Archive for February, 2011

Digital Video Formats: CODECS Compression and CCTV Video

Sunday, February 27th, 2011

CCTV VideoDigital video is also involved in many litigation cases and is quickly finding its way into court rooms around the world.

In the following paragraphs, my goal is to help you understand digital video with regards to closed circuit television systems and its many formats.

In its simplest terms, digital video can be defined as a video that has been recorded using a software program and digitally stored in a computer. A CCTV system is a computer. That digitized information can be controlled from a computer and displayed directly on a computer monitor.

All current digital video file formats, which are listed below, are PCM or Pulse-code modulation based PCM is a digital representation of an analog signal where the magnitude of the signal is sampled regularly at uniform intervals, then quantized to a series of symbols in a numeric usually binary code based.

Here is a brief catalog of digital video file types so you better understand how digital video is used.

CCIR 601 (or RE 601) is a digital video file used for broadcast television stations because of the analogue and digital television conversion. This digital video file format converts and encodes interlaced analogue video signals into digital video.

In the old days, television commercials were distributed at first on analogue then digital tape. Today, TV commercials can be distributed over wireless networks electronically using digital video technology.

Services like SpotMixer allow businesses to create their own commercials on line and distribute them over a plethora of media including television and the internet.

MPEG-4 good for online distribution of large videos and video recorded to flash memory. This is a digital video format used for video IPods, uploading to YouTube and other social media networks, but keep reading.

MPEG-2 used for DVDs is a digital file format used to make DVD’s. An MPEG-2 digital video file burned onto a DVD will play video on a DVD player as well as computer provided the computer has the ability to play DVD’s. Some computers with older DVD technology will have difficulty reading newer DVD technology burned DVD’s.

MPEG-1 used for video CDs and was the first digital video format that was mass marketed. It is rarely used today but occasionally pops up. Many DVD players will play MPEG-1 but not all can read this digital file format.

H.261 was the first truly practical digital video coding standard. In fact, all subsequent international digital video encoding like MPEG-1, H.262, MPEG-2, H.263, MPEG-4, and H.264 (MPEG-4 Part 10) have been based closely on the H.261 design which is seldom used any longer.

H.263 is a video codec standard originally designed as a low-bit rate compressed format for videoconferencing. H.263 has since found many applications on the internet: much Flash Video content (as used on sites such as YouTube, Google Video, MySpace, etc.) is encoded in this format.

The original version of Real Video (which I recommend you run away from) was based on H.263 up until the release of Real Video 8. In other words, I tell you about H.263 so you can see the legacy.

H.264 also known as MPEG-4 Part 10, or as AVC is the next enhanced codec developed for sharing digital video on the internet. H.264 provides a significant improvement in capability beyond H.263, the H.263 standard is now considered primarily a legacy design (although this is a recent development).

Most new videoconferencing products now include H.264 as well as H.263 and H.261 capabilities. Primeau Productions uses H 264 digital video in a Quicktime format to send to webmasters for use encoding Flash video on our client websites.

Here is the bottom line. The above digital video files are created using in computers including CCTV systems and can be viewed with video editing software and digital video file converters.

H.264 technology is an excellent beginning file format for creating Flash video. Video editing software programs can output various sizes of H.264 and be used several ways:

1. A source digital video files to create a Flash video for your website.
2. A digital video file that can be emailed
3. A digital video file that can be uploaded to social media like YouTube, Yahoo and Viemo.
4. To view a converted CCTV video codec in court

Flash video is a web based digital video player that is cross platform which is why I recommend its use for digital video content delivery on your website.

Although many digital video editing programs like Final Cut, Vegas and Premiere are capable of exporting finished video productions in Flash video (.FLV), there is more to creating a complete Flash video than just the video file.

When a digital video file is created like a H.264 (encoded to specifications of under 10 minutes and 1Gig) and upload to YouTube, Yahoo, MetaCafe and Viemo, the H.264 file is converted to Flash video during the upload process.

Many services post PR video on their websites now only accept Flash Video (.FLV) files. HTML 5 is out and nearly taking over flash but we have a way to go yet.

Just in case you are interested in posting a Flash video on your website, following are the components you need in addition to the .FLV video file.

1. The.html portion – the html webpage that loads the flash player
2. The .swf portion – the compiled flash file for web (contains the flash video player).
3. The .flv portion – the actual video file for the flash player.
4. ac_runactivecontent.js -the javascript file that loads the player into browsers

A non video production based software program made by Adobe called Flash and is used to create graphics and video for websites.

Flash Video is a file format used to deliver video over the Internet using Adobe Flash Player. The format has quickly established itself as the format of choice for embedded video on the web. Notable users of the Flash Video format include YouTube, Google Video, Yahoo, MetaCafe, Viemo,, and many other news providers.

