COMPRESSION & DATA MANAGEMENT

Compression and Data Management:

As because megapixel cameras resolve so much detail, bandwidth usage and video storage can quickly become an issue. Both are dependant on the compression format used in the camera (Motion JPEG or MPEG-4 are two of the most common) and the frame rate at which the video is transmitted. Without going into too much detail, Motion JPEG is full frames of video, compressed in sequence to give the impression of motion. Each image or file is quite large and can consume an excessive amounts of bandwidth when sent at a full 30 fps (frames per second),but the compression technology is simple and fast and there is virtually no lag or latency which can affect PTZ control, video motion detection or object tracking. When frame rates are adjusted to limit bandwidth usage, image quality is not lost.

 MPEG 2 and 4 compressions are more complex and work by compressing only the changes from one frame to the next in a limited sequence before the process is refreshed and the next full frame is compressed. This method has the advantage of lower volume data to help ease bandwidth usage while maintaining a relatively high level of quality. The compression complexity results in a higher latency or time lag when compared to Motion JPEG. However, because disk storage is directly related to bandwidth, MPEG is usually better suited to restricted space storage devices.

Implementing megapixel cameras into existing and new systems needs to be handled with the utmost attention. Bandwidth and storage need to be calculated up front before a system can be designed and quoted. Look at it this way; a lot of people have digital cameras and e-mail pictures to their friends with image files typically as large as 2MB. Translate that into a security application and imagine sending and recording thirty 2MB images a second over your network every second, 24/7. Even with a few megapixel cameras in place, there is a dramatic increase in bandwidth and storage capacities. So, it’s important to weigh the bandwidth and recording requirements needed to accommodate megapixel cameras in the system then weigh the costs associated with these additions relative to deploying conventional cameras. If video requirements call for the added detail and definition megapixel cameras offer, you may find the associated costs warranted.