CCTV Digital Video Recorder

Video Surveillance Systems Design Guide

This guide is designed to educate you on basic system design and application. It is intended to help you make the right choices when designing a video surveillance system that will meet your expectations.

The first step in designing your own video surveillance system is to understand the different technologies, how they operate and the features and benefits of each type of system.

Currently, video surveillance technologies range from time lapse video recorders to state of the art digital video recorders with video analytics. Security cameras range from analog black and white dome cameras for basic surveillance up to high speed internet enabled pan tilt zoom cameras with auto tracking and window blanking. The technology that is right for you will depend on your budget and what you wish to accomplish with a video surveillance system.

Video Surveillance Recording Systems

One of the first things to consider before you make a purchasing decision is what type of video recording system makes the most sense for your application. There are 3 types of video recorders to consider: Time Lapse VCR Systems, PC Based Digital Video Recorders and Hardware Based Digital Video Recorders.

Time Lapse VCR Systems

The mainstay of the video surveillance industry for over 20 years, the time lapse video cassette recorder is extremely reliable and easy to use. The time lapse recorder differs from a standard VHS tape recorder in that it has the ability to slow down the recording rate from 30 images per second which is considered real time, down to 1 image or less per second. It also adds a time and date stamp to each frame of video for evidentiary purposes.

When a single security camera is connected to a time lapse VCR, it offers very high quality video recordings at up to 30 images per second. Because there is no compression of the video signal, the video tape simply records 100% of the incoming video. To this day, many Casinos still use the tried and true time lapse VCR’s due to the reliability, real time recording speed and the high quality video.

Not everyone has the dedicated security resources of a Casino, so if you are using your time lapse VCR to record at 30 images per second, a standard T-160 video tape will last a little more than 2 hours. Some time lapse video recorders can extend the recording time up to 960 hours on a single videotape.

Be aware that when you are recording 960 hours on one VCR tape you are only recording 1 frame or picture about every 6 to 9 seconds. When programming a time lapse recorder I strongly recommend you do not set the recording duration for more than 3 days or 72 hours. This will allow the minimum amount of tape changing and still record enough frames to make the recording useful. This also allows you to record over a weekend without changing the tape. Three days of recording on one tape records 1.5 frames or pictures per second. Not great, but not bad considering this is a 20 year old technology.

Always make sure you buy only the highest quality tapes. You should also have 10-12 tapes which are rotated in order. For example, if the recorder is set to 72 hour recording or 3 days, the tapes would store 30+ days of video. Changing the tapes also increase the life of the recorder and the tapes.

To this point, we have only discussed a single camera system. Say for example you need 4, 8 or even 16 camera to watch your property. You could either purchase a monitor and a recorder for each camera, or you could add a video multiplexer.

A video multiplexer allows you to view and record multiple cameras on a single time lapse recorder and video monitor. Multiplexers are offered in color or black & white in 4, 9 or 16 camera configurations. A video multiplexer works by digitally dividing the incoming video signals and parsing them out, one at a time, to a time lapse recorder. It sends camera one to frame one, camera two to frame two, camera three to frame three and so on.

An added benefit of multiplexers is the ability to view multiple cameras simultaneously on a single CCTV Monitor. A major drawback is that during the digitizing of the incoming video signals, about half of the information contained in the image is lost. Also remember that you are now limiting the total number of images per second for any given number of cameras. With 16 cameras recording on a single video tape for 72 hours, you are now getting about 1 frame of video from each camera about every 3 seconds.

If a video is recorded in time lapse mode you must use a time lapse recorder for playback. The standard VCR's we all have in our homes cannot break down the digital multiplexing required to process the time lapse format and will not provide a useful playback.

The drawbacks to time lapse video recorders and multiplexers are significant. Once security camera video has been recorded through a multiplexer, it has lost over half of its quality or resolution and it cannot be recovered or enhanced.

You must change the video tape every three days or more, and the quality of the video tapes degrades over time. I would not suggest using a video tape more than 5 or 6 times, which means you must keep rotating in a fresh supply to prevent low quality or un-usable video.

There are lots of moving parts and pieces inside of a VCR and because you are constantly sliding a strip of film across the recording heads, a video tape recorder will require regular cleaning and maintenance to maintain its dependability.

