We propose an overlapped block motion compensation method, called adaptive windowing technique, to improve the performance of variable block-size motion compensation in H.264. First, we restrict the number of neighboring blocks to be overlapped. Then we design adaptive overlapping windows, where each weight is set to be inversely proportional to the distance between the current pixel and the neighboring block. The weights can be computed effciently in both the encoder and the decoder. Also, to further improve the prediction performance, we introduce the notion of reliability of a motion vector
based on the block size, and fine-tune the weights according to the reliability. Extensive simulation results show that the proposed algorithm improves the performance of H.264 both objectively and
In this paper, we propose a novel scalable video coding algorithm based on adaptively weighted multiple reference frame method. To improve the coding efficiency in enhancement layer, double reference
picture and double motion vector algorithms are employed for motion compensated prediction. In addition, the enhancement layer is predicted by the adaptively weighted sum of the double motion
compensated frames in the enhancement layer and the the current frame in the base layer, according to the input video characteristics. By employing adaptive reference selection scheme at the decoder, the proposed method can reduce the drift problem significantly. experimental results show that the proposed algorithm yields higher PSNR performance compared with the fixed weighted scheme and the H.263+ for various packet loss rate channel conditions.
A hybrid mount featuring elastic rubber and piezoelectric material is proposed and applied to the vibration control of a beam structure subjected to high frequency excitations. A mechanical model of the proposed hybrid mount is derived, and then the frequency-dependent dynamic stiffness of rubber and the voltage-dependent stroke of piezoactuator are verified experimentally. After formulating a mathematical model of the beam structure associated with the hybrid mount and the passive rubber mounts, a robust sliding mode controller is designed to attenuate vibration of the beam structure. The controller is experimentally realized and control responses such as accelerations of the beam structure and force transmission through the hybrid mount and rubber mounts are presented in frequency domain.