If you’re thinking about installing a new video surveillance system, then you have to decide between an IP or analog video format. The intent of this article is to provide some information and perspective that will help you in making that choice.
WHAT IS AN ANALOG VIDEO SECURITY SYSTEM?
Cameras on an modern analog CCTV system send their video in the traditional base band format over coax or UTP cabling back to a digital video recorder (DVR). Here, video is digitized and stored on hard drives. Most modern DVRs are a network device, and as such can be accessed remotely from the LAN, or with the proper configuration, from across a WAN or the internet. There are no tapes to change. Video is kept on hard drives, typically on a FIFO basis so there is always a rolling video archive of the past X days. So, despite the fact that video is being transmitted from the cameras in an analog format, live and recorded video is still available over the network.
Note: This is technically a hybrid system since video is recorded and retrieved digitally. But, in the industry the term hybrid system typically refers to a system that has some IP cameras, and some analog cameras. So, we refer to a system that uses all analog cameras as an analog system.
WHAT IS AN IP VIDEO SECURITY SYSTEM?
IP video cameras broadcast their video as a digital stream over an IP network. Like an analog system, video is recorded on hard drives, but since the video is an IP stream straight from the camera, there is more flexibility as to how and where that video is recorded. The DVR is replaced with an NVR (network video recorder), which in some cases is just software since it doesn't need to convert analog to digital. Video footage can then be stored on new or existing network RAID drives as directed by the NVR software.
WHAT IS A HYBRID VIDEO SECURITY SYSTEM?
Hybrid CCTV systems combine IP and analog video, and can be a great way to transition an analog system to IP without needing to replace all of the existing cameras. Many NVR boxes on the market today are actually Hybrids in that they accept analog cameras, and IP cameras and combine them onto a a single platform for the user.
WHY CHOOSE AN ANALOG SYSTEM?
Cost. IP video security systems are generally more expensive, and sometimes a LOT more expensive. But, because the systems are designed differently from the ground up, there are situations where the cost difference between analog and IP is minimal, and even scenarios where IP video is cheaper. More detail on the cost differences later.
WHY CHOOSE AN IP SYSTEM?
Resolution. One of the biggest factors driving interest in IP video systems is the high resolution that they can offer. Analog cameras max out on resolution at about 580 TVL which equates to roughly 0.4 mega pixels. High end IP cameras on the other hand, are currently available at resolutions above 5 mega pixels. This high resolution in turn gives users the ability to zoom in on video after the fact, and still have usable video.
Another benefit to IP video is that it is much more compatible with wireless. Wireless analog systems are available, but they either have to convert to IP anyway and broadcast over the 802.11 IP network (which adds cost for encoders), or they get crammed onto the over saturated regulated frequencies and often encounter interference.
THE COST DIFFERENCES, IN MORE DETAIL
The cost differences between IP and analog can be significant, but that depends on the particulars of the design. Lets break this down into some prime factors that will affect cost:
IP Cameras are more expensive than analog. There are two reasons for this. First, an IP camera needs an internal encoder which adds to the manufacturing costs. To put things in perspective, an external encoder runs from $400 to $1000. Second, IP cameras don’t tend to come packaged with things like outdoor housings or infrared emitters. When things like this are required, they must be purchased and installed separately which drives up cost.
IP cameras are constantly putting high bandwidth video data onto the network, especially if mega pixel cameras are in use. Without the proper network speeds and traffic control mechanisms, an IP video system can bring your network to its knees. Also, don’t forget that each camera needs its own switch port, so more switches may need to be included in the budget.
NVR VS. DVR
DVR costs are fairly simple to understand. A DVR is a single unit, and has a single cost. NVRs on the other hand are more complicated. NVR software is typically licensed on a per camera basis and must be installed on a PC. The storage requirements for megapixel cameras are significant, and may require additional network storage. When comparing costs be sure to include the software, computer, and network storage in the total cost for the IP system’s NVR.
IP cameras use UTP cabling (at least 5), and analog cameras can use either coax or UTP (at least Cat3). In order to transmit analog video over UTP some inexpensive baluns are required, and coax cabling is slightly more expensive than UTP, so cabling cost for an analog system will be slightly higher.
Analog systems often involve a centralized power source for the cameras, and IP systems usually use Power over Ethernet (PoE). If the PoE switches are not already in place, they will be more expensive than the power supplies for the analog cameras.
WHICH APPROACH IS MORE COST-EFFECTIVE?
For now, installing analog cameras coupled with DVRs is still the most cost-effective approach for most security applications. However, the cost of IP cameras and components is rapidly declining, making IP systems more and more affordable and desirable.
