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Video recording in the 21st century

Video monitoring and recording are now very different from the days when the terms CCTV and DVR were coined, and both terms are frequently misused.

Modern IP video cameras are anything but 'closed circuit' (the CC in CCTV), and the rise in popularity of IP video (also termed network video) is in large part due to its flexibility and the capability of providing anywhere access to live images. In the case of digital video recording, the mismatch comes from the name having been attached to specific hardware. IP video image data is also captured digitally and uses similar basic components such as hard disks, but the major difference with a network video recorder (NVR) is that an NVR uses commodity components. It is just a PC with a network connection and hard disk space that can accommodate as many cameras as you wish, can be scaled arbitrarily, and, because it uses common PC components, is far cheaper to implement.

Typical limitations of the older DVR technology are proprietary operating systems and components, and specialised hardware that puts hard limits on the number of cameras supported and requires upgrades in blocks, for example by adding 4-channel or 8-channel digitiser boards, and may well require you throw out one board to replace it with a higher-capacity board. Apart from the cost implications, you also face the risk of obsolescence as proprietary components are discontinued.

Apart from the system configuration flexibility and low cost inherent in NVR systems, the other major differentiator is that an NVR is completely flexible with regard to image frame rate and resolution. In general, DVRs work with either NTSC or PAL frame rates (25 or 30 fps), TV-based resolutions and interlaced images which introduce motion blur. An NVR can record in any resolution and frame rate supported by the camera with progressive scan imaging, and each camera can be different. A single system can for example have cameras operating at mega pixel or higher resolution where great detail is required, and others are low resolution where only basic monitoring is needed. Frame rates can be adjusted for the best trade-off of detail versus storage required.

The fact that NVR systems run on standard PC hardware and operating systems also makes it much easier to integrate them with other applications, such as access control and fraud monitoring systems. Most NVR software provides application programming interfaces for this purpose, and running on a common platform greatly simplifies the task.

Traditional DVR will continue to have a place for some time in stable, closed systems, but there is no doubt that NVR technology is growing fast.

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