Quality evaluation and enhancement of audiovisual signals based on digital watermarking

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The quality measurement of image, video, speech and audio is of critical importance for today's audio and video broadcasting, telephony networks, transmission control, and e-commerce, mainly because quality is both a key determinant of customer satisfaction and a key indicator of transmission condition. Although subjective quality evaluation has been the most reliable method of audiovisual quality assessment, it is highly unsuitable for online monitoring and broadcasting applications, and is also very expensive and time consuming. The current existing objective quality evaluation metrics require original signal to evaluate audiovisual quality. Original signal is not available for some important applications. We propose to evaluate audiovisual quality based on digital watermarking. The basis of the proposed research is that the carefully embedded watermark in an audiovisual signal will undergo the same distortion as the host audiovisual signal does. The audiovisual quality can be measured based on the degradation of the extracted watermark, by referring to an ideal mapping curve between the true detection rate and a particular commonly used quality metric including human subjective evaluation. The watermarking based quality evaluation does not need the original signal and can be very accurate. To deliver audio and video data over the Internet or wireless networks in real time with high quality, it is important to develop simple, robust error-concealment and coding strategies. The idea of including additional perceptually transparent information using audio/video watermarking to help for the recovery of packet or frame losses can also lead to several advantages. A component of the proposed research is therefore to investigate the use of watermarking-based packet loss concealment schemes for audiovisual signals, compression restoration in transmission of video, and adaptive coding and transmission of speech signal over ad-hoc wireless networks.