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The CCTV industry is witnessing a worldwide seismic shift away from analog to IP video. The recent 78.3-percent growth in sales of IP video products proves many analysts correct. The exhibition halls also drown the senses with the latest video compression algorithms and high-performance network video recorders (NVRs), scalable storage, intelligent video analytics and cutting-edge IP cameras.
Video over IP means that video is being transmitted via the IP network; however, it is the interpretation of this simple statement that leads to confusion in the industry. At one extreme, you have IP cameras streaming across the network from the moment the video leaves the camera. At the other extreme, you have regular digital video recorders (DVRs) that record video from analog cameras but also have a network connection, so the live or recorded video can be viewed on a PC via IP.
So, which of these extremes, and the countless variations in between, is really video over IP? The reason people struggle with this answer is that the question is invalid — but it is being repeatedly asked by manufacturers wishing to position their offering as the true video-over-IP solution. The right question to ask is what kind of video-over-IP solution is each one?
The DVR-NVR Evolution
The earliest DVRs were standalone devices with no network connectivity. They were the digital replacement for a VCR and offered multiple benefits. The front panel was used to interact with the device, and live viewing or playback of video was done via a simple analog monitor output. Then, as people wanted to make the DVR viewable remotely, and centrally more manageable, the network port was added. Now, multiple people can share and maintain the DVR via the network.
As the power-to-price ratio for PCs and servers as well as network infrastructure components continued to improve, a new generation of CCTV products appeared — IP cameras that would use the existing network. Suddenly, video was just another kind of data to the network administrator, and overnight, countless software companies sprung up writing software that recorded these streams of video (network video recorders) and that could be used to manage and view them (video management software).
There was demand for IP cameras, and every year since the '90s, the analysts predicted that they would overtake analog cameras in a few years. For a dozen different reasons, the analysts proved to be premature in their predictions. In response to the slower-than-anticipated transition to IP cameras, encoders (or video servers) appeared in various forms. They converted video from an analog camera into a digital form which could be transmitted over the network to the NVR and viewer.
Multi-channel encoders were deployed in huge numbers at the head-end, co-located with the NVRs. It was a safe solution that could benefit from the rapid improvements in encoders and their underlying compression technologies.
Managing an Empire of Recorders
Assume you have hundreds, or even thousands of locations where surveillance is required. Maybe you are a nationwide retailer, a major bank, a government department trying to combine multiple buildings or a mass transit authority linking stations together. These locations are certainly networked, but the WAN is typically not strong enough to carry thousands of camera streams to one central location. If each camera is a modest 1 Mbps stream, then for 10,000 cameras — 10 cameras at 1,000 locations — you need a nationwide 10 Gbps network. Technically, this is possible, but it is unrealistic with many locations that are lucky just to have a DSL connection.
The easiest solution is to push the recording to each location. This solution means installing a NVR at each location and connecting the IP cameras and encoders to it over a LAN. Now, you can view live cameras and playback video remotely.
Being PCs, the IT department knows how to remotely manage them, but the solution costs. IT will have to maintain another 10,000 PCs, 10,000 copies of a Microsoft operating system and 10,000 copies of anti-virus software with regular updates. For every dollar spent on computer hardware, nearly double the amount of time is spent on maintenance.
Life without PC-Recorders
So, what are the non-PC-based alternatives? You could install an embedded (no Microsoft operating system) DVR at each location and connect analog cameras to it. The DVRs could be connected to the WAN for remote viewing. The analog cameras would not use the IP infrastructure at each location, like an IP camera, but it could be installed by anyone.
The DVRs could use internal hard drives to save space. For added recording reliability, you could directly attach a SCSI-based disk array configured for RAID 5. Sure, if you have a 16-channel DVR, then you need to buy another DVR for the 17th camera; however, it is easy to install, configure and maintain.
Is there anything wrong with this solution? The answer is no, as long as it does what you need it to do. Of course, that's the truth with all solutions.
DVRs and Recording at the Edge
If a DVR is just a black box that encodes analog video into a digital format and then stores it internally on a hard drive, then you can do the same thing with an encoder by simply adding a hard drive to it so that it can stream to different receiving devices and record the video at the edge of the network. With this approach, you do not use bandwidth except for viewing live video or for playback of video.
Such devices have existed for years but have been misconstrued as being expensive DVRs. Devices like this offer the benefits of a DVR with the flexibility and manageability of a true IP-based system but without the pain of NVR proliferation.
DVRs with internal hard drives are widely used today. When such a hard drive fails, all video is frequently lost, and if the hard drive is not field-replaceable, then the entire device has to be returned to the manufacturer for repair or replacement.
It is a discomforting thought to imagine what could happen to the critically sensitive video that is stored on it. You have no option but to either keep the unit or to trust the manufacturer's repair center.
If you need flexibility, RAID 5 reliability and the choice of field-replaceable hard drives, but do not want NVR PC servers due to the cost of ownership and maintenance headaches, then you should consider direct-to-iSCSI. Technology now exists that has pushed recording intelligence to the edge device — the IP camera or encoder. Now, the edge device can stream its IP video directly to a disk array that is attached to the network. This is referred to as network-attached iSCSI storage. The protocol that makes this possible is an IP variant of the SCSI disk array, called iSCSI. Now, you can put IP cameras or analog cameras with encoders at each location and install an iSCSI disk array at the same location. Now, IT only has to manage cameras and storage — no more and no less. That seems quite acceptable and, in fact, very achievable, since IT can use existing network monitoring tools.
Some networks are more fragile than others. Better designs and larger budgets help reduce network interruptions, outages and scheduled maintenance. If you feel that you simply cannot rely on your network, or if the LAN lacks bandwidth, then the option is to record at the edge of the network. That means the video gets recorded before it touches the network.
While an encoder with embedded hard drive storage achieves exactly this, there is another innovative solution for external and reliable RAID 5 recording. Since iSCSI disk arrays use IP, some encoders have two network ports — one connecting the encoder to the network and the other connecting the encoder to the iSCSI disk array using a crossover cable. This is referred to as direct-attached iSCSI storage.
Because each iSCSI disk array itself has two ports, two multi-channel encoders can be configured. This means that up to 32 cameras can record directly to an iSCSI disk array without one byte touching the network, without losing any of the flexibility of IP video and without maintaining countless PCs, while keeping RAID 5 storage capacity and reliability.
Dr. Bob Banerjee is the product marketing manager for IP video products at Bosch Security Systems Inc. He has extensive experience in advanced hybrid analog and digital CCTV solutions and has developed Bosch's IP Resource Center (www.boschsecurity.us/ip). He can be reached at bob.banerjee@us.bosch.com.
author: By Dr. Bob Banerjee