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Audio in Video Evidence

Wednesday, April 29th, 2015

Audio EvidenceThough there are many ways to detect an edit within video evidence, sometimes a critical ear can be just as important to a video forensic expert. Though they say “A picture is worth a thousand words,” an audio file can be worth just the same. You just need to know what to look (or listen) for.

Many CCTV systems now have the capability to capture audio, and this audio could be crucial to the legitimacy of the evidence. Audio is one of the easiest ways to detect an edit when watching a piece of footage, but to do so there’s a bit you need to learn about audio, in itself.

Audio is comprised of “sound pressure waves,” which are waveforms representative of the change in air pressure in a recording. One characteristic of sound pressure waves is that they are always smooth and continuous, no matter what.

Let’s say, for example, you’re recording in an open, quiet room. While you’re recording, a rebellious teenager comes in the room and blows off his air-horn. Even though that loud sound completely changed the overall sound in the room, the wave that represents the pressure change will always be smooth and continuous.

The only time that a wave is not smooth and continuous is when an edit is made. Keeping this in mind will give you more of an idea of what you’re listening for.

When an edit is made to a recording, this disturbs the waveform. This makes it temporarily rigid and inconsistent. Now, remember; all sound pressure waves should be the opposite of that. So, the second that you hear a sound that is outside of that smooth, uninterrupted audio file, you know you have an edit.

How is that disturbance represented? Well, it will usually manifest itself in the form of a ‘pop’. In the context of video, it usually will only last a frame, but it will be there. If you hear anything out of the already established waveform, you know that the evidence has been edited.

Adobe (as always in the world of forensics) has other software that can allow you to more accurately detect these edits. For example, Adobe’s “Audition” uses what’s known as a “spectrogram,” that detects something known as the “noise floor”. As with audio waves, your noise floor will always be level and uninterrupted. In regards to a spectrogram, the spectrum recorded for a noise floor will always be consistent in visual characteristics. When you see a disturbance in that consistency, just as if you hear one in the audio file, you can tell that the audio, and sub-sequentially the video, has been altered.

Obviously there are many ways to detect edits visually. However, being a forensic expert means heightening your senses to a critical level, and though sight is the most prominent sense for a video forensic expert, having a critical sense of audio is just as important. The two work hand in hand to present the evidence, so having some knowledge of both will only excel your skills as an expert.

Tips for Mobile Video/Cell Phone Enhancement

Tuesday, January 20th, 2015

cell phone enhancementIn past blog posts, we have discussed techniques that we use as video forensic experts that get the best results when conducting CCTV video enhancement. What we have yet to discuss is how we get the best results when enhancing mobile video recordings.

Since most mobile video evidence is shot freehand on a smart-phone camera, you can’t guarantee that the video evidence will be of legitimate quality. People are often nervous when video recording something like a fight, accident or other public situation and naturally shake while recording. Smart- phone video quality is often good at best. The placement of your subject and method of recording video can lead to poor video evidence that needs forensic enhancement.

As a video forensic expert, we know firsthand about all of the tools available in software programs and out board digital signal processors that can help your video provide valuable information to the authorities.

At Primeau Forensics, we have a team of video experts that have reviewed and enhanced hundreds of videos, some of which are from smart-phone cameras. One of the most prevalent problems that we have noticed through experience is unstable smart-phone video recordings. The chaotic motion of a cell phone video can make it hard to tell what’s happening.

One of the tools we use is made by Adobe; Adobe products have excellent tools for video enhancement assignments. One tool can be found in Adobe After Effects. It’s a plug-in entitled the “warp stabilizer.” This plugin creates a full frame reference for the shakiness of a smart phone video. It enhances the viewer’s ability to view the video better and determine the events that occurred more effectively.

For example, we have posted two clips below. The first clip is from an actual video enhancement case. It was recorded using an iPhone. No stabilization has been applied to this video. Look at how difficult it is to see the events as they occurred.

IMG 1363 from Primeau Forensics on Vimeo.

