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video evidence

  • I stand corrected. First, I did find a reference to Pixel Aspect Ratio (PAR) and down sampling uncompressed NTSC video in the joint Forensic Imaging and Multi-media Glossary (PDF) published by the IAI and LEVA, the final version of which was released in July, 2006. Second, in an effort to simplify this discussion, I’ve over simplified the Interpolation Methodology I described in Part 2. I will be expanding on that in this post, in far more detail than I had originally intended.

  • I was hoping I’d be able to wrap this series up with this post, but it’s clear to me now that I won’t be able to. There’s simply too much to cover and I’m certain that at least a few are still scratching your heads (like I was), wondering why we shouldn’t just rely on the pixel matrices to calculate Pixel Aspect Ratio (PAR) from analog sources. It is critically important to understand that I am approaching this topic from a forensic perspective, with the goal of standardizing the methodology used for forensic processing, interpretation, and presentation.

  • 720p (Black), 1080N (Yellow), 1080P (Blue & Yellow)
    NOTE:720P (Black), 1080N/L/P Lite (Yellow), 1080P (Blue & Yellow)

    1080 for sure, that's in the name.  They're all the same thing folks, and I'll be darned if I can find any formal video specification referencing any of them, so they share that too.  Is it all just marketing BS?  No, but surely the confusion has been leveraged by some DCCTV manufacturers, resellers, and the like to their benefit.

  • A couple of years ago I did a series of posts on aspect ratio correction of DCCTV recordings; more specifically DCCTV recordings captured by analog CCTV cameras, and correcting Display Aspect Ratio (DAR) for forensic interpretation. I pointed out in my posts and the subsequent Video & Display Standards Chart, that the one exception that I'm aware of where a DCCTV recording captured by an analog CCTV camera shouldn't be displayed 4:3, was the relatively new 960H format.

  • Imagine the following scenario:
    You're the first responding officer to a crime scene and have just completed taking the victim's statement. You then tell the victim you have to leave for another call. Before you go you politely ask the victim to take photos of the scene and their injuries, collect all of the DNA and fingerprint evidence, and note that you'll either be back later in the day or maybe tomorrow or the next day to pick it all up. You note that they can just leave the evidence at the front desk for you.

    This is exactly how many agencies have chosen to deal with the overwhelming amount of DCCTV evidence available to them today. "Oh, there's video? Okay, have someone export it and we'll come back to pick it up."

  • The multimedia evidence community has been really buzzing the last couple of years in regards to how useful FFmpeg and Libav can be for dealing with proprietary video formats. Both tools are extremely useful in several aspects of a forensic DME workflow. With that said, however, whether it’s FFmpeg, Libav or another 3rd party tool, there are limitations and causes for concern when using them to process proprietary video file formats.

  • This brief (approx. 9min.) introduction into the world of digital video evidence is intended to provide law enforcement professionals with a better understanding of the basic concepts and related issues.  It was geared towards first responders, who in many cases are the ones initially seizing video evidence.

  • FFmpeg is a great tool to have in your toolbox if you’re a multimedia geek. If you live mostly in the world of Microsoft Windows and have dozens, hundreds, or thousands of files to process though they lose a little luster. Sure, there are tons of free applications built on FFmpeg that provide some limited batch processing capability, but usually they're just that; limited. Here’s a simple way you can process hundreds of files from one format to another, using the full capability of your FFmpeg install.

    First, which scripting languages do you know? Great, we won’t need those, but that’s really cool that you know them. Given that you’re reading this, I’m going to assume you can write plain text into a text file. I don’t like to assume anything, but I’m feeling pretty good about that one. Alright, let’s get started.

  • I posted a new page last week under our Professional Community menu called Free DME & FVA Tools. Hope you find it helpful.

  • Turns out I may just know a thing or two about Mass Video Evidence Collection & Processing.  Who knew? foot-in-mouth

    I have worked several cases that were comprised of thousands of hours of video evidence collected from dozens of sources, including the Vancouver Stanley Cup riots.

    Forensic Video Analysts from around the world were brought to Indianapolis to work together, and although I wasn't there, I was responsible for supporting the infrastructure and solving the DME workflow issues that couldn't be resolved efficiently on-site.

  • It’s sometimes difficult for traditional Computer Forensic (CF) examiners to understand why they should treat video and multimedia any differently than other types of digital evidence. After all, a bit is a bit, and a byte is a byte. Right? CF examiners are typically highly trained and highly technical people. If anyone is going to understand how to recover and interpret multimedia data, one would think that a traditional CF examiner would be at or near the top of your go-to list. The problem with this assumption is that multimedia data is fundamentally different than most other types of data, and in more than one way.

