ClareVision Network Video Recorder Installation Guide
23
Understanding camera capacity in an NVR
When setting up your NVR and cameras, you may notice that some of the
camera images may not display in Live View. This most often occurs when you
are displaying images in 1+5 mode, or 1+7 mode because the total bit rate for all
cameras is exceeding the NVR’s capacity. The actual capacity depends on the
total bit rate from all the cameras. However, it is good practice to allow some
headroom for machine operations, such as remote streaming.
NVR model
Capacity
4-channel
20 Mb
8-channel
40 Mb
16-channel
80 Mb
32-channel
160 Mb
64-channel
160 Mb
To fully understand NVR capacity, it is necessary to understand the concepts of
streaming video, resolution, quality, and bit rate. Streaming video is content sent
in compressed form over a network and processed in real time, that is, as it is
received.
Streaming video types
• Main Stream: the high quality video that is being recorded and may be
streamed.
• Sub Stream: never recorded; intended for streaming only. Default is
704
×
480, 584 Kbps at 8 fps.
• This can be video alone, or video and audio compressed together. Audio
requires very little bandwidth.
The combination of the main stream and sub streams make up the total bit rate
of each camera. This is expressed in Kbps (kilobits per second) or Mbps
(megabits per second).
Bit rate is determined by the selected resolution (1280
×
720, 1920
×
1080,
2560
×
1920, etc.), frame rate (frames per second), and video quality (the
amount of compression being applied to each camera).
Example
32 channels of 720P cameras at 15 fps with good image quality will have
32 x (1536 + 512) = 65536 Kbps (about 66Mbps), so the 32-channel NVR can
support them.
