In the investigation at hand, we last left with our elusive suspect still painting the walls red at our manufacturing site's main office. While every reactive security measure has failed to identify and catch this finger-painting vandal, you have just selected your new low lux, infrared board camera after reading Covert Investigations: Cameras to catch your suspect red handed. (Literally.)
Also see the investigations primer Internal Investigations: The Basics
Unless you want to wire your new camera to a television and watch for hours live, your next, often underestimated step is selecting a video recording device to capture the incident for posterity. Much like the selecting your covert camera for size, resolution, lux level and power consumption, recording devices also have a few vital requirements to help you meet your goals. This time size is not an important issue; in my next column, covering covert installs, we will discuss setting up your recording device covertly near your camera or remotely across the globe. The real concerns in recording video are:
- Resolution (Again)
- Frames per decond (FPS)
- Retention requirements
- Recording device type
Even though you just spent a few hundred dollars on a state-of-the-art covert camera with 720 lines of resolution, if your recording device doesn't have equal or greater resolution, the video playback is going to suffer. Less lines of resolution means less detail to capture important identifiers that will help catch your suspect. Covert cameras and recording devices aren't magical tools that can record the inscribed name off your suspect's watch, closing the case between commercials. Instead, good resolution will help you clearly identify the suspect's face and other minor details that will hold up in a real court of law, not an episode of CSI. All reputable recording devices and their vendors will tell you the true resolution of the machine.
Frames per second (FPS or IPS) is a factor that many ignore until it's too late. In an attempt at saving storage space (retention), many recording devices remove frames from the image, making playback of the video look choppy. Instead of the fluid, natural movement of 30 frames per second, cheap recording/storage devices drop as low as 3 frames per second. Even the common 15 frames per second will show your suspect standing in one area and jumping across a room in the next frame.
The high price of saving money
Although great at reducing storage issues by over 50%, low frames-per-second make for an opening to miss something. The last thing a jury needs to see is a suspect holding stolen money one second and then not holding the money after a skipped frame. For a good example of how each frame per second looks compared to 30 frames per second, check out this simulation video: http://www.aventuracctv.com/howthingswork/fps.asp . Also make sure your recording device isn't being deceptive about its frames per second. Many devices that allow for multiple cameras lose frames per second as the numbers of cameras are installed. I prefer 30 frames per second per camera.
What do you get when you multiply resolution (the file size of one frame) x 30 Frames Per Second x Number of Days of planned surveillance? That's right, the amount of storage needed in your recording device or retention. Using this simple calculation or going to websites that offer a more precise formula (http://www.dvrmaster.com/dvr_calc.php) will help you determine how much storage space you need, from a stack of video cassette tapes to a few gigabytes of digital data. Obviously in the retention arena, bigger is better, but not always needed or cheap. For covert applications, use the formula to find a recording device that fits your needs and budget or is upgradeable in the future with more tapes or expanding hard drives.
VCR tapes?!
Yes, I have mentioned VCR cassette tapes twice now. I know this is not 1995, but sometimes our budgets leave us stuck using old security VCR machines or our personal Sony player that is (or should be) collecting dust in the garage. Although a VCR will work for a recording device, most lack the resolution, frames per seconds and retention that your investigation needs. Today most recording devices revolve around the use of Digital Video Recording (DVR) or Network Video Recording (NVR, which we will discuss in part 3). These devices use digital storage from hard drives (and some flash) to record months of full 30 frames per second, high resolution video. Most DVRs offer easy to use setup on their machine or even plug into your own computer with great search and video export features.
Remember your recording device is for covert applications, so use your budget wisely. There is no need to buy an enterprise-grade DVR with video analytics if you use it only for a few select investigations. On the flipside, don't cheap out. Covert surveillances can capture important evidence that you don't want to fail. Like many covert cameras, many vendors and spy shop websites are trying to make a quick buck selling you DVR's without the proper resolution, frames per second and retention that you need to close your case successfully.