Video Authentication

FORENSICS: VIDEO AUTHENTICATION PROCESS

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http://www.primeauforensics.com

In audio/visual forensics studies and application, video authentication is an intricate process requiring extensive training, experience and sophisticated tools and equipment. Add ever-changing technological advances and increased use of recording devices by businesses and the general public – and you begin to glimpse the expertise needed by today’s AV forensics professionals.

This post provides an overview of the process of authenticating a digital video file and videotape for purposes of verifying it as legal evidence. Should you need the services of a forensics expert, Ed Primeau has been a practitioner in this scientific field since 1984 and is a certified digital video forensic expert.

Recording over tapes is a common practice with consumers. It’s also quite common with security camera/surveillance tapes. Repeated over-recording of surveillance tapes is pretty much the norm since the use of new, blank tapes for every recording use would be costly, especially if security cameras are on 24/7. As a result of reusing tapes, videotapes being considered for use as evidence in court must often be examined for authenticity and recording integrity by AV forensics professionals.

The first step in the authentication process for an analogue video tape is to make a copy on the VCR used to create the original evidence. This is called making an exemplar.

VCRs actually have an identity, much like humans do. With people, we identify human characteristics like eye color, hair color, weight, body size/type, DNA, fingerprints. VCRs also have record “signatures” which forensics experts need to examine. Essentially, these identifying signatures or recording characteristics are: stop, start, record, record interruptions and other indications discovered on the tape’s audio tracks.

With video recorders, we identify signature characteristics in several ways. First, there are two distinct audio tracks generated on most videotapes that have replicated (or recorded) images existing on tape formats, such as VHS tape. The two tracks are: (1) Linear and (2) Non-linear. Audio tracks provide forensics experts with much information – as does the video control track.

We begin documenting the identity of the (alleged) recording device or VCR by recording a fresh video test pattern – via an NTSC test pattern generator – and a series of audio tones generated by an industry-standard tone generator. These are recorded onto a virgin (blank) tape.

Hertz frequencies are also examined. Hertz, or Hz, is an audio frequency measurement, similar to decibels (db) measuring audio volume intensity. HZ frequencies examined in forensics generally include 250 Hz, 1000 Hz, 3000 Hz and 8000 Hz. Reading and comparing these frequencies is achieved by use of a computer spectrum analyzer. (Primeau Productions uses an industry-standard analyzer made by made by Sound Forge.)

A comparison analysis is conducted on the exemplar and on the original evidence tape. Note that even if the videotape being examined under forensics scrutiny has no picture, the audio tracks can still be examined for evidence, along with the video’s control track.

Once we have an exemplar made on the same equipment on which the evidence was made, it’s time to address further comparisons.

Video recording signatures (think of them as similar to human signatures) are examined. Stop/start record signatures are studied; record-interrupt distances are measured physically. Developing” the tape itself by applying Krylon magnetic tape developing fluid exhibits the nature of the signature or anomolie. This fluid is amazingly effective in revealing the true recording signature – very similar to how fingerprint dusting powder reveals a person’s fingerprints.

After viewing the entire videotape using the “fast forward” mode, where ever a record interrupt is visually observed, the tape is stopped as near as possible to the exact interruption spot. The tape is disengaged (ejected) and physical exam of the tape commences. Krylon magnetic tape developing fluid is applied to the tape itself to reveal stops in the tape. (See exhibit 1, attached, which is a digital snapshot of a VHS tape “developed” with the magnetic tape developing fluid.

Notice the vertical line straight up the tape. This is where the recording stops.

It is apparent that, due to the region to the right of the vertical line, this tape has been re-recorded over a previous program. The distance between the stop signature and the curved restart signature to the right of the dark region is the gap in the engage mechanism. The curved program continuing would be another straight line of the tape, indicating that recording was stopped then restarted.

When a new videotape is inserted into a recorder, the tape is threaded into the engage mechanism. This places the tape against the recording head; this action actually pulls the tape out of the shell and threads it across the tape head. This process can be recreated if it becomes necessary.

If a recording is stopped, the engage mechanism disengages. If the recording is continued, and the tape is not shuttled, the tape is re-engaged and the recording continues. However, some physical “glitch” will be evident in both the TV monitor image and in the physical examination of the developed magnetic tape. In addition, evidence of this interrupt is often obvious (and substantiated) by examining the control track.

Since Exhibit 1 continues with a curved line, this is an indication that the tape was stopped and the time taken for the machine to disengage and stop recording. This is obvious due to the blank space between the vertical line and the curved record disengage which follows.

After the first identified record interrupt is examined and documented, physical study of the tape continues by repeating the process in search for any other interrupts – re-engaging the VHS tape into fast-forward tracking mode until another glitch is noticed. Naturally, the entire above process of developing and observing is again repeated for each instance of noted interruption.

