Application Reseach Of QoS And Congestion Control In Video Live Broadcast System

With the continuous development of Internet and multimedia technology, real-time streaming media services has become a hot spot in the Internet, now the Internet has penetrated into all aspects of people's life, and streaming media services as one of the main application of the Internet, research on its importance is self-evident. streaming media services mainly includes: television, video monitoring, film and television entertainment, sporting events, concerts, etc., these operations have become an indispensable part of daily life, so the research of streaming media technology can promote the progress of the society, to some extent enrich People's Daily life, promote the development of new industries. Video as the main form of streaming media services, it is extremely important to promote the development of streaming media services, so the research of video technology can bring certain benefits for the society. Live video plays an extremely important role in video services, it is also one of the main technical bottlenecks hindering the development of the streaming media technology. Under the background of this research, this paper was based on some problems that exist in the video broadcast services(video delay, transmission delay was too high, the rate of data loss,etc.), starting from the internal system, Focus on studies :how to use the technology(“QoS” in this paper are the QoS of streaming media) of QoS and congestion control to improve some of the problems existing in the video broadcast services.This paper briefly introduces that the commonly used video coding standard h. 264 and the real-time transport protocol RTP/RTCP in the real-time video services. On this basis, we further study the QoS technology solutions, the QoS solutions have two main research directions: one is The QoS control method based on terminal, another is The QoS control method based on internet, With the comparing and researching of the two control methods to conclusion: The QoS control method based on terminal is more economic and applicable,reliable than the QoS control method based on internet. The QoS control method based on terminal is divided into two ways: rate-control and error-control, due to the error control is not suitable for streaming media's transmission that it have high requirement in real-time and TCP-friendly. therefore, this paper starting from The rate control mechanism based on sender, Research is mainly focused on the most extensive and mature TFRC technology currently and on the basis of the original TFRC congestion control mechanism we proposed a TFRC improved algorithm. The improved algotithm has been improved in three aspects: slow start, smooth sending rate and jitter strategy, in order to verify The improved algotithm`s scientific and effectiveness, we need to experience on NS2 network simulator, by the analysis of data and experiment,we can conclude that: When the network is congested, The TFRC improved algotithm has improved in keeping TCP-friendliness, increase data throughput, reduce data transmission delay, etc, so it can provide effective protection for streaming media QoS. In addition, this paper also focused on design a the live video system, system design can be divided into four parts: data collection and coding, TFRC congestion control, transmission design, video decoding and displaying.The video data are from computer`s desktop and encoden in h. 264 format, TFRC transplant into the system by means of adding protocol, RTP/RTCP was selected in the system, video decoding and playing are worked in the VLC player. Finally,By comparing the improved algorithm(system has been transplanted the TFRC improved algorithm) with the original system in this video broadcast system which verified the improved system have more fluid and lower date loss when palying real-time video in this system,which further proved that the improved algorithm is more scientific and effective.Through experiment simulation and test,we verified The TFRC improved algotithm`s scientific and effectiveness.This research have a positive role in promoting the development of real-time video services, it can effectively solve some problems in the video broadcast service that the transmission delay was too high and date loss too much, TCP-friendly droped too quickly When the network is congested.This paper provide a direction for research in how to provide effective guarantee for the QoS of system when video date was transmitting in a congested network.