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70 Clare Controls IP Network Camera User Guide

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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.

• 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.

Each channel can support a different camera, as long as they do not exceed the total bit

rate limit. It is entirely possible to mix 5 MP cameras with 4CIF IP cameras, etc.

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ClareControls CH-THSTAT-W Guia do Utilizador Página 78