Font Size: a A A

Integrated Video Error Control Based On Rate-Distortion Optimization

Posted on:2007-05-20Degree:DoctorType:Dissertation
Country:ChinaCandidate:T W YangFull Text:PDF
GTID:1118360212959915Subject:Traffic Information Engineering & Control
Abstract/Summary:PDF Full Text Request
Real-time video transmission in Internet or wireless environments is a challenging task requiring high-compression efficiency as well as robust error control. Motion compensated hybrid coding is widely utilized to reduce video redundancy in real-time video transmission, but transmission errors will result in serious spatial and temporal error propagation. Error resilient coding, such as FEC, ARQ, RPS and Intra mode updating etc, should be used to combat transmission errors, which is redundancy coding in nature. Under the limitation of bandwidth, it is necessary to jointly consider many error control techniques within a framework of rate-distortion optimization (RDO).Integrated video error control (IVEC) takes advantage of several error control techniques, which can obtain desirable error resilience. Several error control techniques are researched and integrated into a viveo transmission system based on the framework of RDO in this thesis.RDO is based on the estimate of channel distortion. A precise simulative estimate of channel distortion (PSECD) is proposed by analyzing characteristics of error propagation. The PSECD can well combine with the RDO, and achieve higher estimate accuracy of channel distortion than that of 30 simulative decoders.The optimal macro-block mode selection (OMMS) is proposed on the basis of RDO with losses. By introducing two concepts—average channel cost and coding income, the coding distortion caused by redundancy coding and channel distortion caused by error propagation is analyzed for minimizing the transmission distortion in the OMMS。The OMMS obviously outperforms the mode selection optimized by RDO with losses in H.264/AVC test model.A key reference picture selection (KRPS) for multi-frame prediction codec is introduced in this thesis. The selection of key reference picture is combined with the OMMS, which minimizes the transmission distortion at frame level by RDO with losses, while it is in favor of the OMMS. Experiment results demonstrate that the KRPS can further improve the error resilience of the OMMS.The entropy of quantized DCT coefficients has the one parameter—the standard quantization parameter (0) that is the ratio of quantization parameter to mean absolute difference (MAD). A rate curve is obtained offline, and a fixed look-up table is created. Using this look-up table, a simple and effective rate control algorithm is proposed for real-time video. Its computational complexity is very low and its performance is much better than TMN8 rate control in term of Y-PSNR and buffer steadiness.A multi-step multi-weighted block-warping algorithm (MMBWA) for error concealment has researched. The motion of damaged macro-block is classified into several motion cases, and different concealment method is used for each motion case. The motion field interpolation concealment will be implemented once block-warping motion is detected. Simulation results show that the MMBWA can obtain more satisfactory concealment performance compared with traditional error concealment, especially for the damaged blocks with intense and complicated motion.Based on the research of several error control techniques, a video transmission system is discussed, which intergrate with OMMS, KRPS, error concealment, rate control and forward error correction (FEC) etc. The system implements a two-step RDO strategy, where bandwidth is optimally allocated at frame level and macro-block level, and it allows considering several error control techniques at the same time. Because the optimal bandwidth allocation in frame level has taken macro-block level error control into accout, the sytem gains ideal unitary error-resilient performance.
Keywords/Search Tags:video transmission, error control, reference picture selection, rate-disototion optimization
PDF Full Text Request
Related items