Abstract
H.264/AVC utilizes variable block size motion estimation and rate distortion optimized mode decision to achieve high coding efficiency. However, the exhaustive mode checking procedure takes up most part of the computational load. To reduce the computational complexity, many works focus on expediting the mode decision process but are not aware of the relationship between the foreground/background and the chosen mode. In this thesis, we propose a background-modeling-based fast mode decision algorithm which will first generate the background information using intrinsic image technique. According to the background information, macroblocks are classified into three foreground/background macroblock types which will be assigned different candidate modes. Rate-distortion cost will be the comparison to skip unnecessary block mode checking, and with the assistance of background information, fast motion estimation mechanism is proposed. We also use a QP dependent threshold value as an early termination yardstick. The experimental results demonstrate that the proposed algorithm reduces, on average, 48% of the entire encoding time with negligible PSNR drop and bit-rate increase. Moreover, we endeavor to find out the true motion in the video sequences, while retaining the foreground quality.