Expert Tips On Digital Video Storage
Digital video revolutionized the accessibility and ease of sharing CCTV images. But with the high resolution new cameras offer, archiving these detailed images at lifelike frame speeds can escalate storage needs quickly, despite new image compression methods.
Although hard drive costs have decreased substantially in the last year, end users still can receive a rude awakening when they realize the expense of the storage they have been contemplating. When one can store seemingly unlimited quantities of video, the question becomes how much do you really need and at what frame speed and resolution?
Andy Ryan, vice president of sales and marketing for systems integrator ASG Security, Beltsville Md., is impressed with the sales aids now available for customers. But it was not always that way, he asserts.
â€œAs an industry, we did a really good job of confusing customers and early adopters of the technology,â€ he admits. â€œWe really didnâ€™t do a good job of translating for the client exactly what having an 80GB hard drive meant to them. Now weâ€™re using customer-friendly vernacular so they understand what theyâ€™re going to get or not going to get.â€
Adds Andrew Young, CCTV sales manager for First Service Security Division, Norristown, Pa., doing business as SST & Intercon Security, which ranks as No. 6 on SDMâ€™s Top Systems Integrators Report, â€œItâ€™s critical to determine what the clientâ€™s operational requirement is. What tends to happen less so now but used to be prevalent many years ago is that clients were buying CCTV, and they were not even sure why they were buying it in the first place, other than everybody else was buying it!â€
Only Hard Drives Need ApplyWhen storing digital video, three technologies are most practical â€“ hard drives in digital video recorders (DVRs), more hard drives in network video recorders (NVRs) that can be linked with RAID technology, and server farms of hard drives.
Although some companies are still using libraries of industrial digital tape, this is an IT product, stresses David Ngau, product manager â€“ network video recorders, for Honeywell Video Systems, Louisville, Ky.
Once the customer has decided the number of cameras, image speed and resolution, and whether cameras will be on continuously or motion-activated, calculating the necessary storage capacity can begin.
That can be done with tables provided by DVR or NVR manufacturers, software programs they provide on CD-ROMs, or Web sites. Because much digital video is stored in DVRs, their capabilities and capacities become paramount.
Some DVRs are limited in the number or capacities of hard drives they can handle. Some require two to three minutes of rebooting when installing new hard drives. Others have hot-swappable hard drives, which means no rebooting is necessary â€“ the drives can be installed while another hard drive in the DVR is being used. The ability to add external hard drives also is an important factor.
â€œLower-end machines have the number of gigabytes limited by what the BIOS of the machine can handle,â€ points out Gary Perlin, vice president of video products, Speco Technologies, Amityville, N.Y.
Some will record only 120GB even on a 400GB hard drive because of the BIOS, or programming, in the machine itself, Perlin maintains.
RAID technology is a method of recording portions of video on several different hard drives in succession (called striping) in case one or more hard drives fail or for other reasons. Each drive is filled gradually as succeeding portions of video are recorded on one drive and then another.
Some systems create backups automatically, called mirroring. Different types of RAID recording are specified by numbers. A popular RAID recording method is RAID 5.
Go to the NetworksNVRs are used in IT-based systems to expand capacity beyond that offered by DVRs. â€œWe do sell server farms, but they are attached to NVRs,â€ relates Craig Dahlman, senior product manager for digital products at Pelco, Clovis, Calif. â€œWe have NVRs with capacities up to 4.8 terabytes. These are 12-drive systems, and theyâ€™re dual RAID 5, so you have 10 storage drives and two parity drives.â€
If a customer has a coaxial infrastructure, a DVR is needed for storage, but if they have a network, it could be a network-based system application, Dahlman notes. â€œThe key there is we recommend a system based on the userâ€™s requirements,â€ he points out.
Casinos are a specialty of North American Video (NAV), Brick, N.J., a firm that ranks as No. 19 on SDMâ€™s Top Systems Integrators Report. Digital video storage for casinos is regulated.
â€œDigital storage in the gaming industry is determined by federal, state and Native American gaming regulations on a case-by-case, state-by-state basis,â€ points out Cynthia Freschi, North American Videoâ€™s president. â€œNorth American Video uses all RAID 5 storage solutions for its gaming clients.
â€œEvery installation has its own set of parameters and requirements which determines the type of DVR system we specify,â€ she says. â€œFor large video surveillance and security installations such as the Wynn Las Vegas, which North American Video recently completed, enterprise solutions offer the most flexible means of recording information.
