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Posts Tagged ‘Digital Video Evidence’

Creating Video Work Products as an Audio/Video Forensic Expert

Monday, March 9th, 2015

Video Forensic LabVideo work product is a way to document forensic investigations, like evidence recovery, for reference at a later date. Processes and procedures are documented using a video camera during a forensic investigation for future use. I have referred back to my video work product many times when I have questions later during the evolution of the case.

As an Audio & Video Forensic Expert, I have examined hundreds of audio and video recordings to determine authenticity, as well as enhance characteristics of the digital evidence to clarify the events as they occurred. This video recording is referred to as ‘video work product’ and comes in handy.

There are a few different digital video recording platforms that I use when creating ‘video work product’. I often use VIEVU body worn cameras and HDSLR
photography based cameras. Each one of these types of systems serves a certain purpose in assisting with a forensic investigation, as well as the investigative process.

Over the last few years, I have seen firsthand the significance and overall efficiency that body worn cameras and their recorded video can bring to the public, law enforcement and legal proceedings. I personally use the VIEVU LE2 and LE3 body worn cameras. The LE3 records in 720p HD resolution and utilizes a 68 degree field of view. Other competitor cameras tend to use a 130 degree field of view, which captures a wider field of view but captures less detail. Detail is often more important when it comes to video evidence, which is one of the reasons I prefer to use VIEVU cameras.

These body worn cameras also contain digital audio recorders, which record MP3 format audio at a 44.1kHz sampling rate and a 64kbps bit rate. This high sampling rate captures the full range of human hearing, making any audio that is recorded on the camera more audible. In some cases, the client lawyer or law enforcement agencies that I work for require that no audio be recorded while video is being taken. The LE3 audio recorder can be switched off separately from the video, which gives me flexibility in such a situation. The LE3 records to either MP4 or AVI video format for easy playability across various platforms utilizing the H.264 codec. These formats also allow easy integration into my forensic programs, such as the Adobe Production Premium Suite. The 16 GB flash style storage system allows for either 12 hours of SD video or 6 hours of HD video and quick data transfer rates. The battery will last 5 hours during SD recording and 3 hours during HD recordings. The unit is also compatible with an external battery pack for extended battery life.

My main use for the LE3 body camera in my investigations is recording my forensic process in the field. This includes retrieving evidence from different systems so I can review the video later and include it in my report to support the authenticity of my work product and any evidence used in the case. Often times a forensic expert will be challenged by a client or opposing lawyer to verify the chain of custody of the materials produced during an investigation. Even minor details about how the investigation was conducted can have a large bearing on the authenticity of the evidence. Having a digital video recorder on my person during my forensic investigation allows me to capture both video of my process and my dialogue explaining the process. Including this work product to my forensic reports verifies the chain of custody and protects me as a forensic expert.

Another type of digital video camera that I use to produce video work product is an HDSLR photography camera. This type of camera equipment has become popular among the scientific community, as well as production companies, for its portability, versatility, quality and functionality. An HDSLR photography camera can use different size lenses to capture both images, as well as video, in different ways depending on the investigation requirements. HDSLR cameras record in 720p, 1080p, anamorphic and even 4k resolution. These cameras typically record at 30 minute intervals and have a battery life of approximately 2 hours of recording time, depending on the preferred quality and the available storage space. When connected to an external power source, these cameras can record for longer intervals of time. HDSLR cameras are great for recording a locked down alternative perspective to body cameras of an investigation or retrieval process. The flexibility of being able to produce individual still images as well as video throughout an investigation is also helpful with my forensic process.

In some investigations, a single video recorded perspective may not be sufficient to display the forensic process or document the events. Having another high quality camera with flexibility of perspectives and interchangeable lenses can capture aspects of my investigation that body worn cameras cannot. This lockdown feature of a point and shoot camera can also allow an investigator or client attorney to view the process as if they are sitting there watching in real time. Another use for HDSLR cameras as a forensic expert is recording accident reconstruction videos. An accident reconstruction video is a recreation of an event or series of events in the same environment that they occurred so they can be shown to a client investigator, client attorney and/or law enforcement. An accident reconstruction video is most effective to show the real life series of events as opposed to a 3D animation or a written statement of the events.

Video recorded by Closed Circuit television (CCTV) surveillance systems has been the dominant source of video evidence that I have investigated during my 30 years of being an audio video forensic expert.

Video evidence produced by CCTV systems can help solve crime, as well as reproduce accidents and disasters as they occurred for play back in many different settings. One significant use a video forensic expert has when recording video from a CCTV system is to create an exemplar. An exemplar recording is a recording made in the most similar way possible to the original piece of evidence using the same equipment, settings, environment and conditions of the original evidence. This recording is used as a comparison file to the original evidence to help determine the authenticity of the original evidence. Both the quality of the video and the metadata included in the files will be compared when conducting a forensic investigation.

It is a best practice of ours at Primeau Forensics to video record many forensic investigations, such as our exemplar creation process or evidence recovery, so if our client has any questions during the life of their case, this video work product can be referenced.

Smartphone Forensics and the Future of Forensic Analysis

Tuesday, March 26th, 2013

smartphone forensicsTwenty 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.

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, Reuters.com, 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.

 

 

 

 

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