - analog and digital, through different technologies (methods) of signal transmission.

Analog drone-free video cameras can be difficult to recode and, most often, produce images that are being transmitted, but are much cheaper to purchase. It’s true that most fallouts, analog video cameras protected by law.

Digital drone-free video cameras (IP cameras) transmit signals in a digital format, and the digital signal is not subject to flux and transcoding, including the output of other cameras. Such a signal is absolutely not detected during the hour of transmission. These devices do not require a mandatory connection to the computer; they themselves are adjacent nodes with a powerful IP address (the name and name of the IP camera). In fact, there are their own servers that transmit the signal independently using the TCP protocol or via UDP.

There are two types of drone-free digital cameras - those that transmit a video signal via a radio channel (WiFi wireless cameras, USB, Wi-Max) and those that transmit the signal via Stilnikovy ligament(GSM droneless cameras, 3G cameras, CDMA droneless cameras).

Benefit from the greatest popularity WiFi cameras, as the most accessible and simplest type of digital drone-free video cameras.

Drone-free GSM video cameras (GPRS, EDGE, 3G communication protocols) are compatible with those who have daily access to the Internet via WiFi. Then they profit from the services of mobile phone operators.

USB cameras transmit a signal via Bluetooth, but they also operate in a nearby area, vikorist and radio communications.

Droneless IP cameras are comparable to web cameras, because... transmit video and audio signals to the Internet. The drone-less webcam can capture and transmit digital video signals via additional local monitoring.

Drone webcams are divided into existing and used ones. External webcams Please connect to a USB port or an additional FireWire interface. In the drone webcam you can use the original video camera, since it supports such functionality.

The built-in webcams are located directly in the device itself. It is important to recognize yourself current laptop without webcam. Let go of the middle wickedness, otherwise the presence is still to blame.

2. STRUCTURE AND PURPOSE OF WEB CAMERAS

2.1 Webcam structure

Today's webcam is a digital device that captures, digitizes, compresses, and transmits video over a computer network. The webcam includes the following components:

PZZ matrix;

Lens;

Optical filter;

Video capture fee;

Video compression block;

Central processor and web server;

Flash memory;

Grid interface;

Sequential ports;

Alarm entry/exit.

As a photo receiver, most web cameras use a CCD matrix (CCD, CCD - charge-coupled device) - a rectangular light-sensitive conductor plate with 3:4 sides, which transforms the light that falls on no, into an electrical signal. The CZZ matrix is ​​composed of a large number of light-sensitive centers. In order to improve the light sensitivity of the CZZ matrix, it is often necessary to form a structure that creates a microlens in front of the skin center. The technical parameters of the webcam include specifying the format of the PZZ matrix (the maximum diagonal of the matrix in inches), the number of effective pixels, the type of projection (row or interrow) and sensitivity. Typical web- a camera with a lens, an optical filter, a CZZ matrix, a digital image processing circuit, an image compression circuit and a web server for connecting to the /2/. The skin-edge video camera shares its IP address, computing functions, and embedded software that allows it to function as a web server, FTP server, FTP client and client e-mail. Most daily video cameras include many other useful functions, such as rocco detector, alarm input/output and e-mail support.

The webcam folds in front of the sensor. It is very common for standard CCD matrices to be replaced by cheaper CMOS sensors for video surveillance. I want the stench to be less sensitive and there is no need garn transfer to color, Their choice makes it possible to greatly reduce the cost of devices, including sensors “all in one chip” with digital output tributes

A light-sensitive sensor is, in a way, the heart of any digital camera. It itself allows you to convert light into electrical signals that are available for further electronic processing. The basic principle of operation of both PZZ and CMOS sensors is the same: under the infusion of light conductor materials They are used to carry a charge, which is always converted to voltage. The difference between PCD and CMOS sensors lies primarily in the method of accumulating and transferring charge, as well as in the technology of converting it into an analog voltage. Without going into details of the design different types sensors, it is also significant that CMOS sensors are significantly cheaper in production, and “noisier”.

