【 Weak current College 】 on software-based video conferencing systems technology development trends---Power By 【 China power house network 】

Today, limited video conference system development bottleneck problem (network bandwidth and computing power) is resolved, this means that the video conference system development speed will be faster and faster. The following technologies will open in a new software-based video conferencing systems has been widely used. New coding the pursuit of better quality and less bandwidth consumption, is a video conference system a permanent objective. Therefore, coding, especially image coding technology, will effectively promote the application of video conference system. And applied to the streaming media codec technology, used for video conferencing system decoding must be capable of real-time applications, the required delay cannot be too large, this limits the coding is the use of some techniques. For example, you cannot use some has higher compression performance, but the algorithm does not meet the required delay time compression technologies (like a wavelet-based image compression techniques). Another example, as in g.729 coding standards, each voice packet duration must be small to meet the requirements of the delay, but at the same time limiting the compression rate of increase. ITU (International Telecommunication Union) recently introduced H.264 decoding of the image. In the same quality of the image, H.264-encoded data is only about 50% of H.263, but at the cost of increased complexity of decoding. H.263 H.264 encoding complexity is three times more, decoding complexity is twice that of H.263. H.264 launched the popular, and will soon be approved as ISO MPEG4 decoding of the image. This is H.26x standard series for the first time with the fusion of the MPEG standard series, foretells a vitality of H.264. Some manufacturers have begun to provide support for the H.264 standard products. Service quality assurance (QoS) technologies as IP networks ", to the greatest extent possible to provide services" strategy, all data on an equal footing. But video conferencing system, the importance of the data transferred is different, such as a small amount of video data loss could affect, the certification will result in a loss of information throughout the Conference call failed. QoS is an existing conditions as far as possible, access to good effect, such as ensuring important data priority for transmission. Necessary, you can drop some less important data, and so on. QoS can be on a different level, because IP network does not provide QoS, video conference system QoS needs on the application tier. Application level QoS technology needs and codecs and other parts with to take advantage of. Multicast (Multicast) technologies multicast is a sender of a sending data to multiple recipients of technology. Corresponding two concepts is unicast (one to one of transfer) and broadcast (one to all of the transmission). The obvious benefit is that you can reduce the amount of data transferred. The design of the Internet, it has designed a multicast scenarios, and to reserve some IP addresses for multicast address. But because the device capabilities, security, and other factors, the multicast IP level cannot be achieved within the scope of the wide area network. Therefore, it is relatively optimistic about the application layer multicast, essentially through multiple unicast "multicast" effect, but at the same time introduces such as dynamic load balancing and other technologies, the outcome will be superior to straightforward multiple unicast. Information security technology H.323 system is an open system, basically did not consider the security issues. Solving information security problems. At present, is used for video conferencing system for information security technology there are two broad categories: the first is descrambling technology: class technology is designed to prevent unauthorized usage of the information may be used for the encryption of the audio data. This technology has been widely used for digital television in the encrypted channel. The basic principle is the sender of the data to send while scrambling, authorized by the receiver (with the corresponding decryption key) on the received data decryption. Descrambling technology can have a lot of changes, such as using third-party descrambling system can different users authorize different receive channels. The second category is the digital signature: class technology is designed to prevent counterfeiting and tampering with information, but also can prevent someone did not. Can be used in identity authentication and data authenticity verification, electronic document signing, etc. In the standard agreement, application, etc., the future of software-based video conferencing system will render the following new features: protocol type conversion occurs in the video conference system at an early stage of development, because the IP network is not yet a widespread, strong and able to support high bandwidth applications network, based on the ISDN line, in line with the agreement of products covers H.320 major scale. But in recent years the popularity of the IP network and performance improvement, make the product conform to the H.323 protocol in occupies the overall market share has risen dramatically. Thanks to the H.323 protocol designed for local area network design, while at the same time can also be applied to a wide area network, but its network adaptability is not very good, such as H.323 system cannot support firewall penetration, does not support NAT (network address translation). At the same time, the H.323 protocol is also itself is too complicated, the lack of security flaws, so new agreements and programmes (such as SIP protocol) will be added to the existing framework. System open and software-based video conferencing system, the most important capability is to transfer the video. But because the video data volume is large, must be compressed before transmission, transmission encoding, so after unpacking on Terminal computing capabilities that require higher. At the same bandwidth requirements are still relatively high. With the popularity of the PC, computing power has increased and the rapid increase of network bandwidth, IP-based network and PC software video conferencing system will be a video conference and a major development trends. Application desktop-with the business environment of globalization trends, long distance, low-cost, real-time communication needs more and more urgent, and desktop video conferencing system is to meet this demand. Because of the simplicity and low cost, software-based desktop video conferencing system will be the trend. Functional diversity, system of simple audio and video communication has become increasingly unable to meet the needs and requirements of video conference system work together towards the "Visual platform" (CSCW) direction. CanAs the cooperative work can provide audio, documents, data exchange, collaborative browsing, application sharing, and other capabilities to meet a wider range of application needs, such as remote Coordination Office, business meetings, remote project management, customer service, technical training, etc. In addition, based on knowledge management and content management background support systems, and video conference systems with closer cooperation. Link: market grandstands authoritative analysis of the results of: 2003 China video conference market scale of up to $ 1 billion. In the next two years, China's video conferencing market growth rate will remain at 32 percent. Authority forecast, 2004 will be the video conference system growth "inflection point", the global video conferencing market will reach $ 4 billion. According to authoritative analysis, video conferencing market in recent years the development of the main stem from three driving forces: technology advances. Our ADSL market prices are lower, count the number of users continues to grow, gradually occupy the primary means of business online. Broadband, DSP, high-speed streaming media technology; business-driven development. The idea of cost control, reduce the cost of travel, speed up the decision-making time and improve the efficiency of market-driven. End users, operators, product providers, service providers, Government, the market value chain, after years of development has been well developed.