Next, as required by the scientific community and forensics procedures, the exact length of the videotape must be established. While most videotapes have a time/length stamped on the spine, length verification is needed. The length is imprinted on the spine of the plastic shell that houses the physical tape itself – example: 120 or 160 may be imprinted. However, the stated length must be verified by taking a measurement. This is verified using information obtained using the hours/minutes/seconds display on a well-maintained, professional videotape recorder.

To do this, the tape is completely rewound to the beginning and the tape counter is reset as the start point. Then, fast-forwarding the tape to the end, the digital counter’s reading at the tape’s end point is observed and noted. Now, if the reading on the videotape display count is less than the indicated stamped length, this can be an indication that the tape has been tampered with. If the time is more than what is indicated on the spine, that’s acceptable. (Most tapes are loaded “long” from the factory; a manufacturer’s 120 minute-length tape may actually be 121¼ minutes, or thereabouts.)

Then, using a cross pulse monitor, any glitches discovered on the tape are measured and checked considering other conditions that exist on the tape (i.e., the tape’s “fingerprints.”)

The cross pulse monitor measures the glitches – different electrical and magnetic fields on the videotape – similar to how an EKG records and measures electronic signals from a human heart. Even if there is no video image on the tape, tape signatures can still be revealed during this monitoring test as long as the tape has been recorded on at some point.

Glitches are also examined using a frame-accurate professional tape deck. Since NTSC video (the standard in the U.S.) is 29.95 frames per second, one can observe individual video frames using the frame-accurate machine. If a tape has been re-recorded, a stop signature will be frame accurate (i.e., one frame has an image and the next frame does not).

On the frame-accurate deck, one will notice video frame deterioration over a series of several frames after the stop occurs, the deterioration appearing as “snow,” or video noise, on the screen/monitor. Basically, the image kind of fades out; then we can observe a gradual fade back-in from “snow” to the resumed image that was captured on the tape during recording. (Hence, Exhibit 1’s curved restart of previous recorded program.)

If a recording is stopped, and the tape was disengaged from the tape head then re-recorded, we would notice something very different. Physical examination using the magnetic tape developing fluid would reveal a straight vertical line, indicating the stop, and a straight vertical line indicating the re-start of the recording. A professional, frame-accurate video deck would reveal frame-accurate stop/start with no fade-in. Many of these tests can be conducted or recreated using a professional frame-accurate video deck.

If any frames need to be examined further, the video sequence is loaded into a computer using a professional video capture card, manufactured by Targa. NOTE: Targa is a professional-brand capture card. Off-market and consumer video capture cards are not of the highest resolution; they should not be used when forensics/scientific reliability is at stake.

Once the footage has been loaded into the computer, using the Adobe Premiere program, we can further examine the frame sequence and print out any exhibits as necessary.

Note, also, that videotapes can be physically cut and spliced. Thus, glitches detected during the process will also prompt the forensics expert to examine a tape for physical splicing (as opposed to electronic splicing or edits resulting from re-recording over tape images). A splice repair is generally made with an adhesive-style clear tape on the videotape. To the untrained eye, these could appear to be several scene changes. To the trained eye, these indicate that the tape has been recorded on previously or is possibly a physical splice to be examined.

Note, too, that it’s a good idea to read these and other stop/start signatures using an oscilloscope, as well as physically using Krylon fluid to confirm record-interrupt theories.

Next, all test results must be compared from the original evidence tape to the exemplar test results to determine if both tapes were made on the same equipment. The scientific community requires that forensics experts document all test steps and procedures, as well as equipment type, as in the authentication process in order to substantiate conclusions arrived at.

The digital video examination process uses similar equipment but involves a much different testing process. Digital video files are examined and authenticated based on their chain of custody. The equipment used to create the digital video files must be understood and examined as well. Compression, image rate and codes are also studied as part of this investigative process.

Video Forensic Analysis and Tips

Today, evidence from video recordings plays an increasingly significant role in the criminal justice process. It’s an example of the newer forms of evidence that law enforcement officials take into consideration when presenting facts in court cases.

Video footage from in-car mounted cameras in police cars, security cameras used for businesses, institutions, stores, etc. – plus footage from private citizens – is often surfacing as evidence in legal situations. Perhaps you have convinced your department head or company to install a surveillance system to monitor security situations and possibly detect instances of crime. And perhaps the camera/recorder has captured footage that may be key to a convicting a perpetrator. Unfortunately, during the “discovery” stage of the case, the defendant’s attorney states that something happened to the video recording; there is a glitch. He announces that a forensics expert is now on his defense team to prove that your video has been falsified and/or inadmissible.

This brief article covers video forensic examination tips that may keep your recordings glitch-free. If you are involved in video recordings that can be used for legal evidence, this article may save you from having your evidence challenged in court.

As a Video Forensic Expert, I’m often hired by law enforcement officials, attorneys and corporations to report on the methodology used in videos cited as legal evidence. As part of my work, I review many resources, like police chase footage, hidden-camera coverage from workplaces, retail store surveillance footage, and so on. The question I’m most often asked is to respond to is: “Was this video recording edited or altered in any way?”

