Video quality enhancement methods using new accurate motion estimation for video encoder system

Abstract

This thesis proposes video quality enhancement algorithms using motion estimation and compensation for video encoder system. At first, we propose a new accurate binary motion estimation algorithm. Motion estimation and compensation are critical components of digital video compression systems. More accurate motion estimation ensures more enhanced video quality. Another main functional block to enhance video quality in the video encoder system is rate control. Secondly, we propose a new adaptive quantization algorithm for rate control using I-frame motion estimation. In general, video encoder system includes pre-processor for input video stream such as noise reducer to enhance encoding efficiency and video quality. Finally, we propose a noise robust motion vector refinement algorithm to find more accurate motion vectors for motion compensated noise reducer. The new binary motion estimation algorithm improves the motion vector accuracy by using a hybrid distortion measure. Unlike conventional binary motion estimation algorithms, the proposed algorithm considers the sum of absolute difference (SAD) as well as the sum of bit-wise difference (SBD) as a block-matching criterion. In order to reduce the computational complexity and remove additional memory accesses, a new scheme is used for SAD calculation. This scheme uses 8-bit data of the lowest layer already moved into the local buffer to calculate the SAD of other higher binary layer. The proposed algorithm finds more accurate motion vectors and removes the blocky of the reconstructed video sequence effectively. The new adaptive quantization algorithm uses the motion information in Intra frame by using I-frame motion estimation (IME). It finds optimal quantization values in I-frame and removes unnecessary bit-usage in I-frame. And it results in the improvement of entire visual quality. Also, the effective activity measure in I-frame is proposed. Instead of the reconstructed frame, the original frame is used as...