IP camera

Network cameras ( IP cameras ) are CCTV cameras that provide the output digital signals in the form of a video stream, which is further processed by IP networks. Like the analog CCTV cameras being installed permanently in one place and have as main application monitoring tasks.

Network cameras include not only the actual camera component also a computer. Its task is to digitize and compress the image data as well as providing and sending the data over the network. The machine consists essentially of a CPU, a flash memory and a DRAM memory. Through the network camera software, it is possible that the device occurs in the network as a web server, FTP server and an FTP client and an e- mail client.

Differentiation from Webcams

Webcams can be seen as the forerunner of the modern network cameras. A classic webcam needs to connect to a computer. Only from this computer, the data can be brought into the net. A network camera can contrast independently to share their data to other stations in the network. A webcam can not be addressed by other stations here, but only from that PC to which it is connected. A network camera, however, can get all sorts of instructions from a distance and be powered from a distance if necessary with new software. Webcams are simple devices that are used primarily for communication among Internet users. Network cameras provide contrast with the functions a greater variety. For example, they are often equipped with motion sensors and night lenses.

Advantages over analog video cameras

Network cameras offer advantages over analog video cameras distinct advantages, so they have now (10/ 2012) well established:

  • The data are already available in digital form, so they managed to not application- neutral IP network structures, can be sent and archived. Thus, to workstations, which live images and recordings are edited and managed by many cameras are located at remote locations. While analog cameras are usually connected to a fixed wiring with the associated central technology as well as monitors, a network camera requires a connection to an IP network, so that their data can be viewed by all authorized network users. The archiving to network recorders works over an IP network. A part of the IP network may be the Internet.
  • While an analog video camera requires a local power supply, a network camera can receive power via Power over Ethernet. However, the network must be suitable for this purpose and equipped.
  • The images can provide straightforward for many people.

But even analog cameras offered earlier ( 10/2005) advantages. These devices were mature and cost-effective. The main advantage, however, was that these cameras at any time provided an unqualified live image in PAL quality. If a network camera should provide images of comparable quality, they had to generate 25 frames per second and transmitted over the network in 4CIF resolution ( DVD quality). In that time the widespread MPEG- 2 method be up to 8 Mbit / second came together. Component video monitoring system of multiple cameras, had, due to the bandwidth of the network, have restrictions on resolution, compression and frame rate are taken into account. So sometimes arisen either blurred, coarse images or jerky movements. Since then established the H.264 procedures and ever more powerful networks are emerging, the data from cameras with conventional resolutions (about 0.4 megapixels) can now be (10/ 2012) usually processed without problems. However, data rates for megapixel cameras are still a limiting factor.

Design and operation

Network cameras work just like analog cameras with analog CCD or CMOS sensors. Also the pictures on the DSP ( digital signal processor ) are as with analogue cameras afterwards ( Highlight Compensation, lighting, etc.) With the aforementioned Computer, the images but then digitized and compressed. Network cameras, some have digital inputs and output contacts. The inputs can be connected to alarm imaging sensors. An alarm, the camera may respond in different ways. Thus, a transfer of images, e-mail or SMS messages are triggered. Using the outputs, circuits, such as: lighting or danger warning system be made. Network cameras often have image storage ring with memory function, with the help of targeted pre-alarm can be sent.

If a network camera, for example, Stores images on a 20- GB hard drive on the network, can be in good compression, depending on the frame rate and resolution, for example, save the continuously captured images of an entire month. However, it is not absolutely necessary, that will be recorded permanently. You can also record the time-controlled or event-controlled drive ( external sensors, motion detection of the camera).

Network cameras are often equipped with bi-directional audio capabilities. The camera then combines microphone and speaker. The microphone can be used for room monitoring, which is why this feature in Germany is hardly legally feasible. The speaker can be used to address a person in the camera, use cases, there are but few.

Resolution

Analog cameras were linked by their relationship to television in PAL or NTSC format (or the resulting 4CIF format). IP cameras have, however, when it comes to resolution no restrictions. Were initially often 4CIF similar VGA resolutions offered, there are now a plethora of formats and resolutions up to several megapixels. However, the process to encode megapixel resolutions in smooth image playback in near-real time is very computationally intensive. Also, it is in the nature of things that such a large data streams are generated. Furthermore megapixel sensors are less sensitive to light than conventional sensors because the size of each pixel is smaller and thus less incident light per pixel. On the other hand, does not require any monitoring task many megapixels: It is important to select the right solution for the intended use.

Areas of application

Terms of function, it is in network cameras primarily to security cameras. In addition to use for surveillance applications, the use for commercial purposes is widespread. In the area of tourism network cameras are used, therefore, for example, automatically switched from the Tourist Office of the Shetland Islands in the audience for live over the Internet turns on the different cameras on the islands. Another application is the construction site documentation.

Connection

In principle, the camera will be integrated into an Ethernet structure. Usually copper or can be used ( via media conversion) fiber-optic structures, the terminal may also wirelessly via Wi-Fi. For any necessary internet connectivity in practice DSL or even ISDN used, but also cellular standards, such as UMTS, are conceivable.

Security

As with any network component also arises for network cameras is a risk that there will be access by unauthorized persons. Most modern cameras have a password protection and other protection mechanisms that make a takeover by Cracker difficult or impossible. In addition, the image data can be transmitted via SSL encryption.

However, some commercially available IP cameras have vulnerabilities that allow unauthorized persons to access the pictures or the video stream or the camera even control.

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