The principle of a webcam is similar to the principle of any digital camera or camera. Between the optical lens and the light-sensitive PCD or CMOS sensor, there is the presence of an analog-to-digital converter (ADC), the main purpose of which is to convert the analog signals of the light-sensitive sensor, then voltage into a digital code. In addition, a color molding system is required /6/. Another important element of the camera is the circuitry, which ensures data compression and preparation before transmission to required format. For web cameras, video data is transmitted to a computer via a USB interface, so the final circuit of the camera acts as a controller to the USB interface.

Further: a microprocessor for video compression and radio detection (or simply a compressor microcircuit) enters the warehouse of the boundary chamber. The most popular JPEG, as the simplest and cheapest; MPEG4 is also often used, while MPEG2 is the most popular and the most expensive. With the completion of a patent on arithmetic coding, WaveLet is gaining popularity. I, decide, enter the security chamber warehouse hemline controller 10/100 Mbit/s.

2.2 Purposes of web cameras

Webcams enter our life. They are used to install video systems both in large and small areas. They become especially important when controlling and monitoring remote points, where there is a need for stationary equipment that cannot be serviced.

The webcam can be used as a watchdog camera, for example, to protect your car under the window, or as a web nanny, to watch over everything that happens to your child while you are away from home.

A webcam can be useful and useful in business, you can organize virtual exhibitions, hold video conferences or remotely attend meetings, and take part in meetings.

In addition, the capabilities of robots with web cameras have appeared in programs primarily for text chat (for programs such as Instant Messenger) - including Skype, Yahoo Messenger, AOL Instant Messenger, Windows Live Messenger - millions of popular users in The whole world was denied the ability to communicate with one videophone. The increased brilliance of video data has allowed web cameras to compete with video conferencing systems that have been in existence until now /4/. All webcams will be equipped with new functions, specifically aimed at the increased popularity and ease of video communication (including functions that provide automatic photo retouching, wrinkle smoothing, etc.).

Dartless cameras allow you to take precautions where it is difficult no cable connection or full mobility is required. Droneless video cameras can interact with other dart equipment. At this time it is necessary to take care dartless solutions It is time to design any measures from a small office to enterprise. This may save money, costs, and hours.

All drone-free systems support both infrastructure mode (connection via an access point) and ad-hoc mode (setting up a robot without a separate access point). You can add new cables at any time and install new hemlock units at any place without the need to remove hemlock cords. Bezdrotov's measures They can also be installed for a time clock station in areas where there is no installed cable management or laying edge cables complicated.

To ensure that drone-free users have access to corporate databases or resources that are shared with servers and printers, you can install an access point /5/. This device allows droneless workstations to communicate over an existing Ethernet network. D-Link access points are great with Wi-Fi protocol They are easily integrated with an Ethernet network. Droneless workstations can be added without affecting productivity. Interruption of traffic jams can be easily overcome by adding an access point to speed up the traffic jam time.

Some webcams are used in security systems. Companies are using webcams to monitor and videotape what is going on in offices, at front offices, in warehouses, and at elections. In Russia, cameras for reviewing and recording elections were installed on January 4, 2012. Webcams broadcast commissions and ballot boxes. Housekeepers behind the help of web cameras watch out for everything - from the child to the back yard.

The webcam itself, as a rule, is not capable of saving video, but simply taking pictures; To save video, you need to use a special security program on the computer to which the webcam is connected. Webcams can also be victorious in games, which are victorious using simple roc recognition algorithms.

LIST OF VIKORISTANIH JEREL

1. Informatics: Handbook for universities/Ed. prof. N.V. Makarova. - 3 types. overworked - M: F i S, 2004.

2. Kolesnichenka S., Shishigin I. PC hardware. BHV 1999.

3. Kristiansen T., Torkington N. Perl: Program Library: Trans. from English - St. Petersburg. : "Peter", 2000.

4. Ostreykovsky V.A. Informatics: Handbook for universities. - M: Visch. school, 1999. MS Excel 97 (2000). Krok by krok. Ecom 1999 (2000).

5. Svitlozarova G.I., Melnikov A.A. Workshop on programming my BASIC. – M. – Nauka, 1986.

6. Figurnov V.E. IBM PC for koristuvach. Short course M.: Finance and statistics. 1997.

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Webcams. Purpose, operating principle and main characteristics.

from the discipline (specialization) “Hardware Features” computing technology»

I misinterpreted it

Mikilska K.Yu.

student group PS-170

Badalova A.A.

