Digital Recorders

Over the last 17 years, we have performed over 2,000 covert video surveillance operations and many thousands more overt CCTV installations. During this time, we have seen the evolution of CCTV recording infrastructure from Reel to Reel Tape Recorders to VHS, SVHS Timelapse and Multiplexed Systems to the latest in Digital Video Recording systems.

Quality digital systems of today will go beyond the high frame rate and large database to intelligent, proactive management of the system. Users are informed and alerted to any anomalies – this includes internal watchdogs that monitor the health of the DVR and camera system to internal business rules that allow users to be informed of certain movement or behaviours.

Digital recorders offer easy reconstruction of incidents of interest. Unlike analogue systems which require multiple video tapes to reconstruct incidents, digital recorders offer a single interface to all of the cameras in the system.

Some universal rules can be applied when considering a DVR, some of these include:

No One Size Fits All

Unlike multiplexers, the Digital Video Recorder allows much greater discrimination of camera record rates and quality settings. Nowadays we can set these rules based on the job of each individual camera; be that a cash counting area, to an Entry ID point, etc.

Compression

There are currently half a dozen major forms of compression used in today’s DVR’s; the most common include: JPEG, M-JPEG, Wavelet, MPEG 2, MPEG 4, H.263 and H.264.

All forms of compression offer some advantages and disadvantages. Generally, there is a correlation between large file size and good quality. However with large file size is the challenge of storage requirements and network bandwidth (if video is required to be accessed over a WAN)

RAID

RAID or Redundant Array of Inexpensive Disks is the name given to the grouping of multiple hard disks to act as one. This is done to add capacity, performance and/or reliability.

In the Digital Video Recorder world it’s important to appreciate the risk involved in storing information on hard drives. Unlike a video tape which could hold up to a days worth of footage a single hard drive can hold up to twenty times that. With so much information held on just one disk, a single failure could mean the loss of all of the video footage in the DVR.

To overcome this we offer a form of RAID which allows for a disk to completely fail without any loss of information. Along with this technology we also offer special diagnostic and monitoring tools which can help predict errors in hard drives and report them via e-mail to the Crimewatch™ Video support team.

Frame Rates

All of our Digital Video Recorders have the ability to adjust the frame rates (pictures per second) on detection of an evenet; such as movement, time ranges, alarm panel, wireless duress and panic buttons. This allows us to strike a balance between high quality video during events of interest while maximising the systems overall archive.

Archive

Every client faces site specific threats that will determine what will be their optimum archive. We will ensure that the highest quality recordings are achieved whilst meeting your archive requirements. The length of an archive is determined by the capacity of the disk sub-system, the frame rate, the video picture size and the quality of that video.

Motion Detection

The key to Motion Detection is to accurately record events of interest while ignoring all else. Sophisticated Motion Detection software allows the DVR to maximises its efficiency without compromising recordings. High-end Motion Detection can discriminate movement by direction, by size, etc. This is particularly important when used in an out door environment where climatically conditions (cloud movement, trees blowing in the breeze etc) require the intelligence to manage these variables without missing a fame when legitimate motion occurs.