â€œThey allow simultaneous recording and playback of multiple cameras in real time, which allows security personnel the ability to isolate specific DVRs for dedicated operations without disrupting the balance of the system,â€ she explains. â€œThis is especially important when dealing with systems that employ hundreds or thousands of cameras. Utilizing a series of networked enterprise solutions also provides recording redundancy and reduces the risk of system-wide failure.â€
â€œIn the Wynn Las Vegas, the enterprise recording solution that NAV recently implemented and [had] approved by the Las Vegas Gaming Control Board is the first truly network recording enterprise system deployed in Las Vegas,â€ she maintains. â€œThe enterprise system controls everything integrated to the security/surveillance system â€“ cameras, alarms, doors, POS systems and more â€“ along with the ability to access recorded information and related data via any workstation on the network.â€
How Long to be Stored?Larry Matson, president of Matson Alarm Co. Inc., Fresno, Calif., has worked closely with customers to fit their real storage needs to their budgets.
â€œA lot of customers at first think they can get four or five months of real-time video at a reasonable cost, but these are people who really arenâ€™t yet knowledgeable about todayâ€™s systems â€“ theyâ€™re doing their initial discovery,â€ Matson concedes. â€œTheir expectations may be way out of line with costs.
â€œI had a situation where [the customer] requested an unreasonable amount of storage until they found out how much it was going to cost them, and then they came down to reality and found they could live with 30 or 60 days of storage,â€ he recalls.
â€œSometimes you have to bring them into reality a bit and show them if they really want that storage, we can burn a DVD-ROM and permanently store it,â€ Matson explains. â€œSo we give them some other options if they want permanent storage.â€
Adds Justin Lott, product marketing manager for Bosch Security Systems Inc., Fairport, N.Y., â€œSome people have just been given a magic number of 30 days and thatâ€™s the way it always comes out in the quotes. If youâ€™re dealing with an extremely budget-conscious customer where cost is a major factor, 30 days is pretty affordable with many of the products we have today â€“ even longer if they can manipulate the recorder to record only motion.â€
What Resolution?â€œPeople arenâ€™t concerned about storage because hard drive capacity and prices are dropping so rapidly that theyâ€™ll choose quality of image every time,â€ maintains Gerald Spradlin, CEO of Intellicam Systems Corp., West Chester, Ohio.
Young, of First Service Security Division, points out that storage requirements can be affected by the quality of a video picture. â€œIf youâ€™re using a hybrid system with analog cameras into a digital recording system, if the cameras are set up incorrectly, they generate noise,â€ he explains. â€œThat noise itself will generate additional storage requirements.
â€œSo for instance, you could have a system set up in two identical locations with identical equipment, and if one is set up poorly, that system may require dramatically more storage than another properly set up,â€ he asserts. â€œWeâ€™ve actually set up a test lab so that we can quantify tangible performance.
â€œThis is done for a number of reasons: to determine what the right product is for the job, and also so that we can understand from a price/performance ratio which equipment is performing well, excellently or not performing well at all,â€ he stresses. â€œIt really means that now that weâ€™ve gone digital, the research required is much more involved than it used to be.
Young maintains that performance standards in the industry are â€œeither totally ignored or misunderstood.
â€œAs you speak to different people, youâ€™ll find that everybody has their own flavor of the month, and thatâ€™s because they may never have done testing of the products theyâ€™re selling or representing,â€ he insists. â€œThatâ€™s why we set up the lab situation so we can quantify the performance of digital equipment.â€
Young maintains that specifications for measuring video resolution, such as 480 horizontal lines, 640 x 480 pixels, or 4 CIF do not necessarily give the full picture. â€œWhen weâ€™re specifying a system to a client, we talk in terms of visual resolution,â€ he reveals. â€œWhat that really means is weâ€™re actually measuring the visual details that remain in the picture during playback after recording, which is totally different from format resolution.
â€œTo the best of my knowledge, nobody has determined a simple way of measuring what I like to call dynamic resolution in a digital format, which is visual quality during movement. We have the equipment to measure static resolution,â€ Young notes. â€œWhat Iâ€™m really saying is regardless of the image compression technique used, it should always be quantified from a visual performance standpoint.â€
What Image Rate?Image or frame rates also affect storage. Gareth McClean, director of research and development for American Dynamics, San Diego, part of Tyco Fire & Securityâ€™s Access Control and Video Systems business unit, prefers the term image rate.
