Semi-blind quality estimation of compressed videos using digital watermarking

A semi-blind method that estimates the quality of a video distorted by H.264/AVC compression/decompression is introduced. The method embeds pseudo-random binary watermarks in the I-frames of the original undistorted video. To assess the quality of a segment of a distorted watermarked video, the watermark bits are extracted and the quality is estimated based on the similarity between the embedded and the extracted watermarks. To enable quality assessment for a large range of distortions, the derivative vectors of different scaled versions of each I-frame of the original video are obtained, using wavelet transform. The watermark bits that are embedded in the small wavelet scales are used to estimate the small distortions, while the bits embedded in the large wavelet scales are used to estimate large distortions. This is because the latter bits are more robust (to distortions) than those bits embedded in the small wavelet scales. The proposed method was tested on different video sequences which were distorted by compression/decompression using H.264/AVC with different quality factors. The simulation results show that the proposed method can accurately estimate the quality of a video and its frames in terms of the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM) quality measures.