H.264/AVC視訊編碼標準採用許多新的編碼技術，和以往的視訊編碼標準相比有更好的編碼效率，但同時也大幅度增加編碼端的計算複雜度，特別是模式選擇和動態估測的部份，對於即時視訊的應用無疑是一大挑戰。因此，本論文引入時空相關性與編碼區塊形態(Coded Block Patterns, CBP)等概念，整合CBP在不同編碼模式下分佈之特性及多幅參考畫面中鄰近區塊於空間及時間上的關聯性，找出參考區塊；針對H.264編碼端提出一個畫面間快速模式決策演算法。實驗結果顯示，無論在任何特性的視訊資料下，都能在幾乎不影響影像品質的前提下(稍降0.1dB)，節省高達86%之編碼時間且位元率僅上升0.7%，代表本論文所提之畫面間編碼模式決策機制可大幅降低系統之編碼時間且保持畫面品質。The H.264/AVC video coding standard employs several new coding techniques to achieve better coding efficiency than previous standards. However it also greatly increases computational complexity at the encoder, especially for motion estimation and mode decision. Undoubtedly, it is a challenge to utilize H.264/AVC for real-time video applications.In this thesis, we propose an efficient inter mode decision algorithm based on spatial and temporal correlation of blocks and Coded Block Patterns (CBP). The characteristics of mode distribution at different values of CBP and the amount of skip mode of spatial and temporal neighboring blocks in multiple reference frames are utilized to the early determination of the type of the current macroblock. The search candidates during inter mode decision can be significantly reduced hence encoding time saving is achieved.The proposed algorithm can significantly reduce the computational complexity while keeping the video quality. The experimental results show that the proposed algorithm can save up to 86% of total encoding time compared to fast full search in H.264/AVC reference software with negligible performance degradation.
