Multiple Adaptations and Content-Adaptive FEC Using Parameterized RD Model for Embedded Wavelet Video
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Research Article Multiple Adaptations and Content-Adaptive FEC Using Parameterized RD Model for Embedded Wavelet Video Ya-Huei Yu, Chien-Peng Ho, and Chun-Jen Tsai Department of Computer Science and Information Engineering, National Chiao Tung University, Hsinchu 30010, Taiwan Received 12 September 2006; Revised 16 February 2007; Accepted 16 April 2007 Recommended by Anthony Vetro Scalable video coding (SVC) has been an active research topic for the past decade. In the past, most SVC technologies were based on a coarse-granularity scalable model which puts many scalability constraints on the encoded bitstreams. As a result, the application scenario of adapting a preencoded bitstream multiple times along the distribution chain has not been seriously investigated before. In this paper, a model-based multiple-adaptation framework based on a wavelet video codec, MC-EZBC, is proposed. The proposed technology allows multiple adaptations on both the video data and the content-adaptive FEC protection codes. For multiple adaptations of video data, rate-distortion information must be embedded within the video bitstream in order to allow rate-distortion optimized operations for each adaptation. Experimental results show that the proposed method reduces the amount of side information by more than 50% on average when compared to the existing technique. It also reduces the number of iterations required to perform the tier-2 entropy coding by more than 64% on average. In addition, due to the nondiscrete nature of the rate-distortion model, the proposed framework also enables multiple adaptations of content-adaptive FEC protection scheme for more flexible error-resilient transmission of bitstreams. Copyright © 2007 Ya-Huei Yu 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
Multimedia distribution over heterogeneous networks and devices has become the mainstream enabling technology for new generations of services. For distribution and playback of a video content on various devices under different network conditions, scalable video coding schemes are usually used. A typical approach for scalable coding is to use a layered coding approach such as that of MPEG-4 simple scalable profile [1] or FGS [2]. In these approaches, the video bitstream quality is optimized for certain bitrate conditions. Adaptation of such content to a new target bitrate after the encoding process usually results in suboptimal bitstreams. A different approach from the layered coding schemes is to design a scalable codec that produces embedded scalable bitstreams without inherent layered structures. The wavelets-based video codecs belong to this category [3–5]. Because there is no inherent layer structure for wavelet video bitstreams, video parameters such as resolution, frame rate, and bitrate can be dynamically adapted with fine granularity after the encoding procedure. If
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