Video surveillance enters into HDTV era, and now we are embracing many new technologies including 4K/UHD, H.265, IoT, SaaS etc. Many factors affect the performance of your network cameras. As IP in video surveillance has reached maturity, knowing this can help you choose the appropriate network cameras when you have so many choices.
Light first passes through the lens then enters to a image sensor, the quality of lens will affect the overall video quality. When choosing a camera making sure to check its lens specification. Focal length and Aperture (F number) these two key factors determine lens performance. Focal length = field of view (FoV), Aperture (F number) = image depth and light sensitivity. It's important to know what the focal length is required for the monitoring area, then selecting the camera comes with right lens accordingly. The smaller the value of F number, the higher the light sensitivity. e.g F1.2 is better than F1.4. In order to obtain the optimum performance, it's recommended to select a network camera supports the detachable lens, this means you can have a great flexibility to choose different lenses. Selecting a network camera comes with a vari-focal lens allows you to adjust focal length to get ideal viewing angle for various video surveillance applications.
Image sensor is the key factor affects image quality. In the past, we have CMOS and CCD two types of image sensor, in terms of imaging performance, CCD image sensor can provide high clarity and true color reproduction images with good exposure. While conventional CMOS image sensor has poor image clarity and poor color reproduction capability, exposure is also not good. CMOS image sensor can provide much higher resolution than CCD image sensor, while the cost of CMOS image sensor is much lower than CCD. Now progressive scan CMOS image sensors are widely used in both analog and digital HDTV video surveillance cameras. Image quality can be enhanced by hardware & software image processing technology such as HDR. High dynamic range imaging can reproduce a greater dynamic range of luminosity than is possible with image sensor or standard digital imaging. However, please note a CCD image sensor has good light sensitivity than CMOS image sensor.
There are few CMOS image sensor manufacturers, your network camera may adopt a CMOS image sensor from Sony, OmniVision, Aptina etc. Among them, Sony's Exmor-R CMOS image sensor is the best image sensor, if considering image quality and light sensitivity.
Video compression also effects video quality, video streaming latency time and required video storage capacity. Most of network cameras support H.264 video compression technology, H.264 supports good video compression ratio and maintain high image quality, greatly reduced the bandwidth and video storage capacity, so that it becomes a video standard nearly two decades. In the end of 2014, both Hisilicon and Ambarella unveiled HDTV multimedia SoC based on H.265 compression technology. Now, you can find some network cameras support both H.264 and H.265 video compression two formats.
When using the H.265 video compression, the network camera can deliver HD video stream with low bitrate/bandwidth. Compared with regular H.264, H.265 network cameras can save 50% network bandwidth, file size is much smaller than H.264, saving up to 50% video storage capacity. Some experts expect that H.265 will become the next video standard, this trend is inevitable. H.265 still is in its early adoption stage, you may not find a complete H.265 product portfolio for your current video surveillance solution. A network camera that supports both H.264 and H.265 video compression can allow you use the existing H.264 equipment, meanwhile be compatible with future H.265 back-end products (NVR, VMS, NAS, Decoder...etc).
Video format determines the real resolution of video, can be HD (720P), Full HD (1080P), 4K/UHD (8MP). 4K/UHD is the highest resolution among these three video formats. When searching products, you will find network cameras are based on different resolution including 1.3MP, 2MP, 3MP, 4MP, 5MP, 6MP etc. Should you choose the network cameras according to megapixel resolution factor? The answer is No.
If you want to choose a network camera between 2MP and 3MP, it's highly recommended to choose the 2MP camera, because all of them comply Full HD 1080p format, and the cost of 2MP network camera is lower than 3MP network camera. In real video surveillance application, all the equipment should comply the video format to solve the compatibility issue. When you use 3 megapixel network camera, you have to use Full HD 1080p format to transmit the video, because the back-end equipment including NVR, NAS possibly can not support 3MP resolution, especially you can not find a monitor/display that perfectly fits your network camera's resolution.
Frame rate, also known as frame frequency and frames per second (FPS), is the frequency (rate) at which an imaging device produces unique consecutive images called frames. 25fps is the frame rate for real-time video in PAL TV system, while 30fps is the frame rate in NTSC TV system. For example a 5MP network camera supports 25fps is better than a 5MP network camera only delivers 15fps. The hardware processing capability determines the camera's frame rate.
