Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Improved Bit Rate Control for Real-Time MPEG Watermarking | EURASIP Journal on Applied Signal Processing 2004 14 2132-2141 2004 Hindawi Publishing Corporation Improved Bit Rate Control for Real-Time MPEG Watermarking Sugiri Pranata Nanyang Technological University School of Electrical Electronic Engineering EEE Nanyang Avenue Singapore 639798 Email sugiri@ Viktor Wahadaniah Nanyang Technological University School of Electrical Electronic Engineering EEE Nanyang Avenue Singapore 639798 Email viktorw@ Yong Liang Guan Nanyang Technological University School of Electrical Electronic Engineering EEE Nanyang Avenue Singapore 639798 Email eylguan@ HockChuan Chua Nanyang Technological University School of Electrical Electronic Engineering EEE Nanyang Avenue Singapore 639798 Email ehchua@ Received 2 April 2003 Revised 2 October 2003 The alteration of compressed video bitstream due to embedding of digital watermark tends to produce unpredictable video bit rate variations which may in turn lead to video playback buffer overflow underflow or transmission bandwidth violation problems. This paper presents a novel bit rate control technique for real-time MPEG watermarking applications. In our experiments spread spectrum watermarks are embedded in the quantized DCT domain without requantization and motion reestimation to achieve fast watermarking. The proposed bit rate control scheme evaluates the combined bit lengths of a set of multiple watermarked VLC codewords and successively replaces watermarked VLC codewords having the largest increase in bit length with their corresponding unmarked VLC codewords until a target bit length is achieved. The proposed method offers flexibility and scalability which are neglected by similar works reported in the literature. Experimental results show that the proposed bit rate control scheme is effective in meeting the bit rate targets and capable of improving the watermark detection robustness for different video contents compressed at different bit .
