| With the rapid innovation of video coding and decoding technology in the Internet field,multimedia communications have gradually developed into the main business of IP networks.Although the mainstream H.264 video coding and decoding technology has better compression performance than before,because the IP network itself provides "best effort" service,video transmission in the network channel would inevitably suffer from network packet loss,delay and jitter.Nowadays higher video transmission quality are demanded by users.It is of great value for network operators and video service providers to reasonably allocate network resources and improve the quality of user experience by evaluating the quality of network video transmission in advance.To solve these problems,a network layer and application layer QoS(Quality of Service)association mapping model was proposed in this thesis.this model could help in predicting the video quality according to the network QoS.Practical tests verified its functions.Main content of the thesis is as follows:(1)the two major factors causing network video distortion,namely network channel transmission distortion and video codec distortion,were studied and analyzed.the research status of network video quality evaluation methods was introduced.(2)combined with the research objectives of this thesis,the suitable mapping evaluation model for this thesis was analyzed.(3)In view of the main factor affecting video distortion in network transmission,namely network packet loss,this thesis analyzes its characteristics from the causes,and analyzes the models describing different network packet loss characteristics from the perspectives of practicability and applicable scenarios.(3)Combined with the selected network packet loss model,a two-layer mapping model was established for Group of Pictures(GOP)intra frame loss and video distortion index.Finally,the effectiveness of the proposed parameter mapping model was tested and verified in the actual cloud network environment. |
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