In real life, people often encounter problems. Using telephones or e-mails does not work. People must communicate face-to-face. Videoconferencing is undoubtedly an important way to solve such problems. The traditional video conferencing system, due to the lack of clear picture and large delay in speech, will often seriously affect the effect of the conference. With the development of science and technology and the demand of the market, the high-definition video conference system has been more and more widely used.
1. High-definition video conference system
The video conference system is a communication technology that communicates through images and sounds. The system broadcasts video and audio information in real time, enabling conference participants to realize intuitive and real communication in their own conference rooms. Studies have shown that 55% of the effective information people receive comes from face-to-face visual effects, 38% rely on speech, and only 7% depend on content. Therefore, an excellent video conference system has an extremely important effect on the effectiveness of the conference.
With the continuous development of science and technology, especially the introduction of the H.323 protocol, video conferencing has been applied to more and more fields such as government, military, finance, telecommunications, education, and enterprises. Video conferencing has been widely used. application. At the beginning of 2006, the first 720P high-definition video conferencing product came out, kicking off the prelude to high-definition video conferencing. In 2008, KEDACOM released the first 1080P HD video conferencing system, marking the video conferencing system has entered the era of high-definition.
Compared with the traditional SD videoconferencing system, the HD videoconferencing system provides participants with a more efficient and high-quality video experience by providing clearer picture quality and better sound effects, enabling participants to conduct conferences more effectively. communicate with. In addition, high-definition video conferencing systems are capable of displaying high-resolution content in high-definition, which is crucial for certain specific areas such as medical care, maps, and mapping.
With the popularity of HDTV, HD video cameras and other devices, high-definition video conferencing systems have been more widely used, and video conferencing systems have also moved from the SD era to the HD era. More companies and organizations recognize that information construction plays a crucial role in the development of enterprises. More demands are placed on high-definition video conferencing systems. At the same time, many manufacturers have emerged in the market and actively apply high-definition video. The new video conference technology, and constantly develop new products, the application of high-definition video conferencing system to a new situation.
2. High-definition video conference system technology
The technologies of high-definition video conferencing systems mainly include video encoding technology, network communication protocols, and image standards.
2.1 video coding technology and H.264
Video coding technology is one of the most basic conditions for videoconferencing. Only efficient video coding can guarantee the provision of video services in a realistic Internet environment. H.264 is a high-performance video codec technology. It is a digital video coding standard jointly organized by two organizations, ITU-T and ISO. It is both ITU-T H.264 and ISO MPEG-4 standard. 10 parts.
H.264 is built on the basis of MPEG-4 technology and adopts a "return to basic" design. Its greatest advantage is its high data compression ratio and its high compression ratio, as well as its high quality and smooth images. . The multimedia system adopting H.264 is much superior to the traditional system in image quality. H.264 improves the coding efficiency by about 50% compared with the previous H.263 and MPEG-4.
Under the same image quality conditions, the data compression ratio of H.264 can be 2 to 3 times higher than that of MPEG-2 used in the current DVD system, 1.5 to 2 times higher than MPEG-4, and 2 times higher than that of H.263. To this end, H.264 is the cornerstone of today's high-definition multimedia communications. Both HD-DVD and Blu-ray DVD adopt H.264 as their production standard.
2.2 Network Communication Protocol
The network communication protocols commonly used in high-definition video conference systems include the ITU-T H.323 protocol and the IETF-proposed SIP protocol. H.323 is a framework construction. It follows the traditional implementation of the telephone signaling model. The technology is relatively mature. In the current market, there are many products that support its standards. H.323 centralized control facilitates billing, and management of bandwidth is relatively simple and effective.
However, since all participating conference terminals send control messages to the multipoint control unit (MCU), it may become a bottleneck for large conference MCUs, and H.323 does not support the signaling multicast function, so the scalability is poor.
The H.323 protocol specifies that audio and video packets must be encapsulated in the real-time protocol RTP and carried over a UDP Socket pair at the sender and receiver. The real-time control protocol RTCP is used to evaluate the quality of sessions and connections and to provide feedback between communicating parties.
The corresponding data and its supporting groupings can be operated via TCP or UDP. The H.323 protocol also stipulates that all H.323 terminals must have a voice encoder. The minimum requirement is that G.711 must be supported. SIP does not define the type of session to be established, but only defines how the session should be managed.
SIP messages are text-based and therefore easy to read and debug. The programming of new services is simpler and more intuitive for designers. SIP is designed for distributed calls. It has distributed multicast functions and is convenient for conference control. It also simplifies user positioning, group invitations, etc., and can save bandwidth, being concise, open, compatible, and extensible.
