Research And Implementation Of Adaptive Streaming Transmission Technologies Based On DASH

As the “Internet+” action plan becomes a national strategy of China, the future of the Internet industry in China is brighter than ever before. The network media is widely applied, which promotes the development of one key technology, media streaming media. Streaming media still has network jitter, equipment performance fragmentation and some other limitations in the mobile Internet transmission. Adaptive streaming is one of the forefront and the most efficient solutions. The bitrate-adaptation algorithm is the core technology in streaming. However, some algorithms only concern about one single factor or only stay in simulation stage, which were rarely used in application development. Built on the analysis of different streaming protocols and bitrate-adaptation algorithms, this research proposes an optimal bitrate-adaptation algorithm based on bandwidth and buffer, and implements an MPEG-DASH adaptive streaming system.After comparing the MPEG-DASH standard with different types of streaming protocol and different adaptive streaming protocol respectively, and analyzing the existing bitrate-adaptation algorithm in-depth, this research comes up with the conclusion that the bandwidth and buffer are the two main factors affecting the streaming quality. The research proposes an optimal bitrate-adaptation algorithm, which quantifies the bandwidth and buffer by an optimization equation. This algorithm’s workflow is as follow. Firstly, the upper limit value of the subset in the segment set that contains different bitrates is estimated by a bandwidth estimation method. Secondly, the optimal bitrate for the next media segment is calculated by adjusting the two coefficients. Finally, this algorithm is implemented and tested in the MPEG-DASH system. The experiments showed that this algorithm has two advantages:(1) the video quantity can be improved and far beyond the common streaming technology. Clients can smooth video playback in the case of poor network.(2) This algorithm also reaches or exceeds the existing algorithm. It offsets the bandwidth flutter by choosing a segment with lower bitrate. In the meanwhile, the segment length in buffer is maintained at a minimum value so that the local buffer can avoid underflow.This research implements an MPEG-DASH system with the proposed optimal algorithm and tests it in real-world scenarios. This system has two main advantages:(1) applying the “Browser/Server” structure and HTML5 can solve the problem including compatibility and stability, which are commonly seen in the mobile Internet.(2) With the help of the optimal bitrate-adaptation algorithm, the system can resolve the problem of network jitter, equipment performance fragmentation and other limitations. The system uses the bandwidth resources as much as possible, providing the best quantity of network video service. Considering the MPEG-DASH protocol specification and the application scenarios, this research achieves the optimal values of parameter configuration by conducting three groups of contrast experiments, which are classified by different equipment, different amounts of bitrates in segment sets, and different durations of each segment.