To respond to this, forensic experts must gather scientific clues to answer the following questions:

• What do we know about this recording to be true (within a reasonable degree of professional certainty)?
• On what type of equipment was the video recording made?
• Is the original recording of the video available for examination?
• Is the original recording equipment that made the tape also available for examination?

While extensive technology is certainly involved in the video recording process, and this article cannot begin to address it fully, here are theories/procedures regarding examination which provide an overview of how forensic experts may need to examine and identify video anomalies.

Anomalies are abnormalities, deviations or “breaks” in the recording process as evidenced on the physical tape or digital video file. These aberrations can impact the legitimacy of a video (digital or analogue) as a piece of legal evidence.

Digital Video
When a videotape recorder or digital video recorder (DVR)/video camera records to videotape or DVR, the recording process creates a very structured format of code and information that is embedded on the tape or hard drive to create pictures and sound and signals. (Note, all videotape, except ¾” format video, travels from the left spool to the right spool when the machine is in the “Record,” “Playback” or “Fast Forward” modes. DVR recordings store video signal on hard drives using proprietary codecs or code and compression).

Digital video requires a different forensic process than analogue. Instead of recording the video image on tape, digital video is recorded on computer hard drives or digital video recorders (DVR).

Video systems that record digital video have several variable settings like frame rate and recycle time. If you look at the video below, you will better understand the importance of frame rate and forensic examination. Some officials and owners of digital video systems choose a lower frame rate to save on hard drive storage space. This makes it difficult for the forensic examiner to authenticate and identify events in question on the video recording. It is more efficient and effective for closed circuit television (CCTV) owners or purchase additional hard drive storage instead of choose a low digital video frame rate.

There are also several manufactures of digital video CCTV systems making it necessary for the video forensic expert to review operators and installation manuals for each system. I have been certified by the Pelco Global Institure in digital video and understand the details of digital video systems and the processes necessary to investigate digital video surveillance footage.








Analogue Video
On analogue tape, at the bottom of the tape (running just parallel to the tape edge) is the control track, or recording signature. Just above the control track is the composite picture and audio signal. On hi-fi VHS video recorders, above the composite signal, there are the hi-fi tracks. These are the physical areas of the recorded tape that forensic experts look at to determine if glitches – or anomalies, as they are professionally termed – exist.

There are two types of anomalies: non-destructive and destructive. A non-destructive anomaly is any deviation from the normal events one would expect to see and hear when viewing a videotape. In other words, a non-destructive anomaly or glitch in the tape could be an edit, an indication of a record interrupt or an over-record (recording over a previously recorded tape or segment of the tape).

When examining a tape for anomalies, the forensic expert must take all things into consideration. For this reason, it’s strongly recommended that the examination start by determining the origin of the recording device. If the machine that made the recording is available, a test recording – or exemplar – should be made using blank, unrecorded (virgin) tape. The goal here is to gather information on the alleged machine signatures from the original recording device used – that is, signals from the control track and the stop and start signatures. This is done for comparison purposes and to identify facts that may exist about the anomaly.

Next the tape being examined – i.e., the evidence or the alleged video containing the in-question anomaly – is viewed in “Play” or “Fast Forward” mode to determine the number of deviations or anomalies. Each deviation is carefully noted and examined using test equipment that helps to determine the characteristic of the anomaly. Much like the medical profession uses testing to research and document the reason for an illness, diagnostic tests are also necessary for forensics professionals; testing will eliminate certain factors so that real facts can be isolated to conclude, to a reasonable degree of professional certainty, the source or cause of the anomaly.

Many times it is necessary to physically examine the tape at the actual spot where the anomaly exists. An expert will physically examine the videotape itself to accomplish this, applying a special, non-destructive liquid to the tape which then develops the digital information so it can be reviewed. (This is much like how a photograph is developed, applying developer chemicals to the film.) Once the tape is “developed,” the expert can continue with the physical examination processes.

For a jaunt back in history – yes, in the “olden” days when I began my career – video recording tape was not yet in plastic shells but rather on spools, making it fairly easy to physically review the tape; but it was also quite easy to damage the tape’s edges since the tape was a good deal more exposed to mishandling. Videotape edge damage is considered a “destructive anomaly.” This damage can be in the form of a crease, tape crinkle, the result of a liquid spilled on the tape, etc. Of course, this can still occur with today’s videotape, even in the protective shell or tape housing, but not as easily.

Also, back then, videotape was comparatively more expensive than it is now. Thus, videotape was quite often recycled and recorded over for economy’s sake. As you might imagine, anomalies were fairly prevalent in those years. In one respect, this was good for my skills development as a forensics expert since I had the opportunity to experience dozens and dozens of destructive anomaly situations during the late ‘70s, for instance. This permitted me to gain great insight into their cause and nature.

