Scaling The Video Network

Aug 1, 2007 12:00 PM, By Richard Howes

As the physical security landscape evolves, video surveillance systems are getting bigger and more complex. Enabling a surveillance system to capture and make high-quality imagery available is the linchpin of these critical physical security systems — the surveillance camera. Many organizations are finding that there are never enough cameras to effectively monitor and protect their assets.

As the number of cameras grows, so does the complexity of connecting the vast network of surveillance assets. To further complicate matters, video surveillance technologies are advancing at a staggering pace with the transition to network-based systems. With careful planning and thoughtful consideration for future requirements, however, it is possible to design a networked video surveillance system that is equipped to handle both changing technologies and additional cameras.

Security video in transition

The video surveillance systems in place today — mostly based on analog video technologies — have met organizations' surveillance needs fairly well to date. They can capture high-quality imagery and are reliable. However, two common requirements of modern surveillance systems — more cameras and more video archiving — can challenge these systems.

Dedicated cabling and the physical infrastructure required for their installation make it hard for analog systems to grow. Point-to-point coaxial cable connections are required from every camera in the system back to wherever the video is to be viewed and stored — an expensive proposition. At the center of this hub-and-spoke approach is either a viewing station with multiplexers and banks of analog monitors or a video archival device.

Surveillance video originally relied on video cassette recorders (VCR) to store video on VHS tapes, but most users larger than a convenience store have moved on to digital recording. Digital video recorders (DVR) that digitize and compress the analog video before storing it on a hard drive offer much more flexibility than VCRs — higher storage capacity, quicker search and retrieval, remote access over networks and the ability to export clips or images for analysis and sharing.

But DVRs also have limitations that make future system growth difficult and expensive. For example, the limited processing power available in standalone DVRs or in PC-based DVR software can only handle 16 or 32 cameras each. An additional DVR is required for each batch of cameras added to the system. Once a system grows beyond the capacity of a single DVR - usually 16 cameras - users now have to physically jump from one DVR to the next to play back video from all of the cameras in the system.

Networked video surveillance

Networked video surveillance systems based on Internet protocol (IP) networks offer solutions to the problems inherent in analog systems, but require careful equipment selection and network planning to address modern surveillance needs. Networked DVRs, or NDVRs, are a step forward in convenience as they include a network card that allows connection and retrieval of the video remotely. However, the system scaling problem remains.

The latest evolution in surveillance video recording is the network video recorder, or NVR. It is a device that receives video that has already been compressed and converted to digital format and is sent over IP or asynchronous transfer mode (ATM) network connections. The video is converted to the digital format either by dedicated video encoders also on the network or by an IP camera, essentially an analog camera with a built-in encoder. Some newer cameras have digital image sensors so the video is captured directly in digital form for transfer over the network. Video playback from NVRs is subsequently sent to hardware decoders for display on analog monitors or is displayed on PCs by software decoders, e.g. QuickTime.

NVRs have several benefits. For one, the video is typically encoded closer to the camera, thus avoiding signal loss and noise resulting from long runs of analog cables. In addition, since the encoding process is external, the typical NVR is able to handle many more cameras than DVRs, thus simplifying support and management and usually reducing cost. Furthermore, some NVRs can simultaneously support various encoding formats (MPEG, JPEG) and multiple vendors' encoders.

Other advantages of NVRs are related to continuing advances in encoding schemes and high-definition video. As these technologies emerge, systems employing DVRs will need to be replaced with newer models to support the advancements of camera or encoder technologies. The management systems that support the DVRs would also have to change. Systems using NVRs, however, can keep the existing infrastructure, and a software upgrade to the NVR can add support for new technologies. Even installation and maintenance are cheaper and easier. Networked video uses the same cables, power supplies and other equipment used by PC- and server-based data networks, thus allowing businesses to leverage and extend existing IT infrastructure investment for use by the video surveillance system.

Smart growth

But NVRs are not without their challenges, especially with regard to network bandwidth and video storage. Networked video greatly simplifies how video is transported from camera to viewer and how it is stored to disk by using mature networking technologies that are likely already in use by the IT organization. To reap the full benefit of network video and to future-proof the surveillance system, users must properly plan their network and select the right NVR equipment to accommodate growth in the amount of video they plan to move around and store.

