Many friends often mention a problem. How do you plan to monitor the project from the beginning to the end? These questions are good. In fact, this is the process of monitoring the basics to the entry. We have mentioned it many times before. Today, I will learn more about how to implement the 100-channel network camera monitoring solution. How to choose a device.
First, how to calculate the line bandwidth
The first step is to determine the bandwidth required for the video output of each camera. The camera parameter introduction is generally called "compressed output code rate".
Almost all cameras, this parameter can be manually adjusted, generally adjustable range of a few hundred K to 8M or 16M. The adjustable range of different models of different manufacturers is different, which needs to be determined according to your image clarity requirements.
For example, it is assumed here that the compression output code rate of each camera is 4 megabytes. The 100 cameras are 400 megabytes. Therefore, when we monitor a certain number, if there are some cards in the picture, we can first try to lower the bit rate of the camera to ease it.
Second, how to choose the right switch
Generally, several cameras share one switch. A switch directly connected to the camera can use a 100M switch. Several cameras are connected to a switch based on the geographic distribution of the camera. Then 100 Mbps switch can choose 5 port, 8 port, 12 port 100 Mbps switch. They can connect up to 4, 7 and 11 cameras respectively. Difficult to call this switch directly connected to the camera is called "access layer switch."
Of course, if some cameras are more concentrated, 12 or 24 ports can connect 11 or 23 cameras, and the output rate of the camera is relatively large. If the total output code rate exceeds 60 megabytes, then the switch should consider using thousands. The mega switch can be a 22-port 100 Mbps + 2 port Gigabit switch.
Why is the 100M switch not 60M instead of 100M? The usage rate of the general switch is relatively stable at 60%, and the camera can be connected to about 12 or so.
Third, how do 100 cameras access the switch?
If the access layer switch is 8-port, each has 7 cameras. Then the 100-channel camera requires 15 access layer switches. Then the core layer switch can choose 24-port switch, which is the kind of 20 or 22 100M interface, 4 or 2 Gigabit interfaces.
However, if the access layer switch has a Gigabit switch, then all the core layer switches must be Gigabit. This is something we need to pay attention to when networking.
In a special case, 100 cameras have a large distribution area. The length of the network cable between devices cannot exceed 100 meters.
supplement
If there is a distance between some access layer switches and the core switch, a transition switch can be added between the access layer switch and the core layer switch to perform the relay.
This will extend the distance.
Certainly a friend will ask, what if the distance is far away?
If the distance is farther away, such as seven, eight hundred meters, or even further, then do not use the switch to do the relay. A pair of fiber optic transceivers are used, one connected by a network cable next to the core switch and the other by the access layer switch. The two fiber optic transceivers are connected by fiber optics.
However, it is important to note the problems of single mode fiber and multimode fiber. If it is a single-mode fiber, the transceiver must also be single-mode, only need to use one fiber, no need to consider the length and length within a few kilometers, because the distance of single-mode fiber transmission is relatively long.
If it is a multimode fiber, the transceiver must be a multimode fiber, a pair of fibers, a distance of five or six hundred meters, and more than 2 kilometers.
Then it may involve a question, in the end, use single mode or multimode? This complements the difference
In fact, there is no difference between good and bad, only the use is different, multi-mode fiber is mostly used in short-distance building wiring closet, communication between core equipment and core equipment, the advantage is that communication bandwidth is large, and more support for 10G, the disadvantage is that It has a shorter transmission distance than single mode fiber.
Fourth, calculate the amount of hard disk storage required
After calculation, if the camera compression output code rate is 2M (note that its unit is b/s or bps, lowercase b is bit), 1 camera will generate 20GB (note uppercase to byte) data volume.
100 cameras for 30 days, with a data volume of 60,000 GB. (Note that the compression output code rate is 2M).
If it is 4M, it is 120000 GB of data.
If it is 8M, it has a data volume of 240,000 GB.
The formula is as follows:
Rate × 3600 × 24 ÷ 8 ÷ 1024 ÷ 1024 = 1 day
If it is H.265?
The code stream is reduced while ensuring sharpness. Almost double the efficiency, which means that for general monitoring systems, H.265 can save nearly half of the storage space while reducing the near-normal network bandwidth.
It can be understood from the calculation that the storage space of H.265 is reduced by 40% compared to H.264.
