High Efficiency Video coding(HEVC) 是H.264之後被提出的最新一代視訊壓縮標準。 之所以被取名為HEVC的原因是其目標致力於高編碼效率和高影像品質。隨者HEVC的發展，HEVC編碼所花費的時間還是比先前的H.264多了許多。在HEVC中， 一張圖會先被切割成許多同一尺寸的最大邊單元，而每一個最大編碼單元會在被切割成不同尺寸的編碼單元。編碼單元的切割會組成四分樹的架構。Cost會決定如何去切割每一個編碼單元。
由於HEVC必須藉由計算cost來決定編碼單元的切割， 所以cost的計算量占了絕大部分的時間。為了降低運算複雜度，於是我們提出了HEVC快速編碼單元深度決策。這演算法會先比較當前CU與鄰近的CU的關係來預測當前CU的深度範圍。接者，針對這深度範圍內的CU，我們會測試是否提前終止分割，判斷是藉由Hadamard cost所制訂而出。本篇論文所提出的演算法可使編碼時間減少52%，而只有少量的PSNR損失與位元率提高。

　High Efficiency Video Coding (HEVC) is a new generation of video coding, which was the successor of H.264/AVC. The name HEVC was given for the consideration of high quality and high efficiency. As the development of HEVC began, HEVC still required more coding time than H.264/AVC. In HEVC, a frame is divided to Largest Coding Unit (LCU) with uniform size, each LCU will be divided into several Coding Unit (CU) with various size. The coding unit partition will form a quad-tree structure. Cost of each coding unit will make decision for coding unit partition.
Since HEVC needs to calculate many cost during coding unit partition, the calculation of cost usually consumes a lot of coding time. In order to reduce the computational complexity, we propose a Fast Coding Unit Depth Decision for HEVC. The proposed algorithm will first compare current CU with neighbor CU to predict depth range of current CU. Then, for each CU within this depth range, we will test whether splitting process will terminate early. This test is based on Hadamard cost.
The performance of proposed algorithm was capable to speed up the coding time averagely 52% with negligible PSNR loss and slight bitrate increase.

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