A typical medium quality analog dome camera sells retail for about $50 to $150. A similar quality IP camera sells for at least twice that amount. Analog cameras are available with many different features: varifocal lenses, pan/tilt/zoom, and long distance infrared, for example. Finding just the right combination of features in a network camera for your application might be more difficult and expensive. Sometimes you may have to buy an analog camera and add a separate video server to do the job. Single-channel network video servers currently start at about $300 retail.
IP advocates may point out that businesses often have IP networks in place and therefore no additional cabling or hardware is needed. However, each camera requires a port to plug into the switch, so more or bigger switches may need to be purchased. POE adapters might need to be added. If the existing network will not handle the load of the additional network devices, upgrades might need to be made, thereby making the installation more expensive.
Finally, bandwidth on the local area network (LAN) needs to be considered. Video uses a lot of bandwidth. The bandwidth used by each camera varies by many factors including the resolution, the compression method, and even the amount of movement in the field-of-view.
Analog camera systems transmit over coax, not the LAN, so their bandwidth is not much of an issue. The only use of the LAN in analog systems is for the DVR to broadcast video data over the network to local desktop users or to the internet. DVRs tend to broadcast video very efficiently and will only use bandwidth if people are currently viewing the cameras.
In IP camera systems on the other hand, each IP camera uses the LAN to broadcast their signal to the NVR so bandwidth can be a big issue. As a general rule, an IP camera using full CIF (352 x 288) resolution, 30 frames per second (30 fps), and MPEG4 compression will require about 720K bits per second (720Kbps). Therefore, if we put 100 IP cameras running CIF on a network, we would use about 72Mbps of bandwidth. This number will double if audio is also transmitted. However, to make bandwidth matters worse for IP - most of the newest IP cameras are coming out with 'megapixel' resolution. This is wonderful from the standpoint of how much clarity and field-of-view can be captured, but it comes at a huge price to bandwidth. A single 2-megapixel IP camera, running 30 fps with MPEG4 compression will use a whopping 6.5Mbps of bandwidth. It should come as no surprise then that some companies have gone so far as to create an entirely separate IP network just to run their camera system.
High-resolution IP cameras also require a great deal of hard drive space to store the video. The single 2-megapixel camera described above would require approximately 67 Gigs of hard drive space to record one day's worth of video.
WHICH APPROACH IS BETTER QUALITY?
There are poor quality components and good quality components no matter which type of system is used. That being said, network cameras do offer some technological advances in the areas of video quality and wireless installations. Analog cameras cannot provide resolution above TV standards, the maximum being about 0.4 megapixel. Resolution of IP cameras can be many times higher (currently up to 5 megapixel) and they can capture a clearer image when objects are moving. This could make a difference in high risk applications such as for casinos and law enforcement. Wireless communication over IP networks has fewer problems with interference, and encryption security is built into the technology.
WHICH APPROACH IS EASIER TO INSTALL AND CONFIGURE?
If an IP network is already in place at the installation site, and it can handle the additional load of the new cameras, then IP cameras will be easier to install. If additional RJ-45 jacks are needed to plug in the network cameras, then the installer only has to run a CAT-5 cable from the camera to the nearest switch. An inexpensive switch can be installed right at the nearest wall jack. In contrast, each cable for analog cameras must be run all the way back to the DVR. If upgrades need to be made to an existing IP network to handle the additional load, obviously the installation would be more difficult.
The power for the cameras can be handled fairly easily with either technology. For IP networks, built in POE adaptors make sending the power through the existing ethernet cable easy. For analog systems, use RG59 Siamese cable to combine the video and power cables into one jacket. Either way, there is no additional cabling for power. POE can run 328 feet without a repeater. RG59 can be run 1000 feet without a repeater.
WHAT ABOUT WIRELESS?
Analog wireless systems do not work well. This is because the government regulates on which frequencies analog wireless devices can run and how strong the signal can be. Interference from other wireless devices such as cell phones can cause the camera video to be distorted. Interference is especially problematic in buildings with florescent lighting.
Digital IP wireless is much better. The digital transmission does not get interference from other analog wireless devices, and the 802.11x communication standard used has encryption built in. Consequently, there is no problem with unauthorized access to the video.
For what applications should I consider IP?
IP cameras should be considered for large installation sites that already have a high bandwidth network installed - especially if the cameras will be spread out over a wide area, or if wireless cameras will be used.
For large installations with many cameras, some installers still prefer a multiple DVR solution to an IP solution. Software is bundled with higher-end DVRs that allows you to view and record cameras from multiple DVRs. The multiple DVR solution also provides better failover protection. If the network goes down in an IP based system, video is lost from all the cameras. If the network goes down in an analog system, the DVRs are still recording the cameras.