Visual Media Coding and Transmission

4.5 Nonlinear Quantization Technique for Distributed Video Coding

(Portions reprinted, with permission, from M.B. Badem, W.A.R.J. Weerakkody, W.A.C. Fernando, A.M. Kondoz, “Design of a non-linear quantizer for transform domain DVC”, IEICE.)

So far, in all DVC codecs a linear quantizer has been used. The linear quantizer has some limitations in fully exploiting the correlations of the Wyner–Ziv frames. In this section, a nonlinear quantization algorithm is proposed for DVC in order to improve the RD performance. The proposed solution is expected to exploit the dominant contribution to the picture quality from the relatively small coefficients when the high concentration of the coefficients nears zero, as evident when the residual input video signal for the Wyner–Ziv frames is considered in the transform domain. The performance of the proposed solution incorporating the nonlinear quantizer is compared with the performance of an existing transform domain DVC solution that uses a linear quantizer. The simulation results show a consistently improved RD performance at all bit rates when different test video sequences with varying motion levels are considered.

The objective of this work is to propose a novel nonlinear quantization algorithm for DVC, in contrast to the linear quantizer that has traditionally been used in the common transform domain DVC implementations. It is noted that when the residual image is considered, by taking the incremental frame difference compared to the preceding ...