Inside IP Security Cameras
Why is everyone touting IP security cameras? Can’t analog cameras with an analog digital video recorder (DVR) deliver the same results? Answering these questions requires us to go in depth and talk about the benefits of having IP (internet protocol) cameras over analog, the technology behind IP and why it even came in to existence.
Regardless of the shape, style, or size of a camera, the guts are all the same inside, but with slightly different components used. The variations of the inner workings of the camera are what we’ll be discussing today.
An analog security camera consists of 4 main components; a lens with its holder, an image sensor and a DSP (digital signal processor).
Image Sensor
The most common types of image sensors are CMOS and CCD (we go into more technical detail about them here: CMOS vs CCD Image Sensors). Here are some of the more general, key points to consider. CCD has uniform output, thus better image quality. With a CMOS sensor, on the other hand, uniformity is much lower, resulting inless image quality.
IP camera technology uses CCD or CMOS sensors. CMOS sensors tend to be a little bit cheaper than CCD, which is why most IP cameras in the market are currently CMOS. IP camera manufacturers are using the same CMOS image sensors used by mobile phone manufacturers. Due to the high usage of CMOS image sensor in the mobile phone industry, the cost of CMOS became pretty cheap.
DSP
The DSP (digital signal processor) is the brain of the camera. It takes in raw analog image data from the image sensor and converts it to a digital signal. DSPs allow advanced features for the camera, like digital noise reduction, and wide dynamic range. The image is converted back to analog for it to be transmitted over coaxial cable. The disadvantage of that process is that image quality is heavily deteriorated. Every time data is encoded or decoded the data bits are lost, causing less image clarity. The DSP is not necessary to obtain video output from a camera; it is just used to enhance video image quality at night, in color and other common industry requirements.
The more components there are inside a camera the more expensive the camera becomes. There are lots of analog cameras in the marketplace at cheap prices. Those cameras are most likely using CMOS image sensors, without any DSPs, and sell based on resolution, which most likely is inaccurate anyways.
The technology behind IP security cameras is very unlike webcams. Computer webcams are only the image sensors which merely capture a raw video file and transmit the data through USB cables. A software application running on the computer (not the camera) utilizes the computer processor to encode the analog input to digital. IP cameras, on the other hand have their own CPU (central processing unit), and components necessary to do the encoding, decoding, apply algorithms etc. Below is an illustrative diagram of an IP camera. Also highlighted with a dashed red line is the analog part of the camera and all the rest are additional components that make it an IP camera.
Contrary to a webcam, an IP security camera has its own web server. Meaning it has the capacity to stream video independently from a computer. That’s why similar to a computer, memory components and a CPU exist within a camera to handle video compression, web server firmware, de-interlace preprocessing, noise filtering and so on.
IP Camera Recording
IP cameras are not connected directly to a digital video recorder for surveillance recording; rather they are connected on a local area network or a wide area network through a router. A computer or a standalone NVR on the same network would then pick up the video streaming through the network and use that digital stream to record it digitally on the hard drive.
The video audio codec as seen in the diagram above takes a video data file and digitally compresses it using a specific type of compression algorithm. Some IP cameras have multiple streaming capabilities, where the video codec will compress each data file input to multiple video files such as H.264, MPEG4, or MJPEG at the same time.
In analog cameras, the DSP encodes the analog signal to digital signal without compressing the video file.
Digital video is streamed through the network, processed at the computer, and stored digitally. Basically, video remains digital and no unnecessary conversions are made resulting in superior image quality.
IP cameras are intelligent devices that include many beneficial features. They compress video images to minimize video streaming over the network. IP cameras use frame rate control technology which sends images at a specified frame rate, therefore, only necessary frames are sent, whereas analog cameras stream the video data through the coax. The downside of using IP cameras is that the network bandwidth may limit the number of cameras that can be on the network without overloading it.
IP security cameras exist simply because the technological world of analog has died. Similarly to movie technology, all movies were once rented and sold on analog VHS tapes, but now you will only find DVDs or Blu-Rays, which are a digital format of the video. Even though analog cameras are still better sellers in the security surveillance industry, IP cameras are coming strong and will eventually take over completely. Prices of IP security cameras in comparison to analog have kept analog cameras ahead thus far. That trend has started to shift, as IP high definition camera prices have dropped drastically within the past 2 years.
IP security cameras are superior to analog cameras; they provide better video quality, can utilize existing LAN area network, and have far greater capabilities than analog cameras.