In regular video surveillance application, users can choose network cameras support standard real-time frame rate (25/30fps). However, a high frame rate (e.g. 60fps, 120fps) network camera is suitable for some specific video surveillance applications which require capturing high-speed motion objects.
Most of network cameras are designed to support dual stream technology. Dual stream supports one HDTV stream (main-stream) local video recording to maintain image quality, another network video steam (sub-stream) to provide smooth video streaming on network for remote monitoring. Apparently, dual stream technology helps user to get the max. video resolution in video recording and local preview, meanwhile offering smooth remote video surveillance to reduce network bandwidth burden.
Some advanced network cameras support triple stream, Triple stream + ROI, making your video encoding and streaming become smart. Users can select the interested area/region to encode, so this can greatly reduce the bitrate. To know more about ROI, you can read this article: http://www.unifore.net/ip-video-surveillance/briefly-introducing-roi-region-of-interest-video-surveillance.html
Depending on your requirement, you may want to select a network camera that supports HLC, BLC, ATW, WDR, DWDR, 2DNR, 3DNR, Mirror, Flip etc image enhancing function. Among them, WDR is the important feature which helps camera to provide wide dynamic range video in tough/difficult lighting conditions.
Additionally, you may want to have a WiFi support for your network camera, so that you can setup a wireless video surveillance system, or Power-over-Ethernet (PoE) to help you setup centralized power distribution system for easy maintenance, meanwhile reducing installation cost.
Video motion detection is the basic smart video analytics, high false detection rate, many users don't use it. Are smart video analytics valueless to common users? It depends on what the type of video analytics you want to use. How will you implement it in your real video surveillance application. When choosing a network camera, it's better to choose the one that supports detection sensitivity adjustment, so you can reduce the false alarm rate.
In terms of whether they are designed for indoor use only or indoor and outdoor use, network cameras can be easily classified. However, based on different types of camera housing, network cameras can be also categorized into bullet type, vandal-proof dome type, PTZ type, Panoramic type and covert type.
Bullet type: Bullet network cameras usually are mounted to the side of the wall and it’s point to surveillance areas look like the barrel of a gun or a bullet. With weatherproof design. they are installed outdoor applications, they are with large size and can provide the best way to deter theft. Majority of bullet cameras come with mounting bracket, The mounting bracket can make bullet camera with flexibility to swivel horizontally and vertically for getting best field of view. Camera can be large size, and equipped with big lens for long range view distance, also can be added with Infrared illuminators for long range night vision.
Dome type: Dome network cameras are installed indoor and hang on ceiling. Dome cameras are installed indoor applications, equipped with small focal length lens to provide short view distance but wide viewing angle. Most of network dome cameras support vandalism protection, vandal-proof is very important feature when mounting the camera for an application involves lots of people in reach of the camera. Vandal-proof dome camera are suitable for car, bus, retail store, banks, bars and homes.
PTZ type: Pan, Tilt, Zoom, the PTZ network camera is suitable for professional video surveillance application, it can have your entire parking lot or lobby covered. In addition to mechanical pan & tilt rotation, a PTZ network camera is equipped with zoom lens that offers powerful optical zoom capability. Some smart PTZ network cameras even support auto-tracking and face recognition function, user can track suspicious people, automatically zoom in to see details.
Panoramic type: Equipped with the fisheye lens, the panoramic network camera can offer some unique benefits that conventional security cameras can't compare. The panoramic network camera can offer ultra wide viewing angle including 180° and 360°. Most of panoramic network cameras support ePTZ function, electrical pan/tilt/zoom technology,allowing user to zoom in or rotate the image, when rotating viewing angle from left to right, no mechanical noise, hidden and difficult to realize. With no mechanical moving parts, the camera allows you to rotate camera smoothly, provides you much stable performance.
Covert type: Covert/hidden network cameras are designed to blend into the environment and be virtually impossible to discover. They can be placed at eye-level at entrances or integrated into things such as ATM machines for discreet or covert surveillance. They can enable close-up shots for identification purposes or overview surveillance. Tampering risks are also reduced.
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