Technical development of software video conference system: IT168 Office Communications Updated: 2004-08-05 Price nationwide phone inquiries and national mobile phone market inquiry IT168 communication channel - Elite raids Tianjin mobile phone market, a dynamic market in mobile phone instant kick Gods MOTO CLUB You will enter the MOTO V80 without the bottom price [IT168 Office Communication] Today, the bottleneck problem (network bandwidth and computing power) that restricts the development of video conferencing systems is being resolved, which means that the speed of video conferencing systems will be faster. The following techniques will be widely used in new software-based video conferencing systems. New codec technology
The pursuit of better quality and less bandwidth is a permanent goal of the video conferencing system. Therefore, the development of codec technology, especially image codec technology will effectively promote the application of video conferencing systems.
Unlike the codec technology used in the flow media, the codec for the video conferencing system must be able to apply real-time, requiring delays that cannot be too large, which limits some technologies when compressed encoding.
For example, it cannot be used with compression techniques with higher compression performance, but the algorithm delay cannot meet the requirements (image compression techniques based on wavelet transform). For example, in G.729 speech compression coding standard, each sound data packet must be small to meet the delay requirements, but it limits the compression ratio.
ITU (International Telecom Alliance) has recently launched an image codec standard for H.264. In the case of the same image quality, the amount of encoded data in H.264 is only about 50% of H.263, but the cost is the complexity of the codec. H.264 encoding complexity is three times the H.263, and the complexity of decoding is twice the H.263.
H.264 has been widely popular, and is quickly approved by ISO to the image codec standard for MPEG4. This is the integration of the H.26X standard series for the first time with the MPEG standard series, indicating the powerful vitality of H.264. Some vendors have begun to provide products that support H.264 standards.
Service Quality Assurance (QoS) Technology
Since the IP network performs a policy that is "best possible to provide services", all data is toned. The importance of data transmitted by video conferencing systems is different. If a small amount of video data is lost, it may have little effect, but the certified information will result in failure of the entire conference call.
The purpose of QoS is to achieve good results as possible under the existing conditions, such as ensuring that important data is preferred. If necessary, you can discard some relatively unimportant data, and the like.
QoS can be implemented at different levels. Since the IP network does not provide QoS, the QoS of the video conferencing system needs to be implemented on the application layer. The application layer QoS technology needs to cooperate with other components such as codecs to play the advantages.
Multicast technology
Multicast technology is a technique for senders to multiple recipients once a sender. The two concepts that correspond to the unicast (one-to-one transmission) and broadcast (transfer of a pair of people). It is obvious that the benefit is that the amount of data transfer can be reduced.
In the design of the Internet, it designs a multicast scheme and reserved some IP addresses as multicast addresses. However, due to factors such as equipment, security, etc., multicast at the IP level cannot be implemented within the wide area network. Therefore, it is currently more optimistic about the application of layer multicast, essentially through multiple unicast achievements, but also introduces technologies such as dynamic load balancing, and the effect will exceed a simple unicast.
Information security technology
The H.323 system is an open system that basically does not consider the issue of security. Solving information security issues.
At present, there are two major categories: information security technology for video conferencing systems:
The first category is an additional restriction technique: the purpose of this type of technology is to prevent information from being illegally stolen, which can be used to encrypt the audio data. This technology has been widely used in the encryption channel of digital TV. The basic principle is to scramble the data to be transmitted on the transmitting end, while the received data is descrambled on the authorized receiver (with the corresponding decryption key). Adding restriction techniques can have a lot of changes, such as using tripartite addexual restriction systems that can be licensed from different users.
The second category is a digital signature: the purpose of this type of technology is to prevent some people from fake and tampering with information, but also prevent someone from doing things to do. You can use the identity authentication, data authenticity verification, and the list of electronic documents. In terms of standard protocols, applications, etc., future software-circuit video conferencing systems will present the following new features:
The protocol type transitions in the early stage of the development of video conferencing systems, because IP networks are not a common, strong, able to support high-bandwidth applications, based on ISDN lines, compliant with H.320 protocols account for main proportions. In recent years, the popularity and performance of IP networks have increased dramatically in the overall market in accordance with H.323 protocols.
Since the H.323 protocol is designed for local area network design, although it can also be applied to a wide area network, its network adaptability is not very good, such as H.323 system cannot support firewall penetration, and cannot support NAT (Network Address Translation). At the same time, the H.323 protocol still has defects that are too complex, lack of security, so new protocols and programs (such as SIP protocols) will be added to existing frameworks.
System Open and Software In video conferencing systems, the most important capabilities is to transmit video. However, due to the large amount of video data, it must be compressed before transmission. After transmission, decompress, so the requirements for terminal computing power are relatively high. At the same time, the requirements for bandwidth are still relatively high.
With the popularity of PCs, the continuous increase in computing power and the rapid increase in network bandwidth, software video conferencing systems based on IP network and PC will be a major trend of video conferences.
Application Desktop With the global trend of business environment, long distance, low-cost instant communication needs more and more urgent, and desktop video conferencing systems have just catering this requirement. Software desktop video conferencing systems will be a development trend due to the simple and low cost of use.
Functional diversification, systematic simple video and audio exchanges have become more and more unsuitable, requiring video conferencing systems to develop in the direction of "visible co-work platform" (CSCW).
Visual coherence can provide video and audio, document, data exchange, collaborative browsing, application sharing, etc., to meet users' large-scale applications, such as remote collaborative office, business meetings, remote project management, customer service, technical training and many more. In addition, the background support system based on knowledge management and content management will have a more close cooperation with the video conferencing system.
The analysis results of the authoritative institution show that the scale of my country's video conference market is 1 billion in 2003. Two years old today, the growth rate of my country's video conference market will remain over 32%.
The authoritative institution predicts that in 2004, it will be the "turning point" of the video conferencing system, and the global video conference market will reach $ 4 billion.
According to the analysis of authoritative institutions, the development of the video conferencing market has been mainly derived from three driving power: technology promotion. my country's ADSL market prices continue to decrease, and the number of new users is increasing, and gradually occupying the main way of enterprises. Broadband, DSP, streaming medium technology development; business driver. Enterprise cost control awareness, reduce travel costs, speed up decision-making time, improve efficiency; market driver. End users, operators, product providers, service providers, and governments have been quite mature through these years.
