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model-aided coding: A new approach to incorporate facial animation into motion-compensated video coding

IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS FOR VIDEO TECHNOLOGY 2000年第3期10卷 344-358页

作者： Eisert, P Wiegand, T Girod, B Univ Erlangen Nurnberg Telecommun Lab D-91058 Erlangen Germany

We show that traditional waveform coding and 3-D model-based coding are not competing alternatives, but should be combined to support and complement each other. Both approaches are combined such that the generality of waveform coding and the efficiency of 3-D model-based coding are available where needed. The combination is achieved by providing the block-based video coder with a second reference frame for prediction, which is synthesized by the model-based coder. The model-based coder uses a parameterized 3-D head model, specifying shape and color of a person. We therefore restrict our investigations to typical videotelephony scenarios that show head-and-shoulder scenes. Motion and deformation of the 3-D head model constitute facial expressions which are represented by facial animation parameters (FAP's) based on the MPEG-4 standard. An intensity gradient based approach that exploits the 3-D model information is used to estimate the FAP's, as well as illumination parameters, that describe changes of the brightness in the scene. model failures and objects that are not known at the decoder are handled by standard block-based motion-compensated prediction, which is not restricted to a special scene content, but results in lower coding efficiency. A Lagrangian approach is employed to determine the most efficient prediction for each block from either the synthesized model frame or the previous decoded frame. Experiments on five video sequences show that bit-rate savings of about 35% are achieved at equal average peak signal-to-noise ratio (PSNR) when comparing the model-aided codec to TMN-10, the state-of-the-art test model of the H.263 standard. This corresponds to a gain of 2-3 dB in PSNR when encoding at the same average bit rate.

关键词： facial animation model-aided coding model-based coding multiframe prediction

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A novel rate-control model-aided hybrid coding 6

A novel rate-control model-aided hybrid coding

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6th International Conference on Signal Processing

作者： Yang, XH Li, ZK Wu, LN SE Univ Dept Radio Engn Nanjing 210096 Peoples R China

ISBN: (纸本)0780374886

A novel rate-controllable model-aided hybrid codec is proposed in this paper, which is more adaptive with the controllable frame-rate. We also proposed a new self-adaptable merging algorithm to improve the subjective quality of the synthetic B-frame(bi-direction prediction frame) image. The use of P.-frame(prediction frame) and B-frame enhances the video compression, ratio, and affine-transform makes the synthesis algorithm fast and easy. The high efficiency, of this codec was demostrat in two experiments.

关键词： motion estimation parameters image synthesis model-aided coding

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MPEG-4 facial animation in video analysis and synthesis

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INTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY 2003年第5期13卷 245-256页

作者： Eisert, P Heinrich Hertz Inst Nachrichtentech Berlin GmbH Fraunhofer Inst Telecommun Image Proc Dept D-10587 Berlin Germany

MPEG-4 supports the definition, encoding, transmission, and animation of 3-D head and body models. These features can be used for a variety of different applications ranging from low bit-rate video coding to character and avatar animation. In this article, an entire system for the analysis of facial expressions from image sequences and their synthesis is presented. New methods for the estimation of MPEG-4 facial animation parameters as well as scene illumination are proposed. Experiments for different applications demonstrate the potential of using facial animation techniques in video analysis and synthesis. A model-based codec is presented that is able to encode head-and-shoulder video sequences at bit-rates of about 1 kbit/s. Besides the low bit-rate, many enhancements and scene modifications can be easily applied, like scene lighting changes or cloning of expressions for character animation. But also for the encoding of arbitrary sequences, 3-D knowledge can help to increase the coding efficiency. With our model-aided codec, bit-rate reductions of up to 45% at the same quality can be achieved in comparison to standard hybrid video codecs. (C) 2004 Wiley Periodicals, Inc.

关键词： MPEG-4 facial animation video compression model-based coding model-aided coding

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