| Summary: | 碩士 === 國立臺灣科技大學 === 資訊工程系 === 101 === The state-of-the-art video codec, high efficiency video coding (HEVC), adopts quadtree-structured coding units (CUs) for efficient compression of high resolution video sequences. However, at the encoder side, motion estimation (ME) for the CUs in each quadtree-structured depth level should be preformed to find the optimized rate-distortion depth level, resulting in extremely high computational complexity. In this thesis, we propose an efficient CU depth level decision algorithm based on adaptive weight mechanism. By utilizing the residuals and depth levels of neighboring CUs in the current frame and co-located CU in the previous frame, the proposed algorithm can adaptively determine an appropriate depth level range for the current CU. Since ME process is only performed in the determined depth level range rather than all the depth levels, it leads to significant reduction of computational complexity. Experimental results demonstrate that the proposed algorithm can significantly reduce computational complexity while preserving quite similar quality of the reconstructed video sequences to that by standard HEVC encoder. Furthermore, when compared with Shen et al.'s method, the proposed method has some benefit on reducing bitrate and encoding time.
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