When videotape started to be enclosed in cassette-styled plastic housings as VCRs gained in popularity, it became a bit more difficult to physically examine tapes for anomalies. So the scientific community evolved accordingly and developed new ways of testing.

Once you understand the science of how video recording works, how recordings and devices can be distinguished from each other, you’ll have a better understanding of how to go about identifying anomalies. I encourage you to read up on today’s video technology to advance your knowledge.
(You may also wish to refer to another article, “Forensics: Video Authentication Process,” included on this website.) Meantime, for simple practice in identifying anomalies, try creating your own:

Take a tape that has been previously recorded over. Fast forward the tape to about 10 minutes in and record something new, getting about 30-40 seconds’ worth. Rewind the tape and review your “over-record” characteristics. Take note of how the over-record starts and how it ends. These “in and out” points are characteristic of the equipment on which you recorded the program.

Of course there are many other forensic aspects in the study of anomalies –examination of stop/start record “signatures,” record-interrupt distances on the tape, study of the audio and video tracks, control track examination, application of magnetic tape developing fluid to further detect anomaly conditions – to name key areas.

But getting back to what’s most likely your interest in uncovering reasons for an anomaly, this works down to two essential questions: Did it occur as a result of wishing to intentionally cover up something? How do we know it wasn’t an honest mistake? And finally: Can we recover the images and sounds of the previously recorded material?

The answer is no. Once original material has been recorded over, it’s gone forever. But, as mentioned, the machine control track, audio tracks, etc., can provide recording “signatures” that exist on the physical tape; these may contain the clues toward determining others certain “truths” about the over-record. Our article on “Video Authentication Process” provides added information on these points.

When dealing with a video recording device and tapes that may be needed to substantiate legal situations: Make sure your equipment is cleaned and well-maintained and do not use videotape that has been recorded on previously. Use a new tape.

With the main investment already made in video equipment, the slight cost and effort to maintain that equipment – and the nominal cost of fresh tape stock for all recordings – is well spent. Having a clear recording on new tape stock (which avoids pre-existent anomalies that would exist on recycled tape) is an inexpensive way to better ensure your videotape evidence is solid and will be less apt to be court-challenged for authenticity.

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Closed Circuit TV Video Problems and Solutions

By Edward J Primeau, RI

As a video forensic expert, I have seen almost everything when it comes to Closed Circuit TV. Some of it is very disturbing, but much of it is benign -- from the lady whose ex-husband is stalking her, to the bank that just captured a robbery on video. Understanding CCTV systems has become part of the video forensic examiner’s job because a majority of video evidence is made on CCTV systems. In the following article, I will give you my tips, from a forensic perspective, on CCTV.

Imagine this. You are the proprietor of a convenience store. Last night at 11:06, you rang up a customer’s Snickers bar and a Jumbo Slurpee. The customer reached in his pocket, pulled out a gun, and put it to your head, demanding all the cash in the register. Terrified for your life, you gave him the money. Luckily you had a CCTV system and turned the tape over to the police. The police sent it to a forensic expert because all you could see on the tape was a dark silhouette of the criminal. Unfortunately, the robber’s face and features were unidentifiable.

Although CCTV systems can prove to be beneficial for many reasons, they can be useless without some well thought out considerations. My hope is that the law enforcement and legal community will read this article and pass on the information to the businesses in their community.

CCTV is a network of cameras hooked to a monitoring system so that various locations or angles can be viewed and/or recorded. It does differ from broadcast television in that CCTV cameras are not openly broadcast through the airwaves. However, some CCTV systems have point-to-point transmissions (wireless cameras) that could be intercepted by someone with the equipment and knowledge to intercept that signal.

The benefits outweigh the drawbacks for implementing CCTV systems for several reasons. Think of how CCTV systems have helped our traffic problems. Having cameras all over our roads and highways allows accidents and traffic jams to be discovered sooner so traffic can be rerouted. In banks, casinos, airports, shopping centers, businesses and military bases, CCTV systems can prove beneficial against crime.

There are some drawbacks that can really cause problems with CCTV systems.

These systems can be expensive. They can be considered an invasion of privacy. Also, a system can fail because of a bad or over-recycled tape, and the crime will not be recorded.”

For some strange reason, businesses who still use VHS tape to record their surveillance often insist in recycling their videos beyond a logical limit. Then, when the expert needs to lift an image off for identification, fuzzy, blurry photos are produced.

In the convenience store example above, the camera was in the wrong position. A light was installed in a recently added display that was not in the store when the CCTV system was installed. Nobody ever updated the CCTV system or performed maintenance to discover the problem.

The purpose of this article is to share some of my experiences with CCTV footage and provide some tips from a forensic expert’s point of view, sound advice to avoid costly mistakes and expensive forensic restoration.