Flash Video is viewable on most operating systems, via the widely available Adobe Flash Player.

Lastly, Theora standardized is still in development and not used very often but still worth mentioning to complete your understanding of the various digital video file formats available today.

What is an important take away is an understanding of the file formats and multiple uses for digital video.





photo credit: IMG_3254.JPG via photopin (license)

Video Forensics: Junk Science…or the Real Deal?

Friday, February 18th, 2011

Video ForensicsIt seemed like a routine traffic stop…or was it? The police said they had probable cause, but did they? The video footage, retrieved from the very sophisticated, digital-video surveillance system mounted in the police car, shows tinted windows on the victim’s car; so how could the police see they had no seat belts on? Bringing in a video forensic expert helped bring truth to the courtroom and prove scientifically that probable cause was not met, and the case was dismissed.

A bank robber thought the baseball cap would hide his face from the surveillance cameras, but the installation company for the closed-circuit television system (CCTV) had experience working with a video forensic expert who helped them figure out how to best position the cameras so all activity in the bank could be caught on video. The thief got away with $780 dollars, but was quickly apprehended and identified through the aid of an expert; he’s now serving seven years for the heist.

In a fatal shooting that was caught on surveillance video, the accuser’s face was identified for a brief second. With a few simple forensic video applications, like clarification and enlargement, as well as importing a frame from PhotoShop, the shooter was identified and brought to justice.

No longer a unique aid to deterring crime or capturing the criminal actions of the unsavory (as well as recording the mundane, casual incidents of everyday life), CCTV is now so pervasive, it can be found in locations from convenience stores to sports arenas, mall parking lots to traffic corners…even in doggy boarding camps where you can check on your family pet from your Blackberry or your computer.

While the protests are rampant that CCTV is a violation of our Constitutional right to privacy – especially given the many ways in which CCTV is now being used – there is no doubt that its value is embraced by litigators, police departments, security stations, airports and so on. With human resources stretched thin, video surveillance has become a critical tool in the war on crime, putting millions of extra “eyes” on the job, 24 hours a day, seven days a week.

But what happens once the perpetrator or action in question has been caught on video? What’s next? What transpires can often be a quagmire of “he saw, she saw,” with differences of opinion varying widely, with convincing arguments presented by both defense and prosecuting attorneys, and sometimes, a manipulation of the facts spinning in favor of one party versus another. This is where a video forensics expert can prove or disprove the layman’s observations, providing authoritative information or testimony based on a keen eye and knowledge of the technology.

Yet, many argue that forensic video technology is a “junk science,” a term used in this instance to label the practice as having no merit or credibility, that which cannot be authenticated, analyzed, or supported by scientific data. Science, by it’s very meaning, refers to that which can be proven systematically, and “junk”…well, that word is self-explanatory! The main reasons forensic video technology is often branded a “junk science” are three-fold: First, there are no governing boards or licensing groups overseeing the video forensics profession, like you find in the legal or medical fields, for example. Because of this, theoretically, anyone could be touted as an expert, affecting the credibility and opinions of those with reputations previously held in high regard. Second, because video forensics is a complicated process and there are no standards on which to base testimony or proof – with no cohesiveness within the science itself – there can be wide gaps in opinions and observations. Third, because the technology and interpretation of video forensics (and audio) science can be difficult to understand by nonprofessionals, it’s often discounted as not having any value, especially by the side not presenting the video evidence in court.

Such is often the case in the courtroom where a Daubert motion can occur (in those states that have adopted its use). The word “Daubert” comes from an actual proceeding, taken from the U.S. Supreme Court’s Daubert v. Merrell Dow Pharmaceuticals, Inc. (1993) decision whereby the judges were directed to examine the scientific method beneath expert evidence, ruling what was scientifically relevant, reliable and admissible. In short, because of the Daubert case, The Supreme Court mandated that federal judges shall act as “gatekeepers” by deciding whether expert evidence be allowed before the jury.

If a Daubert motion is exercised, based on the Supreme Court’s opinion, the following is considered admissible scientific evidence: 1) evidence based on a theory or technique that can be tested; 2) the theory or technique has been reviewed by the expert’s peers; 3) the technique has a known error rate; and 4) there is general acceptance of the underlying science in the scientific community.

Where this can adversely affect the admissible testimony of a video forensics expert is that judges are expected to examine and understand the methods of the expert and determine whether or not they are qualified to testify. Since there are no clear guidelines on which to base such credible witnesses, in many cases judges are left to render an opinion without adequate knowledge of the science.

