Shape Error Concealment Technology Based On Geometry Analysis

With the establishment of video compression encoding standard,the contradiction between video communication and channel bandwidth is released greatly.However,the compressed video streams are vulnerable to the random noise in channel and generate errors,therefore,error concealment in video communication draw more and more attention.Especially after MPEG-4 international standard is issued,its features of efficiency,scalability,interaction and robustness extend the application area of digital video from image storage and digital TV to networks and wireless channels. At present error concealment techniques based on this standard have been developed greatly.Firstly,we provide an overview of MPEG-4 video compression encoding standard,chiefly introduce the basic coding principle and encoding scheme based on content.Then we introduce error concealment techniques from three aspects.The aspects are error concealment at the encoder side,decoding side and the error concealment of interaction between encoder side and decoder side. And discuss the error concealment at the decoder side from two aspects: time domain and space domain.We discuss shape error concealment algorithms based on MPEG-4 standard in detail,analyse and point out the advantages and disadvantages of various types of algorithms and their application environments.Secondly,in view of the disadvantages existing space domain shape error concealment,we adopt a shape error concealment algorithm based on geometry analysis.The algorithm first definite the four rectangular neighborhood of the missing area,and then detected the intersection with the boundary line in the adjacent domain,and analyze them in geometric coordinates.Match them into pairs in an optimization criterion,then they can connect each other in the missing area smoothly.Each group of lines will be concluded and corrected recursively until there is a closed curve.Experiments are tested in different sequences,in different error rate conditions and compared with other shape error concealment methods.The results of the algorithm proposed in this paper show a more robust effect.At last,according to the complex video objects'shape information lost,we analyze the disadvantages of error concelment based on Second-order Besier curve fitting,and adopt a error concealment method based on cubic B-spline interpolation to deal with wrong video frame.The experimental results show that this method could conceal the error effectively.