Research On Video Encoding Optimization And Transmission Control Strategy Based On Android Mobile Phone

As the rapid development of the3G communication technology and the smartphone platform, wireless video transmission system has become the important part ofvideo monitoring and communication system. This paper studied video communica-tion system based on Android platform against the background of the patrol system ofthe state grid. Considering the processing ability of Android platform and the charac-teristics of3G network, this paper researched Android platform optimization of re-al-time video coding and video transmission control strategy of3G channel.In view of the real-time video coding optimization, this paper did many researcheson kinds of fast search algorithm and matching criterion for motion search in x264library. Based on original x264diamond search algorithm, this paper proposed a newalgorithm with early termination strategy and new diamond search strategy to im-prove the performance of the algorithm. Experiments show that, the new algorithmcan effectively reduce the computation during the matching process. To further im-prove the encoding speed, this paper studied on matching algorithm for motionsearch SAD, and proposed a new matching strategy which is using subset of macroblock which SAD algorithm used. This paper found a way of selecting a subset of themacro block during several experiments comparing. Using those two improved strate-gies, the new algorithm can reduce the computation in the motion search process andimprove the encoding speed without changing the coding quality obviously.For the3G transmission, this paper focused on the packet loss rate control strategy.With the research of RTP/RTCP transfer protocol, paper proposed on new packet lossrate control strategy bases on the feedback control information of RTCP protocol. Inthis paper, using RTCP protocol of feedback current3G transmission of packet lossrate to predict the rate of packet loss value with weighted prediction. And this valuecan be used to estimate the packet length and the size of the video bit rate. Estimatingthe length of the data packet, paper used the model of the channel bit error rate toadaptive the packet length. Video bit rate adaptive algorithm is a new AMID algo-rithm. This new algorithm associates with the predict rate of packet loss value anduses smooth operator to make the video bit rate changes smoother, more suitable for 3G transmission channel. Experiments show that the strategies of using RTCP packetloss rate of the feedback information to adaptive packet length and video bit rate caneffectively reduce the packet loss rate of3G transmission. It has certain actual appli-cation value with the advantages of low computational complexity and easy imple-mentation.In the practical system, Optimized encoding algorithm improves the efficiency ofreal-time video encoding and3G transmission control strategy effectively improve thequality of video transmission. The Low complexity and simply optimization algo-rithms played a key role in improving system performance, so they have some practi-cal value.