UBC Theses and Dissertations
Complexity reduction schemes for video compression Tohidypour, Hamid Reza
With consumers having access to a plethora of video enabled devices, efficient transmission of video content with different quality levels and specifications has become essential. The primary way of achieving this task is using the simulcast approach, where different versions of the same video sequence are encoded and transmitted separately. This approach, however, requires significantly large amounts of bandwidth. Another solution is to use scalable Video Coding (SVC), where a single bitstream consists of a base layer (BL) and one or more enhancement layers (ELs). At the decoder side, based on bandwidth or type of application, the appropriate part of an SVC bit stream is used/decoded. While SVC enables delivery of different versions of the same video content within one bit stream at a reduced bitrate compared to simulcast approach, it significantly increases coding complexity. However, the redundancies introduced between the different versions of the same stream allow for complexity reduction, which in turn will result in simpler hardware and software implementation and facilitate the wide adoption of SVC. This thesis addresses complexity reduction for spatial scalability, SNR/Quality/Fidelity scalability, and multiview scalability for the High Efficiency Video Coding (HEVC) standard. First, we propose a fast method for motion estimation of spatial scalability, followed by a probabilistic method for predicting block partitioning for the same scalability. Next, we propose a content adaptive complexity reduction method, a mode prediction approach based on statistical studies, and a Bayesian based mode prediction method all for the quality scalability. An online-learning based mode prediction method is also proposed for quality scalability. For the same bitrate and quality, our methods outperform the original SVC approach by 39% for spatial scalability and by 45% for quality scalability. Finally, we propose a content adaptive complexity reduction scheme and a Bayesian based mode prediction scheme. Then, an online-learning based complexity reduction scheme is proposed for 3D scalability, which incorporates the two other schemes. Results show that our methods reduce the complexity by approximately 23% compared to the original 3D approach for the same quality/bitrate. In summary, our methods can significantly reduce the complexity of SVC, enabling its market adoption.
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