Number one: Plan your CCTV system layout in advance. Do not put in a CCTV system without planning for your potential crime circumstances. What crimes could be executed under the watchful eyes of your CCTV system? You can call this crisis management. Draw a diagram of this activity, and use it as your blue print for locating your camera positions. If you own a business that has a back lot to cover, don’t just mount a camera to the back of your building, thinking it will do the job. Consider what you have to protect, the value of these items, and the various ways a criminal could get at them. Then, place the camera (s) to cover all potential activity. Consider multiple cameras because, in the long run, it will save you money.

Because so many systems were not planned thoroughly in advance, the majority of my forensic cases involve video restoration and clarification. So much of this can be avoided.

Number two: Use a digital video recorder and record direct to hard drive. If at all possible, do not use VHS . There are some great companies like Focus Micro and Crest Electronics who specialize in DVR CCTV systems, maintenance of the system, and training your staff to use them properly. They offer some excellent products and CCTV systems, and will even help you plan your system layout.

Number three: Make sure to account for lighting conditions as well as sun positions.

About one out of ten of my cases require comparison of a frame of evidence from darkly lit video with an exemplar frame or photo. Make sure there is light where your camera is located. If necessary, hire an electrician to put in a light or two near your camera, especially if the potential crimes that warrant the installation of your CCTV system can occur at night. Duh! I can hear the installer now, “Sure looked good in daylight”!

In addition, consider sun positions all year long. Remember sixth grade science class? The sun changes positions with the seasons. Bright sun facing the camera will cause the iris in the camera to close (in automatic position), causing the image of the perpetrator to darken. Try this with your home camera. Take a video of your friends with the sun behind them instead of behind you. The friends will appear dark because of the camera’s lenses adjusting for the high light level.

Number four: Plan camera positions for all possible situations. I have heard it said that if you want to rob a bank, wear a baseball cap. Why is it that CCTV installers put the cameras in high positions that will never show a criminal’s face?

Number five: Keep your camera clean. Car dealerships wash their windows and cars weekly if not more often. Why don’t they wash their cameras? Think about it. Many outdoor cameras are somewhat protected from the elements, but after awhile, dirt will still gather on the surface of the camera lenses.

A solution of Shaklee basic H or white vinegar in hot water will clean them nicely without scratching or clouding the lenses or protective housing. Harsh cleaning chemicals can scratch or cloud the glass, especially on Plexiglas camera housings.

Number six: Do not use wireless cameras. If at all possible, run cable and go wired for your entire network. Wireless cameras are unreliable, especially in storms.

Almost all maintenance can be performed by you or done very reasonably by a professional. Avoid costly mistakes and tragedy by keeping your system maintained and updated. (Use Google to seek a professional in your area who can help with your circumstances.)

Ed Primeau is a video forensic expert, Author, professional speaker and business owner in Rochester Hills Michigan. He is the author of two books, “The Art of Production” and “The Video Revolution”

email Ed@PrimeauProductions.com 

800-647-4281 

Video Forensics "Caught on Video"

CAUGHT On Video
Cameras, Computers and Control; Convenience or Conspiracy

Edward J Primeau
Primeau Productions Inc.
www.VideoProductionPrimeau.com
Free consultation 800-647-4281

Abstract
This article takes an insider’s look at the ever-expanding role of security cameras and surveillance video in contemporary society – as a means of monitoring public activity and offering protection to its citizens. I provide a basic overview of the various types of surveillance applications, and compare their functional capabilities – their strengths and weaknesses. I also examine the role of surveillance video in litigation, and the many issues that can arise from its use as evidence in a legal proceeding. Finally, I offer my insights into the ways surveillance video and other monitoring devices will likely play a far larger role in our lives in the future.

March 11, 2009
Copyright © March 11, 2009
Edward J Primeau


Learning Objectives
This blog will help the reader understand closed circuit television systems, the ways they deter crime and help secure businesses, institutions and communities. This article also helps criminal justice personnel to understand the power and potential of video security systems to secure the truth of an investigation or traffic stop and communicate the circumstances surrounding that event in the court room. Another learning objective is to help the reader understand other uses for CCTV systems beside security and helping fight crime. Help the reader understand the difference between analogue and video closed circuit television systems and provide examples of how CCTV systems are used. The reader will learn about video evidence, understand how to handle video evidence should it become necessary and how to preserve the chain of custody for digital and analogue video forensic evidence.

The next time you walk down a city street, take a look around you and notice the number of video cameras and motion activation devices present that help control traffic, regulate complicated machinery and deter crime. They’re right there next to the street lights and traffic signals. Government buildings, police cars and even shopping malls use video surveillance equipment in many ways. This same equipment used to control and regulates traffic flow and machinery is known as CCTV video systems. One purpose is to regulate and another is to deter.

