UBC Theses and Dissertations

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UBC Theses and Dissertations

Compression efficiency improvement for 2D and 3D video Valizadeh, Sima


Advances in video compression technologies have resulted in high visual quality at constrained amounts of bitrate. This is crucial in video transmission and storage, considering the limited bandwidth of communication channels and storage media with limited capacities. In this thesis, we propose new methods for improving the compression efficiency of HEVC and its 3D extension for stereo and multiview video content. To achieve high video quality while keeping the bitrate within certain constraints, the characteristics of the human visual system (HVS) play an important role. The utilization of video quality metrics that are based on the human visual system and their integration within the video encoder can improve compression efficiency. We, therefore, propose to measure the distortion using a perceptual video quality metric (instead of sum of squared errors) inside the coding unit structure and for mode selection in the rate distortion optimization process of HEVC. Experiments show that our method improves HEVC compression efficiency by 10.21%. Next, we adjust the trade-off between the perceptual distortion and the bitrate based on the characteristics of the video content. The value of the Lagrange multiplier is estimated from the first frame for every scene in the video. Experimental results show that the proposed approach further improves the compression efficiency of HEVC (up to 2.62% with an average of 0.60%). Furthermore, we extend our work to address the HEVC extension for 3D video. First, we integrate the perceptual video quality in the rate distortion optimization process of stereo video coding where the dependencies between the two views are exploited to improve coding efficiency. Next, we extend our approach to multiview video coding for auto-stereoscopic displays (where 3D content can be viewed without using 3D glasses). In this case, two or three views and their corresponding depth maps need to be coded. Our proposed perceptual 3D video coding increases the compression efficiency of multi-view video coding by 2.78%. Finally, we show that compression efficiency of stereoscopic videos improves if we take advantage of asymmetric video coding. The proposed approach reduces the amount of bitrate required for transmitting stereoscopic video while maintaining the stereoscopic quality.

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