Design Of Video Transmission System Based On H.264 And DASH

With the rapid development of video coding technology,it is possible to transmit high-definition video at low bandwidth.The traditional streaming media transmission protocol cannot make full use of bandwidth,lack of flexible session management function and intelligent flow control mechanism,The generation of the new adaptive streaming media protocol(DASH)provides a better choice for the transmission of streaming media data in an unstable network environment.In the streaming media system,the choice of coding and transmission protocol is a key part of the design,how to combine H.264 and DASH to better serve audio and video field become one of the hot technology.Firstly,this paper makes a deep research on the specification of DASH technology,existing methods based on DASH rate adaptive algorithms which fully utilize bandwidth and buffe were summarized.Based on H.264 adaptive coding,wireless network bandwidth,and combined with real-time transport protocol,a joint control strategy of bandwidth and buffer is proposed,this strategy first create the data transmission model,define network change detection parameters,establish the relationship between the rate adjustment factor and network change detection parameters based on the logistic equation model,and then through the marker sending packets,using RTCP feedback mechanism in different threshold bandwidth and buffer to achieve the dynamic change of the sending rate,Then,by marking the sending packets,using RTCP feedback mechanism in different threshold bandwidth and buffer to achieve the dynamic change of the sending rate,When buffer and bandwidth at the same time is sufficient,using a variable constant to increase the bit rate,When buffer and bandwidth at the same time is nervous,using multiplicative decrease to reduce the bit rate,eventually to improve QoS of the video transmission.Secondly,According to the basic frame of video transmission system,a video transmission system based on H.264 and DASH is designed.In this paper,the whole system is divided into three layers under the premise,in turn gives the specific design of each layer and the key code,video content generation layer is responsible for encoding video data acquisition and RTP transmission,video content storage layer is mainly responsible for the original video information processing form conforms to the DASH standard format for streaming media,video content the distribution layer is responsible for the ExoPlayer player and browser for playback,then gives the design scheme using JS to broadcast rate based on adaptive bandwidth.And for the video transmission system,a switching protocol for multiple video source access is designed,which allows the video source of legitimate terminals to flow into the server by token authentication.Finally,the actual application system is built,and the system performance is tested from video quality and image clarity,so as to verify the practicability of the system.The results show that after applying the control strategy,the network load is reduced,the packet loss rate is decreased,the video real-time performance is improved,the difference between the two segments of video becomes smaller,the value of PSNR is increased,and the video quality is improved...