An improved R-D optimized motion estimation method for video coding

Motion estimation is one of the key tools to achieve a very low bit rate in video coding. The selection of optimum motion vectors (MV) has a significant impact on the quality of the resulted compressed video, in Rate-Distortion (R-D) sense. The established method uses the Lagrange multiplier to optimally select the MV for each block. However, it does not consider the effect of residual coding at the same time with the effect of MVs. In this paper, we have considered the effect of residual coding in motion vector (MV) selection with modeling motion estimation and residual coding as independent processes which results in a new optimization condition. It is based on local optimization, which is the bit allocation between motion estimation and residual coding, and global optimization, which is the bit allocation among different blocks. The proposed motion estimation algorithm results in a PSNR improvement of 0.5 - 3.0 dB when it is used in the H.264 standard with block size of 4 times 4.