Finding Acceptable Trade-off between Rate and Distortion in Multiple Description Coding based on Zero Padding

In the studies related to Multiple Description Coding (MDC), applying zero padding not only improves the spatial correlation between the descriptions but also increases the size. However, as we pad more zeros, the spatial correlation does not improves linearly. Therefore, the distortion is not reduced as the same amount as the size increases. In this paper we focus on how to efficiently find an acceptable trade-off between the number of padded zeros and the increase of distortion. Based on a MDC method named "Multiple Description Coding with Zero Padding based on spatial Quincunx distribution (QZP-MDC)", in this paper we propose a distortion estimation, which is "Standard Deviation for Distortion Estimation (STD-DE)" to efficiently calculate the distortion with specific padding direction and the number of padded zeros. To search for the acceptable the number of padded zeros, we design two search methods, Naive Search and Best Division Search, based on the proposed rate-distortion trade-off indicator. Our experiment results show that errors of distortion estimation by STD-DE are all less than 2%, and the executing times by best division search is about twice faster more than those of naive search for 11 test sequences. To summarize our work, we confirm that the best division search on STD-DE can find the acceptable trade-off between rate and distortion in low computational complexity.