Abstract of theft

with rating

Chelyabinsk 2014

Badalova A.A. Webcams. Purpose, principle of operation and main characteristics. - Chelyabinsk: SUSU, PS-170, 20 p., 4 ill., bibliography. list – 5 hired.

Meta abstract - learn about the meaning, principles of operation and main characteristics of web cameras.

The task of the essay is to learn the device and operating principle of web cameras, learn how to install web cameras and connect them to the network, learn about the importance of web cameras in the world.

The main characteristics of web cameras and connection methods are reviewed. Learn about programs for webcams and how to connect a webcam to video.

1. Input (side 4)

2. Value (side 5)

3. History of the webcam creation (page 6)

4. Device and operating principle of the webcam (page 7-11)

5. Additional possibilities and functions of web cameras (side 12)

6. Connecting a webcam to the video (page 13-15)

7. Methods of Wikostian webcams (page 16-17)

8. Programs for webcams (page 18)

9. Visnovok (page 19)

10. Bibliographic list (page 20).

Entry

Webcams are increasingly becoming a part of our lives. They are used to install video systems both in large and small areas. They become especially important when controlling and monitoring remote points, where there is a need for stationary equipment that cannot be serviced. If you need to install “time clock” cameras, web cameras are indispensable, and even their installation does not require pulling on the sides, the installation will be quick and easy.

The purpose of my work is to learn about the meanings, operating principles and main characteristics of web cameras.



For this purpose, I will look at the history of the industry, the device and the main characteristics, as well as the scope of operation of web cameras, and find out how to install them and connect them to the end.

Webcam concept.

A digital web camera is a peripheral device that consists of a video camera (CCD matrix), a compression processor and a built-in web server. Typically, a webcam is used as a device for video recording, video conferencing, or video surveillance and video transmission over LAN/WAN/Internet. To operate a webcam, you do not need any special devices or a personal computer. If properly configured, access to the video image captured by the web camera can be granted to all users of the network or to other authorized users.

History of the creation of the webcam.

It all started in one of the computer laboratories in Cambridge back in the early 90s of the last century, when the Global Web was just beginning to move around the planet. A group of apprentices, about 15-20 people, was working on a project from Galusi Merzhevyh Technologies. The robots were spartan in their minds - there was only one cavovarka for the whole team, so they could not please the entire team. Most of the work was carried out in the laboratory, the personnel live in one’s cabin, but in another part. In order to encourage the rational process with a cup of water to spoil, the participants in the scientific project were often excited to open a corridor where, located on top of the place where the cauldron was brewing, was brewing. More often than not, such campaigns ended in failure, and a few colleagues began to dispute the Omrian cause. The situation called for a non-standard solution, and it was found.
One of the computers in the laboratory has a frame grabber. Previously, they connected a camera, aimed directly at the security object. That same computer plays the role of a web server behind a shell of specially written software. It is important to know what it is, you must run the client software program on your computer that connects to the server. The result was a black-and-white image displayed in a small window on the remote computer, which was updated three times a day. A note about this plant complex was published in the Comm-Week magazine on September 27, 1992. Not much time has passed since the first prototypes of IP cameras appeared, but they have already been transformed into a whole new class of devices that make everyday life simpler, more convenient and more fun.

Baby 1. Photo from the first webcam

Apply the principle of a robotic webcam.

Today's webcam is a digital device that captures video, converts analog video into digital, compresses digital video, and transmits video over a computer network. The webcam includes the following components:

PZZ matrix,

lens,

optical filter,

video capture board,

video compression block,

central processor and web server,

flash memory,

edge interface,

subsequent ports,

alarm entry/exit.

·
How the photo sensor of most web cameras gets stuck PZZ matrix ( PZZ, CCD - charge-coupled device) - a rectangular light-sensitive conductor plate with 3:4 sides, which converts the light that falls on it into an electrical signal. The CZZ matrix is ​​composed of a large number of light-sensitive centers. In order to improve the light sensitivity of the CZZ matrix, it is often necessary to form a structure that creates a microlens in front of the skin center. The technical parameters of the webcam include specifying the format of the PZZ matrix (the maximum diagonal of the matrix in inches), the number of effective pixels, the type of projection (row or interrow) and sensitivity.

