Study On Video Error Cocealment Technology Based On H.264

Video communication is one of the main applications in multimedia communication. At present, the most wired and wireless networks can't provide QoS guarantee, so the error and loss of video data during tansmission are inevitable .The latest video coding standard H.264 has higher coding efficiency and better network friendship than other video coding standards. Therefore, H.264 is widely concerned and warmly welcomed in the world and it has become the primary video coding standard applied in various communication systems. But the video stream compressed by H.264 is more sensitive to transmission errors. Once an error occurred in transmission, the effects of fault information would be propagated in spatial and temporal rapidly which would result in the serious decline of video quality. Although H.264 has adopted a series of new error resilient technologies, it still needs to combine with other error resilient technologies to enhance the robustness of video steam in transmission.Video error concealment technology is mainly discussed in this thesis. An adaptive spatial error concealment algorithm based on edge detection (ASEC) is proposed in chapter three. The missing macroblocks are classified into uniform macroblocks and edge macroblocks based on the edge information extracted from surrounding correctly received macroblocks. For the uniform macroblocks,they can be concealed by the bilinear interpolation algorithm(BI). The edge macroblocks can be concealed by the weighted average of muli-direction interpolation method. Extensive experimental results show that the ASEC algorithm has much better error resilient ablity than other spatial error concealment algorithms, and it achieves 0.3～3. 55dB average PSNR increase for recovered images compared with the BI algorithm employed in the H.264 jonit model (JM) decoder especially.Chapter four addresses a refined two-step multi-weighted boundary-matching algorithm(RTMBMA) for temporal error concealment. The missing macroblocks can be concealed by means of 16×16 mode or 8x8 mode according to their motion intensity and the predicted motion vectors of the missing blocks can be refined using the diamond search mothed. Extensive experimental results show that the RTMBMA algorithm further improves the concealment performance for the corrupted video sequences than other temporal error concealment algorithms. Especially, 1.13～2. 52dB average PSNR increase for revovered images is gained by the RTMBMA algorithm compared with the SMA algorithm employed in the JM decoder.Chapter five is devoted to an adaptive spatial-temporal error concealment algorithm(ASTEC).The missing macroblocks are firstly concealed by the temporal error concealment algorithm, and then they are adaptively concealed once again by ASEC or RTMBMA algorithm. Extensive experimental results show that the ASTEC algorithm achieves 1.16～4.01dB average PSNR increase for revovered images compared with the error concealment algorithms employed in the JM decoder and it effectively controls the propagation of video errors.