Research On Adaptive Control Of Available Bandwidth Over Video Transmission Network

With the development of network technology, video compression technology, video surveillanc,video on demand and telemedicine was applied widely. Compared to traditional data service, network video is characterized by real-time demand and large volume of data. To use the network adequately, the video rate should adjust along with the availabe bandwidth, then, measuring the availabe bandwidth is necessary. However, the current network bandwidth changes with time. Therefore, the demand of real-time of streaming video is not guaranteed. Network congestion and bandwidth shortage are the choke point in the service of video streaming. Thus, how to adapt to the variational available bandwidth and how to provide better QoS have already become the key point of the field of real-time video application. What with the characteristic and development status of video network transmission, the transmission technology of real-time video over the Internet with changing bandwidth was researched in this paper.First of all, problem of video network transmission is analyzed, two key issue of self-adaption scheme: bandwidth measurement and rate adjustment was studied in article and disscused evaluating indicator of self-adaption scheme.Secondly, characteristics and measurement of end-to-end available bandwidth is discussed, computation of available bandwidth based on one-way dealy is adopted, which was flexible set on parameters,less resource occupied, easy to realized.In H.264 rate control, the quality of viedo is changed widely when complicate scene switched, the quantization parameter is adjusted to control the output of the bits and improve picture quality. An improved method based on linear discriminant to classified data point is proposed, which jointly consieder scene changes and computational complexity. It is shown by experimental results that the approch can adjusts bits efficiently and smoothes picture quality.The relation between available bandwidth and bit rate was analyzed, and adjustment of quantization parameter over available bandwidth was given a particular description, the method can improve real-time of video transmission.