Because a time lapse tape recorder is completely analog, it does not have the ability for networking or remote viewing of the video through the internet or over the phone line and they do not support any types of LCD or SVGA monitors so they require specialized NTSC video monitors with BNC connectors to view the video.

Perhaps the biggest drawback to time lapse video recorders and multiplexers is the playback features. If you are recording video 24-7 and an event occurs over the weekend and you are not sure of the time, you have no choice but to sit through and watch the entire video tape to try and find the incident. Speaking from experience, this can take hours and be quite frustrating.

The Digital Video Recording Revolution

To address many of the pitfalls of time lapse VCR’s, manufacturers created digital video recorders or DVR’s as they are sometimes called. A digital video recorder uses digital video compression and hard-drives to replace the analog tape recording functions of the time lapse VCR.

Streaming video files are huge, so digital video recorders utilize video compression formats such as MPEG or H.264 to make the images and files easier to work with and record. Video compression allows a large amount of security camera video to be stored onto a hard drive. Depending on the compression format, a four camera system recording at 7.5 images per second for each camera could conceivably record at least 30 days of video on an 80 gig hard drive. To double the recording days simply add another 80 gig hard drive.

The benefits of digital video recording are huge and their use has exploded over the last decade. The introduction of digital video recorders to the security industry created a revolution and with very few exceptions, they have completely replaced VCR’s as the video surveillance system of choice.

Digital video processing allows manufacturers to create applications that make the old time lapse recorders seem antiquated. Pixel based video motion detection, pre and post event recording, motion and event based searches and remote video transmission are just some of the innovations that the digital video recorder has brought to the video surveillance industry.

Digital video recorders are designed so they do not require any scheduled action to maintain the video recordings. They utilize a process called FIFO, or first in first out to insure that your system maintains recordings. Once the space dedicated to security camera recordings on your hard drive is full, the system will throw away the oldest events and use the freed up space to record the newest video clips.

A Word about Digital Video Compression

When you are digitally recording an image, higher quality equals more pixels. The more pixels you record, the larger the file size. The larger the file size, the more processing speed is required to capture the image.

Video compression refers to the process of reducing the data used to represent digital video images by a combination of image compression and motion compensation. By compressing video, digital video recorders can reduced the bandwidth and processing power required to transmit and record video images.

Most video compression represents a trade-off between disk space, video quality and the cost of hardware required to compress and decompress the video in a reasonable amount of time.

For video surveillance recorders, the video compression codec compares the pixels or individual image elements from one frame to the next and then records only the differences between the images.

This works really well when the video has little to no motion because the system is sending and processing very little new data. When the video content has a huge amount of high frequency details in motion, either the quality of the recording will decrease or the image processor must work harder to provide the same level of detail.

Nearly all digital security camera recorders will utilize either the JPEG or MPEG video compression standard, although recent innovations have pioneered the use of H.264 video compression due to its lower bandwidth requirements and higher image quality.

MPEG is a commonly used method of video compression for video images. MPEG allows the degree of compression to be adjusted to provide a balance between storage size and image quality. MPEG compression consists of 4 different parts, MPEG-1, MPEG-2, MPEG-3 and MPEG-4. MPEG is an acronym for the committee that created the compression format, the Moving Picture Experts Group (MPEG).

H.264 video compression presents a huge step forward in video compression technology and it was developed to provide high quality video at a much lower bit rate the standard MPEG-4 or JPEG. The immediate benefit to using H.264 video compression is drastically reduced file sizes, higher quality recordings and quicker refresh times for remote viewing applications using limited bandwidth.

Without compromising image quality, the H.264 codec can reduce the size of a digital video file by more than 80% compared with the Motion JPEG format and as much as 50% more than with the traditional MPEG-4 standard.

MPEG-4 digital video recorders are still the industry standard, but H.264 is the video compression of choice for higher quality images with the smallest possible file sizes.

