Enhanced video coding based on video analysis and metadata information
Date
2007-08-20T18:36:48Z
Authors
Jeon, Hyun-Ho
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Abstract
Achieving high compression ratio without significant loss of quality is the main goal of the most standard video coding systems. Since consecutive frames of a general video sequence have high correlations, the temporal redundancy between frames is removed by using motion estimation and motion compensation techniques. In this thesis, we investigate the use of video content information within the video coding system and propose a new video coding approach that can save significant bit-rates of the compressed video. Main units of the proposed coding scheme include the scene analyzer and image interpolator. The scene analyzer at the encoder extracts scene-modeling parameters from input sequences. The image interpolator at the decoder reconstructs the video frames by using the transmitted modeling parameters.
The scene analyzer consists of the camera motion detector and image-matching module. We propose a new camera motion detection method that directly analyzes the 2-D distribution of inter-frame motion fields. Experimental results show that the proposed method provides higher detection accuracy and faster computation time than the 1-D angle histogram-based method. A robust image-matching method that is invariant to scale changes, rotations, and illumination changes has been presented. Invariance to these changes is achieved by adopting mutual information as a measure of similarity and adaptively changing the size and orientation of the local matching windows. To reduce ambiguities of the local matching, a global matching technique has been combined with the local matching.
To evaluate the performance of the proposed coding scheme, we have integrated the camera motion detector, the image-matching module, and the image interpolator with the standard MPEG-4 video codec. We compare our method with the standard MPEG-4 codec in terms of bit rates, computation time, and subjective and objective qualities.
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Keywords
Video coding, Motion analysis, Metadata, Image matching