Friday, September 12, 2008

What is Bandwidth and How Much is Required

Ever wonder why it takes so long to get a picture loaded on your computer screen? Do you sometimes have problems using your new cable telephone or VoIP system? What bandwidth is required for your Internet connection? Do you need 512 Kbits/sec or 20 Mbits/sec? This article provides the information you need to determine the best service and will help you correct problems you may encounter with your Internet connection.

We receive information in a number of ways. For example, we can listen to the radio, watch TV, talk on the telephone or use our computers to reach the Internet. In general we are receiving information in two distinct ways. In one case we are listening to the same information that is broadcast to everyone, and in the other case we are receiving a private message. No matter how we receive the information it is important that the message is loud and clear. Let’s take a look at some of the factors that affect the quality of what we receive.

Broadcast versus Addressed Information

First let’s understand the difference between receiving the information that’s broadcast versus getting information that’s addressed to us. The reason I’m reviewing the two types of communication is because it is helpful to know this when you are talking to your network provider. Some of these providers actually don’t understand this concept, so you have to help them along, especially when you are trying to explain a problem you’re having with their service.

When information is broadcast electronically, it is like a water pipe filled with fish. The pipe goes from one house to another and at each house there is a window in the pipe through which you can see the fish swimming. Since people are all looking at the same fish (information), you just need to have enough water pressure for the water to reach all the houses in the neighborhood. No one is taking any of the fish away. Cable television broadcasts TV signals so that everyone sees the same information (the fish) at the same time. Cable companies monitor the quality of the signal reaching each location to assure you get a good quality TV signal.

Sending information that’s addressed to specific computers is like delivering the fish to each person’s house. When you connect your computer to the Internet you get some data (fish) that’s addressed just to you. Each house takes some of the fish away so you need lots of fish. IP addresses are used on the network to address each of the computers and to assure that the information gets to the right place. Telephones are another example of addressed information. You call a specific house by using a specific phone number. Internet providers that focus on good data service should not only be interested in the quality of the signal, but also the bandwidth (amount of fish) that each user receives.

Data rate (or do we have enough fish).

The data or bit rate is related to the bandwidth available and it is a measure of the amount of information (number of fish) that can be sent over any transmission media. The data is sent over a transmission media that can be a cable wire, an optical fibre wire, or wirelessly using a radio. No matter what the transmission media, we are always concerned about the data rate.

If many people are trying to get the fish at the same time, you have a fish delay because you don’t have enough fish to go around. For example if the Internet provider tells you that you have a 10 Mbits/sec connection, you may not receive this data rate all the time. The problem is that the network is shared by many people so sometimes the bandwidth that you receive is reduced and you end up waiting a long time for a picture to load on your web browser. It’s far worse when you are talking to someone on the telephone, and there are missing sounds or interruptions to the voice.

When you have these problems it’s time to talk to your provider about the bandwidth they are actually providing.

How High a Data Rate Do We Really Need?

The data rate you need depends on what information you want to send. When you send real-time audio or video data it’s very important to receive a continuous flow of information. For example if you want to transfer video on the Internet, the data rate required will be determined by the resolution of the picture, the frame rate (or how many pictures you want to send per second), and the compression scheme you use. If you send video with a resolution of 640 x 480, it uses about 300 Kbits/picture when using MJPEG compression. If I want to send 10 pictures or frames per second, then I will need a data rate or bandwidth of 10 frames/second x 300 Kbits = 3000 K bits/second. This is the same as 3 Mbits/sec. So if we want to see the video at 10 frames/sec, we will require a bandwidth of at least 3 Mbits/sec.

Many DSL, cable companies and Verizon FIOS have one data rate for incoming (download) data rate and another for the outgoing (upload) data rate. Usually you would like a higher download rate, but sometimes, especially if you are viewing a camera, you would like a higher upload rate.

Now that you understand the concept of data rates, you will be better able to make the right choices for your Internet connection. These same concepts also apply to your local area network and even your wireless network.

If you need more help determining bandwidth (how many fish) you need, just give us a call at 914-944-3425 or use the contact form to send us a message.

Friday, May 30, 2008

Video Recording for IP Cameras

The Changing Technology of Video Recording
Pros and Cons of the latest IP Camera Recording systems
by Bob Mesnik

Recording video from surveillance cameras has changed over the years. First there were Video Cassette Recorders (VCR’s) and then Digital Video Recorders (DVRs) and now there are Network Video Recorders (NVR). VCRs were around for many years and have been replaced by DVRs that use hard drives. Now, NVRs that support the latest network attached IP cameras, are starting to replace the DVR. This article reviews the technology and how it has evolved over the last few years.

Video Recorder
Early video tape recorders were introduced in the 1950’s. In the 1960’s Sony introduced the first videocassette units (U-matic) which lead to the Beta and VHS VCR products. In the 1970’s the VCR started to be used in the surveillance market.

