| Summary: | 碩士 === 國立清華大學 === 資訊工程學系 === 92 === With the rapid growth of the Internet recently, more and more digital content are in widespread use. Because digital content are easily obtained, duplicated, and forged, how to protect the copyright of the digital content providers has become an important issue. Digital rights management systems are required to protect rights and business. DRM systems typically incorporate encryption, conditional access, copy control mechanisms, media identification and distribution tracing. Digital watermarking is a technology which embeds an invisible signal including owner identification and copy control information into multimedia data such as audio, video, images, for copyright protection against illegal copying and distribution. Thus, digital watermarking is an essential component of modern DRM systems.
The watermark can be either embedded in the uncompressed video sequence or the compressed video sequence. In this paper, we embed the watermark in I-pictures of the MPEG video sequence by modifying VLCs (Variable Length Codes) directly to avoid inverse DCT (Discrete Cosine Transform) and inverse quantization. The modification of VLCs is intended to minimize the perceptual degradation of video quality caused by the embedded watermark. Furthermore, our proposed watermarking scheme protects the embedded information by means of a secret key and a PRNG (Pseudo Random Number Generator) to generate a random binary sequence for watermarking.
We apply three MPEG-1 video sequences to test our proposed real-time watermarking scheme for digital video. Since the watermark can be extracted by simple table lookup without using original video sequences, the computational overhead is very small. Therefore, the decoding of the watermarked video sequence can be real time for viewing. The proposed algorithm can be easily applied to MPEG-2 and MPEG-4 videos also.
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