· Lens - a whole lens system designed to project the image of a security object onto the light-sensitive element of the web camera. The lens is an invisible part of the webcam, so the correct choice and installation contains the content of the video image that is captured by the webcam. The webcam is often equipped with a lens. Lenses are characterized by a number of important parameters, such as focal length, lens aperture (F), depth of sharpness, mount type (C, CS), format.

· Optical infrared filters , which are installed at the webcam, are optically precise plane-parallel plates that are mounted on the CZZ matrix. They operate as optical low-frequency filters with a frequency around 700 nm near the red color. The stinks appear in the infrared warehouse of light colors, ensuring the webcams correctly transfer colors. Prote, on most black-and-white webcams such filters are not installed, which is why monochrome webcams may be more sensitive.

· Video capture fee Web cameras (digitization unit) convert an analog electrical signal generated by a CCD matrix into a digital format. The process of signal transformation consists of three stages:

Discretization, quantization, coding.

Discretization- Reading the amplitude of the electrical signal at equal intervals of an hour (period). This stage of signal transformation is characterized by the sampling frequency.

Quantuvannya- this is the process of presenting the results of sampling in digital form. The change in the level of the electrical signal during the sampling period is given in the form of a code word with 8, 10 or 12 bits, which gives a total of 256, 1024 and 4096 quantization levels. The number of quantization steps determines the accuracy of the signal in digital form.

Koduvannya. In addition to the information about the change in the level of the signal captured at the advanced stage, during the encoding process, beats are formed that indicate the end of the synchronization pulse and the start of a new frame, as well as additional beats for protection loc.

· Compression block webcams compress the digitized video signal into one of the compression formats (JPEG, MJPEG, MPEG-1/2/4, Wavelet). I’m really embarrassed, the size of the video frame is getting shorter. This is necessary to save and transfer video over time. If the local network to which the webcam is connected is limited in bandwidth, then in order to avoid overloading the network traffic, it is necessary to completely reduce the amount of information that is transmitted by reducing either the frequency of frame transmission across the network or Great number of frames. Most compression formats such as webcams provide a reasonable compromise between these two methods of overcoming the problem of video transmission at a time.

Currently available formats and restrictions allow you to stream digitized streams with a small bandwidth of 64 KB - 2 MB (with such a smooth bandwidth, video streams can be processed in parallel with other data streams at intervals).

· central processor є computing core of the webcam. This operation involves the display of digitized and compressed video, and also corresponds to the associated functions of the built-in web server and other programs for web cameras.

· Interface for Ethernet Used to connect a webcam to the Ethernet standard 10/100 Mbit/s.

· For robots, a webcam can be used serial port to connect to a modem and work in dial-up mode over a local network. You can also connect to a peripheral webcam via the serial port.

· Flash memory card Allows you to update other webcam programs and save corrupt HTML pages.

· RAM Serve to save time data that is generated when installing certain programs and scripts. Many Internet cameras are called video buffers. The whole part of the OZP is reserved for recording and saving video frames captured by the web camera. The information in the video buffer is updated cyclically. a new frame is recorded instead of the oldest one. This function is necessary if the webcam is a security video alarm, and allows you to update the steps that transmit and attack the alarm signal from security sensors connected to the webcam.

· Alarm entries/exits serve to connect alarm sensors to the webcam. When one of the sensors is activated, an alarm signal is generated, as a result of which the webcam processor compiles a set of frames recorded in the video buffer before, after and at the time the alarm signal is received. This recruitment can be done using the specified e-mail address or FTP.

Malyunok 2. Vlashtuvannya webcam.

5. Additional capabilities and functions of the webcam

· Roc detector - This is a software module whose main task is to detect a web camera that moves into the field of view, on a video surveillance site. The roc detector not only detects movement in the image field, but also the dimensions of the object and the fluidity of its roc. It is important to set the video alarm, adjust the web camera rogue detector to detect object movements by limiting the minimization of processing steps (by filtering out the code), set the processing logic alarms (alarm recording, integration with other security equipment).