Stand Alone Digital Video Recorders

The latest generation of standalone surveillance camera DVR’s utilize a Linux real time operating system (RTOS), so there is no need for computer to control or manage the system. Hardware based DVR’s are designed for one thing and that is to provide high quality, extremely reliable video recording. Simply plug in the unit and hook up any standard VGA computer monitor and you can immediately begin recording high quality digital images from your security cameras right away.

An embedded Linux operating system is extremely reliable and stable because there is no need to change hard-drives, re-boot the operating system, run virus scans or update the software. You can literally set up the DVR and forget about it. A hardware DVR will simply and reliably record video so you will have the evidence when you need it.

Operating much like a VCR, most hardware based digital video recorders offer a clear and intuitive on screen menu that can be accessed from the front panel or through an infrared remote control. With default programs that pre-configure some of the most popular options, most hardware based DVR’s can be up and running within minutes of taking it out of the box.

High end standalone DVR’s offer advanced features such as video based motion detection which allows you to only record video when there is movement or action in the picture. You can mask out certain areas of the picture such as trees, roadways or sidewalks so you only record the action that you want.

Because hardware DVR’s are essentially purpose built computers, they store all of their memory in RAM before they archive it to the hard drive. The random access memory provides the ability for pre and post event recording. Imagine a system so sophisticated that they will begin to record 5-seconds prior to sensing any motion and then continue to record for up to 60 seconds after the motion ends. Each security camera can be programmed with its own customized recording schedule so you can elect to record 24-7 or only when there are external alarm triggers or video motion based events.

Another popular feature of modern digital surveillance systems is remote viewing. Most of the higher quality DVR’s have an integrated network interface that supports remote viewing from anywhere in the world. It’s as easy as plugging the DVR into your router or network connection and setting up the IP address and port forwarding.

The DVR is shipped with a simple to use remote viewing client software package that allows you to connect and control your DVR through a network connection. More sophisticated software packages allow you to connect to multiple DVR’s at the same time which means you could manage hundreds of security cameras in multiple locations with a network of hardware DVR’s.

Many digital video recorders offer the ability to integrate external security alarms, relays and complete pan tilt zoom camera control through built-in RS232/422 serial data ports. Combine PTZ camera control and alarm inputs with internet based remote viewing and now you can operate and interface with your video surveillance system from anywhere in the world.

Perhaps the biggest benefit to digital video recording is the ability to quickly sift through hours or days of video recordings in seconds. With simple to navigate on-screen displays you can quickly find motion or alarm based events or you can go right to a specific time and date to review recorded video. What used to take hours can be accomplished in minutes.

Once you find the evidence you need, you can easily back-up or transfer the recorded video to a network drive, onto a DVD with the built-in burner or you can even use a USB Flash Drive by plugging it into the port conveniently located on the front of the DVR.

PC Based Digital Video Systems

A PC based DVR combines all of the best features of a hardware DVR with the ease of use and flexibility of a personal computer. A computer based digital security recorder is comprised of a personal computer, a video capture card and a video recording software package. At the time of this writing, 99% of digital recording software is designed to work on a Windows operating system.

PC based DVR's are programmed and operated with a keyboard and mouse just like any standard Windows application, which makes them very user friendly for even moderately skilled computer users.

You can purchase a complete, bundled DVR that is custom designed for security camera recording or you can purchase a kit that allows you to turn your existing PC into a digital video recorder.

A bundled digital recorder comes with a computer with video capture cards and the software pre-loaded. Many of these pre-loaded systems will have shell menus that limit the end users ability to interface with the operating system, but they offer the benefit of all of the components being designed to work together seamlessly. In addition, many manufacturers will not allow you to field upgrade your DVR by adding additional video capture cards. If your plans include expansion of your security system, you should make sure that the DVR you are purchasing allows expansion.

Several manufactures offer cost effective kits designed to turn your computer into a digital video recorder. They typically consist of a video capture card and software package that you install on your own personal computer. There are many advantages to building your own DVR including the ability to expand the system as the need arises by simply adding additional PCI capture cards.

Depending on the application, these do it yourself video surveillance kits still provide you with the ability to use your PC for tasks other than video recording. That means your computer is not just dedicated to video recording, it can multi-task as it was designed to do. Of course there are limitations based on the speed of your computer, the number of images per second you are recording and the amount of RAM installed on your machine.

