FireWire, the IEEE 1394 interface, has become the optimal choice for a wide range of industrial automation and vision systems applications. Now, companies making security systems that rely on multiple cameras are facing a major technology transition - the swap to an all-digital system. That transition will necessitate a digital network that links all of the cameras in an installation.
For many video-centric security applications, a 1394-based network offers the best match. Relative to alternatives such as Ethernet, 1394 offers greater bandwidth, isochronous capabilities that can synchronize streams from multiple cameras, a flexible topology, and fault tolerance.
The generic use of the 1394 term implies the IEEE 1394-2008 standard that combined all of the prior versions of the standard. That version also introduced such features as an 800-Mbps bandwidth over 100m twisted-pair cables and coax, which--as you will see below--are very important capabilities in a digital security application.
The advantages of 1394 come down to a physical layer (PHY) that offers a much more robust set of capabilities than does Ethernet. Let's examine what the 1394 PHY offers in terms of:
* Isochronous functionality
* Network monitoring and management
* Fault tolerance
* Flexible topology
In terms of bandwidth, 1394 matches or exceeds the fastest flavors of Ethernet. Currently Ethernet tops out at 1 Gbps in terms of widely shipping technology. The industry has developed 10-Gbps flavors but that technology has not gone mainstream. Moreover it's unlikely that 10-Gbps Ethernet will ever use the low-cost cabling required in security applications. The 10-Gbps technology will either require expensive fiber media or relay on very short-range copper cables that wouldn't suffice in the security application.
The 400-Mbps (S400) and 800-Mbps (S800) flavors of 1394 are broadly available and proven in computer-centric products. Moreover, S800 1394 is the equal of 1-Gbps Ethernet because the latter uses 8B/10B data encoding, and that encoding overhead effectively reduces Ethernet performance by 20%. Moreover 1.6-Gbps (S1600) 1394 is due within the next year and will be compatible with the low-cost cooper cabling that will be required in security installations.
A 1394 network affords sufficient bandwidth to carry many compressed video streams. The total depends on the resolution of the cameras and the color-depth of the capture devices. A typical security camera might use the H.264 video-encoding standard that might yield a 5- to 6-Mbps stream. A 1394 network could carry more than 20 such streams simultaneously with plenty of headroom to spare.
Some security applications also require carriage of uncompressed video. Compression always adds a small amount of latency in the encode and decode processes. And in some security installations, a fraction of a second delay may be critical.
Security system vendors have deployed 1394 technology in installations to carry a mix of compressed and uncompressed streams. For example, an installation might utilize a relatively lower resolution uncompressed stream for absolute real-time monitoring of a scene. A higher-resolution compressed stream is transmitted and stored to support detailed review by security personnel.
While 1394 and Ethernet have essentially equivalent maximum bandwidth, all bandwidth isn't created equally. The 1394 standard inherently supports quality of service (QoS). The Ethernet community has added QoS layers, but those added layers simply prioritize traffic. Conversely, a system designer can schedule 1394 traffic guaranteeing real-time delivery of video streams.
The 1394 advantage in carrying video streams goes even further in a security application. From the beginning 1394 has supported isochronous capabilities. In a security application, the isochronous feature can be used to precisely synchronize video streams from different cameras.
Companies that are using 1394 in security systems have used the isochronous capability to actually stitch together streams from multiple cameras. That technique can create a continuous streaming presentation that exceeds what any single camera can capture.
The 1394 physical layer (PHY) is also a good match for the requirements of a security camera network. The PHY allows a central control system in the surveillance center to monitor and manage a network of video cameras. Moreover, the control system can detect attempted network hacks.
A 1394 network offers full plug-and-play convenience. Devices connected to the network can be fully discovered by every other node on the network. A central controller can configure devices such as cameras over the network greatly simplifying the system installation process.
The PHY features allow the central controller to continuously monitor the health of each node/camera. Indeed the control system has complete visibility into the network topology. If a node fails, the system can pinpoint the location of the failure immediately. Ethernet, in contrast, would require installers to map IP addresses to camera locations so that personnel could locate a failed camera.
The plug-and-play aspects of 1394 PHY also ensure that a central controller can detect any unauthorized device that's added to the network. For example, consider a case where an intruder might attempt to insert a video recorder or storage device on the network to capture streams. The controller on the 1394 network would automatically detect that device.
The 1394 PHY also allows the controller to manage the network both in the face of equipment failure or based on a schedule of operation. For example, the controller could remotely power down a portion of the camera network. That act could be triggered by a camera failure. Or perhaps an installation doesn't need the security system to be active at certain times of the day. The controller could programmatically power down all or some of the camera nodes.
By nature, security systems require high levels of reliability. A video-surveillance system does an owner little good if the system can't continuously capture video data.
A 1394 network offers far greater reliability and fault tolerance than does an Ethernet network. The 1394 PHY supports a variety of topologies including loops. In a loop installation, the failure of any single connection around the loop has no impact on the operation of the network.
The 1394 Trade Association has demonstrated the reliability features using off-the-shelf products and impromptu network configurations. The demonstration relies on cameras and a PC connected in a loop with video streamed from each camera to the PC. You can subsequently remove any one cable from the network and the video streaming will continue flawlessly from every camera.
