Real-time adaptive bandwidth streaming media delivery technology, is a broadband streaming media can significantly improve key quality of service delivery bottlenecks in the process of international technology. At present, the constraints of broadband streaming media application development is the core issue of quality of service. In short, because the Internet is not reliable, bandwidth, load and other dramatic changes, can not meet the real-time streaming broadband quality of service requirements, and often occur player stuck, Yan Chi, such as poor video quality Doudongjulie Qing Kuang, to Shi Yongzhe sensory the cause greatly. Therefore, streaming media broadband applications to solve the service quality of broadband applications for streaming media is extremely important. In a typical streaming media broadband system, the video server to the client through the network streaming real-time transmission of information.
Streaming media system to solve QoS issues there are two ideas: one is to make an issue of the road; the other is making an issue of streaming media system itself. ISDN, ATM and the future of IPv6 is a network protocol such as the former approach, but, as of now, ISDN and ATM network technology does not become the mainstream, TCP / IP is still the de facto standard. Streaming media system itself has been thoroughly researched, mainly from electronics and computer science point of view, such as various coding techniques, compression techniques, which seem to have reached the end of the road Zi, but the core and streaming media system problems and bottlenecks not well resolved.
Another angle, starting from the idea of cybernetics, a breakthrough will be found one step further. To overcome the network conditions the impact of uncertainty, the video server must be adaptive to adjust the sending strategy to ensure video service quality and real-time. From the control theory point of view, depth, real-time adaptive bandwidth streaming media delivery issues, to achieve a set of easy to use, works well in real-time streaming transmission scheme: adaptive network bandwidth streaming media delivery technology. The technology uses adaptive control, fuzzy control, feedback and feedforward control and other advanced control technology. Figure 2 Adaptive Scheduling and regulators is one of the core technology, an international initiative. Rigorous theoretical and technical tests shows that the program works well, very easy to implement. At the same time, this solution, a prototype system tested in the Tsinghua University campus network, the effect is very good.
Dramatic changes in the bandwidth, the application of the technology of video-on-demand systems to achieve performance. In Figure 3, (a) that the bandwidth used by the situation; (b) that clients get the quality of video playback; (c) and (d), respectively, during playback receive buffers and transmit data buffer volume of cases. Comparison of Figure 3 (a) (b) we can see dramatic changes in network bandwidth case, changes in the quality of video playback is smooth. From Figure 3 (c) knows, the receiver buffer does not overflow or underflow occurred, indicating that customers always enjoy a continuous video playback, no player stuck; there is no buffer overflow occurs because the lost transmission from the network come data. Figure 3 (d) indicates that the 80K byte send buffer is always around, no underflow, indicating the data transmission module, data can always be made that the network bandwidth was fully utilized.
In particular, with international streaming media transmission technology has been compared to, our technology has the following advantages:
(1) The technology enables streaming media server automatically adapt to network conditions streaming real-time transmission of data. Even in the dramatic changes in the network environment, using the technology able to ensure that customers enjoy continuous, stable, and the highest quality video services.
(2) estimate the technology without network bandwidth, avoid network bandwidth estimation are not allowed to bring the performance dropped significantly.
(3) the quality of the technology system and network systems adaptive decoupling, allowing the quality of adaptive technology in the system can work to any existing network environment, which greatly reduces the technical promotion more difficult.
(4) The technology is well shielded network bandwidth of the short time scale fluctuations of the video playback quality. As the role of congestion control, network bandwidth is often relatively large short-scale fluctuations, if real-time directly in accordance with the network bandwidth video quality adjustment, will inevitably result in violent video quality jitter greatly affect the playback.
(5) greatly simplifies the technical parameters of the adjustment difficult. In the technical programs, parameters can give a rigorous theoretical analysis range, and a very small number of parameters to adjust.
The technology program is totally different from the real RealNetworks flow (Sure Streaming) and Microsoft's Intelligent Streaming (Intelligent Streaming). Both solutions are in fact the initial connection with the user, detect the user's network bandwidth and connectivity as the number state, in order to judge, to send the file Daxiao most suitable streaming media file. In the users to watch streaming media files during the 2-3 hours, network conditions and bandwidth resources has in fact been changing, and may continue to have a new user to connect up, the number of concurrent constantly changing, but the system unable to real-time adjustments, resulting in Often, the client still image stuck, jitter, and stop the situation of parking place, still can not guarantee quality of service. Our real-time adaptive streaming technology, is always on the file size and dynamically adjust the sending rate, and real-time accurate calculation of network resources and client buffer status of the fine-tuning, to ensure smoother playback and the clear end-user and does not cost any system resources.