The Basics of IP Video
What is an IP camera?
In basic terms, an IP camera is a camera, computer processor and web server in one device. This combination of technologies makes it possible to capture images, compress them, analyze their content and transmit them over an IP network. An IP camera has its own IP address and is connected directly to a network; it works completely independently. A ‘webcam’ is something totally different, as it must be connected to a PC (via a USB port) in order to be able to operate.
Viewing IP cameras
All IP network cameras can be viewed using a standard web browser. Various software packages are available for advanced viewing and control.
Fixed v. Pan, tilt and zoom
A main differentiator between cameras is whether they are ‘fixed’ or ‘pan-tilt-zoom’. Fixed cameras, also referred to as ‘static’ cameras, provide one single view. On the other hand, a camera with pan, tilt and zoom (often abbreviated to PTZ) provides many views from within its panning, tilting and zooming range. High end PTZ cameras offer 360 degrees of rotation and a 35x optical zoom or more, allowing operators to cover large areas with just one camera. Note that fixed cameras with a wide angle lens also provide large area coverage, albeit without as much detail.
In addition to the transmission of video images, a network camera can also be used for sending and receiving sound. Cameras with one-way audio allow users to listen to sounds near the camera. Using IP cameras with two-way audio allows users not to only listen in but also to verbally communicate with people at the camera end. Some cameras have a built-in microphone and/or speaker and some require an external microphone and/or speaker to be connected.
Alarm inputs and outputs
A network camera can also include features allowing other functions and functionalities to be transmitted over the network, e.g. digital alarm inputs and outputs and serial data. This allows network cameras to be fully integrated within a larger security system, including for example access control and fire alarms.
Indoor v. outdoor
To fit an IP camera outside, it will need a weatherproof enclosure with some form of internal temperature control, e.g. a heater and/or fan (thermostatically controlled). Some cameras are designed purely for indoor use. Installing indoor cameras in outdoor locations, even in an outdoor housing, is not recommended. The simplest reason is that indoor cameras perform well under constant light conditions but do not do so when light conditions are constantly changing, as happens outside.
Wireless IP cameras
IP cameras with 802.11 compatibility can be directly connected to a wireless network of the same standard. Cameras without the wireless capability built in can be connected to a wireless network using a wireless bridge. Note that no IP camera is truly wireless, as the camera will always need power to operate (battery powered IP cameras are currently [March 2008] not available).
Megapixel network cameras
Megapixel technology in IP cameras has been developing quickly and ever higher resolutions can be found within IP cameras. This means larger, crisper and clearer images but at the same time larger image file sizes.
Video motion detection
In basic terms, motion detection takes place by comparing an image with the previous image and on the basis of the changes within a number of subsequent images trigger an action such as to start recording, set off an alarm or send out email notifications. This motion detection function can be built in the network camera itself or can be controlled by additional management or recording software installed on a PC.
A video server, also called a video encoder, takes the analog input from a conventional analog camera and converts this signal in to an IP output. During this conversion process the video server compresses the images, it can analyze its content and make it transmittable over an IP network. Like an IP camera, a video server has its own IP address and is connected directly to a network. Video servers make it possible to move toward an IP video system without having to discard existing analog cameras. Video servers can have similar additional features like IP cameras, including pan-tilt-zoom control, one and two way audio and support for digital inputs and outputs, and serial data.
Recording from IP network cameras
You can record video images from network cameras by means of a Network Video Recorder (NVR) or using Recording Software. As part of the network, a NVR communicates directly to the cameras. The same is achieved by installing recording software on to a PC or server, which is often a more cost-effective solution and also offers more flexibility and scalability than a NVR. Recording software is available in one camera to unlimited camera licenses. Note that some network cameras come with free recording software included.
Please be aware that IP cameras do not work with Digital Video Recorders (DVR).
Power over Ethernet (PoE)
Power over Ethernet is the technology that allows you to run data and power over an Ethernet cable simultaneously. This means that you only need to install one cable to operate a camera, reducing the cost of installation drastically, particularly if you are installing the camera in a location where there is no conventional power at hand. The majority of fixed network cameras have built-in Power over Ethernet support. PoE is also available with pan-tilt-zoom cameras but this is less widespread as these type of cameras often require too much power for PoE to work (this may change when the new high power IEEE802.3AT standard for PoE is released). To transmit power via an Ethernet cable you will need a PoE injector (called a PoE midspan) or PoE capable network switch. If a camera has no PoE capability built in, you can use a PoE splitter. This device is connected to the camera and ‘splits’ the data from the power to deliver both in to the camera separately.
Here, we only covered the basics of network video. If you want to read more please refer to our Blog or our Forum. Both offer up-to-date information on developments within the field of networked video technology.