In the next video, we take the same source clip, but this time apply several filters including warp stabilization. Notice how it is easier to view the video as the frame follows the motion of the video, creating a more stable picture for analysis.

IMG 1363.MOV CLARIFIED VIDEO from Primeau Forensics on Vimeo.

In many cases, such as the video above, the subject at hand will not be close enough to the smart-phone capturing the video, making it nearly impossible to make out the events as they occurred. In the first video example above, the subjects are very far away, making it difficult to make out what is happening.

A trained video forensic expert knows how to apply tools that will enhance the video evidence. These tools allow you to zoom in on a video and clarify difficult-to-see events. This process may lower your overall video quality, and as Hollywood may lead you to believe, fixing it isn’t nearly as simple as pushing the “enhance” button.

The reason that the quality of this video is reduced when zoomed in has to do with the video “pixels.”Simply put, pixels are the small boxes of color code that combine to make up a given image. Each image is composed of a specific amount of pixels that make up the clear image you see in front of you.

To further explain, think of a collage. Have you ever seen a collage composed of much smaller pictures? Once the pictures are combined in a specific order (usually by color), it creates a much bigger image. Think of pixels as those smaller square pictures that make up the entire picture.

Expanding an image also means increasing the size of each pixel. Because each pixel is a representative of one “frame” of a bigger picture, such as the photos making up a collage, each individual square pixel will expand along with the image. The increase of pixel size can cause distortion to the image, therefore making it even harder to decipher the contents of an image.

Luckily, Photoshop and other Adobe programs provide solutions called “pixel interpolation.”

Generally, pixel interpolation provides two options for this video enhancement situation. You can utilize a plugin known as the “bi-cubic smoother,” which blends each cubic pixel together to create a more cohesive image.

The other plugin is known as the “pyramid shaper.” This allows for a similar process, however, this follows what’s known as pyramid coordinates, an alternate method of morphing the pixels.

Which one of these methods is best comes down to the circumstances surrounding your investigation.

As you see in the second video, the image has been enhanced so the viewer can better see the events that occurred. It is important to note that the quality of the video hasn’t been compromised. This is because steps were taken like applying the bi-cubic smoother allowing the pixels to cooperate making a image more clear.

The biggest problem we see at Primeau Forensics with mobile video evidence is the orientation of the cell phone while recording.

If you should find yourself recording a video using a smart-phone, first and most importantly be sure to turn the phone on it’s side or ‘landscape’. We receive a lot of video evidence where the phone was held vertically instead of horizontally. This is fine when your intent is to view the footage directly on the phone, but when that footage becomes evidence; not having a full frame horizontal recorded video eliminates a large portion of the scene being video recorded. The vertical position records a much more narrow view of the scene and instead records larger height dimensions. This keeps potentially valuable information off the videos and out of the court room. It dramatically constricts the viewer’s range of sight of a given event.

Regarding the footage shown above; notice that around the 0:25 second mark, the camera focuses on the Jeep pulling up as another officer runs toward the scene. This distracts our focus away from the scene, and we miss a substantial amount of the incident.

Had this evidence been shot horizontally, we would have been able to view more of the events including the activity that happened as the officer arrived at the scene. We would also have been able to better see the white Jeep in the background which was an important detail.

Using another smart-phone video as another example, the footage below is a recording from a smart-phone of the events that transpired after this year’s tragic Charlie Hebdo shooting in Paris. The two gunmen are seen driving away from the scene of the crime before encountering a police car. The suspects shoot at the police car, causing the police to retreat, and speed off again.

If you notice, you’ll see two black bars along the outside of the vertical video. This video was also recorded holding the smart phone in a vertical position. Had this video been recorded holding the phone horizontally we would have more information recorded that may have revealed additional useful information. This scene happened just before the gunmen got away and killed additional people.

With the expansion of mobile video technology, any cell phone could effectively record a crime scene that can go on to become crucial evidence. The highest quality video recording can help litigators more effectively.