2.3 HD video conference image standards
At the beginning of the video conference development, the CIF (352×288) format was adopted as the video conference standard. By the beginning of the 21st century, the video conferencing system has been upgraded to 4CIF (704×576), which is 4x higher resolution than the original CIF standard for video conferencing.
The 720P (1280×720) that appeared in 2006 and the 1080P (1920×1080) that became available in 2008 have reached 9× and 20× the CIF resolution, which is also the HD standard of the popular digital TV standard.
"High Definition Video (HDV) is a high-definition standard used by digital video cameras introduced by Canon, Sharp, Sony, and JVC. It has more than ten times the resolution compared with video standards used in standard definition video conferencing. Rate, clearer picture.
The video ratio must be 16:9 and the resolution is higher than or equal to 1280×720. Obviously, high-definition video makes video conferences more realistic and realistic, giving participants a better conference effect.
3. Build a high-definition video conferencing system
To build a high-definition video conferencing system, we must first ensure that all terminal-to-display devices require high-definition compatible devices. All of them must support high-definition data compression, decoding, and display so that video participants can enjoy high-definition video. These terminals include cameras, high-definition video displays (liquid crystals, plasma or projectors), hi-fi audio systems, high-definition video conferencing terminals, high-definition access MCUs, and more.
In addition, there must be sufficient network bandwidth guarantees. High-definition video conferencing requires the lowest data rate of 768 Kbps, and the best bandwidth can reach 1 to 2 Mbits. In addition, QoS control is also necessary, it can guarantee the stability of the video conference effect.
How to build a high-definition video conferencing system? High-definition video conferencing system design should follow several major principles.
a. The system's video coding technology should adopt video compression algorithm H.264, high-definition image standard 720P (1080P) and broadband audio technology to achieve high-definition picture quality, high-fidelity sound quality, while controlling network latency at a low level, fully Ensure the high quality of video conferencing.
b. Ensure the stability of the communication network and ensure sufficient bandwidth for the video system.
c. Ensure that the video conferencing system can operate continuously for a long time. There is an automatic recovery link function between the conference terminal and the MCU. If a line problem occurs in the conference, it causes an instant terminal and has the ability to recover in a very short time.
d. The system must have a video conference management system and provide the log function. The administrator can query the running log to understand the running status of the device and solve problems at any time. In addition, the network management device should have strict security protection measures.
1. High-definition video conference system
The video conference system is a communication technology that communicates through images and sounds. The system broadcasts video and audio information in real time, enabling conference participants to realize intuitive and real communication in their own conference rooms. Studies have shown that 55% of the effective information people receive comes from face-to-face visual effects, 38% rely on speech, and only 7% depend on content. Therefore, an excellent video conference system has an extremely important effect on the effectiveness of the conference.
With the continuous development of science and technology, especially the introduction of the H.323 protocol, video conferencing has been applied to more and more fields such as government, military, finance, telecommunications, education, and enterprises. Video conferencing has been widely used. application. At the beginning of 2006, the first 720P high-definition video conferencing product came out, kicking off the prelude to high-definition video conferencing. In 2008, KEDACOM released the first 1080P HD video conferencing system, marking the video conferencing system has entered the era of high-definition.
Compared with the traditional SD videoconferencing system, the HD videoconferencing system provides participants with a more efficient and high-quality video experience by providing clearer picture quality and better sound effects, enabling participants to conduct conferences more effectively. communicate with. In addition, high-definition video conferencing systems are capable of displaying high-resolution content in high-definition, which is crucial for certain specific areas such as medical care, maps, and mapping.
With the popularity of HDTV, HD video cameras and other devices, high-definition video conferencing systems have been more widely used, and video conferencing systems have also moved from the SD era to the HD era. More companies and organizations recognize that information construction plays a crucial role in the development of enterprises. More demands are placed on high-definition video conferencing systems. At the same time, many manufacturers have emerged in the market and actively apply high-definition video. The new video conference technology, and constantly develop new products, the application of high-definition video conferencing system to a new situation.
2. High-definition video conference system technology
The technologies of high-definition video conferencing systems mainly include video encoding technology, network communication protocols, and image standards.
2.1 video coding technology and H.264
Video coding technology is one of the most basic conditions for videoconferencing. Only efficient video coding can guarantee the provision of video services in a realistic Internet environment. H.264 is a high-performance video codec technology. It is a digital video coding standard jointly organized by two organizations, ITU-T and ISO. It is both ITU-T H.264 and ISO MPEG-4 standard. 10 parts.
