近幾年，在無線網路上傳輸多媒體碼流的技術逐漸受到重視。但在網路傳輸時產生的錯誤，卻會對即時編解碼的應用造成視覺品質失真。H.264/AVC採用了一些錯誤回復的工具來提供穩定的傳輸品質，但並沒有提供一個完善的錯誤修補能力，因此本文提出了改善的方法。在時間上的錯誤修補法裡，採用了具高度彈性之子區塊分類以及相對應的邊界匹配法來提供可利用的運動向量以修補錯誤的區塊。而在空間上的錯誤修補法裡，則採用了多邊擴張與權重內插法。結合以上兩種方法，組成了一個運用時間與空間特性且可調適之錯誤修補法。它可以偵測並改善在非預期場景變換後下一個畫面發生的品質失真，也可以改善在使用幀內編碼(intra coding)的畫面中所產生的失真。本文提出的方法並不需要修改任何H.264的語法或是編碼端的架構，而能夠提供良好的錯誤修補效果。另外，在與H.264內建的錯誤修補法的實驗比較中，不管在客觀的數據上或是主觀的視覺上，都驗證了所提方法具備更強健的抗傳輸誤差的能力。

Transmitting multimedia bitstreams over wireless network becomes popular in recent years. However, due to network transmission errors, the real-time codec applications suffer unpleasant perceptual quality degradations. For H.264/AVC, it adopts some error resilient utilities to provide stable transmissions, but its coded streams are still vulnerable to transmission errors. The temporal error concealment is based on flexible sub-block classification with suitable boundary match algorithm. The motion compensated blocks can be used to replace error blocks. The spatial error concealment is based on multi-edge propagation and weighted interpolation. The lost image block due to transmission errors can be interpolated by referencing pixel values of adjacent blocks. Combining above two algorithms, we have proposed an adaptive spatial/temporal error concealment method. It can reinforce the video from errors due to unexpected scene changes and errors in an intra frame. The most promising feature of the proposed method is that there's no need to modify H.264 syntax or encoder framework to perform the error concealment. As compared to methods suggested by H.264, it demonstrates good capabilities of robustness to transmission errors and still provides better video qualities, subjectively or objectively.

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