System designers can leverage the fault-tolerant capabilities of 1394 through unique topologies and develop much more robust capabilities relative to the simple example described above. Ethernet could potentially be deployed with some level of fault tolerance. But the fact is that most Ethernet switches and routers don't support such capabilities.
System designers and installers will benefit from the flexibility that's inherent in the 1394 PHY both in terms of topology and media. For example, you can daisy chain 1394 cameras - a feature that Ethernet does not support. Ethernet can only be used in a star networks or tiered-star networks. With 1394 you can mix stars, loops, and other topologies.
The 1394 standard also supports a variety of media types including Cat-5/6 cables, coax, and fiber optics. In fact, a 1394-based system could in most cases use coax cable that is in place, deployed previously for an analog security system.
The IP camera
Ethernet proponents have been exalting the simplicity of an IP camera. Presumably the IP camera would be simple to install and use because people have a growing level of comfort with Internet technology. Moreover, some Ethernet proponents point out that security systems can use existing Internet applications such as telnet so long as the camera has an integrated IP node.
Whether or not there are any real advantages to the IP concept remains to be seen. But the IP-camera concept does not require an Ethernet network. The 1394 Trade Association long ago published standards allowing IP to operate over 1394 networks. An IP camera could easily be built using 1394 as the network of choice.
The most likely implementation of a digital security network will require a dedicated network for video traffic in any case. Mixing enterprise IT traffic with video stream would saturate the network can cause issues with both the IT users that want fast access to the Internet and the security personnel that need guaranteed video delivery.
Still there is almost assuredly a need to allow access to captured video from and enterprises IT network. The ideal implementation would use a 1394 network to connect the cameras to the control center. But the video servers in the control center would also be accessible on the IT network. None of the real-time video capture would impact the IT network. But employees could access stored video selectively via the IT network.
Security applications span a broad range in terms of the size of a network and the fidelity required. A convenience store or other small retail establishment might need a few relatively low-resolution cameras. Security at a site such as a large sports stadium might require tens or even hundreds of cameras spread around a large area. And demanding applications such as casino gambling floors require many cameras with resolution suitable to view details on the gaming tables.
A manufacturer of security systems that wants to develop a range of systems capabilities will find that 1394 can scale to meet applications across the spectrum. The 1394 choice is an affordable one even in a system with a few cameras. For large installations, system designers can use multiple 1394 segments to serve hundreds of cameras. Moreover 1394 can support any resolution required and the mix of compressed and uncompressed streams.
As security camera networks move toward the digital domain, 1394 is proving to be the best choice to network the cameras. The technology delivers the fidelity, flexibility, and reliability required for security applications. The installer community will find the plug-and-play 1394 devices simpler to deal with than Ethernet. And while Ethernet may offer a slight cost advantage, 1394 more than covers that advantage through simpler installations and a more robust feature set in the end product.
A 1394-based camera surveillance video system developed by Ann Arbor-based Pixel Velocity Inc. integrates with the existing IT infrastructure at the University of Michigan, serving current security surveillance requirements while meeting their future needs in providing advanced video capabilities. Pixel Video FusionTM creates panoramic views that allow staff to drill down into high definition detail on live and recorded video. Its unique architecture conserves bandwidth while delivering high definition video on a wide-area panoramic basis. For details visit: Pixel Velocity.
Video-centric security systems have typically used analog connections that link remote cameras to a surveillance control center in the past. Older systems have even stored video on analog media such as tape drives. More modern analog designs encode the video using servers in the control center. Industry-standard compression techniques yield video that is stored disk drives for quick access and the ability to jump instantaneously to any spot in a recorded stream. There are a number of good reasons to move to an all-digital security system with the compression/encoding step being integrated directly into the camera.
With codec ICs and fast-and-affordable microprocessors enabling real-time compression in the camera, the amount of equipment, and the power and cooling requirements, in the surveillance center are greatly reduced. Moreover, analog systems often suffered from lost frames or image distortion. The digital cameras place the A/D conversion and encoding function adjacent to the CCD or CMOS imaging sensor, eliminating distortion of noise and long cable runs. The digital network can then stream perfect video through noisy environments.
Digital networks also offer flexibility in terms of topology relative to the dedicated cables that must run from the surveillance center to each camera in an analog system. Technologies such as 1394 can carry the data payload and control information such as pan and zoom to a camera and in some cases even power the camera. In analog systems, separate cables are typically required for data and control.
Once a product design team decides to develop a digital security system, choosing the network technology is a critical decision. The installer community demands simplicity. But the chosen network must meet extraordinary requirements including the support of multiple video streams, support for some level of uncompressed video, and extreme reliability.
A wireless network might offer the ultimate in simplicity. But no wireless network can meet the reliability or bandwidth requirements of anything beyond hobbyist security systems. The choice will come down to wired options such as Ethernet and 1394.
About the Author
In addition to his work at Taipei-based Codemost Technology, Inc., Dimitrios Staikos is a member of the board of directors of the 1394 Trade Association.