IP is an abbreviation for Internet Protocol, the most common protocol for communication over computer networks and the Internet. An IP-Surveillance device creates digitized video streams that are transferred via a wired or wireless IP network. This network enables monitoring and video recording as far away as the network reaches, as well as integration with access control and other systems.
Network cameras are a fast growing product category; a clear indicator that IP-based CCTV systems are poised to take over. Due to its scalability, among other advantages, IP-Surveillance is an attractive technology not only for enhancing or revitalizing existing surveillance and remote monitoring applications, but also for new installations.
Network cameras are connected directly to an IP-based network and integrate to applications on the network, enabling users to have cameras at remote locations and view, store and analyze live video at another location, or multiple locations, over the network/Internet. Vendors in the video surveillance equipment market are responding to this trend with IP-networked systems that can capture and transmit images in real time to personal computers, laptops, or even personal digital assistants (PDA).
A Determination Is Needed FOR EACH PROJECT
The video camera is evolving into an intelligent sensor. Smart it is, but first the dealer must evaluate a project to determine if New Video is appropriate. Answering these questions can help:
- What is the project budget?
- Based on risk assessment, what features are required?
- Do the products support full integration or basic operation?
- Is the New Video equipment you are specifying manufactured by an established vendor? What is the vendor’s support profile? (You just might need a lot of hand holding while you are gaining experience with the New Video technology.)
IP-networked surveillance systems are most suited for large-scale enterprise networks where a large number of cameras are needed. Oftentimes your customers may be reluctant to go completely digital because they have already invested in existing analog technology.
An option is to use digital video reorders (DVRs) that convert downloaded video data into digital format for transmission over an IP network. DVRs themselves are being supplanted by network based solutions; Network video recorders (NVR) comprise a management system that is essentially a software solution. NVRs use generic computer and IT hardware.
Power over Ethernet is an upcoming power solution for network video devices because it consolidates power and data and simplifies installation and deployment. The IEEE 802.3af standard defines the specifications to deliver power over standard Ethernet cables.
It is an approved standard by the Institute of Electrical and Electronic Engineers (IEEE). Power over Ethernet technology allows appliances such as network cameras to receive power as well as data over existing LAN cabling, without needing to modify the existing Ethernet infrastructure.
Vicon’s new revision to its ViconNet software. Rev 3.0 provides a number of improvements to the previous ViconNet platform version. ViconNet’s Rev 3.0 unveils the true power of a Digital Management System that was designed to support DVR and IP video solutions. The VN1000 is a software solution that loads onto common PC and server platforms running Windows XP and turns a computer into an NVR with complete video management capabilities. This solution is also made available in a pre-configured PC that includes extended storage options and RAID compatibility (model VN5000 series).
Rev 3.0 features include a flexible Geographic User Interface (MAP GUI) used to overlay camera icons for intuitive physical positioning for easier selection and control of fixed and PTZ cameras. Also, future upgrades will be possible over the network from remote sites.
Integration has become a standard requirement for video systems and ViconNet Rev 3.0 supports that need with integration to Hirsch and Lenel Card Access and ObjectVideo’s VEW Video Analytics System. For more information, visit www.vicon-cctv.com.
A Bridge from Analog to Digital Video
GE’s Security’s SymNet encoders/decoders allow connections of any existing analog cameras, domes, keyboards and monitors to an IP network. The encoder converts video from analog cameras into a MPEG-4 data stream of 2Mb/s. Decoders convert the MPEG-4 data stream back to composite NTSC output for viewing on traditional analog monitors. Two built-in serial ports on each unit let users communicate with PTZ cameras on the network using RS-232 or RS-485 protocol from a PC or keypad connected to an encoder. For more information, visit www.GESecurity.com.
Irrelevant and Immaterial
In North America and Japan, the NTSC standard (National Television System Committee) is the predominant analog video standard. In Europe the PAL standard (Phase Alternation by Line) is used. Both standards originate from the television industry.
NTSC has a resolution of 480 horizontal lines, and a frame rate of 30 fps. PAL has a higher resolution with 576 horizontal lines, but a lower frame rate of 25 fps. The total amount of information per second is the same in both standards.
When analog video is digitized, the maximum amount of pixels that can be created is based on the number of TV lines available to be digitized. In most analog security applications only a quarter of the analog picture is used, based on quads making 4 cameras share the maximum resolution. This quarter of the total image size has become known as CIF (Common Intermediate Format) in the video surveillance industry. In NTSC CIF means 352x240 pixels, and in PAL 352x288 pixels.
With the introduction of network cameras, CCTV has suddenly become 100% digital systems. This renders the limitations of NTSC and PAL irrelevant. Several new resolutions derived from the computer industry have been introduced, providing better flexibility. Moreover, they are worldwide standards.
Two different techniques are available to render the video: interlaced scanning and progressive scanning.
- Interlaced Scanning is a technique developed for CRT-based TV monitor displays. It is comprised of 576 visible horizontal lines across a standard TV screen. Interlacing divides these into odd and even lines and then alternately refreshes them at 30 frames per second.
- Progressive Scanning scans the entire picture line by line every sixteenth of a second. Computer monitors do not need interlace to show the picture on the screen. This technology eliminates flickering and improves image detail.
Camera Image Sensors
The image sensor transforms light into electrical signals. Two technologies used for camera image sensors are:
- CCD (Charged Coupled Device). CCD sensors were developed specifically for the camera industry and have been in use for over 20 years. Advantages of CCD include better light sensitivity than CMOS sensors, therefore better images in low light conditions. In extremely bright conditions, CCD images may smear or bleed.
- CMOS (Complementary Metal Oxide Semiconductor) sensors are based on standard technology already in use in computer memory chips. Most high quality cameras use CCD sensors but CMOS sensors are improving.
