For the server side, there are two other factors to consider when deploying lossy compression. They are scene motion and object speed. Lossy compression will certainly save money on storage, but may require significantly more processing power (more processors, more money) to perform the task. The more motion in the field-of-view and the speed of the objects, the more processing is required when using a lossy compression algorithm. The algorithm is basically estimating the location of those objects moving within the field-of-view and their speed when compressing (encoding). It then must recreate the stream when accessing data (decoding). In areas of significant changes from static images to high motion/high speed, processing requirements become overwhelming. There are also visual effects that occur when systems are not configured to take higher processing needs into account including ghost images, artifacts, storage spikes, bandwidth overconsumption and video corruption.
It is interesting to discover that each camera manufacturer’s products perform differently depending on the type of video management software and the compression algorithm. The differences can be vast. In order to make certain there is an accurate server and storage configuration, you need to verify these details with not only the video management software provider, but the camera manufacturer. Storage server suppliers are also a great resource as theses companies test and benchmark the various open architecture video management systems available to determine the most effective hardware platform. These vendors typically have more expertise in data payload to disk delivery and processing requirements.
With all of the options available for compression, with price as the primary consideration, the lossy schemes are most common. The surveillance environment helps determine the best compression fit for the needs of the user. Lossless compression provides a higher quality image and better evidentiary data than lossy compression and should be considered in appropriate environments.
About the author: Kevin Klemmer CISSP PSP, is director of Sales, Pacific Northwest/Western Canada, for Pivot3. An ASIS member since 2000, he obtained his PSP certification in 2003. He previously held the position of Chairman of the Puget Sound Chapter for 2007 and 2008 and is currently Assistant Regional Vice President for ASIS International Region 1A. Klemmer holds the CISSP credential: Certified Information Systems Security Professional.