Like a lot of things involving technology, the world of CCTV is a little confusing if you do not educate yourself on how this stuff works. This can be a major problem when you are ready to have a surveillance system installed because you won’t know what to buy, what’s best for you or who to trust. This only causes headaches, stress and will cost you lots of money in the end. One of the single most, if not the most important aspect of CCTV you need to know about is RESOLUTION. Resolution can be summed up as the recording quality from the cameras and DVR or how clear the video will be. You need to know this before you have a system installed. CCTV resolution is measured in horizontal and vertical pixels and is only limited by the quality of both the cameras and the DVR that you are using. Below are a list of CCTV resolutions and definitions.
CIF (pronounced “sif”) recording is an old, outdated recording resolution (352 x 240) and is really only used today for the “extra stream” video for DVR remote viewing (when you view your system over the Internet, iPad or Smartphone this is what you get). Some DVRs still offer one or even several channels of CIF recording because the DVRs are not hi-quality or because, I guess, to use for “less important” channels/cameras. This way, the “more important” (higher res) channels can be used and this saves on hard disc space. Older systems use CIF recording because they had to, but with today’s technology, stay away from this if possible. 420-480 TVL cameras.
D1 (720 x 480) DVRs have this resolution and only the best recorders can record D1 at 30 fps (frames per second). Many DVRs are advertised that they support “D1 real time recording” or “full D1” (30 fps), but if you read the DVRs small print, they are only recording at a much reduced frame rate, or at an outdated VHS quality CIF resolution (360 x 240) on many of the channels. D1 camera resolution maxes out at around 600 TV lines. D1 has about 400% the resolution than CIF.
Also known as WD1, 960H is the name given to a series of CCD image sensors developed by Sony in 2009. These CCD image sensors are capable of capturing video images at a resolution of 960 x 480. The 960H CCD sensor is often used with Sony's new DSP (Digital Signal Processor) known as Effio, which further enhances the quality of the video image. Traditionally, the maximum resolution from an analog CCTV camera was around 600 TV lines. With the use of Sony's new 960H CCD and features from the Effio DSP, resolutions of 700 TVL can be achieved with 960H DVRs (beware of DVRs that have 960 in the model name because this often refers to the total frames the DVR can support, not the resolution).
1280 x 720 (720p) and 1920 x 1080 (1080p) hi-def systems. This is very exciting news: Dahua Technology has developed HD-CVI (high definition composite video interface) technology that gives users affordable hi-def video systems. HD-CVI can use standard coax cable that can transmit audio, hi-def video and data signals together. Higher end coax will allow runs over 1500 ft. without interference or degradation. This is the best of IP and HD-SDI without the cost and tech issues found in both formats. 1.3MP (720p) and 2.2MP (1080p) HD-CVI cameras are used.
IP hi-def 1280 x 720 (720p) and 1920 x 1080 (1080p) are probably the most common formats. An IP (Internet protocol) camera sends and receives data via a computer network and the Internet (the term "IP camera" usually only applies to surveillance cameras). Centralized IP cameras require an NVR (network video recorder) to handle the recording. Decentralized cameras have recording functions built-in and can record directly to a flash drive or hard drive. IP cameras vary in pixel resolutions (measured in millions or MP) from 1 MP (1200 x 900), 2MP (1224x1632), 3MP (1536x2048), 4MP (1704x2272) and up to 29MP. With a “true to spec” high MP camera, higher resolutions and much larger video images will be recorded. With this, a user can zoom in on the digital images to pull up a person’s face or license plate from across the street.
1920 x 1080. HD-SDI is the name given to hi-def CCTV systems. HD-SDI CCTV cameras are capable of hi-def 1080p resolution. The technology behind HD-SDI cameras is the same as the cameras used for hi-def movies. Until a few years ago, the only available option for hi-def systems was to use network IP cameras. With HD-SDI, users can now capture 1080p resolution surveillance video. One of the most impressive features is the DVR digital zoom. Like IP and HD-CVI, you can zoom in on recorded video (faces, license plates) to make positive IDs without loss of quality. In most cases, the same RG59 coaxial cable already in place can be used to upgrade to HD-SDI as top shelf (i.e. not junk) systems can be expensive. In other words, you save money on the installation. 2.2 MP HD-SDI cameras are used.
To sum things up, below is a diagram that illustrates the differences between CIF, D1, 960H, 720p and 1080p pixel dimensions and image sizes. This translates to not only an increase in pixels and size but in image detail, resolution and clarity.
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