Archive for the ‘Smartphone Forensics’ Category

Tips for Mobile Video/Cell Phone Video Enhancement

Tuesday, January 20th, 2015

unsplash_525f012329589_1-300x198 Tips for Mobile Video/Cell Phone Video EnhancementIn past blog posts, we have discussed techniques that we use as video forensic experts that get the best results when conducting mobile video/cell phone 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.

Smartphone Forensics and the Future of Forensic Analysis

Tuesday, March 26th, 2013

smartphone-forensics-1024x682 Smartphone Forensics and the Future of Forensic AnalysisTwenty nine years ago when I entered the forensic field of study as an audio and video engineer. All recordings were created on analog tape. There were many different types of formats, such as ¾ inch video, ½ inch video, Beta and VHS. Then along came digital tape – that started to complicate things a bit.

Then came tapeless video recording on digital video recorders. This is when the field of video forensics got even more complicated. By complicated I mean that continuing education for the video forensic expert became more important so the expert could keep up with the various formats and technologies that were starting to enter the marketplace. One of the classes that I took to better understand closed circuit television systems (CCTV) was at a leader in global closed circuit television systems called Pelco. Pelco, based out of Indianapolis, Indiana, facilitated learning processes to help installers, end users and law enforcement better understand how to operate their software and digital storage hardware.

I remember learning, back then, that many cities were installing digital closed circuit television systems into their downtown areas to help law enforcement personnel better supervise and keep their streets safe. I was thinking at the time how this was going to cause more demand for video forensic experts because more video footage was going to surface that would need to be examined, clarified, subjects in the videos would need to be identified, and processes were going to have to be established.

By ‘processes’ I mean chain of custody, exporting for admittance into court and preservation and storage, which, at the time, was a costly endeavor. Hard drive space was very  expensive. Today, hard drive space costs very little in comparison to the value of preserving all of your digital footage for an extended period of time.

Now there is another form of digital video that has surface and that is smartphone video. The need has developed for smartphone video experts to be able to authenticate, clarify, identify portions of the video and be able to testify on the authenticity of cell phone video that is used in litigation.

Within the last several months, previous to the writing of this post, more than half of the video that I have received as a video forensic expert to authenticate, identify and clarify has been recorded in a smartphone. One of the reasons is that a smartphone is very convenient, and when a person feels threatened or an altercation occurs it has become human nature for one – if not both – of the people involved to turn on their video recorder on their smartphone and capture the events as they occur. That video can later be used to help support testimony in the courtroom.

Just like any other digital video recorder a smartphone creates a video recording and saves the video on the hard drive of the phone. The video forensic expert retrieves that video recording from the phone that created it in order to create a solid chain of custody and authenticity of that video recording. One of the biggest problems that I am encountering today is that before I am retained in a case the person’s involved in the criminal or civil proceedings have already removed the video recording from their smartphone, loaded it into a laptop, imported it into a video editing program and burned the file to a disk. Sometimes that file name has been preserved, meaning the same name the phone gave it is transferred onto the disk – sometimes it’s been renamed. I’ve even seen times when the file formats have changed. iPhones record .mov files, droids record 3gp files, as a rule of thumb. There are exceptions and some of the different software updates may modify these file formats.

It’s important that any video evidence that has been created on a smartphone and is going to be used in litigation have the same chain of custody as any other video recording created on a digital video recorder. And that is to preserve the original on the original device that created the recording until the video expert has had the opportunity to remove the video from that device giving it integrity to use as evidence in the litigation.

If the video file is copied from the phone so that it can be viewed on a larger screen, that’s fine. It’s extremely important not to delete the original file on the phone until a forensic expert has the opportunity to examine it.

The easiest way for a forensic expert to authenticate that file is on the device that created it. Many times I encounter digital video files that were created on a smartphone and the phone is either no longer available or the file has been deleted. To me, as a video forensic expert, that is a red flag because there is no need for anyone to delete a file from an original recorder, especially today when storage space has become inexpensive as well as readily available. Most of the integrity that can be established for that digital video recording comes in the process of the forensic investigation that starts with the digital file on that smartphone.

The same is true for tablet video recording. The tablet has a hard drive just like the smartphone, just like any digital video recorder. It creates a video file and automatically assigns it a name and that file name is part of the integrity of that video recording on that device.

So today the amount of video evidence that is appearing in court has grown dramatically as the result of the different devices that are readily available to create video and capture altercations, crime and other activity people want to document in order to use in the courtroom. It is very important to preserve the original recording, rather than delete it, to maintain the integrity and authenticity of that video file for the legal proceeding.

Video Forensic Expert Edward J Primeau Curriculum Vitae