  • Understanding video standards is fundamental to aspect ratio correction. Back in the predominantly analog days we had three main standards referenced or used for most video recordings; NTSC, PAL, and SECAM. Then in the early ‘90’s came the first digital multimedia frameworks to reach the average consumer; QuickTime and, shortly thereafter, Video for Windows (VfW).

    Today we have dozens of multimedia frameworks, digital video and digital display standards, all of which lead to a great deal of confusion regarding the plethora of acronyms and what they truly mean. AVC or H.264? HEVC or H.265? CIF or SIF? Don’t even get me started on the profiles and parameters available for each standard, as the combinations are truly mindboggling. When it comes to proper Display Aspect Ratio (DAR) though, it really boils down to “Are the originally recorded pixels square or non-square?”

  • I was out in Tacoma, WA last week to teach our DVR Assessment & Video Recovery course, and to provide a free seminar on Digital & Multimedia Evidence for area prosecutors, law enforcement and support staff. It was a really great class, and as always the group discussions during both the class and the seminar were really interesting and informative. Thank you to everyone who attended for their participation, and many thanks to Kim, Chris, and the entire Tacoma Police Department for being such amazing hosts.

    If you missed the free seminar, we’ll be back out that way to provide it again on July 8th at the Washington State Criminal Justice Training Center, in cooperation with the Washington State Homicide Investigators Association (WHIA).

    If you’re interested in our DVR Assessment & Video Recovery training course, check out our upcoming training dates and locations or contact us to inquire about hosting one of our training events.

    Thanks again everyone. Be safe out there my friends!

  • * Updated with Corrected Images & Explanations. 

    After the break you'll find several images of a bogus Person of Interest (PoI) that were recorded by a DCCTV system. Two different analog CCTV cameras with built-in IR illuminators were connected to the black-box, h.264 DVR. These JPG images were exported from the DVR’s proprietary player. All of these images exported at 704 pixels by 480 pixels. When the recorded video is played back via the proprietary player it is displayed at 630 x 455; however, analysis of the proprietary file and exported AVI files reveals both of those contain a 704 x 480 video stream.

    Your task, should you choose to accept it, is to:

    • Describe the PoI’s clothing items from these images as you would for producing a BOLO. Note any issues that may affect your description.
    • Identify the single most important correction that should be made to these images prior to printing. (BONUS - Why does this correction need to be made, and what tipped you off to it?)

    If you’ve taken one of my recovery classes or attended one of my presentations on the topic at a LEVA conference or other event, you may have seen these examples.

  • I probably should’ve just dropped the mic after the last post, but we’re going to continue on. I’m not one for dropping names, and in this case I don’t have to either. Everyone has gotten this wrong at some point, and I mean everyone. The people working on related standards; the people making the world’s leading non-linear professional editing systems; the people who make a living professionally processing and transcoding video; the people making multimedia playback software; the people making DCCTV systems; the people making operating systems; and yes, even forensic video and digital evidence technicians and analysts. We’re all human, my friends. It is a long, convoluted, complex process with its very foundation based on sampling an analog signal.

  • Let’s talk a little more about aspect ratio. Always a lively topic everywhere I go, and regularly misunderstood by industry leading CCTV equipment manufacturers, engineers, and other video professionals. Should we correct, when do we correct, how do we correct, and of course the why. I’ve done a few short posts on the topic in the past (here's one), but this will be in a little more detail. Still writing on the fly, just going to break it down into a few posts over time.

  • Several other things I should be doing on a Saturday morning, but I find myself anxious to continue this discussion. Maybe it’s because although multiple industry Best Practice documents talk about correcting Aspect Ratio, none of them discuss the proper way to do it. It could also be my new coffee maker, which I'm hypothesizing has increased my caffeine intake substantially, although I have not increased my coffee intake. Who knows. Anyway, let’s start by recapping Part 1.

  • Last week I was back in Albany, NY to provide a free seminar on digital video evidence at the New York State Police Academy, followed by Ocean Systems 3-day DVR Assessment & Video Recovery training course. It was a sold-out class comprised of both students new to the field, as well as very seasoned digital and video evidence technicians and analysts. The end result was a really great week of training and peer networking. Many thanks to all of those who attended, and special thanks to the New York State Police (NYSP) for hosting both events!

