August 8, 2022
In the surveillance video system, we all know that the size of the storage space, the number of channel pictures and the picture quality are inseparable. Today we make a brief summary of the calculation of monitoring storage space and transmission bandwidth.
First clarify a few concepts:
Bit rate: The number of bits transmitted per second, in bps. The higher the bit rate of broadband transmission, the larger the data transmitted.
Note: Many people are not easy to distinguish the concepts of bits and bytes, and ask why there is a division by 8 in the formula for calculating capacity. I will explain these two concepts to you in the next article. If you haven't paid attention, please pay attention to the public number: first monitoring. You can see the second article.
In the case of the same resolution, the larger the code stream of the video file, the smaller the compression ratio and the higher the definition of the picture.
Upstream bandwidth: The bandwidth for uploading local information to the network. Size is usually expressed in upstream rate.
Downlink bandwidth: The bandwidth for downloading network information to the local. The size is usually expressed in terms of downlink rate. Transmission broadband calculation:
1. Network bandwidth size = bit rate size × monitoring number
The first monitoring note: Some professional books write bit rate as bit rate. Everyone can understand it. According to my understanding, the bit rate refers to the network speed, and the bit rate refers to the size of the surveillance video generated per second.
The bandwidth on the surveillance camera side refers to the upstream bandwidth. Because the monitoring terminal uploads video information to the video monitoring room)
The bandwidth of the monitoring center refers to the downlink bandwidth.
2. The bit rate of the specific surveillance camera (slightly different for each brand of camera)
1080P (2 million pixels) video format, the bit rate of each camera is 4Mbps
That is, the data transmission bandwidth required by each camera is 4Mbps, and the data transmission bandwidth required by 10 cameras is: 4Mbps (bit rate of video format) × 10 (the number of cameras) = 40Mbps (upstream bandwidth)
That is: the network uplink bandwidth required for monitoring in various places using 1080P video format is at least 40Mbps
960P (1.3 million pixels) video format, the bit rate of each camera is 3Mbps
720P (1 million pixel) video format, the bit rate of each camera is 2Mbps
3. Bandwidth required by the monitoring center:
The required bandwidth of the 1080P (2 million pixel) video format: 4Mbps (bit rate of the video format) × 50 (the sum of the total number of cameras at the monitoring point) = 200Mbps (downlink bandwidth)
That is: the network downlink bandwidth required by the monitoring center using 1080P video format is at least 200Mbps
The required bandwidth of the 960P (1.3 million pixel) video format: 3Mbps (the bit rate of the video format) × 50 (the sum of the total number of cameras at the monitoring point) = 150Mbps (downlink bandwidth)
The required bandwidth of the video format of 720P (1 million pixels): 2Mbps (bit rate of the video format) × 50 (the sum of the total number of cameras at the monitoring point) = 100Mbps (downlink bandwidth)
4. Calculation of storage space capacity:
(Note: storage unit conversion 1TB=1024GB; 1GB=1024MB; 1MB=1024KB)
Stream size (unit: KB/s; i.e.: bit rate ÷ 8) × 3600 (unit: second; seconds in 1 hour) × 24 (unit: hour; length of one day) × 30 (days saved) × 50 (the total number of camera recordings to be saved at the monitoring point) ÷ 0.9 (10% space loss from disk formatting) = the size of the required storage space.
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