It is interesting that criminals have become aware of CCTV systems and consider the cameras when planning their strategy for a criminal activity.
CCTV is a visual assessment tool. Visual Assessment means having proper identifiable or descriptive information during or after an incident. These systems should not be used independently from other security measures. Identification goals to consider when implementing a CCTV system:
1. Personal Identification: ability of the viewer to personally identify something within the scene, beyond a shadow of a doubt. This does not reflect human identification, but rather, the ability to identify specific information or objects within an image.
Personal identification has two very important phases: The relationship of size and detail of an image, and the angle of view from which the scene is viewed. Without careful consideration of both aspects, your CCTV system merely records useless, unidentifiable images.
2. Action Identification: ability of the system to capture the events occurring in front of the camera as they actually happened. Because of the need for accuracy, using time-lapse video could cause problems. For example, if using a digital recorder or DVR, with a low image per second frame rate setting, some images may not be captured on the recorder. The lower frame rate setting is desired by many digital CCTV system users to reduce storage requirements of surveillance video on hard drives. The upside is with the cost of hard drive space becoming more economical, digital CCTV systems should be upgraded so the images per second feature can be increased and more surveillance video stored for review should it become necessary. On the Primeau Productions You Tube page, there are video examples of this frame rate scenario.[1]
Another problem in the analogue systems, when a Multiplexor switches between cameras for viewing different areas under security, an activity could occur at one of surveillance areas while that camera is off and another is on. Multiplexor’s are like video switchers, they periodically switch cameras to view by security personnel. The output of the multiplexor is most always recorded to a time lapse video tape recorder using ½ inch tape stock.
3. Scene Identification: ability for the scene to stand on its own merit. In a building with many similar hallways, equipped with surveillance cameras having similar angles of view, how can the hallways be differentiated when a CCTV monitor or tape is viewed? If an action is being recorded, how can each hallway be distinguished from the others? Scene identification is an important, but often overlooked, form of identification vital to effective video systems.

There’s no margin for error when it comes to public safety. Metropolitan police departments all across the country are doing their best to deter criminal activity. When it can’t be prevented, the agencies want to apprehend and help prosecute the perpetrators. With human resources stretched thin, video surveillance has become a critical tool in the war on crime; it puts thousands of extra “eyes” on the street 24 hours a day, seven days a week.

Insight Video Net, LLC (IVN) has emerged as a leading provider of digital media software and services to capture and manage video, especially for the public safety market. IVN has developed software called the Central Management System, or CMS, to store, retain and manage the video that comes from “fixed” as well as “mobile” cameras. CMS makes sense of huge amounts of raw video and turns it into indisputable evidence admissible in court.[2]

Cameras in public have become a way of life and we have grown to accept them and are use to them. In a city environment, a camera is connected to a closed circuit video television system hence the term (CCTV). This system has the ability to regulate the traffic by adjusting traffic signals according to traffic conditions.

In law enforcement, video recording systems are installed in most police cruisers and help bring accidents, drunk driving and other traffic stop situations into the court room. Video forensic experts help courts understand video evidence and video evidence admissibility.

From high tech tom low tech, CCTV systems come in many shapes and sizes and wired and wireless combinations. Two manufacturers of high tech systems are Pelco and IVC. [3] Less complicated systems are manufactured by Fairfax Electronics and Safe Mart. [4]

Pelco has one of the largest CCTV systems is in place in the Denver, Colorado. It is one of the most intricate and largest CCTV systems in place in a city today.
The Denver system manufactured by Pelco is comprised of hundreds of closed circuit cameras in dozens of municipal locations both indoor and outdoor and all connected to a very large computer that can be monitored in many different locations.

IVC also specializes in multi-site video networks with remote access to live and stored video and equipment activity.

CCTV systems play a major role in healthcare organizations and hospital operations. Medical practitioners rely on CCTV systems to critical care units under observation 24 hours a day seven days a week.

It is this author’s contention that:
1. Within five years, every major city across America will have a surveillance system similar to Denver’s in place as well as surveillance systems that will require Video Forensic Consultants involved in litigation to help courts understand the evidence being presented.

2. There are three primary drivers of video surveillance.
a. The ability to control access to areas that have restrictions, i.e., birth centers, emergency departments, pharmacies, surgical areas.
b. The ability to deter crime
c. The ability to record data and measure statistical information over a period of time.

3. General surveillance for after-the-fact (Forensic) investigations will continue to play a major role in litigation.

4. The ability to activity for security and non-security purposes will save institutions substantial amounts of money annually[5].