Body Worn Cameras; More Safe than Dash Cam for Police

Tuesday, December 9th, 2014

body worn camera policeAfter the controversial grand jury announcement in the case of Michael Brown, President Obama has proposed the idea of issuing police departments across the nation with body-worn cameras for law enforcement. Between Michael Brown, and the controversy behind the Eric Garner case, citizens are asking: Will body-worn cameras help police as well as the public? In this video forensic expert’s opinion, the answer to that question is a resounding YES!

Video is the least challenged of all digital media forensic evidence. It provides a clear indication of the events as they occurred by allowing the judge and jury to observe the event with their own eyes. Nothing is as revealing as video to clearly show the court exactly what happened.

Had Darren Wilson, the officer involved in the Michael Brown shooting, worn a body-worn camera, the case might have had a different outcome. The ability for the jury to see something first person can be invaluable to their decision.

Here’s an example: In the video embedded below, courtesy of ABC News, we see two pieces of evidence: footage of a confrontation taken from the dash-cam, along with evidence taken from the body worn camera. As the first half of the video shows, the police officer in question tackles the suspect for seemingly no reason. The body-cam, however, tells a completely different story.


More ABC US news | ABC World News

What the white Kia in the driveway blocks is the event that takes place at 1:53 of the video, whereas the suspect openly tries to assault the police officer in question. In this instance, had a body worn camera not been issued, the jury may have interpreted this in a completely different way.

Last year, Primeau Forensics had the opportunity to test and review one of these body worn cameras, the VieVu LE2. These cameras would be phenomenal for police forces all over the U.S. It’s 72-degree wide angle lens allows for a wider first person perspective, so that even a suspect standing at a distance from the officer is still being recorded. The near-professional quality of the audio and video ensure a clear understanding of the situation, and the digital signature security ensures that the video footage cannot be tampered with while on the device.

Body-worn cameras could completely revolutionize the court system and how it interprets evidence. Video like this can be instrumental to the outcome of a case, as it provides the most realistic representation of what exactly transpired in a given confrontation. As shown above, not even a dash-cam can always show us everything, but having a first person perspective of a given confrontation is pivotal to the jury’s final decision.

For more info on body-worn cameras, check out CEO Ed Primeau’s interview with VIEVU CEO Steve Ward here!

Police Misconduct and Mobile Video – DeShawn Currie

Friday, October 10th, 2014

police misconductLast night, ABC News ran a story about a young foster child who was pepper-sprayed in his own home. The boy, DeShawn Currie, was mistaken for a burglar reported by neighbors, and was pepper-sprayed at the front door of his home in North Carolina.

Stories like this really emphasize how powerful the consumer video revolution really is. Police misconduct of this kind may have gone completely unnoticed without the advancement of video that has taken place over the past decade. Video is the most powerful evidence in situations like these, and we need to remain aware of the power that video as evidence has in the world today. Without the advancement of the smartphone camera, dash-cams, body worn cameras such as the GoPro, along with advancements in CCTV technology, this absurd behavior from police may have gone completely undocumented. Now that we have all of this technology at our fingertips, we have a much higher chance of exposing misconduct of this degree.

To read more about the consumer video revolution and it’s effects on the courtroom, click here.

Watch the full story from ABC News below.


More ABC news videos | ABC Entertainment News

The Evolution of Mobile Video and What It Could Mean for Video Forensics

Thursday, September 4th, 2014

mobile video forensicsOver the past few years, we’ve seen a significant acceleration in the development and manufacture of consumer-grade, mobile video devices. From smartphones to GoPros, video recording has become substantially less expensive and far more accessible to consumers, and this may change the game regarding digital evidence.

This consumer video revolution now allows us to capture video of events as they occur. This phenomenon has created powerful repercussions in the courtroom. Thanks to the easy availability of video devices and trends in social media, we now have presented at trial video evidence of events that, until recently, have rarely been made known.

For example, take this video of a woman from Mississippi. As she begins to merge onto the highway, a truck hits her car, causing the car to catch fire. She seems trapped in the car (either physically, or due to shock), and with her children in the back and the flames coming ever closer to the gas tank, she needs to act quickly.