As with hardware based digital video recorders, you can playback the video on a standard SVGA monitor. Once you find the images you wish to save or transfer, you can burn a CD or DVD, use a USB thumb drive, or transfer the video to a network drive. Most systems download a native version of the playback software onto the CD/DVD so that the video can be authenticated with watermark images.

PC based DVR’s typically have superior processing power than an equivalent hardware DVR so they can record more images per second. In addition, software is constantly being developed that provides enhanced usability. One such software enhancement that promises to change the face of video surveillance forever is video analytics.

One of the universally limiting factors of CCTV was that there always needed to be someone manning and controlling the surveillance cameras to make it effect for anything other than forensic investigations.

Now you can purchase software based video analytics systems that utilize complex algorithms to monitor behavior and react accordingly. Video analytics, or real time video intelligence and analysis is one of latest trends to hit the industry.

Intelligent video analytics systems can respond to certain behavior and automatically generate alarms to alert security or even dispatch an emergency response team. A simple example would include a series of cameras that are deployed along a fence line. People and vehicles can move on the non-secure side of the fence at any time. If a person or a vehicle should stop to long or loiter in one place, the camera system could generate an alarm to alert security. If a person tried to climb the fence, the system is intelligent enough to immediately dispatch a response team.

Normal behavior in a parking structure at the Mall is for a person to park their car and then walk to the elevators. If a person is moving from car to car, or staggering around the lot, the system will immediately call attention to the situation and alert security. You can see how this use of technology could possibly prevent vehicle burglaries or even assaults.

Although most of this technology is being driven in response to terrorism, the uses and applications in commercial and retail security environments are endless. From catching shoplifters to alerting grocery store of the potentially dangerous spills on aisle 5, this technology is headed to a store near you.

Several manufactures have incorporated simple video analytics into their standard software packages, such as missing object or directional people counting functions such as a reverse flow exit detection system. A number of CCTV manufacturers have provided high end video analytics as an option to their mid-grade and high end digital video management systems. The addition of custom video analytics to any digital video recorder is an expensive and time consuming proposition.

Another key feature of a PC based DVR is the ability to repair, replace or upgrade components and or software as it becomes available. The immediate benefit to you is sustainability and extended use of your resources. If you want to expand a 4 camera system into a 16 camera system, you do not need to throw it all away and start from scratch with a whole new system. You simply add or replace your video capture card in your existing PC which can save you money.

Choosing the Right DVR

Choosing between a hardware, or stand-alone DVR, and a PC-based DVR can be a intimidating task. There are many factors to consider before making your decision: your computer skills, the physical size of the DVR, the compression format, how often will you interface with the DVR, how to secure the DVR and maintain the integrity of its data, will there be multiple users, do you require remote access, the list goes on and on.

DVR Physical Size/Footprint

The footprint is the size of the DVR and the space requirements for the recorder and all of the necessary components. A hardware DVR is about the size of a VCR or DVD player and it does not need a keyboard, mouse, or even a monitor to operate. A PC based DVR is a computer and it requires a significant amount of space for all of the necessary components including the keyboard, mouse and monitor.

A hardware recorder can easily be secured in a dvr lock box, while a PC based DVR is significantly harder to protect. Unless you install it in a rack mount in a locked data center, it is difficult to completely secure a computer from theft.

If you have limited space where you need to place the DVR, or if there is a real threat of the digital recorder being stolen or tampered with during a crime then going with a Hardware DVR is going to be the best option.

DVR Software Features

When it comes to software features most PC-Based DVR’s will offer better search functions and motion detection features than hardware digital video recorders. Normally the PC based DVR’s will also have a more user friendly interface for alarming and other activity detection than a stand alone DVR.

A PC based DVR also offer more options including video analytics, hybrid interface to internet based cameras, point-of-sale device connectivity, networking and an enhanced ability to control the DVR over the internet from a remote location. Software upgrades and enhancements are readily available for PC based recorders and they are relatively easy to implement. Hardware DVR’s are much harder to upgrade to the latest revision of software.

If you want all of the latest software features, are relatively adept with a Windows operating system and are familiar with how networks operate, then a PC based DVR will be your best choice.

