Efficient calculation of adaptive interpolation filter with distortion modelling

A novel method is proposed to calculate the coefficients of adaptive interpolation filter used in hybrid video coders for improving the coding efficiency. The proposed algorithm first selects the motion blocks where the majority of prediction errors result from mismatches in motion estimation and from aliasing present in the signal. This is realized by using a second order distortion model to estimate the effect of quantization on motion prediction error and coding results of the previous frames. Then, the filter coefficients are calculated analytically by minimizing the prediction error of those selected blocks. Experimental results show that the proposed method achieves up-to 0.6 dB gain compared to the standard H.264/AVC. Compared to other methods that calculate the filter coefficients using all motion blocks of the frame, the proposed method has significantly less encoding complexity (83% on average) with practically no penalty on coding efficiency.