    The NYSP had a new academy class under way as well, with approximately 250 new recruits marching to-and-from the various classrooms within their renovated facilities. It was very cool to see so much activity at the academy again throughout the entire week. Best of luck to all the recruits in training. Hang in there and regardless of the outcome, thanks for stepping up to the plate!

  • Please note that this article was originally published in February, 2005.

    Let me start by saying that I am by no means trying to imply that DVR, NVR or any other digital or IP based video system cannot produce good quality video evidence. There are even 2 or 3 high-end, mega-pixel quality digital surveillance cameras and systems on the market today whose capabilities far exceed those of a traditional analog based system. However, to my point, it seems more often than not digital based systems are producing very poor quality video evidence regardless of the system's actual capabilities.

    So why do DVRs typically provide poor quality video evidence? Here are a few of the common reasons:

  • Evidence Technology Magazine has published their May-June, 2010 issue featuring a story on Forensic Video. The story was written by LEVA's Principal Forensic Video Instructor and features several LEVA members. The question you need to answer: Can video evidence be trusted?

    Full Story

  • I just returned from another great week of DME training at our office out on the east coast last week. One of the themes I've come to recognize through my travels teaching the fundamentals of DME Processing, is that even some of the most seasoned technicians and analysts don’t really understand the significance of hardware to accurate and proper processing of DME. It’s completely understandable why, given the marketing messages of some DME vendors, the fact that we're all constantly asked to do more with less, and the rate of related technological advancements.

  • A brief video discussing the basics of multimedia metadata analysis & some of the Open Source and/or Freeware solutions that can help. Solutions discussed include:

  • Acceptance of body-worn video and audio recorders is rapidly growing among police and emergency service departments while manufacturers are pointing to steady advances in their technology and ease of use.

    Full Story

  • Photoshop has grown into a very powerful and capable platform for working with video since the capability was introduced in CS3 Extended. I’ve dabbled with it over the years, but despite its impressive capabilities I always end up going with what I know best, relying on other video editing tools for most video related tasks. Well, this old dog is always trying to learn new tricks that improve efficiencies in my various personal and professional workflows, so I’ve been making an effort to explore Photoshop’s video capabilities more often.

  • Medical experts, accident reconstruction experts, and other types of experts are frequently asked to interpret data from images that were obtained from video evidence. When these experts have no training or background in processing multimedia evidence, and/or make no effort to consult someone who does, bad things generally happen. Really bad things, like having all of their evidence thrown out of court, for one.

  • Ocean Systems just announced that the Anaheim Police Department will be hosting our DVR Assessment & Video Recovery training course September 16th - 18th in Anaheim, CA. Seats have been filling up fast in our DCCTV Recovery classes, with next month's class at the New York State Police Academy already sold out!

    If your agency is looking to standardize your video evidence recoveries based on industry best practices, and you'd like hands-on training for those officers collecting your video evidence out in the field, get a quote from us today and then reserve your seat! Hope to see you in class soon. Be safe out there my friends.

  • Those who have been recovering video evidence from CCTV systems for any length of time know that every case starts as a research project. In some cases DCCTV evidence is submitted with little or no information about the recording device. In other cases the entire device may be submitted, but more often than not it’s submitted without any manuals or documentation.

  • In a ruling that promises to revamp jury deliberations in New Jersey, the state Supreme Court says jurors should be allowed to see video playbacks of recorded testimony upon request, subject to safeguards.

    "As advances in modern technology make their way into the courtroom, the Judiciary -- like the rest of society -- must adapt," Chief Justice Stuart Rabner wrote for a unanimous Court on Monday in State v. Miller, A-94-09.

    Full story:

  • Magnet Forensics launched the evolution of DVR Examiner today, Magnet WITNESSWITNESS includes all of the capabilities of DVR Examiner plus many new features, essentially creating a single solution to acquire, review, analyze and report on all of the video evidence from your case, regardless of source.  Proprietary DCCTV systems and files, cloud CCTV sources such as Ring & Arlo, MP4 & AVI exports from other sources such as in-car and body worn systems.

    Unlike DVR ExaminerWITNESS includes the ability to create sub-clips, create synchronized previews, convert proprietary DCCTV files and more.  Learn more at

  • Manufacturers often skew their specification sheets to make their product seem better than it really is, typically by providing confusing references and the like. Not cool, but what’s worse than that? When they don’t know what the hell they're talking about, then convince the majority that they do. This is the case for a lot of Digital CCTV (DCCTV) manufacturers. If you’re going to reference a video specification and plaster it all over your video output, AND you’re one of the world’s leading manufacturers of IP-based CCTV equipment, you should probably have your shit together. Here’s why you don’t.

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