· Audio transmission In most cases, the connection to the webcam of the additional audio module is affected. For example, to expand the functionality of web cameras, AXIS Communications releases a special audio module AXIS 2191, compatible with most AXIS web cameras.

· Password protector serve to limit access to the webcam to persons who do not have access rights.

You can watch video from a webcam on any desktop computer with a standard web browser installed, such as Internet Explorer or Netscape Navigator. However, you can restrict a number of people from the rights to access the webcam by entering a password on the same page. Many webcams support extensive password protection for delineating access rights and administration.

A webcam is a device that is most often used simultaneously with a computer and does not give it any special significance. At the same time, pay attention to the characteristics of the product, otherwise disappointment and frustration may appear during the first session or the bonding session.

By watching our videos, you will be able to learn all about the capabilities, functions and applications of web cameras. We are confident that this information will help readers earn correct choice I'll add it when I buy it.

  1. What is a webcam, how does it work and where does it stand?

Webcam is not enough small appliance It is a photo or video camera that connects to a computer or laptop. Web cameras capture images in real time and then send them to the recipient via an additional Internet connection. Upgrading to a digital camera is primarily due to the cost of living and the inability to function without a computer, which is increasingly recognized.

Web cameras are used for video chats and video calls, video conferences, security purposes, for monitoring and security, etc.

  1. Main characteristics of web cameras

The characteristics of webcams affect both the size of the device and its price, which can vary greatly from model to model. What are the main parameters and what can you do when choosing a webcam?

  • Webcam matrix type. The webcam matrix can be created using one of the following technologies:

a) CCD- a technology that is used in digital cameras, and is also used for web cameras. Among these advantages: high sensitivity, high filling rate, efficiency – close to 95%, more low rhubarb crossing the hour of work. It is worth remembering that a very weak block of life with great virtuousness will come out of order at the moment of maximum attraction of the system or its surrounding elements. The life block with too high tension can reduce the CCD of any computer;

b) CMOS- Cheaper technology, which is used in most web cameras. Such matrices have low productivity, capture up to 500 frames per second, and can consume little energy during operation. Among these few experts see a large amount of noise in the image, a low pixel filling ratio and, consequently, low sensitivity;

c) BSI CMOS- with the use of such a matrix, it will be easier to produce light on the photodiode. Such sensors are also called “rear-illuminated sensors” - they are significantly more sensitive to odors. As a result, the amount of noise in the image is equal to that of normal CMOS.

    • Separate building of the cell- Another one of the most important characteristics. There's a lot of vitriol in there transmitted image. Please note that separate structures can be directly and interpolated. With software interpolation, the number of pixels in the output image is calculated using mathematical methods, multiplied by a small number, and then a larger image is formed. In this case, the coarseness of the image does not change, but the brightness may be lost. When choosing a camera, consider the real size of 1.3 megapixels – which is enough for HD quality.
    • Frame rate- A characteristic that indicates the smoothness of the lift. The most interesting feature is the shooting speed of 15 frames per second - which will be sufficient for shooting in Merezhi. For clear video broadcasts, you need at least 30 frames per second.
    • Focus The webcam allows you to improve image clarity. It can be either manual or automatic. The wrapping of the wheel and the shaved white of the lens are done by hand. Automatic focusing means that the webcam itself sets the focus to the object and adjusts the focus. U various models Autofocus speed and brightness may vary greatly.
    • Sensitivity- parameter of the minimum acceptable lightness at which the camera can be used. However, when purchasing a camera with infrared light, this characteristic will immediately be presented at the same level.
    • Connection type. All webcams are connected via a USB port version 1.1, 2.0 or 3.0. The remaining type works more quickly and is less common on modern computers.

  1. Additional functions of web cameras:

      • Detection of a defective microphone. Eliminating the need to add another device, it allows large companies to conduct video calls. Today, all cameras are equipped with a built-in microphone.
      • Possibility of using a webcam as a camera. Current models of webcams allow you to use these devices like digital cameras. Whenever you choose a camera for these purposes, be careful about using a device with a lot of space, otherwise the intensity of the photos will likely overwhelm you. The cameras are also equipped with a release button on the body – you can press the button to activate the photo mode and launch the graphic editor.
      • Availability of special software security. Kozhen virobnik webcams proponujam koristuvacham vlasne security program for installation or vikoristannya. In addition to standard functions, you can add personalized characteristics to the camera robot. For example, Logitech is introducing a new graphics editor.