H.264 is built on the basis of MPEG-4 technology and adopts a "return to basic" design. Its greatest advantage is its high data compression ratio and its high compression ratio, as well as its high quality and smooth images. . The multimedia system adopting H.264 is much superior to the traditional system in image quality. H.264 improves the coding efficiency by about 50% compared with the previous H.263 and MPEG-4.
Under the same image quality conditions, the data compression ratio of H.264 can be 2 to 3 times higher than that of MPEG-2 used in the current DVD system, 1.5 to 2 times higher than MPEG-4, and 2 times higher than that of H.263. To this end, H.264 is the cornerstone of today's high-definition multimedia communications. Both HD-DVD and Blu-ray DVD adopt H.264 as their production standard.
2.2 Network Communication Protocol
The network communication protocols commonly used in high-definition video conference systems include the ITU-T H.323 protocol and the IETF-proposed SIP protocol. H.323 is a framework construction. It follows the traditional implementation of the telephone signaling model. The technology is relatively mature. In the current market, there are many products that support its standards. H.323 centralized control facilitates billing, and management of bandwidth is relatively simple and effective.
However, since all participating conference terminals send control messages to the multipoint control unit (MCU), it may become a bottleneck for large conference MCUs, and H.323 does not support the signaling multicast function, so the scalability is poor.
The H.323 protocol specifies that audio and video packets must be encapsulated in the real-time protocol RTP and carried over a UDP Socket pair at the sender and receiver. The real-time control protocol RTCP is used to evaluate the quality of sessions and connections and to provide feedback between communicating parties.
The corresponding data and its supporting groupings can be operated via TCP or UDP. The H.323 protocol also stipulates that all H.323 terminals must have a voice encoder. The minimum requirement is that G.711 must be supported. SIP does not define the type of session to be established, but only defines how the session should be managed.
SIP messages are text-based and therefore easy to read and debug. The programming of new services is simpler and more intuitive for designers. SIP is designed for distributed calls. It has distributed multicast functions and is convenient for conference control. It also simplifies user positioning, group invitations, etc., and can save bandwidth, being concise, open, compatible, and extensible.
2.3 HD video conference image standards
At the beginning of the video conference development, the CIF (352×288) format was adopted as the video conference standard. By the beginning of the 21st century, the video conferencing system has been upgraded to 4CIF (704×576), which is 4x higher resolution than the original CIF standard for video conferencing.
The 720P (1280×720) that appeared in 2006 and the 1080P (1920×1080) that became available in 2008 have reached 9× and 20× the CIF resolution, which is also the HD standard of the popular digital TV standard.
"High Definition Video (HDV) is a high-definition standard used by digital video cameras introduced by Canon, Sharp, Sony, and JVC. It has more than ten times the resolution compared with video standards used in standard definition video conferencing. Rate, clearer picture.
The video ratio must be 16:9 and the resolution is higher than or equal to 1280×720. Obviously, high-definition video makes video conferences more realistic and realistic, giving participants a better conference effect.
3. Build a high-definition video conferencing system
To build a high-definition video conferencing system, we must first ensure that all terminal-to-display devices require high-definition compatible devices. All of them must support high-definition data compression, decoding, and display so that video participants can enjoy high-definition video. These terminals include cameras, high-definition video displays (liquid crystals, plasma or projectors), hi-fi audio systems, high-definition video conferencing terminals, high-definition access MCUs, and more.
In addition, there must be sufficient network bandwidth guarantees. High-definition video conferencing requires the lowest data rate of 768 Kbps, and the best bandwidth can reach 1 to 2 Mbits. In addition, QoS control is also necessary, it can guarantee the stability of the video conference effect.
How to build a high-definition video conferencing system? High-definition video conferencing system design should follow several major principles.
a. The system's video coding technology should adopt video compression algorithm H.264, high-definition image standard 720P (1080P) and broadband audio technology to achieve high-definition picture quality, high-fidelity sound quality, while controlling network latency at a low level, fully Ensure the high quality of video conferencing.
b. Ensure the stability of the communication network and ensure sufficient bandwidth for the video system.
c. Ensure that the video conferencing system can operate continuously for a long time. There is an automatic recovery link function between the conference terminal and the MCU. If a line problem occurs in the conference, it causes an instant terminal and has the ability to recover in a very short time.
d. The system must have a video conference management system and provide the log function. The administrator can query the running log to understand the running status of the device and solve problems at any time. In addition, the network management device should have strict security protection measures.
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