130w≈12G/day
200W ≈ 25G / day
300W≈37G/day
400W≈48G/day
In fact, H.265 compresses the code stream, which reduces the code rate by about 40% compared to H.264.
So how do you figure out how many hard drives you need?
Calculated on the market 4T hard drive, it shows about 3700GB on the computer. Considering that the file system itself maintains data in the hard disk, it takes a certain amount of space, and it is estimated that it can actually use about 3500 GB.
100 cameras store one month hard drive calculation
1M code rate, 30000GB, requires 9 hard drives.
2M code rate, 60,000GB, requires 18 hard drives.
4M code rate, 120000GB, requires 35 hard drives.
8M code rate, 240000GB, requires 69 hard drives.
If you use a hard disk recorder that supports h.265, the hard disk can be reduced by about 40%.
DVRs generally have 2 bays and 4 bays, and some are 8 hard drives or 16 bays. Haikang's NVR has the largest support for 24 bays, and the maximum capacity of each interface is 8TB.
You can also use a storage server. Two servers are required for 2M code rate and 4M code rate. 8M code rate, can be a 48-disk server, a 24-bay server. Or use the storage server + hard disk cabinet solution. These programs can be considered on their own project budget.
5. How to determine how many splicing screens are used?
If more than one hundred monitoring signals are required to be displayed on the screen at the same time, there is a certain requirement for the number of liquid crystal splicing screens. If the number is small, it will definitely not meet the requirements. Under normal circumstances, in order to achieve the desired viewing effect, a liquid crystal splicing screen is basically All are divided into 4 channels, 9 channels or 16 channels of monitoring screens for common display.
Although it is also possible to achieve 36-way segmentation, the entire screen is too small after segmentation, and the specific content is not seen a little further. Therefore, if we want to achieve the desired display effect, we will count the single-screen 9-channel monitoring signal display, and 100-channel monitoring will require at least 12 screens.
Sixth, how to make the monitoring display on the wall?
100 channels of monitoring on the wall we need to use the decoder, basically every brand of monitoring manufacturers are equipped with a decoder of their own brand, like Haikang DS-6400HD-T series, up to 16 outputs, also It can be used within 16 LCD splicing screens, supporting 8 channels 800W, or 16 channels 500W, or 24 channels 300W, or 32 channels 1080P, or 64 channels 720P, or 100 channels 4CIF and below resolution.
In other words, if we calculated the 100-channel monitoring into a single-screen 9-channel monitoring signal, we need 12 screens. We choose a 16-channel decoder on the wall, and we can put 12 splicing screens. All decoded on the wall.
However, this method also has the disadvantage that the decoder of the same brand can only decode the surveillance cameras of its own brand. If the front end of the user has multiple brands of monitoring, then it is not compatible.
At this time, you can use the digital matrix.
The digital matrix is ​​a mid-to-high-end decoding device that decodes the front-end digital video signal onto the wall. The input end of the signal is a Gigabit Ethernet port, and the output end is a standard VGA/DVI/HDMI video interface, which can be directly connected to the display. A splicing controller can also be connected.
In addition to the full functionality of the decoder, it has more features and more decoding capabilities. It can support DVR, DVS, IPC and NVR devices of different manufacturers to decode the wall at the same time, and has the functions of video switching, picture segmentation, picture stitching, round-robin display, cloud mirror control, video playback, alarm linkage, etc. .
Seven, how to network?
Solution 1, a network
We said above, 100 channels of monitoring, so the access layer of the 100-megabit switch is 15, 22 access switches through the fiber transceiver into the computer room, even the core switch, the core switch in the NVR, the core switch uses Gigabit 24 Port switch.
Among them, 15 ports of the core switch are connected to the access layer switch, and other ports can be connected to the NVR. If the 100-way switch uses the 32-way NVR, then four NVRs are needed, which is completely sufficient.
Solution 2, splitting two networks
Of course, the entire monitoring network can be split into two parts, with two 16-port Gigabit switches, one connected to seven, and one connected to eight access layer switches.
In this way, there are about seven ports left, one port is connected to the top segment of the switch, and the remaining ports can be connected to the NVR.
It is assumed here that we have to use four NVRs. That one core switch only needs two, and the core switch on the other side is the same.
Of course, this method is not necessary at all, but for solution 1, if the number of access layer switches is large, the core switch port is not enough, then scheme 2 can be used.
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