AV over IP technology based on network protocol for audio and video signal transmission is being adopted by more and more audio-visual industry customers and even radio and television producers. New retail, corporate collaboration, hospitals, security surveillance, transportation, radio and television production and other professional fields are gradually opening up the use of network-based audio and video transmission solutions. In fact, AV over IP technology has been around for a long time, but in recent years, it has been out of circles frequently. It has developed from the audio-visual industry to the broadcasting and television industry. It has been favored in IP distributed projects and gradually formed a "hybrid" workflow. This article is mainly based on the technology itself and its industry application to analyze the reasons behind its development.
【 AV over IP Industry Interpretation】
AV over IP (full name Audio-Visual over Internet Protocol, also known as AV/IP) refers to a technology that transmits audio, video and control signals through network infrastructure (such as WAN, LAN, 4G/5G network, and public Internet). Compared with the traditional way of point-to-point transmission using HDMI/SDI cables, the AV over IP architecture can greatly increase the throughput of data transmission by adding network switching equipment, and is not limited by the number of physical interfaces of the equipment. In the AV over IP architecture, the traditional audio and video signal transmitter has become an IP encoder, and the audio and video signal receiver has become an IP decoder, which performs compressed or uncompressed audio and video transmission, and completes the part through the codec Video processing work, such as up and down scaling, color space conversion, picture flipping, etc.
【AV over IP Transmission Standard】
At present, there are rich and mature network transmission standards available in the industry. Users can choose different transmission protocols according to specific project requirements, such as SMPTE 2110, NDI, SRT, RTMP, SDVoE, Dante, etc., and different transmission protocols are in use The above is the game between audio and video quality, bandwidth, delay and reliability. At present, many AV products in the market can basically realize the transmission of audio and video signals, but the differences are mainly reflected in the compatibility of different network transmission protocols, different video source equipment and different platforms and production software, as well as the quality and quality of signal transmission. On stability.
【AV over IP Technical advantages】
Compared with the traditional way of signal transmission through cables, the advantages of AV over IP are mainly reflected in the following three aspects:
High scalability: When the network bandwidth allows, users can add multiple endpoints to the AV over IP architecture, and can distribute a single video signal to thousands of terminals for display and monitoring, and meet the needs of a broad system with minimal investment Upgrade requirements.
High flexibility: From the perspective of the actual deployment of the project, while maintaining the original network infrastructure without any changes, a network cable is used as an IP-based port device (including IP phones, IP codecs, and network cameras). Etc.) While transmitting data signals, it can also supply power to such devices (PoE), which not only maintains compatibility with existing network systems, but also simplifies project deployment.
High efficiency and high cost performance: AV over IP technology breaks the limitation of the physical distance of signal transmission, and the range that the network can cover, audio and video signals can be effectively communicated. In large-scale projects, integrators or engineers do not need to deploy additional signal cables to extend the transmission distance, and can flexibly manage and maintain equipment distributed in different locations in the network through web-based management software, which greatly improves The efficiency of project deployment is improved, while cost is controlled.
【AV over IP industry application solutions】
AV over IP technology has been widely used in traffic emergency command, smart classroom, radio and television video production, medical demonstration, and social service organizations including scenic spots, theaters, and airports.
Video production
Video production is the process of re-editing, integrating, and arranging pictures, videos and background music to generate a new video file. In the radio and television industry, it is usually necessary to connect all audio and video equipment (cameras, microphones, video switchers and mixers, etc.) at the event site to an IP encoder. The director or producer monitors the shooting pictures and remotely controls the equipment and Adjust the lens. The IP encoder transmits audio and video data through the network to the video production studio for decoding and video production, and then sends the generated video content to the final destination (TV station, CDN, etc.). The video production studio can be within tens of meters near the event (on-site video production) or several kilometers away (remote video production).
Medical teaching
Traditional medical teaching is in the form of field observation. In order to improve the quality of surgical treatment and reduce the rate of surgical infection, hospitals have gradually adopted a new method of digital surgical teaching. In a surgical teaching activity based on network transmission, an IP encoder will be installed in the operating room to receive audio and video signals from surgical field cameras, panoramic cameras, 4K ultra-high-definition endoscopes and other medical equipment, and transmit the signals as IP streams To the network. In the demonstration classroom, the surgical teaching host decodes the IP stream from the operating room, and realizes video production such as picture-in-picture, screen trimming and enlargement based on the surgical teaching software, and finally converts the produced image into a baseband signal and transmits it to a projection such as Facilities such as instruments and displays are available for instructing physicians or medical students to watch on-site. In addition, real-time surgery images can also be streamed to a live broadcast platform for doctors in remote classrooms to observe and learn.
Traffic emergency command
In order to improve the coordination and linkage mechanism of emergency response and improve the emergency response capability in response to public emergencies, the transportation unit will formulate emergency plans in advance, build emergency scenes and joint command plans for the headquarters. In such a scheme, the emergency site needs to maintain real-time communication with the headquarters. The audio and video images of drones and cameras on the emergency site are transmitted to the headquarters through the IP encoder. Similarly, the headquarters will then send the commanders on the site to the headquarters. The pictures and computer pictures are also transmitted to the emergency scene through the IP encoder, realizing real-time communication between the two places, and achieving the goal of efficient emergency management.
【to sum up】
In terms of infrastructure, from the traditional AV architecture to the AV over IP architecture, the core change of the AV equipment in the entire workflow is that the video matrix switcher has become a standard IP switch, and audio and video appear on both ends of the switch. IP encoding and decoding equipment. Users can still get the functions of capturing and switching videos in the traditional AV architecture. The surprise of the AV over IP architecture is that it allows users to have the ability to expand the entire work architecture indefinitely, and has the ability to The ability of an IP device for remote control and management.