Because of this, a Daubert motion can be used by either side of the litigation table to exclude evidence made by an expert which might support other proof, or further incriminate. Such was the case where the author of this article was called in to testify in a federal court drug trial on behalf of the defense. I was prepared to provide an expert, detailed opinion involving “voice recognition” evidence. But the prosecuting attorney convinced the judge to do a Daubert hearing, in an attempt to prove I wasn’t credible.

In this scenario, I was required to answer questions proving I was qualified to give the court an expert opinion on audio evidence. This included verifying I was a certified digital video expert; that I’d completed several successful court cases; that I’d published articles to support my expertise; and so forth. Yet, the court deemed me unqualified to testify, thus proving there are always two sides to every court case; that rulings can be based less on experience and fact, and sometime more by a lack of understanding the scientific nature of video/audio forensics by the court.

In 2007 Kelly Gorham, a vibrant nursing student from a small town in Maine, missing for nearly a month, was found murdered, the result of strangulation, and buried in a shallow grave on property owned by the father of her ex-fiancé, Jason Twardus. Having been jilted by Gorham two months prior to her disappearance, Twardus is accused of killing Gorham in Maine and burying her in his native state of New Hampshire. Twardus’ alibi was inconsistent with some of the evidence found.

Flash-forward to late 2009 when the murder case goes to trial…and crucial evidence based on video footage hangs in the balance. Friends and family of Gorham believe Twardus is the man seen on surveillance footage from a convenience store in Colebrook, N.H. the day after Gorham was last seen alive. The store is only a few miles from where Gorham’s body was found. The footage shows a car that appears to be the same color and make as Twardus’ vehicle, and the image of a man Gorham’s family swears is her ex-fiancé (even though his face is not discernable) based on his posture, baggy clothing, profile and characteristic walk.
The prosecution brought in video forensic analyst Grant Fredericks to verify the family’s contention. After questioning Fredericks extensively on his background and qualifications, the defense attorney called video forensics, as a whole, “voodoo science” and a “pseudoscience.” Fredericks contested the defense’s viewpoint during testimony, citing his ability to analyze beyond that of a layperson’s eye.

In addition to other aspects cited, the affidavit Fredericks submitted to the court states there is a “strong likelihood” the car seen in the security footage is Twardus’ green Subaru Impreza, and that the sweatshirt the man was wearing is “consistent with in every respect” to a sweat shirt seized by police from Twardus’ home. “That man cannot be eliminated, in my opinion, as the man in the video,” Fredericks said. However, as of this writing, the defense filed a motion to suppress the testimony of Fredericks, which the judge is expected to rule on sometime in early 2010.

The courts that accept video evidence – supported by a video forensic expert – are usually those that involve an experienced trial attorney, with admissibility boiling down to the strength of the presenting attorney’s argument. When accepted, video evidence can help a judge or jury understand a crime scene or situation more clearly. Admissibility is stronger if a video forensic expert is involved.

In another milestone U.S. Supreme Court ruling, setting precedence for how video evidence may be decided on in a court case, consider the outcome of Scott v. Harris (2007), where appellate courts were given more freedom to decide issues on summary judgment. In a summary judgment practice a court generally considers the evidence to be more conducive to the nonmovant (a “nonmovant” refers to the party not filing a motion).

The eventual case of Scott v. Harris was preceded by a high-speed chase whereby a Georgia county deputy, on the tail of the speeding vehicle, was given permission from his supervisor to employ a PIT maneuver (allowing the patrol car to pull alongside the vehicle and force it to spin out or exit the road in an effort to bring it to a standstill). Instead, deciding not to exercise the PIT maneuver, Deputy Scott pushed the rear bumper of the fleeing vehicle, resulting in the driver (Harris) losing control of the car, jumping an embankment, overturning and crashing – whereby Harris became a quadriplegic.

Harris filed suit asserting that Scott violated his Fourth Amendment rights during the pursuit by using excessive force. After rulings in the lower courts denied Scott’s summary judgment motion on a qualified immunity claim, the matter went before the Supreme Court where, in an 8-1 ruling, they reversed and held that Scott’s effort to end the chase by forcing Harris off the road was justifiable and reasonable, and that Scott was entitled to immunity.

With a quadriplegic plaintiff looking for relief from the judicial system, how is that the Supreme Court found in Defendant Scott’s favor? In a rare and uncommon move for the Supreme Court, they accepted the presentation of video evidence of the chase, the main contributing factor that influenced the court’s decision. Writing for the Court, Justice Scalia concluded, “It is clear from the videotape (Harris) posed an actual and imminent threat to the lives of any pedestrians who might have been present, to other civilian motorists, and to the officers involved in the chase,” thus contradicting Harris’ version of the facts.

