Lip Tracking for MPEG-4 Facial Animation
ICMI '02 Proceedings of the 4th IEEE International Conference on Multimodal Interfaces
Audio-visual speech recognition using MPEG-4 compliant visual features
EURASIP Journal on Applied Signal Processing
Facial Expression Synthesis Using PAD Emotional Parameters for a Chinese Expressive Avatar
ACII '07 Proceedings of the 2nd international conference on Affective Computing and Intelligent Interaction
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An efficient algorithm is proposed to exploit the facial animation parameter (FAP) interpolation modality specified by the MPEG-4 standard in order to allow very low bit-rate transmission of the animation parameters. The proposed algorithm is based on a comprehensive analysis of the cross-correlation properties that characterize FAPs, which is here reported and discussed extensively. Based on this analysis, a subset of ten almost independent FAPs has been selected from the full set of 66 low-level FAPs to be transmitted and used at the decoder to interpolate the remaining ones. The performance achievable through the proposed algorithm have been evaluated objectively by means of conventional PSNR measures and compared to an alternative solution based on the increase of the quantization scale factor used for FAP encoding. The subjective evaluation and comparison of the results has also been made possible by uploading mpg movies on a freely accessible Web site. Experimental results demonstrate that the proposed FAP interpolation algorithm allows efficient parameter encoding at around 70 bits/frame or, in other words, at less than 2 kbits/s for smooth synthetic video at 25 frames/s