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Analog Versus IP Cameras

IP video surveillance can be defined as the transmission of video utilizing open internet protocols and standards for the purpose of recording and monitoring. This should not be confused with more proprietary methodologies of transmitting video in which only the manufacturer of the camera can decode the video for the purpose of recording and/or display.

As with still digital cameras, resolution are increasing all the time. multi-megapixel IP-CCTV cameras are now available at resolutions of 1, 2, 3, 5 and even 11 megapixels. This said, affordable lenses that can deliver sharp enough images for cameras of 5Mpix and above are not yet available

Some of the advantages of IP-based video surveillance include:

  • Reduced system cost and added functionality due to general-purpose IP networking equipment infrastructure.
  • Choice of open-platform video recording hardware and software.
  • Greatly reduced system cost due to low-cost cabling in large installations (CAT5e instead of RG-59 coaxial cable).
  • Ability to use Power over Ethernet allowing for one cable to handle power and data.
  • Flexible and seamless support for a variety of standard and multi-megapixel image resolutions way beyond NTSC, PAL and SECAM.
  • Transmission of commands for PTZ (pan, tilt, zoom) cameras via the same cable.
  • On-camera automated alerting via email or file transfer in response to video motion detection or dry-contact alarms.
  • Support for different streaming media and compression formats to relieve transmission bandwidth and data storage requirements.
  • Support for new embedded intelligent video motion detection with shape recognition/counting applied to objects, people, and vehicles.
  • Integration of video surveillance with other systems and functions such as access control, alarm systems, building management, traffic management, etc.
  • Future-proof installations with field-upgradeable products due to the ability to upgrade camera firmware over the network.

Today there are many vendors of IP cameras and many vendors for digital video recorders and network video recorder (NVR) software. IP surveillance equipment vendors typically include both specialized digital imaging equipment manufacturers and larger manufacturers that are active in consumer, broadcast, and security video.

 

 Some specific advantages and disadvantages of IP cameras

Advantages

  • Higher resolution. Megapixel cameras can far exceed image detail from conventional CCTV cameras.
  • Convergence onto existing IP cabling infrastructure
  • Easy to route long distances over existing IP infrastructure on multibuilding sites
  • Reduced space requirements in large (many camera) CCTV setups as video switching and routing is done via computer and does not need physically large and expensive video matrix switchers.
  • Progressive scan (versus interlaced scanning). Allows still images to be removed in better quality from a video feed and can render clearer images from a fast moving target (interlaced scanning will have shutter blind artifacting). Not all IP cameras are progressive scan. Those that are currently progressive scan seem to use CMOS image sensors (as opposed to CCD sensors) and have some disadvantages.
  • No additional hardware required to convert vision signal into computer domain for recording onto hard drives.

Disadvantages

  • Current generation CMOS sensors (for high resolution/megapixel and progressive scan) do not have the light sensitivity of the more mature interlaced CCD image sensors. Low light performance is currently not a real option for IP camera’s unless they are built on conventional PAL/NTSC resolution interlaced CCD image sensors. As such, low light performance does not currently seem available with quality progressive scanning or megapixel technology.
  • Image sensors generally seem to be of a far cheaper grade than the quality of the current line of conventional analog CCTV sensors.
  • The range of IP cameras is still significantly limited when compared to analog CCTV (although this is beginning to change quickly).
  • Consistent framerates do not seem to be a strong point of IP cameras when compared to the almost real-life smooth and consistent frame rate of analog CCTV. Many IP cameras seem to be underpowered as well. When it gets dark, their image processors spend more time trying to compensate for low light images and can not output the same higher frame rate from normal lighting conditions (e.g. Axis 206 appears to deliver 20-30fps in normal light, but drops to less than 5fps in dark conditions). On playback (unless the frame has been timestamped in a way that the playback engine can use) a consistent playback framerate causes strange time warping problems manifesting as speed-ups and slow-downs.
  • Lack of standards for IP Video protocol. Not all IP cameras send video the same way and this means only certain cameras work with certain IP video recording solutions (which again further limits the range of cameras that can be chosen for an installation). Analog CCTV has practically one standard of transmission (being either PAL or NTSC depending on the world region).

Source Wikipedia