Intelligent storage

Video files are large even when compressed by IP cameras or encoders, and the volume of video grows quickly over time. The data must be moved across the network and stored somewhere. The right indexing and searching technologies can facilitate retrieval of critical footage.

Once the user decides how much video to keep and which video is most critical, the system should automatically be able to respond. It can do so by recording the most important events at high video frame rates, say 30 frames-per-second (fps), and then reducing the frame rate when there is no activity. For example, a camera placed in a lightly traveled hallway only needs to record at a higher frame rate in the presence of a person. Any system that can do so with minimal manual intervention reduces the storage space needed for the video — and the time administrators must spend configuring individual cameras. Storage systems should also be able to reduce the frame rate automatically as video ages to save space, continuing to record new video at high frame rates. Networked video storage should also be a true point-to-point storage and retrieval topology, not the hub-and-spoke model used with DVRs.

Network design for video

Many network video systems rely on IP multicast to transport video. If the existing security requirements include the ability to view live video on one or more monitors and record the same video simultaneously, most DVR or NVR solutions require the use of IP multicast. Although often dismissed as “just a network issue” by the security professional, IP multicast is not an acceptable solution to most IT professionals. First, IP multicast is complex, difficult to provision and manage, more costly to implement and requires high levels of support. Second, IP multicast introduces network security issues, as there is no accountability as to who has access to the video streams, and it is difficult to forecast bandwidth usage and allocation. Most corporate networks will not allow IP multicast routing, which alone renders most DVR and NVR solutions invalid. IP multicast also results in every user receiving the exact same video experience, which prevents users from individually reviewing, pausing and searching the video for their own needs. For the most demanding surveillance environments, it is important to have a video system that supports multiple simultaneous but different user experiences, and with unicast transmission.

Network topology presents another issue in complexity and cost-efficiency. Many systems cluster cameras and monitors around a server with the network as a hub as older analog systems required. These multiple PCs must pass information back and forth to each other, rather than operating as a seamless whole. This arrangement is inefficient, especially when information on one server must be viewed on a monitor attached to a different server. The longer the daisy chain between servers, the greater the potential for poor performance or a break in communication.

Openness

Proprietary video security solutions present another challenge as surveillance systems grow. This issue might not be a significant problem for smaller companies that purchase equipment for the first time or that can find a suitable end-to-end system with no future need for growth. However, let's say that a big business lacks a centralized purchasing system - or has just acquired a new division that uses its own video surveillance system. It's not difficult to imagine the major headache that comes when the company must integrate and upgrade incompatible systems. Now consider the challenges to law enforcement organizations that need to access multiple existing systems from different vendors as part of routine investigation.

Integrated data security

Finally, security itself is an issue. Every company using networked video must decide who has access to the servers, when and under what conditions. That access must be documented. The video must be protected from being altered, damaged or stolen. The same security tools used by IT departments to protect online assets such as accounting systems are typically applied to the problem. However, these solutions are grafted onto the digital video network, rather than being built-in from the beginning. This lack of integration increases the chance for an oversight or gap in protection.

Data security is an absolute requirement for networked video, especially given the constantly growing numbers of legal and regulatory requirements that apply to any type of corporate data. Ideally, data security should be an integrated part of the network, such as network routers and intrusion detection systems, rather than an add-on that affects throughput and leaves potential gaps in coverage.

Instant retrieval and scalability

IP video surveillance technologies have changed the way businesses manage video. These new technologies integrate video capture, indexing and storage with proven data management methodologies, all while leveraging investments in existing IT infrastructure. The result is a new type of networked video, with fast efficient storage, instant retrieval of any frame and scalability that supports even the largest enterprise organizations. But organizations must commit to the upfront planning and consideration for how the system will grow in the future in order to receive the most benefit from networked video.

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Richard “Chip” Howes, CEO, Steelbox Networks, has more than 25 years of experience in the digital video, telecommunications and Internet industries working with companies such as Cisco, Nortel and Scientific-Atlanta. He holds 30 Internet and networking patents.

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