H.264/AVC優異的編碼壓縮效能使其被廣泛地使用於網路視訊串流傳輸的各種應用。然而，網路與壓縮技術所帶來的方便性也讓未授權視訊更容易地被散播，數位影片的智權管理因此成為一項重要的議題。本論文針對H.264/AVC提出一個結合選擇性加密與低運算複雜度數位浮水印的智權管理機制。本機制利用選擇性加密，在儘量不影響影片大小的前提下，有效率地擾亂原來的視訊畫面，加密後的影片依然保有H.264/AVC的相容性，雖可被播放但有著凌亂的畫面。選擇性加密可以減少影片加解密時所需要的時間，也間接減少了電力上損耗。此外，本機制更在視訊壓縮與加密的過程中，抽換視訊串流中的一部分資料，並在此段資料中嵌入相對應使用者的個人資訊，在缺乏該段資料的情況下，視訊畫面將受到進一步的擾亂。使用者為了觀賞正確畫面必須另行下載此段資料，而在該資料與原先視訊串流結合的過程中，代表使用者的數位浮水印將被嵌入，以供日後追蹤之用，也就是當非法散播的H.264/AVC影片被發現後，可經由此訊息追溯下載使用者。此部份設計的目標在於如何減少額外資料的傳輸量，以及對於影片畫質的保障。實驗結果顯示本論文所提出的演算法能夠有效擾亂畫面，並且對於影片的壓縮率只有些微的影響，而視訊串流壓縮的時間則幾乎沒有增加，浮水印嵌入演算法亦不影響視訊畫質。 H.264/AVC is expected to be widely used in streaming applications due to its decent coding performance. Many commercial and surveillance systems will employ H.264/AVC to facilitate the transmission and archiving of video content. However, the convenience of distributing digital videos may also raise certain concerns from content providers and owners so the issues of Digital Rights Management (DRM) of videos become critical these days. In this research, we propose a joint encryption and digital watermarking scheme in H.264/AVC compressed videos. We first present a novel selective encryption scheme under the framework of this state-of-the-art video codec. The main idea is to not only make the encrypted video useless for anyone who does not own the correct key for decryption but also keep the compatibility of H.264/AVC syntax so that the complexity of decoding can be reduced. In other words, the video frame can be extracted for viewing but is scrambled to conceal its intelligibility. The ideas of partial encryption lead to more efficient power management. In addition, we also present a low complexity fingerprinting algorithm by using the techniques of digital watermarking for encrypted videos. The information of target user can be embedded for the purposes of trailer tracking. Experimental results demonstrate that the proposed scheme effectively scramble the video frame content and bring a negligible impact on the coding performance. Moreover, the coding complexity is almost not affected. The proposed fingerprinting algorithm can embed a reasonable amount of information into the compressed bit-stream without degrading the video quality.
