IP cameras use the Internet protocol (IP) to transmit audio and video data, along with control signals, over Ethernet links in closed-circuit television (CCTV) systems. They offer numerous advantages over traditional analog security cameras, which typically transmit an analog NTSC/PAL signal over coaxial cable. Unlike analog cameras, IP cameras support high-definition (HD) images, intelligent analytics, local video storage, and remote control.
Video compression is performed in the IP camera together with analytic functions, video encryption (to stop hackers), and encapsulation of video data into Ethernet packets. The compressed video stream is usually sent to a hybrid digital video recorder (DVR) or network video recorder (NVR) for storage, playback, and display. The use of an IP network for video monitoring can enable security staff to be located at geographically remote locations, allowing centralized control over security cameras across campuses or multiple sites using pan-tilt-zoom (PTZ) commands sent over the IP network.
Low-power camera designs can be powered over Ethernet (PoE) without additional power sources. By using the same cable to transmit both data and power, PoE installations can substantially reduce cabling costs. In some cases, wireless networks such as Wi-Fi® can be used to replace Ethernet, thus easing camera placement. This is especially true of home security cameras where Ethernet wiring may not be readily available, and where "cloud computing" DVR applications replace physical DVRs.
Multistream H.264 and Motion-JPEG Compression
The H.264 video compression standard provides approximately twice the compression of the previous MPEG-4 standard for the same video quality. Within the H.264 standard, the "high" profile defines the highest video quality with the lowest bit rate, making it especially relevant for applications such as video security. Achieving very-low-latency (delay) encoding minimizes the response time from security personnel. Meanwhile, high-definition video encoding enables the IP camera to capture details such as facial features and license plates for enhanced security imaging. Since network bandwidth may be limited, systems can require the ability to encode/record one HD stream over a local area network (LAN) while simultaneously streaming a lower resolution feed for remote viewing over a wide area network (WAN).
Mobicam3 720p H.264/M-JPEG IP camera reference design
In addition to H.264, many security systems require backward compatibility with existing equipment that does not support H.264. The Motion-JPEG (M-JPEG) standard can provide backward compatibility in such systems, as well as the ability to take high-resolution lossless snapshots. Specifically, it supports simultaneous encoding of H.264 video for uninterrupted video recording while capturing JPEG still images, which may be driven by specific events.
Video analytics is the process of analyzing video data and making decisions based upon it. Supporting analytics in software within the camera enables actions to be taken immediately based on specific events and without the need for inputs from security personnel. For example, an alarm may be sounded if the camera detects that a person has crossed into a secure area. Analytic functions include motion detection, trip wire, and image tracking. All of these functions need to be configurable from the PC-based security management software using an intuitive graphical user interface (GUI).
IP camera block diagram. For a list of Maxim's recommended solutions, please visit: www.maximintegrated.com/IPcamera.
Embedded Linux® Software and Networking
IP cameras need to provide the capability for streaming video to multiple clients. For example, Maxim's IP camera reference design (Mobicam3) supports up to 16 clients and both the real-time transport protocol (RTP) and the real-time streaming protocol (RTSP). The following Ethernet protocols are also supported: HTTP, DHCP, SMTP, TCP/IP, UDP, TFTP, FTP, NTP, and UPnP™. Streams can be encrypted using AES or SHA encryption to prevent hacking or tampering.