Model-based bit allocation between wavelet subbands and motion information in MCWT video coders

A precise motion estimation is necessary, in motion-compensated wavelet based video coders (MCWT), in order to minimize the wavelet coefficients energy. Nevertheless, a motion vectors field of high precision is expensive in binary resources compared to wavelet subbands and it is thus necessary to optimize the rate-distortion trade-off between motion information and wavelet coefficients. To this end, we have proposed in previous works to quantize the motion vectors using a scalable and open-loop lossy coder [1] and, to evaluate the impact of this lossy motion coding on the decoded sequence, we have established a theoretical distortion model of the motion coding error [2]. We present in this paper an approach to realize an optimal model-based bit-rate allocation between motion and wavelet subbands. This method is based on the total distortion model of coding error on several decomposition levels, including both motion information and subbands quantization noise. Experimental validations are satisfactory.