The relationship between the number of NVR access channels and bandwidth: how to calculate access capability

Triple constraints

How many roads the NVR can carry is jointly limited by three indicators, and the minimum value is taken:

1. Number of access channels (License): The upper limit of the number of channels authorized by the software.
2. Access bandwidth (Mbps): The sum of all camera bit rates cannot exceed it.
3. Decoding/forwarding capabilities: Decoding resources required for local preview and wall splicing.

Bandwidth calculation

Total access bandwidth = Σ each main stream + Σ each sub-stream (if streams are taken at the same time)

Example: 16-channel 4 million cameras, main stream 4Mbps, sub-stream 0.5Mbps:

• If only the main stream is saved: 16 × 4 = 64 Mbps
• If sub-stream preview is taken at the same time: 16 × (4 + 0.5) = 72 Mbps

If the nominal access bandwidth of the NVR is 80Mbps, it is available; if it is only 64Mbps, it is fully loaded and there is no margin.

Common parameter reference

The pitfalls of decoding ability

• The nominal "8×1080P decoding" usually refers to 8 channels of 1080P@30fps. If 4K channels are turned on, the number will be significantly reduced.
• Enabling intelligent analysis (such as face comparison) will occupy computing power and reduce the number of available decoding channels.
• Splicing screens on the wall and multi-channel playback also consume decoding resources and need to be included in the calculation.
• Remote client streaming does not occupy decoding, but does occupy forwarding bandwidth.

Suggestions for selection

• First count the total code rate of all points, and then select NVR bandwidth by 1.3 times.
• Reserve 20% to 30% of the channel number to facilitate later expansion.
• For large projects, give priority to distributed architecture or streaming server offloading, rather than stacking a single NVR.
• Pay attention to the number of disks: No matter how large the number of channels is, there will not be enough disks to store it.