Suddenly, from behind the scene of the accident, another truck driver leaves his rig and tries to save the family by pulling them out of the burning car. Minutes after they are successfully rescued, the car explodes. Had the truck driver been a few minutes later, it is likely that the entire family would have been killed.

This is a heroic, inspiring story. An inspiring story that would have gone completely unnoticed if weren’t for the rescuer’s dash cam recording the entire incident. A heroic act so great that it has rarely been seen outside of movies and television, it became a huge story, and something that would have been unrecognized by the public without the technology of this generation.

However, the documentation of heroic stories like this is only the beginning of the positive effects from the spread of video devices to every pocket, purse, and vehicle. This public video revolution can also make or break a court case, providing the crucial evidence that makes true justice possible.

For this, let’s use the currently infamous video, “Officer Go-F***-Yourself.” The officer in Ferguson appeared at a peaceful protest late one night in August. He approached a group of young adult protesters with an assault weapon drawn, pointed it at them, and he told them that if they did not return to their homes, he would “f***ing kill” them.

In the world of law enforcement, this kind of behavior on the part of an officer is absolutely improper and illegal. The protest was peaceful; the young adults weren’t causing any harm or exhibiting disorderly behavior. Hell, even if they were, threatening protesters in such a crude manor is clearly unacceptable in a free society.

Had this happened 10 years ago, it might have gone completely unnoticed. The officer in question may have gotten away with blatantly making death threats to civilians, and the only evidence from the protesters would’ve turned into a game of “he said, she said.” However, because one of the protesters was smart enough to take out their cell phone and document the entire confrontation, justice was done and the officer was suspended from the force. The police in Ferguson were able to see the events exactly as they transpired, so it was indisputable that he was guilty. This, in itself, is revolutionary, and is an indication of how much power video evidence can have in the courtroom.

The fact stands that a clear representation, such as video, is the most indisputable evidence there is, and allowing the jury, officials and lawyers to witness the event with their own eyes and ears is the most effective way to present evidence. Other forms of evidence can be easily disputed, but allowing the court to see, hear, and experience the event for themselves is the most effective method of presenting evidence, even more reliable than an eyewitness account.

Think about it this way. Consider the most powerful documentaries you’ve ever seen. What do they all have in common? Generally, they all rely on the reality of the situation by allowing viewers to experience it for themselves. You can throw out as many facts and statistics as you want, but seeing, hearing, and experiencing actual issues, people, circumstances, and actions is what will stick with people most. The feeling viewers derive from seeing the faces and hearing the people speak is incomparable to any statistic in the world. This is why Charlie LeDuff’s piece on Ferguson is one of the most powerful, yet. It doesn’t focus on the narrative; it doesn’t focus on stats; it focuses on the people. It focuses on those who are so passionate about this cause that they would fight, risk arrest, or even die for it.

The consumer video device revolution is so important to the justice system, and the best way to reap its benefits is to remain aware of its power. If you experience anything unlawful, always remember that the little rectangle sitting in your pocket could make or break the fate of those guilty. These devices allow us to capture indisputable evidence about what truly took place, and this is a privilege we can’t ignore. If these developments continue, they could completely change the face of digital forensic evidence forever.

Evidence Recovery

Monday, April 14th, 2014

Evidence Retrieval As an audio/video forensic expert I have witnessed a huge growth in digital video recordings admitted into evidence in court over the last several years. Much of the work I do on these recordings is video enhancement which allows the Trier of Fact a better opportunity to view the events as they occurred. Sometimes this digital video evidence was recorded in video surveillance systems, other times it is from smart-phones.  Video surveillance recordings that I enhance are removed from both mobile surveillance systems and stationary surveillance systems.

Stationary surveillance systems record digital video at stationary locations like convenience stores, banks and other businesses or institutions. Mobile surveillance systems are being used more and more in busses, trains and other types of public transportation.

Many people involved in litigation who retain audio and video forensic experts like me do not realize how important professional evidence retrieval is.

