Why video is demanding
Most household network traffic is bursty: a page loads, a message sends, and the connection goes quiet. A camera is different. It produces a stream of data for as long as it is running, whether or not anyone is watching. One camera is rarely a problem. Eight or twelve, all running around the clock, can account for a large share of a small network’s capacity.
The amount of data a camera produces is its bitrate, usually quoted in megabits per second (Mbps). It depends on resolution, frame rate, the compression format, quality settings and the scene itself. A busy scene with trees moving in the wind produces more data than a still hallway. Sensible planning starts with finding the actual bitrate in each camera’s settings rather than assuming a figure.
A hypothetical example
Suppose a small office has eight cameras, each set to a 4 Mbps stream. Eight times 4 is 32 Mbps of video flowing continuously. The numbers here are made up for illustration, but the method is general: add up the bitrates of all streams that travel over the same link.
Where that 32 Mbps goes matters:
- Camera to recorder, on the local network. If the recorder is on the same switch or router, the traffic stays inside the building. A wired gigabit connection has a nominal capacity of 1,000 Mbps, so 32 Mbps is a small slice of it. Wired links handle this comfortably.
- Camera over Wi-Fi. Wireless links share airtime, and their real-world throughput is often far below the advertised speed. Several high-bitrate cameras on one access point can cause dropouts, especially with distance or interference. Wi-Fi reliability is a recurring problem for video.
- Out to the internet. If every camera also sends a stream to a remote service, the 32 Mbps must fit through your upload speed. Many home and small-business internet plans have much slower upload than download speeds. If your upload were 20 Mbps in this example, the cameras alone would exceed it and other uses, such as video calls, would suffer.
Download and upload are different things
Internet plans often advertise a large download number and a smaller upload number. Cameras that send footage to the cloud use upload. So do remote viewing sessions, because the video leaves your building to reach your phone. Watching one live stream remotely uses roughly that camera’s bitrate in upload capacity for as long as you watch. Check your plan’s upload speed, then compare it with the combined bitrate of anything that uploads continuously.
Ways to reduce the load
You usually do not need to give up coverage. Common adjustments include:
- Lower the bitrate or frame rate on cameras that do not need detail. A camera watching a storage shelf may be fine at a lower frame rate than one watching a cash counter.
- Use sub-streams. Many cameras offer a second, lower-quality stream for live viewing on a phone, while the full-quality stream goes only to the recorder. Remote access then uses much less upload.
- Record on motion instead of continuously, if that suits your needs. For uploads to a remote service, this can reduce traffic sharply, though it relies on the motion trigger working properly.
- Use efficient compression when the cameras and recorder support it. Newer formats generally produce less data for similar quality, but compatibility differs by equipment.
- Keep video on the local recorder and upload only clips or alerts, rather than constant streams.
Wired versus wireless cameras
Cabling carries video more predictably than radio. Cameras connected by Ethernet are less affected by neighbors’ networks, walls and microwave ovens. Power over ethernet can supply power through the same cable, which simplifies installation. When wireless cameras are the only practical option, plan for their load: fewer cameras per access point, good signal strength at every camera location, and a separate network for the cameras so they do not compete with laptops and phones. Setting up a guest network or other separate segment for smart devices also keeps cameras away from more sensitive computers.
Signs your network is strained
- Live views stutter, freeze or show a lag of several seconds.
- Recordings have gaps, or cameras show as offline for a few minutes at a time.
- Video calls or streaming slow down whenever cameras are active.
- The router or switch becomes warm and unresponsive, or needs frequent restarts.
If any of these appear, look at the busiest links first. Often a single overloaded access point or a modest upload speed is the cause, and one change, such as running a cable or enabling sub-streams, fixes most of it.
Planning ahead
Before adding cameras, list each one with its bitrate and note whether it connects by wire or Wi-Fi and whether it uploads off-site. Total each link. Leave generous headroom, since bitrates rise at night when the image has more noise and when more motion occurs. If you plan to expand later, choose network gear with spare ports and capacity. The aim is a network that carries the video without becoming unreliable for everything else, and that keeps recording even when you are not looking.