Research And Implementation Of DASH Video On Demand System

With the rapid development of network facilities and intelligent mobile devices,the demand for video services is increasing,and constant pursuit of high-quality video experience.The traditional streaming media transmission scheme can not adaptively adjust the video bit rate under the condition that the network bandwidth is changing constantly.In addition,although the current three mainstream HTTP adaptive streaming media solutions to achieve the video bit rate adaptation,but they have commercial natures,not open,and incompatible.In view of this situation,DASH came into being,DASH not only compatible with different adaptive streaming media solutions,but also in accordance with real-time changes in the network environment to adapt to the corresponding video bit rate,thereby improving the quality of video viewing experience.As a new technical standard,DASH has become a hot research.In this paper,we design and implement a DASH video on demand system based on DASH standard,the main work is as follows:(1)A brief introduction to the three mainstream HTTP adaptive streaming media technology,detailing the main content of DASH,such as DASH basic principles,system architecture,MPD file and video segments and so on.(2)On the basis of two typical DASH adaptive bit rate algorithms,an rate adaptation algorithm based on segment is proposed.The algorithm not only considers the network bandwidth and buffer occupancy,but also considers the duration of video segments.It is verified that the adaptive bit rate algorithm based on segment has lower rate of code switching,higher video quality and faster convergence time,which brings the user higher quality of experience.(3)Design and implement a DASH video on demand system,and in-depth study of the system server and client.On the server,use the DASHEncoder to complete the video encoding,generate DASH video segments and MPD files;on the client,use the dash.js to build DASH video player,in order to predict the bit rate of the next video segment more accurately,the rate adaptation algorithm based on segment is applied tothe client.Server and client design and implementation in line with DASH technical standard,through the interaction between client and server,the system implements the DASH function.