Exciting (and Cautious) Times for DVR Technology

A few years ago, I remember telling myself that digital video recording technology would be exciting if a few significant drawbacks could be remedied. The process had to be faster, more digital memory was required, and CCTV systems needed to truly become digital rather than simply converting digital camera sensors to analog coax and then back to digital. I am happy to report that all of my reservations are being addressed.

In fact, DVRs are now becoming the norm rather than the exception. However, along with this comes the understanding of what is and is not acceptable in digital video technology. As you will see, the professional security world has learned some serious lessons in its blind acceptance of DVR technology.

New Acronyms Around Every Turn
Just when we got used to the acronym DVR instead of VCR, the term NVR cropped up. Many times, manufactures like to create new terminology just to make their product unique, at least for a short time.

Network video recorders will accept direct digital and network camera feeds from a network, whereas a DVR typically accepts only BNC-type analog connects via coax. Additionally, I have started to see the term DVMR (digital video motion recorder). This represents DVR systems that have video motion technology built into them or into the manufacturer’s software. Look for how well the motion algorithms can adapt to constant motion, such as trees in the wind. Also check out how well and fast you can search through recorded video using video motion detection.

Resource Management Is Important
As more demand gets placed on DVR systems, the management of processing resources becomes very important. Intelligent graphical software, such as the screen shown at left from manufacturer Blancom, can help administrative personnel better understand the demand being placed on a DVR system’s resources.

In the diagram, the red region indicates the current computer’s central processing unit (CPU) load, the green area shows the amount of free storage, and the blue section represents the average system load (engage memory, CPU load, number of programs running, hard-drive load). The areas of yellow and white are the outcome of other colors mixing.

Look for the overall trends in performance graphs. In this diagram, initiating playback causes the first red peak as the video database is loading. Notice that the green area (free memory) has decreased. The average system load (blue) has increased because of the video base loading and increased hard disk load. As a result, you see the purple color (overlapping of blue and red). The purple color period is brief due to rapid loading of the video base.

The second red peak is caused by repeated playback initialization and searching motion. The motion search lasts a bit longer and the larger blue area shows the additional demand placed on the hard drive. Once the motion search is over, the system load returns to normal.

Some DVR systems, such as Blancom’s, have also improved their operational performance by using a Linux-based operating system rather than Windows®-based. Linux has proven itself in many ways and has gained the reputation of being a “crash-proof” operating system. It is the choice of IT professionals for their network server operations.

Since Linux is an open source operating system, cost can be saved in licensing and upgrade fees. Linux has also been found to provide a good defense against viruses.

Good Evidential Images Paramount
In my past writings, you have heard me emphasize that the most important thing a DVR system can do is provide “good quality evidential recordings” for use in a legal courtroom. This is why many legal entities refer to video as the “silent witness.”

However, the improper use of digital recording technology has created a bad reputation in the legal and law enforcement community.

One good example is the creation of incomplete digital records, better known as digital artifacts (see photo on page 23 of January issue).

These concerns have been reflected by the Law Enforcement-Emergency Services Video Association Int’l (LEVA), a professional organization of video forensic law enforcement officers. Also showing concern is the International Association of Chiefs of Police (IACP). In fact, most police departments now have officers dedicated to the gathering of video evidence for crime investigations.

A good example is the fast work that was made in gathering evidence recently in the London terrorist bombings. It is because of results like this that forensic officers are now making databases of known video recording sources, such as gas stations and convenience stores, to quickly gather video evidence when a crime has happened.

This brings up another point: How well do your DVR operations people know how to reliably extract digital video from your DVR system? Can they quickly provide law enforcement with a good exact copy of your video? Can you show a documented trail for this video evidence? Can you prove that the copy has not been tampered with? Can police officers play back the video, say on a DVD or CD, at their office? Can you provide a series of still images from the original clips?

The kicker is if a serious crime has been committed and you cannot answer “Yes” to the above questions, the police may either confiscate your hard drive or even confiscate your entire $10,000 DVR. If the police are not confident you can provide them with a good exact copy of the digital video evidence, they will do the next best thing and seize your entire system. You will get the system back after all court cases and appeals have run out. That could be years away.

As I have stated in the past, take a moment and see what your local jurisdiction requires as far as video evidence BEFORE you get your DVR system. They will be glad you talked with them.


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