3D Scan-Based Wavelet Transform and Quality Control for Video Coding
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3D Scan-Based Wavelet Transform and Quality Control for Video Coding Christophe Parisot Laboratoire I3S, UMR 6070 (CNRS, Universit´e de Nice-Sophia Antipolis) Bˆat. Algorithmes/Euclide 2000, route des Lucioles, BP 121 F-06903 Sophia Antipolis Cedex, France Email: [email protected]
Marc Antonini Laboratoire I3S, UMR 6070 (CNRS, Universit´e de Nice-Sophia Antipolis) Bˆat. Algorithmes/Euclide 2000, route des Lucioles, BP 121 F-06903 Sophia Antipolis Cedex, France Email: [email protected]
Michel Barlaud Laboratoire I3S, UMR 6070 (CNRS, Universit´e de Nice-Sophia Antipolis) Bˆat. Algorithmes/Euclide 2000, route des Lucioles, BP 121 F-06903 Sophia Antipolis Cedex, France Email: [email protected] Received 4 March 2002 and in revised form 17 October 2002 Wavelet coding has been shown to achieve better compression than DCT coding and moreover allows scalability. 2D DWT can be easily extended to 3D and thus applied to video coding. However, 3D subband coding of video suffers from two drawbacks. The first is the amount of memory required for coding large 3D blocks; the second is the lack of temporal quality due to the sequence temporal splitting. In fact, 3D block-based video coders produce jerks. They appear at blocks temporal borders during video playback. In this paper, we propose a new temporal scan-based wavelet transform method for video coding combining the advantages of wavelet coding (performance, scalability) with acceptable reduced memory requirements, no additional CPU complexity, and avoiding jerks. We also propose an efficient quality allocation procedure to ensure a constant quality over time. Keywords and phrases: scan-based DWT, 3D subband coding, quality control, video coding.
1.
INTRODUCTION
Although 3D subband coding of video [1, 2, 3, 4, 5] provides encouraging results compared to MPEG [6, 7, 8, 9], its generalization suffers from significant memory requirements. One way to reduce memory requirements is to apply the temporal discrete wavelet transform (DWT) on 3D blocks coming from a temporal splitting of the sequence. But this blockbased DWT method introduces temporal blocking artifacts which result in undesirable jerks during video playback. In this paper, we propose new tools for 3D subband codecs to guarantee the output frames a constant quality over time. Scan-based 2D wavelet transforms were first suggested for on-board satellite compression in [10, 11] and by Chrysafis and Ortega in [12]. In Section 2, we propose a 3D scan-based DWT method and a 3D scan-based motion-compensated lifting DWT for video coding. The method allows the computation of the temporal wavelet decomposition of a sequence with infinite length using little memory and no extra CPU. Furthermore,
the proposed wavelet transform provides higher quality control than 3D block-based video compression schemes (avoiding jerks). In Section 3, we propose an efficient model-based quality control procedure. This bit-allocation procedure controls the output frames quality over time. This new quality-control procedure takes advantage of the mo
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