The Research And Realization Of Video Transmission System Based On MPEG-DASH

Nowadays,video traffic accounts for nearly 80% of total Internet consumer traffic,at the same time,ultra-high definition video and multimedia on mobile terminals are favored by more and more consumers.Therefore,new challenges are accured in video transmission technology.MPEG-DASH,as a new multimedia transmission technology,can provide high-quality client-side streaming service.This article describes in detail the basic principles and framework of MPEG-DASH,and analyzes the advantages of MPEG-DASH by comparing with other multimedia transmission technologies.Due to the inherent randomness of bandwidth,the existing rate adaptation algorithms based on Dynamic Adaptive Streaming over HTTP fail to make a balance between playback fluency and video quality.Concerning the above problem,a rate adaptation algorithm based on state machine for DASH was proposed to analyze and control the rate switching process.Firstly,the influence factors of client's experience quality were fully considered and numerically analyzed.Secondly,six bitrate transition states were proposed according to the influence factors,and the relations between the video bitrate and the changes in influence factors' values were used as the state transition conditions.Finally,under the condition that the playback buffer and the bitrate deviation ratio being balanced between a fixed threshold,the video bitrate was switched to a rate level which has the relatively optimum overall performance of playback fluency and video quality.The experimental results demonstrate that the proposed algorithm can not only improve the video bitrate but also avoid bitrate plunging and pausing compared with the fuzzy-based DASH adaptation algorithm and bandwidth-based adaptation algorithm,thus reaching a balance between playback fluency and video quality,and leading to an improvement of experience quality at the client side.Concerning the problem that many domestic Internet video content providers have limited support for MPEG-DASH,this article realized a multimedia streaming system based on MPEG-DASH by using Nginx as the web server to distribute the multimedia content and using the libdash open source library to realize the DASH content control module at the client side.The experimental results demonstrate that by inserting the SDASH algorithm,the MPEG-DASH system can provide higher mean video bitrate with less bitrate switch while streaming the video content compared with the bandwidth-based adaptation algorithm,and the proposed algorithm can lift the initial bitrate to a higher level quicker than the fuzzy-based DASH adaptation algorithm.