Surveillance System Considerations
There are a number of factors to consider when setting up an IP-based surveillance system. Network cameras transmit data over your existing IP network, so optimizing bandwidth is important. You'll also need to think about storage: How long will footage be archived? What type of image quality do you require? Will recording be continuous or triggered by motion? Other key considerations include network security and system scalability. Putting thought into these areas before you set up your system will help to ensure that you have the right equipment and the proper game plan to fulfill your surveillance requirements.
Video Storage & Archival
While analog CCTV systems rely on bulky cassette tapes for storage, IP-based surveillance systems are able to store video footage straight to hard disk. This process offers several key benefits, including vastly improved storage capacity, and greatly enhanced searching capabilities. Because the video images are stored digitally, users can quickly sort through archived footage by time and date, and can even add reference tags.
There are a number of factors to consider when calculating the amount of hard disk space required for your specific storage needs.
- How many surveillance cameras are you operating?
- Will the cameras be recording continuously or only at certain hours of the day?
- Will your IP cameras be set to record only when motion is detected?
- How long will the video footage be stored on the hard disk?
- What level of image quality is required (this will determine parameters such as frame rate and compression)?
As with any video surveillance system, privacy and security are important factors to consider when setting up an IP-based video solution. Users want to be assured that no one can tap into their video feeds. Those concerns are understandable, but with IP network cameras, it’s quite easy to protect your files from unauthorized viewing and tampering. In most cases, the network camera encrypts the surveillance video before sending it over the network. This helps to ensure that only authorized viewers can access the camera feeds. Most systems also include password protection and different levels of authentication that work to prevent hacking and outside access.
In the case of wireless IP cameras, WPA (WiFi Protected Access) is considered the base level of wireless network protection. With WPA, video is encrypted and the key for each transmitted frame is changed using TKIP (Temporal Key Integrity Protocol). Other advanced security standards found with wireless network cameras include WPA2, AES, and 802.1x authentication.
Another tool for protecting network video feeds is digital watermarking. IP cameras are capable of adding encrypted watermarks into the video stream. The watermarks can include information such as time, location, and user activity, while time stamping can create a trail that shows who has accessed specific video images, and whether any edits have been made to the files.
The amount of bandwidth used by network cameras is determined by several factors, most notably: image resolution, frame rate, and compression ratio.
An IP camera's resolution is determined by pixels. The higher the resolution, the higher the pixel-count, and the greater amount of detail you'll be able to capture in a video image. It's important to determine how much detail is enough to meet the requirements of your particular surveillance application. Typically, as the image quality goes up, so does the amount of bandwidth required, so it's best to find a level that meets your needs while optimizing network bandwidth.
Video compression is an important tool in helping to ease strain on the network. Compression technologies such as Motion JPEG, MPEG-4, and H.264 allow users to stream and record high-quality video without hoarding bandwidth. H.264 is the latest compression technique, dramatically reducing video file sizes while increasing overall efficiency and lowering storage costs.
Frame rate is something that can be adjusted within your IP camera, video server, or video management software. By controlling the frame rate, you can greatly reduce bandwidth usage and can eliminate unnecessary frames from traveling over the network. One common technique is to set the surveillance system to increase the frame rate only when motion is detected. Another is to send higher frame rates for local viewing, and lower frame rates over the Internet for remote viewing.
One of the great advantages of IP surveillance is system scalability. With analog surveillance systems, adding new cameras often involves complicated and expensive cabling. But with an IP-based system, it's as simple as connecting the additional cameras to your existing IP network, the same way you would any other network device. Power over Ethernet (PoE) and wireless network cameras enhance flexibility even further by allowing you to install cameras in locations without a readily available power outlet.
Since a PC server records and manages the video footage in an IP surveillance system, there's no limit to the size and scope of the installation. Different types of servers can be chosen depending on how many cameras are needed and what frame rate is required.