In future cases where video evidence is introduced, litigants will be able to cite Scott v. Harris that a court, not a jury, is competent to decide issues usually left to the jury to determine, particularly where video evidence contradicts the nonmovant’s account of the facts.

While security footage can be used to support or refute criminal behaviors, or aid in civil cases, it has also proven valuable in uncovering police corruption and/or ineptness, and in fact, may be the best way to circumvent police lies and collusion.

In 2004, during the Republican National Convention in New York City, a massive number of protesters participated in a broad range of activities, resulting in over 1800 arrests, a record number for any political convention in the U.S. Most of those arrested were carrying out lawful and peaceful actions, yet the NYPD claimed disorderly conduct and fabricated a number of the charges. Video evidence, contradicting the assertions of the police, and much of it provided by private parties, proved the innocence of hundreds of people, with over 400 of the cases dropped.

In another incident last summer, near the Philadelphia airport, four friends made a 3:00 a.m. stop in a convenience store shortly after being involved in a minor fender-bender with their Mazda. The driver of the other vehicle, the son of a police officer, rear-ended the Mazda with his Buick, then left the scene after a purported exchange between the parties.

The Buick’s driver located his father, on duty that night, and the two set out to locate the Mazda, spotted in the store’s parking lot.
Moments after entering the store, 20-year-old Agnes Lawless was standing at the counter when Officer Lopez, father to the other driver, grabbed Lawless from behind and violently pushed her, striking her with his left hand and shoving and striking his gun in her face with his right hand. In a frantic struggle to defend herself, Lawless was arrested and charged with assaulting the officer.
Lawless and her friends filed complaints with the police department’s Internal Affairs division, but in many cases like this it’s the defendant’s word against that of the police…except when there’s surveillance video to prove one’s innocence. The case against Lawless was dropped after video footage from the store’s four security cameras were examined.

In some instances when viewing video evidence, such as with the Lawless incident, the truth is blatantly clear-cut, by even the untrained observer. But in many cases, the proof often falls into gray areas easily argued between opposing parties. When a video forensic expert’s observations, analysis and opinion are based on his own perceptions, experience and expertise, especially without a governing of the profession or widespread acceptance of the science, it’s easy to see why video forensics is sometimes discounted.

Yet, in a world laden with video technology, and with video surveillance systems in nearly every public environment you can imagine, the task of interpreting what is seen on video, including authenticating and clarifying the images, is not within the realm of the legal profession. When the “videotape” is rewound, it is best left to the experts who can help the court better understand the technology and circumstances as they relate to each incident. That is, unless you’re on the side of the fence that thinks video forensics is a bunch of bunk…er, junk. Ultimately, however, in this author’s opinion, especially given the amount of forensic video evidence surfacing in the courts today, the science of video forensics will soon earn the respect of all legal personnel.




photo credit: Security Camera Portrait via photopin (license)

Caught on Video: CCTV Surveillance

Friday, February 18th, 2011

CCTV Surveillance 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 Forensics YouTube page, there are video examples of this frame rate scenario:

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.

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. Less complicated systems are manufactured by Fairfax Electronics and Safe Mart.

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 .

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.

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”.

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.

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”.

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  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.


photo credit: IMG_1257 via photopin (license)

Original Digital Media Evidence is Mandatory

Saturday, February 5th, 2011

original media evidenceDigital audio and video is recorded and stored in electronic equipment. If the audio or video is needed in court, the original device that created the recording must be identified and kept in a chain of custody. The only exception is when both parties involved in the litigation agree that a copy is sufficient. If there is doubt in the authenticity, the audio expert must refer to the original to support the authentication of the audio evidence.

The reason is that the audio or video copy has been removed from its original environment and is vulnerable to alteration. In addition, if a computer created the original recording, additional information can be examined by the audio expert such as file creation, last accessed and other computer forensic information that can support the audio evidence authenticity.

If the original audio recording was created in a digital pocket recorder (which many law enforcement officials use) then that original pocket recorder must maintain a chain of custody and become the original evidence. Any external copy created by a number of methods and played outside of the digital pocket recorder is a copy. Unless an audio expert can authenticate the copy (which can be done once the original has been examined) it cannot be used in a court proceeding. If the audio copy has been authenticated by an expert, than it will be easier to play and amplify in the court for a judge and jury.

I have testified in criminal cases for the defense when the client swore under oath that the audio recording had been altered and did not represent the facts as they occurred. Now it’s their word against the other side and when the court has to decide, the prosecution most always, will prevail.

If you have had an experience with Audio/Video evidence and would like to share your story, please comment on this post and your story will be heard.