Analysis of Video Transmission Equipment Technology and Features

The Internet era has created an information-rich world. Through the Internet, we can learn a lot of new things and knowledge, and broaden our horizons. The network video server brings us more intuitive experience. Let’s briefly explore the following together. Network video server.

Network video server concept

The network video server is a special device that encodes and processes audio and video data and completes network transmission, thereby realizing the function of remote monitoring. The network video server on the market now has products that use M-JPEG, MPEG4, H264, and other encoding technologies to encode video data.

The composition of the video server

The network video surveillance server is a special device for audio and video data encoding and network transmission processing. It is composed of audio and video encoders, network interfaces, audio and video interfaces, RS422/RS485 serial interfaces, and RS232 serial interfaces.

Audio and video compression encoder: As the amount of analog video data is very large, the amount of data after conversion through digital-to-analogue is also very large, so to use mature coding technology, the video data is subjected to high compression ratio under the technical indicators that meet the requirements of network transmission. Coding foot transmission requirements. Previous network video servers generally used M-JPEG and other encoders, users can not achieve a higher compression rate, suitable for a variety of different network environments, can only achieve the effect of a general network transmission effect by reducing the frame rate. At present, companies have already launched MPEG4 network video servers to meet the requirements of video network transmission.

Network Interface: Since the networking of previous analog products is mainly implemented through the establishment of expensive and independent optical fibers to realize network transmission, the Ethernet interface of the network video server can easily implement IP networking and achieve data transmission. The network video server mainly adopts protocols such as TCP/IP to realize network transmission of data such as audio and video data, control data, and status detection information.

Audio and video interface: Network video server with standard analog audio and video input interface, easy to monitor the video signal of each channel. NetVision uses DynamicStreamControl technology to ensure real-time transmission of two-way audio. The video frame rate is automatically adjusted according to the bandwidth. After the network is disconnected, it is automatically connected.

RS422/RS485 serial interface: The network video server has RS422/RS485 serial communication interface, which can be connected to various peripherals such as PTZ, dome and other peripherals via communication lines.

The network monitoring video server can cooperate with the computer control software to realize the large-scale system networking program. Some manufacturers' network video servers provide an open SDK for users or third-party vendors to develop and construct new application methods.

Digital Video and Audio Coding Techniques for Network Video Surveillance Servers

Digital coding technology, also known as compression, is the core technology of video servers and is the primary object of our selection of network video servers. At present, the more popular digital compression coding formats are MPEG-4 and H.264, and some of the old foreign programs still use wavelet compression and M-JPEG compression.

1. M-JPEG

M-JPEG as a digital compression format, from analog to digital, from video recorders to hard drives, M-JPEG has brought us a new digital broadcast means, it turns the signal into data, it should be said that M-JPEG compression Technology has a landmark in the emergence of video compression. M-JPEG is based on intra-frame, frame-independent compression, so compared to the subsequent MPEG-4, H.264 compression, it is more data, transmission difficulties, so the encoding technology of the network video server has been basic Can not meet the needs of the current remote monitoring, can only be considered once the product.

2. MPEG-4

In the MPEG (Moving Picture Experts Group) series of compression methods, MPEG-4 technology is a better one among code streams and picture quality, so many companies have introduced this coded product. The inter-frame compression method uses the redundant information between frames to greatly reduce the amount of compressed data. To achieve the same video quality, MPEG-4 requires only 1/30 or less of the M-JPEG code rate.

3. H264

The Joint Video Team (JVT) proposed the H.264 encoding technology based on the H26L, which reduces the bitstream and improves the picture quality by increasing the complexity of operations. The emergence of H.264 provides a solution to the realization of low-stream network transmission, and also makes the application of multi-channel network video server possible under the existing bandwidth.

Network video server network technology

Because the network video server has the function of independently performing network transmission and does not need to set up a separate computer, it can realize a simple IP mode networking, which cannot be achieved by traditional analog monitoring. Each network video server has a unique IP address in the network segment. It is convenient and convenient to control and control the device (IP address) through the network connection. That is, the video source connected to the network video server is identified, managed, and controlled by the IP address. Its networking is simply a simple IP network connection. Adding a new device requires only one additional IP address, which greatly facilitates network upgrades and other network requirements that were originally simulated.

IP networking is a feature of network video servers. However, due to the lack of domestic IP address resources, domestic economic broadband (ADSL, cable broadband, etc.) all use dynamic IP to access the Internet, which makes network video servers need to solve Internet access problems. Network video servers can basically use the domain name method to support DDNS (dynamic IP). If the network video server does not support domain name resolution, it will need to increase the cost of the network.

Since the work of the network video server can not require an external computer, it is necessary for the network video server to be able to automatically access the Internet independently. Otherwise, configuring a computer for the dial-up of a network video server will lose the significance of the network video server. Currently, domestic network video servers can basically implement this function. For example, ADSL automatic dialing technology designed specifically for domestic broadband conditions is very convenient.

There are many advantages in the network video server's networking method. In combination with the central control management software and server model, more network applications can be realized. Due to the length of this article, we will not discuss in detail. We will provide dedicated network application articles in the future.

Network video server features

The network video server has many features that are not available in traditional devices. The specific performance is as follows:

(1) Simple integration of multi-channel, network transmission, video recording, and playback functions into the network. This is also very easy to implement for the current H264 network DVRs, but the basic functions of the two products also lead to their application. Differently, at present, for the simulation stage and the first-generation devices with poor network performance, the network video server can provide a lower-cost solution.

(2) The network video server can browse the screen as long as it can access the Internet through network technology. The use of a supporting decoder can eliminate the need for computer equipment to directly transfer to the video wall, which greatly saves remote monitoring. the cost of.

(3) The multi-protocol support of network video server is perfectly combined with the computer equipment to form a larger system integration network to complete the digitization process.

The application of network video server in the current video field is mainly the use of network video server to build a remote monitoring system. The multi-channel digital communication technology based on network video server has many advantages that traditional analog output system based on video tape recorder has unparalleled. The network video server adopts open hardware and software platform and standard or common interface protocol, and the system has strong expansion ability. With the future of all-digital, networked, systematic, multi-channel resource sharing systems such as convergence. It is the best solution for the current transition from analog to digital CCTV equipment.

In the long run, the system integration of network video servers has a huge potential market and far-reaching development prospects, because at a deeper level, video networkization and system integration are not only problems of video transmission, it represents the network of future video applications. The development trend of application and information interaction is a deeper level of interaction from the content, with broad development potential, and is one of the core contents of future 3G and broadband services. Therefore, it can be affirmed that with the continuous development of digital technology and network technology, the application of network video servers in the video field will have more extensions.