對使用熵編碼的 H.263 影像而言，碼字傳送錯誤不僅影響所傳的碼字本身，而且可能會造成連續錯誤使得接收到的影像嚴重破壞﹔雖然利用 H.263 的編碼機制可以偵測部份錯誤，但利用這些機制偵測的成效不彰；因而源自於蔚為風潮的浮水印及資料隱藏概念，我們提出“利用資料隱藏技術應用於 H.263 視訊編碼之錯誤偵測技術”以彌補 H.263 編碼機制偵測能力的不足。 在這篇論文中，我們提出一個利用資料隱藏技術應用於 H.263 視訊編碼之錯誤偵測。利用隱藏在視訊中的資訊，偵測是否有錯誤發生。在編碼端預先將前一張編碼畫面中每一區塊的同位檢測碼，以資料隱藏的方式藏在目前編碼畫面的移動預估向量或殘餘區塊量化值之中，以使解碼端可利用這些同位檢測碼進一步偵測出原有可變長度碼解碼後所無法找出的錯誤。模擬結果展現出這樣的技術對於錯誤偵測能力有重大的改善而且所提出的技術相當具有實用性。 Due to the use of the variable length coding, a single error in the H.263 video bit stream may cause serious error propagation and quality degradation. Many error recovery techniques have been applied to H.263 video coding. Most importantly, the efficiency of the error recovery relies on the capability of the error detection. In this thesis, we propose a parity-embedded error detection technique for the H.263 compatible video coding. The requisite parity-check information is embedded in the encoded bit stream, which could be easily extracted by the decoder for detecting the actual error occurrence locations. At the encoder, all parity-check codes for all macroblocks in the previous frame are embedded into the motion vectors and the quantized residual DCT coefficients of the current encoding frame. Then the decoder can effectively manipulate these embedded bits to enhance the error detection capability at the macroblock-layer. From the simulation results, we can find that the proposed strategy is able to detect errors with extra 10~30% accuracy than the inherent variable length code provides at the bit error rate 10-2∼10-4. Moreover, the computation complexity is considerably low and the additional cost is only one-frame coding delay and little bitrate increase.
