Content-Aware Video Adaptation under Low-Bitrate Constraint
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Research Article Content-Aware Video Adaptation under Low-Bitrate Constraint Ming-Ho Hsiao, Yi-Wen Chen, Hua-Tsung Chen, Kuan-Hung Chou, and Suh-Yin Lee College of Computer Science, National Chiao Tung University, 1001 Ta-Hsueh Road, Hsinchu 300, Taiwan Received 1 September 2006; Revised 25 February 2007; Accepted 14 May 2007 Recommended by Yap-Peng Tan With the development of wireless network and the improvement of mobile device capability, video streaming is more and more widespread in such an environment. Under the condition of limited resource and inherent constraints, appropriate video adaptations have become one of the most important and challenging issues in wireless multimedia applications. In this paper, we propose a novel content-aware video adaptation in order to effectively utilize resource and improve visual perceptual quality. First, the attention model is derived from analyzing the characteristics of brightness, location, motion vector, and energy features in compressed domain to reduce computation complexity. Then, through the integration of attention model, capability of client device and correlational statistic model, attractive regions of video scenes are derived. The information object- (IOB-) weighted rate distortion model is used for adjusting the bit allocation. Finally, the video adaptation scheme dynamically adjusts video bitstream in frame level and object level. Experimental results validate that the proposed scheme achieves better visual quality effectively and efficiently. Copyright © 2007 Ming-Ho Hsiao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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INTRODUCTION
With the development of wireless network and the improvement of mobile device capability, for mobile users, the desire to access videos is becoming stronger. More and more client users in a heterogeneous environment are desirous of universal access, that is, one can access any information over any network through a great diversity of client devices. Today, mobile devices including cellphone (smart phone), PDA, and laptop have enough computing capability to receive and display videos via wireless channels. However, due to some inherent constraints in wireless multimedia applications, such as the limitation of wireless bandwidth and high variation in device resource, how to appropriately utilize resource for universal access and to achieve high visual quality becomes an important issue. Video adaptation is usually employed in response to the huge variation of resource constraints. In traditional video adaptation, the adapter considers the available bitrate and network buffer occupancy to adjust the data transmission while streaming video [1, 2]. Vetro et al. provided an overview of the video transcoding and introduced some transcoding schemes, such as bitrate reduction, spatial and
temporal resolution reduction, and error resilient transcoding [3]. Chang an
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