近年來由於網路的蓬勃發展與壓縮技術的進步，許多的多媒體檔案被任意的散佈或下載，數位智權管理變得日益重要，而數位浮水印技術可被用來追蹤這些多媒體資料的非法散佈者。在本論文中，我們選擇對MPEG-4視訊壓縮標準嵌入數位浮水印。為了減少將浮水印嵌入視訊所需耗費的時間，我們利用部分解碼來實作壓縮域浮水印，即在解碼端解碼出量化指標，加入預先準備好的嵌入資訊，再經由編碼端的可變長度編碼組成壓縮視訊。為了避免嵌入的訊號因視訊壓縮時的預測機制造成飄移錯誤(drift error)，我們提出將訊號只嵌入每張畫面中的不被參考區塊。此外，由於我們使用盲檢測(blind detection)以符合實際應用及偵測的公正性，我們使用特定的SIFT(Scale Invariant Feature Transform)特徵點嵌入樣板以達成偵測的同步。實驗結果顯示，即使因只嵌入不被參考的區塊且經過量化讓嵌入的資訊量大幅減少，我們依然能夠於可能被攻擊的視訊中正確偵測浮水印，且具有一般數位浮水印所必須具備的基本特性。 Due to the prevalent uses of digital video technology and the internet, many authorized videos have been illegally copied, downloaded and distributed. The concerns over intellectual property right infringement of video content are thus raised. Digital fingerprinting is a means of tracking the users who distribute the copyrighted multimedia data to provide a convincing evidence for the litigation. In this thesis, a partially decoding fingerprinting scheme is proposed. The quantization indices of the compressed video are decoded and embedded with the fingerprint and then encoded into the fingerprinted video. The computationally expensive motion estimation can thus be avoided in this transcoding process. In order to avoid the drift errors, which result from the error propagations in the inter-coded frames, only the non-referenced blocks are used for fingerprinting. Since the blind detection is adopted in the proposed scheme, the synchronization templates are embedded and their embedding positions are determined according to SIFT feature points such that the synchronized detection of geometrically attacked video can be achieved. Experimental results show that, even though the fingerprints are only embedded in the non-referenced areas and the video may be geometrically attacked, the fingerprinting watermark can still be detected successfully.
