H.264 Video Coding, Error Concealment Techniques

With the rapid development of multimedia and computer network, and especially the development of mobile communications, video communication applications have become an inevitable trend. However, transmission errors and data loss is always difficult to avoid in IP network or wireless network channels.Compressed Video data is very sensitive to transmission errors, small amount of corrupt data could lead to a failure of the decoding of the whole picture. So we must find a more effectively way to combat transmission errors, because in many applications, heavy error-correcting codes and Retransmission may not suitable as the constraint of transmission efficiency and real-time needs. Therefore, error control and concealment techniques of video transmission are becoming increasingly important.Error concealment is a technique that tries to conceal error Macroblocks by exploring space and time redundancy of the video data; it is more suitable for Real-time applications.In this thesis, we first introduce basic principles of digital video compression coding and popular video coding standard, followed by the description of error control techniques such as error concealment and error resilience coding. Then we analyze some error concealment algorithms of H.264 video coding standards in details and points out problems of each algorithm.After that, we proposed an adaptive spatial interpolation algorithm to solve these problems. The algorithm could adaptively switch between WPVA and an improved directional interpolation algorithm that also proposed by the author here according to edge information around the lost area in a frame. The improved directional interpolation algorithm above use a "Two loop method" to give more precise estimate of edges in the lost area compare to other directional interpolation algorithm.In the experiment, we implemented the algorithm in JM86 (the test model of H.264 video coding standard). Experimental results showed that our algorithm can not only achieve good directional interpolation concealment results in both visual effect and PSNR value but also can avoid fake edges.