Through service agreements, a $2.5 million performance contract, and ongoing support, Johnson Controls has helped WJMC reduce operating costs, improve comfort conditions for patients and staff, enable facility personnel to be more efficient, and significantly
Reduce energy consumption. In mid-2007, WJMC became the first hospital in Louisiana to earn an ENERGY STAR® from the U.S. EPA. In addition, Johnson Controls has helped the hospital to improve ventilation, maximize the efficiency of a new central energy plant,
Manage utility bills effectively and continuously improve facility management practices.[6]

In an interview between Pelco (A global leader in CCTV systems) and Tony W. York, CHPA, and CPP, Mr. York stated:

“Video security is a fabulous tool, when it is integrated with door and alarm controls, inventory tagging systems. Another thing that is really important is the retrieval of the captured video, which provides instant access for those after-the-fact investigations. I would call it revolutionary”.[7]

Concerns over violent crime and civil liability lawsuits have caused schools, large corporations and small businesses to investigate avenues for securing their operations. Closed Circuit Television (CCTV) systems are a popular security tool to combat such problems.
Computer graphics digitally placed on the monitor and video cannot be relied on to provide the sole method of scene identification. These graphics can aid in identifying one scene from another when both have a similar angle of view. Without being able to identify the scene on its own merit, it would be easy to argue that the graphics were added to the tape after the fact.[8]

Preventing crime may be a goal but is not always the result of the billions of dollars worth of closed circuit television systems in use today. Often times the video footage retrieved from CCTV systems adds a degree of perplexity to due process.

Video surveillance evidence has the potential of lengthening a litigation proceeding beyond that same proceeding without video evidence.

It takes additional time and manpower in the legal system for clerical, administrative and legal to have a video forensic expert examine video evidence as well as the video expert. This evidence is either analogue (becoming extinct) or digital.

Motions have to be filed in court for an expert to be able to examine the evidence which adds time and expense to the case. Experts often have to travel to the evidence as law enforcement is often skeptical and reluctant to release video evidence in fear it may become damaged or lost in transit. Authorities must maintain a chain of custody with video forensic evidence the same way they would with any other forensic evidence.
This consideration adds time and cost to a case that has to be paid. Often times it is the court, public defenders office or another branch of government that absorbs these costs in criminal matters. Other times it’s the defense or plaintiff in a civil matter who will incur the costs of having forensic video evidence authenticated and admitted into the courtroom.


As a video forensic expert, I have testified in cases where analogue (VHS) as well as digital video evidence was used. Both require a different methodology for examination and authentication. Every case I have testified in is unique and each judge overseeing those cases has reacted differently to the video evidence presented.

Many courts do not understand video forensic technology which is why it is sometimes looked at as a junk science. However, In an April 12th, 2005 article, the New York Times reported “400 court cases dropped or acquitted because of VIDEO EVIDENCE contradicting POLICE LIES”.[9]

The courts that accept video evidence supported by a video forensic expert are usually those that involve an experienced trial attorney. So when presenting video evidence today, analogue or digital, admissibility boils down to the arguments of admissibility given by the presenting attorney. When accepted, video evidence can help a jury understand a crime scene or situation more clearly.

Digital video evidence has a better chance of admissibility in court if the evidence follows a chain of custody protocol. Just like other evidence in a crime, law enforcement personnel are responsible for witnessing the exporting of the video evidence and delivering to evidence police lock up for examination by a qualified video forensic expert. Analogue tapes should also be picked up by law enforcement and taken to police lock up for future examination by a qualified video forensic personnel.
Often times, each party in the litigation will hire their own video forensic expert. For example, in criminal cases, the police have crime labs that employ forensic video experts and the defense seek outside expert assistance.
In Civil cases, each party will often seek a forensic expert depending on the position of each side with regard to the video evidence. One example would be authentication and another would be admissibility.

Closed circuit TV, crime scene recreation video and cruiser traffic stop footage as evidence has become an element in litigation virtually overnight. Law enforcement agencies and our legal system have come to accept video as evidence in the courtroom and have become accustom to video forensics as a legitimate science.

Unfortunately, those engaged in legal proceedings from time to time try to alter video evidence in their favor which is where the science of video forensics becomes a value to the legal proceeding.

There are two recording formats for Closed Circuit TV security systems CCTV:
1. Digital is video recorded onto a computer hard drive
2. Analogue is video recorded onto a magnetic tape

A CCTV system is a closed circuit television security system that employs cameras and either an analogue tape based recorder or digital computer or DVR-digital video recorder- based video recorder. Both record camera views onto their system and store them for later viewing, reviewing or in the case of a crime committed, identifying.

Multiple cameras can be installed at a large or small location and viewed as well as recorded simultaneously on either analogue or digital format. Analog incorporating multiplexers, digital incorporates software programs.
The more sophisticated systems like the ones Indianapolis manufacturer Pelco carries, and has in place in Denver, have many adjustments, settings, frame options and video export options as well as signal routing features. The lower end VHS systems are pretty straight forward and easy to operate but have less features and options. Both systems can incorporate point, tilt zoom or steady non moving cameras. The point tilt zoom cameras (PTZ) can move to follow action both automatically and manually. This activity can be operated by security personnel manually or through a technology of motion activation that detects the change in gray scale in the dedicated area. In the second situation of motion activation, the PTZ camera will be activated and follow the motion as it occurs.

Non moving cameras capture the area under security in a stationary fashion. The advantage to DVR’s is that the quality is far superior to analogue especially when images must be retrieved for identification purposes or crime scene recreation. Digital formats add compression to the CCTV video which decreases the size of the video files allowing more video to be stored in the DVR.

