Research on Setting Parameter of Deblocking Filter for H.264

Abstract

The emerging coding standard H.264 is mainly intended for video transmission in many areas. Considering the peculiarity of blocking artifacts which results from block based transform using DCT (discrete cosine transform ) that is most popular method for video coding. These blocking which is due to deficiency of correlation between blocks has much troublesome impact at low bit rate encoding. In this paper, we analyzed the performance of common deblocking filter within H.264 standard, investigated the principle of parameter setting for deblocking filter in an open source code(x264). The outputs of deblocking filter depend on the boundary strength parameter “BS” and the gradient of image samples across the boundary [1]. Usually the filter parameters αc and β were specified a default value zero during x264 running, but in fact selecting different values have a significant effect in the view of image quality. The two statistical parameters of Gray Level co-occurrence Matrix (GLCM), energy and entropy, were used to evaluate the texture of each video picture, and then specify appropriate values for the filter parameters αc and β. We may appraise the effect of deblocking in terms of calculating Mean Squared Difference of Slope (MSDS) for each video frame. In the end of this paper, the experimental results show that our approach, comparing with existing deblocking techniques, is one of the significant methods for reducing blocking artifacts.