He points out that frame rate can refer to alternating half-fields produced by interlaced analog video similar to that used by analog televisions. With these systems, two frames with interlaced lines of video are scanned to produce a single picture. Confusion can arise when 60 half-frames are used to produce 30 whole images per second (ips).
McClean prefers the term â€œimage rateâ€ to refer to a single image whether produced by progressive scanning similar to that used by computers or two half-frames of interlaced analog video. When using the term â€œimage rate,â€ 30 whole images per second produce full-motion video.
However, full-motion video at 30 ips is not used in many applications because 15 ips or less may be sufficient. â€œAround 15 ips starts to look like full motion to the human eye,â€ asserts Ngau of Honeywell. Depending on how quickly people move through a scene, lower image rates may be possible.
â€œItâ€™s tough,â€ Lott of Bosch concedes. â€œA lot of people wanting security applications have a vision of very high-speed video coming in, and then once reality sets in about how much it costs to store real-time video, they start bumping down the frame rates to a more manageable state.â€
Adds Anthony Hong, technical sales/R&D for Vitek Industrial Video Products Inc., Sun Valley, Calif., â€œFor general households or convenience stores, recording rates up to 5 pictures per second would be preferable to extend the recording time. [For] any institution with heavy emphasis on monitoring monetary transactions, such as banks, casinos or check-cashing places, a recording rate of 30 pictures per second per camera is not only strongly recommended, but often is required by law.â€
Some installations at Native American gaming casinos use up to 800 cameras that store their video on 100 DVRs, reports Doug Ankele, product marketing manager for digital video, GE Security, Sarasota, Fla. Each DVR records eight cameras â€“ mostly at 20 frames per second (fps), some at 5 fps â€“ and stores the images for periods from 30 days to 45 days.
Adds NAVâ€™s Freschi, â€œNorth American Video uses varying frame rates for its gaming clients depending on the specific location of the cameras. For example, a gaming camera would be 30 fps, as opposed to a back operations camera, which would record at 15 fps â€“ all exceeding conventional analog recording systems.â€
With digital systems, image rates also can be varied by location, says Ngau of Honeywell. â€œThey might record locally at a high frame rate, such as 30 fps, and then trickle data into another location at 1 fps,â€ he notes.
Spradlin of Intellicam Systems reports his company tracked the frame rates customers were using who contacted his technical support people and begs to differ. â€œAlmost all buyers use the maximum frame rates -- itâ€™s in the neighborhood of 90 percent,â€ he insists. â€œWhat Iâ€™ve noticed is that customers want two things: they want low frame rates when nothing is happening, but when motion detection or an alarmed event occurs, they want that DVR in emergency record mode at high resolution and the maximum frame rates.â€
Bill Stuntz, CEO of manufacturer BroadWare Technologies Inc., Cupertino, Calif., points out that the locations in which video is stored can be diverse. With computer-networked digital video, redundant copies can be stored at lower frame rates at different locations.
â€œYou have quite a lot of choices, and figuring out what you do with the limited capacity of a single box, you sit down and decide what you need to protect your operation,â€ Stuntz suggests.
What Compression?Video storage needs are partly determined by the compression method, something that varies with the age of the equipment and the requirements. Wavelet and motion JPEG are older technologies. One of the newer compression technologies is MPEG-4, which was preceded by MPEG-2.
â€œEach one has incremental improvements in the compression algorithms so you get a little bit better video,â€ explains Ngau. â€œDepending on what your needs are, you may want MPEG-2 or 4 because some are better at compressing complex scenes.â€
Technical considerations, such as how often the image changes, can influence the choice of compression, Ngau asserts. He maintains that MPEG-2 and MPEG-4 can be similar in video quality. â€œItâ€™s an industry misconception that MPEG-4 is better because itâ€™s newer,â€ Ngau insists.
Hong of Vitek agrees. â€œWavelet, motion JPEG and MPEG-2 give clearer pictures, but with bigger file sizes,â€ Hong point outs.
â€œInstead of taking whole pictures, MPEG-4 variants refresh only the parts of the screen that change from one frame to the next,â€ Hong explains. â€œThis type of recording speed and resolution is used mostly when they need the maximum recording speed and longer storage capacity.â€
McClean of American Dynamics points out that MPEG-4 was developed for playback of well-lit movies on video, not for security purposes. The compression method used by his company, called Active Content Compression (ACC), can produce the high-quality freeze frames that often are required to identify suspects and also can deal with poor lighting conditions more successfully than MPEG-4, he maintains.