Some video evidence in cases where analogue video was used as evidence was recorded on time lapse VHS tape which has been recycled many times. The examination and authentication process requires a different process to authenticate than digital video. Only Hollywood can produce a high quality image from a worn out pixilated (give a definition) time lapse, low resolution analogue video tape of the suspected crime.

When you factor in how much money it could cost to recover from the crime, pay a forensic expert to try and recover an image, purchasing a digital CCTV system is a much better investment and will produce better forensic results.

Tape or analogue systems often fail to show useable evidence in a court of law. The main reason is because tapes are recycled over and over and even accidentally erased.

Once a crime has been committed and caught on a digital recording device (DVR), a back up digital video can immediately be made of the crime using digital video technology. This back up video often called "book marking" or an” Alarm File" which is immediately taken out of the normal refresh cue and stored in a safe area for further forensic examination.

When analogue video is entered as evidence, the court or police make copies for all parties involved in the litigation. Those copies experience generation loss, similar to making copies of a document on a copy machine. Additionally, when storing analogue video with repeated playing often has degradation to the original crispness of the image on the video tape especially if the tape has been recycled which is often the case. It is much more difficult and expensive to create an image from a 75 dots per inch analogue recycled tape than it is to create an image from a 300 dots per inch digital image. There is no comparison. The digital video proves time and time again a much clearer image.

Think about a crime free society using closed circuit television systems. These security systems reduce the potential for crime in your business, institution or community. There are bleeding edge closed circuit television systems that can increase security, reduce loss and prevent crime as well as control intricate machinery and just about other activity you can imagine. Closed Circuit Video Surveillance is once step closer to having a crime free society safely operating businesses, schools and institutions.


Side Bar:
Here are some suggested maintenance tips for both Analogue and Digital CCTV systems:
1. Clean your camera lenses and weather proof housings often. This will help produce clearer video when you need it.

2. Outdoor cameras and weatherproof housings can become especially dirty and be moved by birds, weather and other unexpected elements. Housings have seals that can become worn out and break to let in vapor that can blur video images.

3. Test your digital or analogue recorder monthly to assure all cameras look good and are pointed at the appropriate areas and replace any poorly functioning cameras or recording equipment.

4. Clean the tape heads of your analogue video record deck with a head cleaner that can be purchased from Radio Shack or on line. In addition, it is also necessary to have your analogue record decks serviced annually. Since they record virtually non stop, the record heads become magnetized from use. Servicing will demagnetize your analogue video recorder tape heads and remove magnetic build up that can cause poor record quality.

5. Prepare for a new world of technology in video evidence. Upgrade your current systems to digital and become familiar with forensic experts who can help you understand video evidence in legal matters.





References

[1] www.YouTube.com/PrimeauProductions
2 Copyright © 2007 Pivot3, Inc. All rights reserved.; specifications subject to change without notice. Pivot3 RAIGE is a trademark or registered trademark of Pivot3. CS IVN V2.1 June 2007
3 www.Pelco.com www.IVCCO.com
4 http://www.at-fairfax.com/ http://www.safemart.com/
5 High-Tech Prisons: Latest Technologies Drive Cost Savings and Staff Efficiencies
By Hodgson, Glen Publication: Corrections Today http://www.allbusiness.com/technology/974661-1.html
6 Case Study West Jefferson Medical Center, Marrero Louisiana-http://www.johnsoncontrols.com/publish/etc/medialib/jci/be/case_studies.Par.42109.File.tmp/WestJeffersonFINAL.pdf
7 Pelco interview with Tony York taken from www.Pelco.com
8 The Professional's Guide to CCTV: Application and Design of CCTV, written by Charlie Pierce, was used as a reference source for this summary.
9 By JIM DWYER The New York Times April 12, 2005





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[1] www.YouTube.com/PrimeauProductions
[2] Copyright © 2007 Pivot3, Inc. All rights reserved.; specifications subject to change without notice. Pivot3 RAIGE is a trademark or registered trademark of Pivot3. CS IVN V2.1 June 2007
[3] www.Pelco.com www.IVCCO.com
[4] http://www.at-fairfax.com/ http://www.safemart.com/

[5] High-Tech Prisons: Latest Technologies Drive Cost Savings and Staff Efficiencies
By Hodgson, Glen Publication: Corrections Today http://www.allbusiness.com/technology/974661-1.html

[6] Case Study West Jefferson Medical Center, Marrero Louisiana-http://www.johnsoncontrols.com/publish/etc/medialib/jci/be/case_studies.Par.42109.File.tmp/WestJeffersonFINAL.pdf
[7] Pelco interview with Tony York taken from www.Pelco.com
[8] The Professional's Guide to CCTV: Application and Design of CCTV, written by Charlie Pierce, was used as a reference source for this summary.
[9] By JIM DWYER The New York Times April 12, 2005