Recent advances in CMOS sensors bring them closer to their CCD counterparts in terms of image quality. However, CMOS sensors remain unsuitable for cameras where the highest possible image quality and smallest camera size are required.
Unlike traditional analog cameras, digital network cameras are equipped with the processing power not only to capture and present images, but also to digitally manage and compress them for network transport.
VGA is an abbreviation of Video Graphics Array, a graphics display system for PCs originally developed by IBM. The resolution is defined at 640x480 pixels, a very similar size to NTSC and PAL. The VGA resolution is normally better suited for network cameras since the video in most cases will be shown on computer screens, with resolutions in VGA or multiples of VGA. Quarter VGA (QVGA) with a resolution of 320x240 pixels is also a commonly used format, very similar in size to CIF.
QVGA is sometimes called SIF (Standard Interchange Format) resolution, which can be easily confused with CIF. Other VGA-based resolutions are XVGA (1024x768 pixels) and 1280x960 pixels, 4 times VGA, providing megapixel resolution.
Day and Night Network Camera
The AXIS 221 Day & Night Network Camera offers progressive scan, Power over Ethernet (PoE) and built-in video motion detection. The AXIS 221produces color video when there is sufficient light and black-and-white video under dark conditions with simultaneous Motion JPEG and true MPEG-4 full frame rate video streams, The AXIS 221 uses a high performance Pentax lens and a progressive scan CCD image sensor that enables moving images to be presented without distortion or blur. Its PoE functionality is built according to the IEEE 802.3af standard, For more information, visit www.axis.com.
Network Video Compression Standards
Without the use of image compression, most local area networks (LANs) are incapable of managing or transporting video data. Digital video is always compressed in order to speed up transmission and to save space on hard disks. Selection and use of the right compression is critical.
- MPEG compression breaks down as follows:
- MPEG-1: 352 x 240 pixels; 30 fps
- MPEG-2: 720 x 480 pixels/ 1280 x 720; 60 fps TV quality.
- MPEG-4: Wavelet based files designed to transmit video over less bandwidth and can combine video with text, graphics and animation.
MPEG-1 was released in 1993 and intended for storing digital video.
MPEG-2 was approved in 1994 as a standard and was designed for high quality digital video (DVD), digital high-definition TV (HDTV), interactive storage media (ISM), digital broadcast video (DBV), and cable TV (CATV). The MPEG-2 project focused on extending the MPEG-1 compression technique to cover larger pictures and higher quality at the expense of a lower compression ratio and higher bit-rate. The frame rate is locked at 25 (PAL)/30 (NTSC) fps, just as in MPEG-1.
MPEG-4 is a major development from MPEG-2. There are many more tools in MPEG-4 to lower the bit-rate needed to achieve a certain image quality for a certain application or image scene.
Furthermore, the frame rate is not locked at 25/30 fps. However, most of the tools used to lower the bit-rate are today only relevant for non real-time applications. This is because some of the new tools require so much processing power that the total time for encoding and decoding (i.e. the latency) makes them impractical for applications other than studio movie encoding, animated movie encoding, and the like. In fact, most of the tools in MPEG-4 that can be used in a real-time application are the same tools that are available in MPEG-1 and MPEG-2.
There are two different approaches to compression standards: still image compression and video compression. All still image compression standards are focused only on one single picture at a time. The most well known and widespread standard is JPEG.
JPEG is short for Joint Photographic Experts Group International. It is a good and very popular standard for still images that is supported by many modern programs. With JPEG, decompression and viewing can be done from standard Web browsers.
JPEG compression can be done at different user-defined compression levels, which determine how much an image is to be compressed. The compression level selected is directly related to the image quality requested.
Motion-JPEG (M-JPEG) compresses individual jpeg images at 16 up to 30 images per second full motion video, depending on available bandwidth. (Individual image quality varies with bandwidth, but frame rate does not.)
Motion JPEG offers video as a sequence of JPEG images. Motion JPEG is the most commonly used standard in network video systems. A network camera, like a digital still picture camera, captures individual images and compresses them into JPEG format.
The network camera can capture and compress, for example, 30 such individual images per second (30 fps – frames per second), and then make them available as a continuous flow of images over a network to a viewing station. At a frame rate of about 16 fps and above, the viewer perceives full motion video.
Megapixel technology permits more data and control features such as perspective correction, light level compensation, and fixed field pan-tilt-zoom. The higher the resolution, the more details can be seen in an image. This is a very important consideration in video surveillance applications, where a high resolution image can enable a criminal to be identified.
The maximum resolution in NTSC and PAL, after the video signal has been digitized in a DVR or a video server, is 400000 pixels (704x576 = 405504). 400000 equals 0.4 Megapixel. Using the CIF format, i.e. a quarter of the image, the resolution is down to a mere 0.1 Megapixel.
Megapixel network cameras also bring the benefit of different aspect ratios. In a standard TV, an aspect ratio of 4:3 is used, while movies and wide-screen TV use 16:9. In a network camera any aspect ratio can be used.
In addition, digital pan/tilt/zoom can be achieved, where the operator selects which part of the megapixel images should be shown. This does not imply any mechanical movement from the camera. It ensures much higher reliability and makes it possible for different operators to pan and tilt to different areas of the image simultaneously.
Keep in Mind
There are a few important items to remember. One is backlight compensation. Automatic exposure technology is designed to adjust the lightness of an image to appear as it does to the human eye and can be fooled by light sources such as headlights, sun and glare moving into the camera’s field of view.
Large images require more data than small images. Highly compressed images require less data than images using low compression. Scenes with a lot of detail generate more data than scenes with little detail. Ample resources are available to assist in educating you on New Video. The transformation from video is happening now. Choose your technology partners carefully and don’t be left behind.