Study On Error Concealment In Video Decoder Based On H.264

With the fast development of the telecommunication technologies, the video communication has been widely applied and the related techniques have been developped quickly. Video carries a huge amount of information and is therefore often compressed before transmission. One inherent problem with any communication system is that information may be altered or lost during transmission due to channel noise. The effect of such information loss can be devastating for the transport of compressed video, because any damage to the compressed bitstream may lead to objectionable visual distortion at the decoder. It is well-known that images of natural scenes have predominantly low frequency components, i.e. the color values of spatial and temporally adjacent pixels vary smoothly. These facts can be used to conceal the artifacts caused by transmission errors.In this paper, the error control and concealment technologies that are relatively often adopted in video communication systems are explained in detail. The error control and concealment technologies with the overall system analysis in the H.264/AVC standard are discussed. The advantages and disadvantages of the technologies are pointed out. How to use the technologies in different situations are put forward. A boundary-matching temporal error concealment algorithm based on multiple-reference is presented. It estimates the motion vectors of the lost blocks, then, finds the lost block candidates in all references, the right blocks can be acquired by the boundary-matching algorithm finally.In the experiment, the algorithm in JM86 (the test model of H.264 video coding standard) is implemented. Experimental results show that the algorithm can restore the lost motion vectors of error blocks more accurately so that better video quality can be obtained.