Based On The Model In The Wavelet Domain Video Compression

Recently, many applied image coding algorithms are mixed coding methods based on the spatial motion estimation and compensation, the DCT and quantification of displaced frame difference (DFD) and entropy coding such as some international standards about still images and video compression coding:JPEG, MPEG-1, MPEG-2 and so on. But the algorithms based on DCT have their inherent disadvantage that is "blocking effect" . The quality of the restored images is too bad at the high compression ratio. So much more effective coding methods have been gone for. Having the good characteristics of temporal-frequency localization and so on, wavelet transform is very suitable for describing nonstationary signal and adapt to man' s vision system. Thereby wavelet transform is increasingly concerned in the field of video compression coding.After wavelet transform ,The current frame and the reference frame are performed motion detection and motion estimation, compared with the traditional method, this method uses little time about motion estimation, the block effect of image disappears after decoded , the decoded image has ideal PSNR(Peak Signal Noise Ratio and subjective quality , but in the block matching algorithm , the full search uses too much time . In the MRME(Multi-resolution Motion Estimation) , the smallest subband is performed motion estimation, thus, because of the structure of wavelet, the corresponding position is performed motion estimation, the whole image must be performed motion estimation , thus the computing time is very large, moreover the range of search is constant that makes motion estimation contradict with matching precision.Motion vector and motion region gained after motion detection is based on the smallest subband, the Motion region is required by moving object detection using three difference method, it is divided some of blocks , according to the I frame and P frame, the block performs motion estimation in corresponding image, obtained motion vector replace that is obtained by constant range in MRME, thus the motion vector is based on motion regions, because of the high correlation of head-shoulder image, the motion regions are few and the range of motion are small, thus only a few of blocks are performed motion search. In MRME, the motion vectors of low frequency are predicted by that of high frequency, so the motion vectorsprecision are very important, in searching the motion vector, the range of search range is comparatively large, so the motion vectors' precision are higher. The simulation results indicate that the performance of the video codec system using the algorithm proposed by author are satisfying.