Research On Transmission Techniques Of Extension Of H.264/AVC Based Scalable Video Coding

With the rapid development of communication, network and multimedia technologies,various applications with digital video have become popular. The scalable video coding(SVC) extension of H.264/AVC provides a powerful solution to various applicationsover the heterogeneous networks and diversified end-users. It is very promising intheory and practice to study various techniques for SVC transmission.This dissertation presents the researches for SVC video on the reliable transmissionmethods in error-prone channels, the transmission design in wireless local networks andthe playout techniques of video streaming. The main contents are as follows:First，the reliable transmission of SVC video using joint source/channel coding(JSCC) is studied in this dissertation. The mathematical model of the JSCC problem isestablished for a typical SVC video transmission system and the distortion of thereconstructed video is evaluated. A typical existing algorithm and its problem areanalyzed. A joint two-dimensional optimization scheme is proposed to derive theoptimal allocation of the SVC data and the protection levels of the error-control codes.The scheme performs the optimization on each frame in a rate-distortion (R-D) sense, aswell as on all frames under the dependency constraints. To compute the R-D points of aframe efficiently, a novel reduced trellis algorithm is developed which uses a discretetrellis structure, layer-based computation method and simplified status structure, and itscomputational efficiency is improved by about20to50times over the existingViterbi-base algorithm. Based on the R-D points of all frames, an overall R-D curve ofthe video transmission system is constructed by the joint two-dimensional optimizationscheme. According to given target rate the curve is extracted and then the best JSCCsolution is derived in R-D sense. Simulation results show that our scheme outperformsthe typical existing scheme in PSNR performance for both progressive andnon-progressive modes.Next, the cross-layer design is studied in this dissertation to improve the SVC videotransmission over802.11e-based wireless local networks. A significance-based adaptivemapping algorithm is proposed which based on the SVC packet’s significance allocates a suitable access category (AC) at medium access control (MAC) layer to transmit thedata and adapts the packet rate to the network load to prevent the congestion on ACpredicatively. To use the ACs more appropriately, the existing general analysis of EDCA(Enhanced distributed channel access) characteristics is extended to our specify case.Unlike the original results, our conclusion is more concise and requires no globalknowledge of overall networks on numbers of various AC stations and etc. Simulationresults show that our algorithm has much better PSNR performance and nice delayperformance, in comparison with the conventional EDCA, existing static mapping andadaptive random mapping algorithms.Finally, adaptive media playout and packet scheduling approaches are studied to copewith the variation of network conditions and enhance the video playout quality in SVCstreaming. A new adaptive media playout (AMP) algorithm is proposed whichpredicates the risk of playout outage and buffer overflow and adjusts the frame rate inadvance. The algorithm estimates the throughput of network and lengths of frames inthe video’s GOP (Group of pictures) structure for risk predication, performs theadjustment in K steps for good smoothness and speed, and minimizes the quality lossdue to overflow by exploiting the scalability of the SVC stream. Simulation resultsshow that our proposed algorithm outperforms the existing smooth and conventionalAMP algorithms in outage suppressing, overflow processing and jitter performance.Besides, a joint transmitter/receiver controlled packet scheduling scheme is proposedwhich extracts the SVC packets based on the network conditions and performs jointcontrol on the packet schedule according to the status of the receiving buffer. Thescheme is able to prevent outage of playout effectively and achieve near optimalreceiving quality under large scale variation of the network throughput.