由於網際網路的蓬勃發展與資料壓縮技術的進步，大量的多媒體影音資訊在網路上被傳遞與下載。數位視訊因具有較高的商業價值與娛樂性，加上影音分享平台的普及，享受數位視訊串流已成為現今普遍的娛樂活動之一。然而，雖然使用者獲得了影視訊數位化所帶來的便利，數位資料的任意散佈引發了影音版權所有人的疑慮，數位智權管理因此成為現今重要的議題。數位浮水印被提出作為協助智權保護的工具之一，其中一項功能是用來追蹤多媒體資料的非法散佈者，即視訊所有人或提供者將資料傳送給某位合法使用者之前，將代表該使用者的資料嵌入於數位視訊當中，在發現某個在網路上流傳的數位視訊後，我們可由該視訊中偵測數位浮水印，一來可依其內容追蹤惡意散佈來源，二來或可用於降低使用者任意無償分享的意願。在本論文中，我們提出以追蹤來源為主要應用的數位視訊浮水印機制，在網路上經常作為分享的MPEG-4視訊中嵌入代表使用者的數位浮水印。為了減少視訊伺服器端嵌入浮水印所需耗費的龐大時間，我們利用部分解碼的方式實作壓縮域浮水印。同時，本機制利用SIFT在選定的畫面中決定嵌入與偵測浮水印位置，以利浮水印訊號在轉檔或是畫面形變後仍能進行盲偵測，另透過成對浮水印的設計以及浮水印位移的方法，增加使用者內容嵌入量以及避免偵測端誤判。實作上考量了數位浮水印的強韌性、不可視性與容量等議題，實驗結果展示此方法的可行性。 With the rapid growth of networking technologies and the advances of data compression, a large number of multimedia files are transmitted, shared and downloaded. Due to the high commercial values and entertainment, digital videos are popular and watching digital video streams has become a common activity in our daily life. Although the users do enjoy the convenience from the digital video streaming, the illegal spreading of copyrighted videos draws concerns from content owners or creators. Digital watermark is proposed as a tool for protecting the intellectual property right. One of its functions is fingerprinting. That is, the content owner will embed the fingerprint, which represents the identity of the recipient, into the digital videos. Once an illegal copy is found, we may detect the watermark and trace the origin of illegal distribution. In this research, we propose a practical fingerprinting scheme for digital video streaming. We embed the watermarks into widely used MPEG-4 videos. In order to avoid the heavy computational burden in the video servers, the watermark is embedded into partially decoded data. SIFT is employed to facilitate the “blind detection” even after the video transcoding. The visibility, capacity, robustness and false detection are examined to satisfy the requirements of such applications. The experimental results show the feasibility of the proposed scheme.
