Research On Dynamic Adaptive Algorithm Based On DASH Technology And System Implementation

With the rapid development of Internet and mobile Internet technology,the use of multimedia information more and more widely,especially in the past two years the rise of small video and the rapid development of Internet live,high-quality video content needs more and more intense.This strong demand to promote the continuous development of streaming media technology.DASH(Dynamic Adaptive Streaming over HTTP)and other adaptive streaming technology proposed to bring users a more high-quality streaming media business experience.And the bit rate adaptive algorithm is the core content of DASH technology,determines the video playback performance.The traditional bit rate adaptive algorithm considers the network bandwidth state or the player buffer state separately,and can’t effectively combine various factors,so it also has a large room for improvement.At the same time,some algorithms are verified by the network simulation experiment,and the experimental environment of the video broadcasting system is lacking.In this paper,we study the existing bit rate adaptive algorithms in various types of streaming media transmission protocols and DASH techniques.Aiming at the problem that the traditional dynamic adaptive bit rate selection algorithm has a single factor,the length of the playback buffer is limited and the bandwidth is unstable,a dynamic adaptive bit rate selection algorithm based on buffer threshold adjustment is proposed.The core idea of this algorithm is to adjust the threshold parameters of the buffer dynamically when considering the bandwidth download rate and the buffer length so that the buffer length is at reasonable value at different stages of video playback.In particular,the algorithm predicts the video download time by obtaining different video segment size and download rate.By dividing the playback process into several different stages,different algorithms are used to reduce the initial delay and guarantee of video playback video for high quality playback when stable.When the network environment is good and the buffer parameters reach the critical value,adjust the buffer threshold parameters and increase the buffer length,to improve the ability to respond to sudden changes in the network.The experimental results show that the algorithm can guarantee the stability of video high quality playback,and reduce the start time of video playback and improve the viewing experience of video.For the application of adaptive streaming media technology to develop fewer problems,this paper designs and implements a bit rate adaptive video playback system based on DASH technology on the basis of the above algorithm.The system uses a browser/server(B/S)architecture,combined with HTML5 and JavaScript cross-platform advantages,to solve the problem of incompatibilities and instability of the mobile video playback.In order to verify the availability of the developed system,two groups of contrast experiments were carried out on the system.The influence of the PC terminal and the mobile end,the number of different bit rate levels and the duration of different video fragments on the system performance were compared.The optimal parameters were obtained.The experimental results show that the adaptive video playback system based on DASH can run normally on the PC side and the mobile side,and the optimal rate level in the system is 5.The research work of this paper is to improve and optimize the traditional dynamic adaptive bit rate algorithm in DASH technology.Based on the improved algorithm,the bit rate adaptive video playback system based on DASH technology is designed and implemented.The research results of this paper have certain academic value and application value.