Design And Implementation Of Network Video Transmission Platform Based On H.264

Along with the development of multimedia on network, the application of video transmission becomes more and more widely. Video conference、video surveillance、video on demand etc., all of these systems need video transmission. So, it’s very necessary to develop a applied video transmission system.DirectShow is a architecture of stream media based on component technology. It can provide a good solution for the problem and challenge of the network multimedia application, and also can improve the universality and expansibility of the system. H.264 is the most recently video compression standard, it can provide a good quality of image and a high compress rate. But, the DirectShow platform don’t support the technology of H.264 encoding and decoding now. RTP/RTCP is the net transport protocol which can transmit the multimedia real time and provide quality control, it can provide a dependable real-time transmission. So, this paper implement a video transmission system over DirectShow platform based on H.264 and RTP/RTCP.The main contributions and innovations of the thesis are as follows:First, in the aspect of rate-distortion optimization, according to the basic encoding rules, we use bit forecasting techniques to predict the number of bits after entropy encoding, which is required by rate-distortion entropy encoding. In this way, we no longer need to do entropy encoding with the quantized transform coefficients in each mode, greatly reducing the time of rate-distortion optimization process. To improve the accuracy of bit prediction, we statistic the actual number of encoded bits, and correct the formula of bits prediction.Second, in the aspect of the error control, according to error detection technique, we propose a digital watermark embedded error detection scheme, which can accurately determinate and locate the bits error occurred during the transmission.Third, according to the error concealment technique, we propose an algorithm for recovering the full frame loss based on the estimation of optical flow, which plays an important role in recovering the loss of the full frame caused by the RTP loss.Forth, considering the security needs of the video transmission, we use a simple arithmetic to encrypt the sign bit of DTC coefficients, which has a certain practicality to meet the security needs.Last but not the least, according to the RTCP message information, using DirectShow quality control mechanisms, we control the quality of transport services, so that it makes the video transmission better adapt to the network and encapsulates all kinds of function algorithm into the corresponding filters to form independent function modules.The whole system includes capture module、encoding module、net transmission module and decoding-playing module etc., every module completes the special function, they are connected by the filter graph to a complete video transmission system. The system gets good application in the real network. It solves the problems in the transmission process of real-time video data, such as error、service quality and so on. It has a good adaptation to the network and fine vision quality.