This article has a big premise, that is, regardless of H.264 or H.265, because it is a common problem, no matter which encoding format is adopted, it may be encountered.
Since the moment the network HD cameras occupied the mainstream of security surveillance, the Caton problem has never been broken. It is not intended to be solved, but because it is a systematic project, every node of the system needs to be thoroughly researched, and it takes a long-term investment to gain.
In the actual project selection, in order to ensure smooth image, the exchange capacity can be used as the reference value for selection, and it is still the most important, but it is not recommended to use the traditional calculation method. The traditional exchange theory is completely transplanted and there is a phenomenon of acclimatization. High-definition monitoring data transmission has its particularity:
1, burst traffic
The video data transmission is very different from the text data. The fixed data size of the video data is fixed at a fixed frame interval. Since the video image I frame (key frame) and P frame (non-key frame) are of different sizes, there is burst traffic. . Take 1080P HD video as an example, the reference bandwidth is 8M. In fact, 8Mbps is an average value, and the actual value is 2~12Mbps (depending on the encoding and decoding compression ratio). Because of the peak rate in burst traffic. The maximum can reach 1.5 times the reference code rate.
2. The transmission method of video image data is uplink, contrary to the tradition.
3, 7 * 24h real-time transmission, real-time requirements are very high, all data is 100% concurrent at any time.
Therefore, in the selection of the switch, it is really important to pay attention to it. Generally speaking, the utilization of network bandwidth should not exceed 50%, otherwise the overall performance of the network will decrease, and once there is bursty traffic in the network, the network is prone to congestion and video. Business Caton is even unresponsive. If the network bandwidth utilization is less than 20%, the network performance is optimal according to the definition of light-duty network of international standards.
In summary, considering the bandwidth utilization and burst traffic, the reserved bandwidth reserved for 1080P video should be calculated 2 to 3 times the reference bandwidth, and the network bandwidth utilization should be equal to 50. %the rules.
Is there any other reason besides the switch? some.
Reason one: camera manufacturing itself has defects, including technology, materials and processes
Some network cameras produced by some manufacturers will have a relatively long delay after running for a long time, which greatly exceeds the delay time required by the national standard. It gives people a feeling that the picture is stuck, and only after the camera is powered off can it return to normal. It is recommended that users choose the monitoring products of big brands, the technology is excellent, and the after-sales is guaranteed.
Reason 2: Improper selection of NVR and decoder
For customers who use the network HD DVR to display storage, the decoding capability of the selected network HD DVR will also affect the smoothness of the picture. If the connection picture exceeds the maximum decoding capability of the DVR, or the core chip itself selected by the DVR, If the processing power is not strong, it will lead to the phenomenon of picture sticking. For this situation, it is recommended that customers choose the products of big brands, and at the same time, be careful not to be fully loaded, and live with a full load indicator when purchasing.
Reason three: insufficient performance of the client computer
For customers who use computer + software for display storage, the performance of the computer configuration, CPU, GPU, memory, etc., will affect the smoothness of the monitoring screen. If the CPU, GPU, memory performance is insufficient, display a certain number of video screens. After that, the picture will be stuck. At this time, the CPU and memory usage can be detected by the computer task manager. For this situation, it is recommended to use a computer with a higher configuration.
Reason 4: The quality of the used network cable is too bad.
Generally, the farthest transmission distance of the regular national standard network cable will not exceed 100 meters, and the transmission performance of the inferior network cable will be greatly discounted. If the inferior network cable is used, the previous picture may be normal, and the oxidation loss of the line may cause the signal transmission to be lost. , when the time is broken, the picture is stuck. In this case, it is recommended to select a good quality national standard network cable during construction.
Reason 5: The details are not considered well
For example, in the middle of the Gigabit network, a 100-megabit fiber optic transceiver is selected;
For example, Gigabit Networks uses five types of network cables;
For example, strong and weak electricity is not isolated, and the network cable is disturbed;
For example, if the dual stream is not properly set, the HD camera can provide a high bit rate stream for local HD storage and a low bit rate stream for network transmission in a remote monitoring environment. According to the network bandwidth, the code stream format is flexibly selected to achieve local high-definition storage and the back-end low-stream network transmission.
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