There are three main factors I would like to mention regarding the reason for professional evidence recovery. First, when I retrieve evidence personally, I record a video of the process using a VIEVU body worn camera, which establishes an indisputable chain of custody. Second, I take special precautions during the retrieval process to make sure I leave with at least one version of the recording and leave with the evidence for future forensic enhancement and authentication.

I retrieve the recording so as to minimize any degradation of quality. When a multi-million dollar lawsuit may turn on the analysis of a surveillance video, it is imprudent to entrust evidence retrieval to an untrained security guard or police officer.

Third, I research the operator’s manual and connect with tech support from the surveillance company before I travel to the location of the surveillance equipment and make the evidence recovery. While I am on site I can also examine the administrative log and determine additional forensic information for the chain of custody.

I want to mention an excellent manual for retrieval of electronic evidence developed jointly by the federal government’s interagency Technical Support Working Group, the FBI Forensic Audio, Video, and Image Analysis Unit, and law enforcement agencies from around the world. Entitled Best Practices for the Retrieval of Video Evidence from Digital CCTV Systems, it contains an authoritative (if somewhat dated) overview of the topic, and covers many of the protocols we have adopted at Primeau Forensics.

Before digital audio and video recorders, retrieving a tape-based analogue recording was fairly straightforward. Recordings were made to tape cassettes, which were stored in climate-controlled conditions. Evidence retrieval was as simple as picking up the original cassette recording. Digital video recorders (DVRs), however, do not record to easily portable cassettes. Rather, they record to the kind of hard disk drives found in computers. These internal hard drives are not portable, making evidence retrieval more difficult. Whether I take the DVR or its internal drive with me or make a lossless copy of its contents, I always follow antistatic procedures and carry all media in specially shielded cases.

All surveillance and standard digital video is recorded using a specific compression/decompression scheme or codec. The compressed file is stored within a wrapper, a file structure, which determines its format. It is not uncommon for surveillance DVRs to use proprietary formats, allowing playback only through the original recording DVR. Some DVRs can recompress the original proprietary format file, transcoding it into a non-proprietary format for easy playback. However, these more accessible files often contain lower quality video and audio. When I retrieve these digital video files, I study the DVR’s operating manual to find the best way to make a high quality copy that retains all data and metadata. By minimizing or eliminating the degradation that can accompany translating the file from one format to another, I ensure that my lab analysis is based on the best video recording available.

The Power of Digital Forensic Analysis and CCTV.

Wednesday, February 20th, 2013

Forensic Analysis CCTVMore and more video evidence is entering the courtroom today than ever before. Some of the reasons for the increase in video evidence include the number of smartphones and closed circuit television network systems (CCTV) today. It is a fact that we are vulnerable to being on a video recording anytime we are in public. Almost all retail locations, including convenience stores, banks and gas stations, as well as almost all major city streets have video recording 24|7. The argument of invasion of privacy is dwindling and CCTV systems are helping report events and give us the ability to view those events as they originally occurred when looking for the truth of the recorded events. Video evidence must of course maintain a proper chain of custody and be authentic before it ever enters the courtroom. Proper handling of the video evidence is imperative. Original videos should always be kept safe in their native environment to avoid evidence spoliation accusations. A trained and qualified video forensic expert will help you understand all protocols for the handling of forensic evidence. One of the advantages of video evidence is the ability to present the courtroom, judge and jury with the actual events, first hand, as they occurred.  These videos help settle litigation quicker than a case that has no video evidence at all. Take the example of a recent CCTV system that recorded an altercation in a laundry mat in Brooklyn, New York. In the video below, the events as they actually occurred can easily be viewed for the litigation process:

On the other side of the forensic lab, these videos taken of the recent meteor hit in Russia from a combination of smartphones and local CCTV cameras show first hand relocation and witnessing of a meteor as it hits earth, and the damage that occurred as a result:


I suspect that as homeowners, businesses and municipalities continue to install CCTV systems to help keep their property secure and protected from crime. An even higher amount of litigation cases will include video recordings. The ability to view an event in question as it originally occurred is valuable, as it will stand as much stronger evidence in the courtroom. It’s hard to put a price tag on the value of digital media and video forensic evidence.