Additionally, not all MPEG-4s are created equal, points out Perlin at Speco Technologies. The majority of manufacturers who employ MPEG-4 use proprietary versions of it.
â€œEverybody figures they can do better than the next guy, and they tweak it,â€ Perlin maintains. â€œI always ask the file sizes, because to me, the file sizes â€“ how many kilobytes each picture takes up â€“ really tell the story. Even within the same MPEG, youâ€™ll see differences from manufacturer to manufacturer.â€
Ankele at GE Security says that the MPEG-4 compression used by most companies is a proprietary version for authentication purposes so it cannot be tampered with or altered. When sending video clips from his companyâ€™s system to agencies on request, such as police departments, the clip is in its original proprietary MPEG-4.
â€œWe are able to package the video with a mini-player so it is in protected format,â€ Ankele explains. He thinks this results in better quality. The software to run the clip need not be installed on the Windows computer, which many usersâ€™ computer systems do not allow. It runs from the CD-ROM with the clip.
Ankele questions whether smaller file sizes necessarily mean lower quality. It depends on the effectiveness of the compression method. â€œMy 4KB to 6KB file might look as good as somebody elseâ€™s 15KB file,â€ he argues.
As people have come to expect from digital technologies, improved compression methods combined with new hardware, lower prices and increasing capacities should enable the digital video storage systems of the future to match customersâ€™ expectations even more closely than they do today.
Sidebar: The Future of Digital Video Storage TechnologyRobert Kramer, product manager at Panasonic Security Systems, Secaucus, N.J., has specific expectations for future products.
â€œAmong hard disk drives (HDDs), capacities should double in size within a few years,â€ he predicts. â€œLower-power 2.5-in. drives are also increasing their storage capacities, which may enable portable recording devices at lower power requirements, weight and size. SATA 2 drives will allow more video to be recorded at higher image rates.â€
Craig Dahlman, senior product manager for digital products, Pelco, Clovis, Calif., predicts lower prices for storage. â€œEvery day that goes by, the cost per gigabyte changes â€“ typically what you see is larger and larger capacity per drive at less base cost,â€ he points out. â€œThe older drives with less capacity get a lower cost-per-gigabyte over time. So, new technology/higher cost and older technology/lower cost â€“ thatâ€™s what we see in video storage.â€
Anthony Hong, technical sales/R&D for Vitek Industrial Video Products Inc., Sun Valley, Calif., expects better storage hardware to be available in the future. â€œAlmost all of the DVRs are based on HDDs, which were never designed to be used 24/7, 365 days a year,â€ he observes. â€œThis usage results in many failures all across the manufacturers. I donâ€™t care what they tell you, but the percentage is about the same for everybody.
â€œNew HDDs are being developed for DVR usage, but eventually I see the DVRs and the like starting to migrate to flash-type storage devices,â€ Hong forecasts. â€œAs their prices drop, there will be more and more usage of such storage devices. Moreover, the smaller file sizes require less and less storage capacity.â€
Bill Stuntz, CEO of manufacturer BroadWare Technologies Inc., Cupertino, Calif., whose company has supplied systems with up to 45 terabytes of storage, thinks the only limit on storage space is cost. â€œOnce you remove the artificial constraints on storage, then you have to figure out, `How much storage do I really want?â€™â€ he asks. â€œYouâ€™re going to see the amount of video being stored go up and up, not necessarily at increased cost, because the cost of storage is coming down pretty fast.â€
Forecasts Justin Lott, product marketing manager for Bosch Security Systems Inc., Fairport, N.Y., "As compression technology moves forward, weâ€™ll see more people being able to come up to 7 images per second and not be frustrated because theyâ€™re only getting a daysâ€™ worth of recording.â€
Sidebar: Varying Resolution Can Relieve Storage RequirementsA system set up to record using multiple resolutions can ease storage requirements, says one expert.
â€œRecording, local viewing and remote viewing can each be characterized independently. With digital video, you can increase your frame rate and resolution based on an event-driven reaction,â€ says David Ngau, product manager â€“ network video recorders, at Honeywell Video Systems, Louisville, Ky.
For example, a hallway could be recorded at low resolution until someone appears in it. The resolution and/or frame rate then could be increased for that event.
A variation on that method can be used when security guards monitor video live, 24/7. â€œSo they have high-quality video for the security guard, but only record it as time-lapse,â€ Ngau suggests.