  1. What should you do to increase your respect?

When choosing and purchasing a webcam, pay attention to its mounting, ability to bend and turn, and also to the angle of view.

Change the characteristics, compare the models of webcams, take care from our review and enjoy comfortable and enjoyable video recordings.

The article has information about how to choose the right webcam for your computer, about the main characteristics of the device to ensure respect, a little about the manufacturers and models, for example, a video on the topic.
A webcam is a small digital video camera that captures real-time images that are then transmitted over time.

You really need a webcam

  • Record a video and post it, for example, on YouTube.
  • Online broadcasts from various places on Earth, for example, the Moscow Zoo or in the area of ​​the volcanic eruption in Kamchatka.
  • With protection. The cameras in connection with this are equipped with rotary sensors.
  • For video conferences.
  • Distance learning.

Basic characteristics of the webcam

Matrix type

There are cameras on the market with CMOS matrices and CCD matrices.
The first ones are to give even the middle images, but they are inexpensive and homemade with a whole lot of extras.
The CCD matrix has much more accurate color transfer, there is significantly less noise in pictures, and the price of webcams with them is much higher.

Dozvil

640×480 and 800×600 are displayed in case of daily use, it is not possible to create a protective image. Conducting a video conference will also be difficult.
1280x720, called HD separation. Allows you to take photos with pleasant clarity and normal photos. In this case, there is no need to tighten the border.
View 1280x960 and larger. There are amazing pictures, but even with cameras, this camera still can’t compete.
Please respect, for normal work web cameras with a large number of separate buildings are necessary High speed internet connection.

How to choose the right webcam Matrix sensitivity

It contains the minimum possible lightening, for which removal is permissible. Follow Lux. If you take pictures with a low-sensitivity camera in a poorly lit area, there will be a lot of electronic “noise.”

Frames per second (fps)

To transmit a continuous image, frame 30 frames per second. Of course, the greatest value will be in the case of frames per second of 40 or more. It is especially important when handling objects that are collapsing. But again, it all comes down to the fluidity of the connection. If the speed is no more than 2 Mbit/s, buy a camera with an fps of more than 30 euros.

Connection type

Most often connect with please help usb rose, there is also a dartless method.
The USB method has two versions. USB 1 attachment only for charging low permission and with little speed. USB 2 will ensure the operation of almost all web cameras without re-code or trouble.
If you don't have a laptop original computer, respectfully supply the cable until it is completed. Won may be no less than 2 m, even system unit You can use it under the table or in a more distant place.
Bezdrotove z'ednannya– This transfers the signal via Wi-Fi to the device that is inserted into the same USB port. A droneless connection may be needed if the web camera is attached to an object that is collapsing, for example, in the face of some kind of trickster.

Subswitching

Placed before it is inferior. On the one hand, with a singing world, the brightness of the film is brightened, on the other hand, good webcams are simply not required.

Kriplennya

Like at the clothespin. On laptops and RK monitors.
Desktop. The webcam is mounted on a stand. Can be placed on a table or in another place.
Universal. Perhaps, shortest option I want to cost the little bits more dearly.

Platform

Mostly all webcams work with Windows. Those who have another OS installed, such as a Mac, should first go to the list of OS drivers on the manufacturer's website.

Use microphone

Most often, when purchasing a webcam with it, you will overpay.
If you have a laptop, then for everyday use you will need to use the built-in microphone.
If the vibrancy of the sound is of great importance to you, then it is better to adjust the microphone level.

bells and whistles

The roc detectors can be seen before them, automatically contrast and brightness, autofocus, automatic highlight correction, frequency change and much more. If you have a limited budget, consider first if you really need this additional function, then buy a camera with it.

Virobniki

For mid-range webcams at a reasonable price, we can recommend products from SVEN, A4Tech, Logitech, Defende.
Other good webcams include Philips, Genius, A4Tech, Oklick, Intel, Ritmix, Hercules, HP, Microsoft, Axis, Canyon, Prestigio, MSI StarCam, Chicony, Creative.
To better understand how to choose the right webcam, watch the video below.

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