DVR Ease of Use & Functionality

Functionality and ease of use can be a relative thing depending on the person and how intuitive the programming interface is. If a digital video recorder is intuitive to program and interact with, then it will be easier to work on even if it is rarely used. This is true of both hardware and PC based digital video recorders.

Many people are very familiar with using a PC and so configuring and using software is a comfortable thing, whereas using and configuring a Hardware DVR is very similar to using and programming a VCR. You use a remote control to access a menu displayed on the TV or Monitor. You then use the remote control to navigate through the menu and select the options.

Ease of setup is another advantage of the Hardware DVR. Since there is no operating system to deal with or software to install all you have to do is connect the security cameras directly to the DVR, setup the recording schedule and you are ready to go. With a do it yourself PC based digital recorder you have to install the PCI video capture card, install the drivers to control the capture card, and install the recording software. Each of those operations can have its own set of challenges for a novice computer user.

If your computer skills are limited to playing solitaire and a window is something that keeps the cold out and lets the light in, you may want to consider the hardware DVR. If you are a knowledgeable PC user who is comfortable with windows, software upgrades and networking then a PC based system will be your best choice.

DVR Reliability & Performance

A hardware DVR uses a real time operating system that is specially built for one single purpose and that is to record video. There is no operating system to deal with which means no viruses, no upgrades, no new releases or different versions and no bugs or worms.

PC based DVR’s run the Windows Operating system and that comes with its own set of issues and challenges. The PC can get infected with viruses or spyware that can seriously affect performance. You can run into device or hardware conflicts caused either by the software controlling the device or just by having two incompatible devices in the same computer.

Windows computers often need to be rebooted in order to reload portions of the operating system. Most PC based DVR’s have a programmable auto-boot command that automatically restarts the system at least once a week.

Hardware DVR’s do not require any software updates, so if you want to set it and forget it and you don’t plan on interfacing with your system very much you might lean towards the hardware DVR. On a PC you will have updates for the operating system, driver updates, and periodic software updates that will need to be installed to keep the computer running smoothly and efficiently.

Because of the design and limited functions of a Hardware DVR they are inherently more reliable than a PC. There are far fewer things that can go wrong inside the unit. You will never need to reload Windows because of virus infection or corrupted system files, uninstall/reinstall software or device drivers or repair the video databases due to indexing errors. With a Hardware DVR then only things that usually ever go wrong is a hard drive failing or having a power supply burn out.

The one caveat to this is with the motherboard. If a motherboard fails on a Hardware DVR you are stuck with purchasing a new DVR. With a PC, if the motherboard fails you can usually just purchase and install a new motherboard and be up and running in a short amount of time.

DVR Expandability

Hardware DVR’s are not expandable. If you purchase a 4 camera security recorder and your needs expand to 6 cameras, you would have to purchase a new DVR. With a do it yourself PC based digital recorder, you can add an additional video capture card to expand the capacity of the system. Of course, as state earlier, some manufacturers such as Pelco, American Dynamics and Honeywell video systems will not allow you to upgrade your DVR’s in the field. You would need to send them back to the factory.

DVR Cost of Ownership

Hardware DVR’s and PC-Based DVR’s are very comparable in price when purchasing a complete DVR. However, you can save quite a bit of money if you already have a PC that you can turn into a DVR. You can save in $1000 or more by converting an existing PC into your security DVR. If cost is a deciding factor for you then building your own digital video recorder is definitely the way to go.

The Bottom Line

No matter which system you choose; A hardware or a PC based DVR will increase your security and provide you with a piece of mind and a return on investment that cannot be matched by any other type of security system.

Choosing the Right DVR Manufacturer & Supplier

Installing your own surveillance system is a lot easier than it sounds if you choose the right system and supplier. This guide is just one example of the support provided to the customers of Security-Kits, the manufacturer of the Armor-Pro digital video management system and the EZWatch-Pro Line of DIY digital video recorders. Plain and simple, we support our customers and the systems we sell.

Our seasoned support staff has more than 60 years of combined experience in the design, sale and installation of video surveillance systems. Our toll free support number is provided for one simple reason, to help and support our customers. Please feel free to use it 1-888-370-4287.