本論文提出使用哈達碼轉換與適應性量化演算法有效地改善H.264/AVC無失真視訊編碼，目的在於降低位元率以助於有限頻寬之傳輸。在H.264/AVC無失真編碼中，經內框或外框預測後所得之殘值，會直接進行熵編碼。為了改善無失真編碼壓縮率，本論文將預測後之殘值經哈達碼轉換，並將轉換後的係數分成商數和餘數部份。由於哈達碼轉換可將區塊能量集中，且轉換係數的商數部份已進行過量化，因此經熵編碼後，位元率會比原始殘值係數編碼大幅降低。為了達到無失真編碼，在移除哈達碼轉換造成的冗餘位元之後，轉換係數的餘數部份使用數個固定位元編碼，並加入到位元流中。最後，本論文提出適應性的演算法，依區塊之間殘值的相關性，以不同量化值將轉換殘值係數區分為商數和餘數部分，以提升壓縮效能和降低位元率。研究模擬結果顯示，本適應性演算法適用在編碼序列IIII和IPPPP，平均而言，分別可降低原來編碼器所產生位元率的13%和10%的位元率。

This thesis proposes an efficient Hadamard transform-based lossless coding with adaptive truncation algorithms in H.264/AVC. The residual data, obtained after inter or intra prediction, are directly encoded by entropy coding in original H.264/AVC lossless coding. To improve the compression performance in lossless coding, the Hadamard transform is applied to the residual data and the transformed residual coefficients are separated into the quotient and remainder parts in the proposed algorithms. The quotient part of the coefficients is encoded by entropy coding to achieve the lower bit rate since the energy of the blocks is compacted by Hadamard transformation, and the encoding coefficients are scaled down by truncating. Moreover, to ensure the lossless reconstruction of the video, the remainder part of the coefficients is also encoded with a few fixed bits after removing the redundancies caused by Hadamard transformation. Finally, the adaptive algorithms are provided to properly separate the transformed residual coefficients into the quotient and remainder parts according to the correlations between the 4x4 blocks. The total bit rate summed from the two parts is decreased successfully.
Simulation results show that the design provides better performance than the original H.264/AVC lossless coding with about 13% and 10% bit rate decrement for sequences with all I frames and for sequences with IPPP frames separately.

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