Ideal traffic flow on the network means the health of the network cameras does not affect other online services, such as teleconferencing, digital signage or television content for large organizations. “If there's not enough bandwidth and the camera uses H.264, the image distorts and you miss a lot,” Moody said. “But with M-JPEG, you have a clean flow of image. H.264 or MPEG-4 will flow, but if it's not set up correctly over the network, the image tends to pixelate, or you lose the image and get image distortion.”
The biggest installation variable is bandwidth capacity available or intended, as well as the distances of cable runs, Zhou said.
Bandwidth varies between WAN and LAN, with many megapixel cameras supporting triple streams to push live, low-resolution video to phones or home computers. “On a local network, you can see whatever you want to see, including megapixel resolution,” said Todd Pinnell, PM for Video at Speco Technologies. “But there's a limit on what you can put on that network.”
Cropping megapixel images may reduce bandwidth requirements. “Since you can crop a network camera with an arbitrary aspect ratio, you can deliberately set up the camera not to record the sky or the immediate foreground — areas you most likely don't care about,” Johnston said.
Storage
The more cameras a site has, the more bandwidth and storage is needed. “We always advise the customers to invest wisely by utilizing event or intelligent video triggering to reduce unnecessary recording,” Lim said. “This also reduces the amount of information the customer has to store and review.”
Fortunately, storage costs are dropping, making megapixel cameras less prohibitively expensive. “A 3-terabyte hard drive retails for only US$179 now,” Johnston said. “That's practically free in today's terms, and two to three years from now, 3 terabytes will be laughably inexpensive and small.”
Redundancy in storage is critical for some sites, but is not supported on all VMS. “You need to look at the software, then buy the right PC servers and storage hardware to match,” Pigram said.