Scalable Video Coding with Interlayer Signal Decorrelation Techniques
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Research Article Scalable Video Coding with Interlayer Signal Decorrelation Techniques Wenxian Yang, Gagan Rath, and Christine Guillemot Institut de Recherche en Informatique et Syst`emes Al´eatoires, Institut National de Recherche en Informatique et en Automatique, 35042 Rennes Cedex, France Received 12 September 2006; Accepted 20 February 2007 Recommended by Chia-Wen Lin Scalability is one of the essential requirements in the compression of visual data for present-day multimedia communications and storage. The basic building block for providing the spatial scalability in the scalable video coding (SVC) standard is the well-known Laplacian pyramid (LP). An LP achieves the multiscale representation of the video as a base-layer signal at lower resolution together with several enhancement-layer signals at successive higher resolutions. In this paper, we propose to improve the coding performance of the enhancement layers through efficient interlayer decorrelation techniques. We first show that, with nonbiorthogonal upsampling and downsampling filters, the base layer and the enhancement layers are correlated. We investigate two structures to reduce this correlation. The first structure updates the base-layer signal by subtracting from it the low-frequency component of the enhancement layer signal. The second structure modifies the prediction in order that the low-frequency component in the new enhancement layer is diminished. The second structure is integrated in the JSVM 4.0 codec with suitable modifications in the prediction modes. Experimental results with some standard test sequences demonstrate coding gains up to 1 dB for I pictures and up to 0.7 dB for both I and P pictures. Copyright © 2007 Wenxian Yang 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
Scalable video coding (SVC) is currently being developed as an extension of the ITU-T Recommendation H.264 |ISO/IEC International Standard ISO/IEC 14496-10 advanced video [1]. It allows to adapt the bit rate of the transmitted stream to the network bandwidth, and/or the resolution of the transmitted stream to the resolution or rendering capability of the receiving device. In the current SVC reference software JSVM, spatial scalability is achieved using layers with different spatial resolutions. The higher-resolution signals, commonly known as enhancement layers, are represented as difference signals where the differencing is performed between the original high-resolution signals and predictions on a macroblock level. These predictions can be spatial (intraframe), temporal, or interlayer. The lower-base layer signal along with the associated interlayer-predicted enhancement layer signal constitutes the well-known Laplacian pyramid (LP) representation [2]. The Laplacian pyramid represents an image as an hierarchy of differential images of increasing resolution such that each level cor
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