Video Cassette Recorders (VCRs) used in surveillance, are modified consumer VCRs that have one or more camera inputs to record video from CCTV analog cameras. Duration of storage is usually only up to ten days, depending on resolution and frame rate. These systems were simple to use and relatively inexpensive. Prices ranged from $200 to $1,000.

The downside was the difficulty in finding a specific videotape and then a specific time period. Tape is not too reliable, so even if you find the right tape you may find the video has deteriorated.

Digital Video Recorder
Around 2000, the DVR was introduced for surveillance applications. The Digital Video Recorder (DVR) converts analog video (from CCTV cameras) to digital data and records the data on computer type hard drives. 4 to 16 analog cameras can be attached to a DVR. These systems provide far more storage than tape, are more reliable and provide almost instant access to the stored video. Prices range from $500 to over $2500 (for up to 16 cameras).

Since the video is stored in a form that’s more compatible with computers, the video can be processed and distributed easily. DVR systems incorporate better video compression, and provide motion detection and alarms. Many DVRs have network connections. Data can be sent over the network and viewed on a PC or it can be stored on CD or DVD-Recordable discs.

The upside is the ability to attach a variety of analog cameras into the network. The downside is that the DVR system has a fixed amount of storage and is not easily expanded.

Network Video Recorders (NVRs)
The NVR or IP software is a major advance over the VCR and DVR. The introduction of network attached IP cameras around 1996 required a new type of recording system to be developed. Instead of using coax cable to distribute the video, the video is digitized and compressed in the camera and attached directly to the Ethernet network. The digitized video is now distributed over the network just like any other computer data. A number of software and hardware products were developed to support these new IP cameras. The software runs on standard computers connected to the same Ethernet network as the IP cameras. The software transformed the standard computer into a Network Video Recorder. Now many hundreds of IP cameras can be supported by this IP NVR software. Prices range from $500 to well over $25,000 (for hundreds of cameras).

Some manufacturers also introduced NVR systems that included a computer. The purpose of this system was to make the transition from analog CCTV technology to the new network attached IP technology as easy as possible for the video dealers. For example, instead of using a 16-channel DVR you could now get a 16-channel NVR.

The NVR systems are much more flexible and expandable than DVR systems. The Ethernet network can support a very large number of IP Cameras and the more advanced NVR software is designed to use multiple computers to support an almost unlimited number of cameras.

Most NVR software runs on a Windows type PC system. An IP camera system consists of the IP cameras, computer with hard drives and IP or NVR software. The computer performance and hard drive capacity depends on the number of cameras, the resolution of the video, the frame rate of the cameras as well as how long you want to store the video.

NVR software can be scaled to the requirements of the surveillance system. You can get low cost camera systems that support up to 25 cameras, medium level solutions that support up to 64 cameras and enterprise solutions that support hundreds of cameras.

Software Overview:
There are a number of software options such as NUUO, ProSightSMB, NetDVR and NetDVMS from OnSSI and a number of versions from Milestone (which are similar to the OnSSI software).

The software uses your own computer and it will allow you to view, store and retrieve video and control the cameras. There are a number of common capabilities and each package also has some unique features and functions. For example, all versions allow you to view the video using a web browser from anywhere on the Internet, store video only when motion is detected, and notify you of motion alarm by email or by an alarm sound on the PC. NetDVR and NetDVMS are more robust server/client type software and add among other things the ability to patrol through preset PTZ positions and to transfer the video to alternative storage on the network.

The software is licensed according to the number of cameras you are supporting. ProSightSMB and NetDVR are both licensed by groups of cameras 4, 9, 16 25, 36 64 cameras while NetDVMS is licensed with a base license plus a per camera license. Here are examples of each type of software license:

NUUO is an entry level software for small numbers of cameras. It runs as an application (rather than a service) so should be used with care in commercial surveillance applications. It is licensed for 4, 8, 12 and 16 cameras.

The following software solutions from OnSSI can run either as an application or a Service.

ProsightSMB is entry level software
that supports a maximum of 25 cameras. It is a single site and single server type product. This is a small-scale video management system that provides live video, recording, playback and camera management and control. It allows viewing of cameras from any computer using a web browser.

NetDVR is a mid-range product
that supports up to 64 cameras on one server, and operates as a server/client. It includes features such as NetGuard client software for viewing up to 64 cameras at a time on any workstation on the network, auto-patrol mode for PTZ cameras, stores audio and allows video to be off-loaded to additional storage on the network. It includes NetMatrix that pops video up on any designated PC monitor whenever there is an alarm condition.

NetDVMS is an Enterprise product
that supports hundreds of cameras. It is licensed with a base license plus a per camera license. Besides having all the features of NetDVR, this software can run on multiple servers that are distributed over many sites. It includes NetMatrix that pops video up on any designated PC monitor whenever there is an alarm condition, and Net-PDA software that allows a user to view and control cameras from their PDA.

Advanced content analytic software can be added that counts people in an area or detects if a package has been left unattended at an airport. The bottom line is that more protection can be provided by these complex systems using much less human resources.

If you would like more information please contact us at 1-800-431-1658 or 914-944-3425 or send a message.