HD network camera network delay analysis

HD network cameras have been widely used in life, but the monitoring system has also experienced network delays. What is the matter?

Coding efficiency

Both analog-to-digital and digital conversion consume time and resources. The image is encoded at the front end, and the time spent in decoding and displaying it at the back end is part of the delay. At present, manufacturers basically adopt the compression algorithm of H.264. The more complex the image scene, the more moving objects, the larger the bit rate and the frame rate, the higher the H.264 category and level used, the more complicated the computation is. The more difficult it is to encode or decode, the more time it takes. Sacrificing system resources is often used in exchange for coding and decoding efficiency, which is one of the reasons why CPU frequencies are getting higher and higher. H.264MainProfile@Level4.1 compression level, which can balance image quality and delay. From the perspective of the image sensor, since CMOS is a direct output digital signal, the effect on delay is lower than that of CCD.

2. Transmission links and devices

The main factors affecting the network delay include the quality of the transmission line (such as the quality of the network cable, the adopted process standard, etc.), the number of routes or exchanges (the time required for route forwarding, the more the number of route hops, the greater the network delay) and the traffic of the network. (The larger the network traffic, the longer the switch and router spend, and the greater the network latency). Since the switch is a common device in the transmission of network cameras, the switch has an important influence on the image quality of the network HD. Problems such as delay, packet loss rate, backplane bandwidth, switching capacity, and packet forwarding rate of the switch affect the performance and latency of data exchange. So the choice of network cable and switch is crucial because it will directly affect the image quality of the entire transmission link.

3. Decoding device performance

The decoding device usually refers to a decoder or a client host for decoding. The quality of the host configuration directly affects the efficiency of decoding, causing problems such as delay or pause. However, sometimes when decoding or encoding, some buffers are artificially added for smooth image.

In order to reduce the delay of high-definition network cameras, it is necessary to increase network bandwidth or reduce video frame rate or bit rate, reduce transmission equipment (such as routers, switches, proxy servers), optimize computer performance, close unrelated network services and software, and reduce customers. End buffer time (choose between real-time and smooth).

Summary: The network delay of HD network cameras is a normal phenomenon, but in the near future, through the acceleration of broadband, I believe that the network delay of network cameras can be well resolved.