The Importance of Remote Access Video Surveillance Systems (CCTV)

Friday, January 11th, 2013

Video Surveillance SystemsIt is a well known fact that closed circuit television (CCTV) systems help to deter crime. In fact, if a building has a CCTV system installed, any crime committed at that building will be recorded on video from the closed circuit television system. In addition to being a deterrent to crime, CCTV systems also record crime and criminal activity.

The truth about the series of heinous events that took place at Sandy Hook Elementary School in Newtown, Connecticut will most likely become clear when reviewed on the school’s closed circuit television system. The police are most likely viewing this CCTV footage in an attempt to better understand the gunman’s activity and methodology for gaining entry into the elementary school and how an event such as this can be prevented in the future. If the school had been equipped with a remote access system an employee (such as the principal) could have tripped an alarm and authorities would have had immediate knowledge of the situation.

Besides shootings and other public crimes, closed circuit television systems also record other types of crime like ‘on-the-job’ crime (employee theft or other illegal activity), breaking and entering and vandalism.

Many newer digital CCTV systems also have Internet access capability. The digital video recorder can be connected to the Internet and the administrator or anyone else who has administrative privileges can sign in remotely to the closed circuit television system from anywhere in the world to view the camera coverage. This remote access is very handy to help prevent crime and keep a building secure for many reasons.

Some employers want to be able to view the activities of their employees during working hours. This can help cut down on people not doing their job as well as activities that are, at worst, illegal, or are against company policies. These activities are often curtailed once employees know about the live CCTV system because they could be at risk of losing their jobs if they are ‘caught’ by the CCTV cameras. Some employees become outraged at the fact that the employer installed a remote access CCTV system and that their day-to-day business activities could be viewed and recorded but it is sometimes necessary.

There are also safety features to remote access CCTV systems. Banks and other financial institutions have done a great job securing their vulnerable environment through the use of CCTV systems. As a video forensic expert I have viewed several bank robbery CCTV videos to create still images from the surveillance video that help identify the criminals.

If a disaster were to occur at a business establishment, police and law enforcement officials could access the CCTV system and view events that are occurring in order to determine how to best handle the disaster. Hostage situations could be better strategized before police gain entry into the building where the hostages are being held.

By: Ed Primeau the Video Forensic Expert

Below is a video demonstrating the benefits of remote CCTV access for a business establishment.

 

The Future of CCTV Video: Body Worn Cameras

Wednesday, May 16th, 2012

vievu body worn camerasBody worn CCTV video cameras come in all shapes and sizes. are easily available on the Internet. Anyone can purchase a wristwatch camera, cell phone camera or button hole camera (see photo below) to name a few. Now you are not only more than likely being video recorded by a public or private CCTV system while walking down the street, but there is also the have the possibility that your lunch time conversation with an ex partner is being video recorded for truth and accuracy.

Our right to privacy is nonexistent in public. No longer can we assume we are having a private conversation if we are outside our home. Is this good or bad news?
Body worn cameras have been used for years by law enforcement to record drug transactions and other illegal activity to bring the illegal activity into the court room. DEA agents as well as the FBI have important work to do and are often accused of altering evidence. Body worn cameras help prove authenticity and avoid false statements like “It was not me” from accused drug traffickers.

Traditionally, audio recording devices were used to record these illegal transactions. However, a lot of money was being spent on voice identification in order to prove or disprove identity when the accused denied involvement. In most cases, police officers and government agents would never sacrifice their reputation, retirement and career by altering evidence for the purpose of making a conviction. I have seen altered evidence in the past but that is another blog post. Wearing a body worn camera is similar in nature to an accident reconstruction video. It brings the crime scene into the court room.

I suspect that one day in the future our government will pass legislation on video recorded evidence that will be presented in the court room. In the mean time, good and bad guys will continue to purchase these body worn cameras and use them to record conversations that document activity verbally and visually. That way there is little doubt as to what was discussed or what went on during the audio and video recorded conversation.